Climate review and Experimental Long Range Forecast for SW England. April 2024.

Published 23 April 2024

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A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies across the North Atlantic remain warmer than climatology for the middle of April. Areas around the south of the UK, Europe, Mediterranean show 1 or 2 Celsius positive anomalies. Pacific ocean anomalies along the equator show a weakening El Nino state and the tropical Atlantic looks to have similar anomalies to those in March.

The Tropical Atlantic sea temperature anomalies are warmer than average and are forecast to maintain positive anomalies through Summer and into Autumn 2024. (see Met Office graphic below).

Tropical Pacific Sea Surface Temperatures (Nino3.4) show a quickly weakening El Nino state and forecast to become neutral during by the start of May becoming La Nina during the Summer. Indication are for the formation of a strong La Nina in the second half of 2024.

The North Atlantic Oscillation index (500hPa index shown below)is in a neutral state. A positive NAO reflects a more mobile westerly type but neutral conditions are inconclusive.

2. Tropical storms etc: (Data from Wikipedia)

Southern Indian Ocean 2023-2024. Tropical cyclones 4, intense cyclones 2. Fatalities 46.

South Pacific Ocean 2023-2024. Tropical cyclones 4, severe cyclones 2. Fatalities 2

Australia region 2023-2024. Tropical cyclones 8, severe cyclones 6. Fatalities 1. Damage 675million USD.

Named storms UK and Eire:

Storm Kathleen, named by the Irish Met Service 4 to 7th April. Details on the WIKI page: https://en.wikipedia.org/wiki/2023%E2%80%9324_European_windstorm_season

Preliminary reports suggest the strongest wind from Kathleen are in Northern Ireland was recorded at 69mph (111 km/h) at Orlock Head in County Down. However, in Scotland, an unofficial windspeed of 101mph (162km/h) was recorded at Cairn Gorm. This is awaiting verification from the Met Office.

See also Storm Nelson was named on 26 March 2024 by Spain‘s AEMET, Storm Pierrick named by Meteo France on 8 April 2024 and Storm Renata named by Meteo France on 14 April 2024. All had some impact on parts of the UK.

3. Recent Climatology

SW England: The mean temperature has been about one degree above the thirty year average up to 22nd April. Rainfall has almost reached the April average in many places and possible exceeded this over the hills.

Reservoir levels, according to SW Water, are above the long term average across SW England as of 14th April 2024.

Met Office provisional Temperature and Rainfall anomalies for January, February and March 2024 are shown below. You can see the effect of an increase in average temperatures in the 1991 to 2020 period (right hand mini pictures) when comparing the images for the earlier 30 year averaging period. Temperatures in most areas were above average for the three month period thanks to a much milder December when compared to the recent 30 year average. Rainfall was notably above average in the S and central England UK whereas W Scotland and parts of N Ireland had near or below average precipitation.

March 2024 – 10th consecutive record warm month globally

According to climate.copernicus.eu March 2024 is the tenth month in a row to be the hottest for the respective month in the ERA5 data record, going back to 1940.

Europe Climate:

Copernicus, European sourced temperature and rainfall anomalies for March 2024 and year to date, compared with the 30 year periods 1991-2020 (top) and 1981-2010 (lower) shown below:

River flows and ground water levels in March 2024 can be found in the Hy d rological Summary

The Global Flood Awareness System – GloFAS – forecast from April 1st 2024 to end of July 2024. The map shows enhanced flood risk across the UK and Eire. Flash flooding, from for example thunderstorms, is not covered by this system.

B: Forecast data:

1. Stratosphere:

The North Polar Stratospheric Vortex completely warmed out early in March and has transitioned to its “summer” state earlier than average. Plot above shows 10hPa temperature anomaly and contour for 23rd April 0600UTC.

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) and NMME anomaly (lower row) for 2024 May June July. Charts suggest that Atlantic mobility is reduced with possible ridging across northern Europe.

3. Lower Troposphere:

A selection of model solutions for May June July 2024 using April data are shown below. The full set can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

May to July 2024

NMME data (above) CAUTION SCALE/COLOURS for rain reversed blue above normal

Data from WMO:

Three month average anomaly followed by May June July 2024. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution.

Data shown is multi model probabilistic mean anomaly.

Individual members of the WMO super ensemble are shown below. (Pune India missing Pretoria looks cold).

Summer model graphics can be seen at https://www.weather-info.co.uk/wxsvc/seaslatest.html

C: Comparing previous output for UK area:

NOTE: 30 year period 1981-2010 no longer available from UKMO web site now using newer 30 year period 1991 to 2020 which has higher temperature averages. 1961-1990 shown for comparison.

Review of details looked for in seasonal forecast for January to March 2024, using December 2023 data.

Observed data

Temperature. Above normal, note January was near normal.

Rainfall. Above normal for most of England and Wales but the N and Scotland normal and probably below in NW Scotland.

Sunshine. Due to sunnier than normal January the three months may work out above average but both February and March had below average sunshine.

Pressure. Below normal overall

Original Summary – 19DEC2023 –

Temperature: For the three month period overall the temperature is expected to be above average. There are a number of models suggesting nearer or normal or even below normal for parts of the UK for February and this may well start later January and not last all of February. Even near normal would be colder than recent winters and models struggle to pick out cold spells.
Precipiation: For the three month period overall rainfall above normal, initially in the west but possible in the East during March. Chance of dier periods across N or NW Scotland later in the period. Chance of drier spells in February more widely. Snow above average for northern mountainsm below average elsewhere except in late January or February when there could be an increased snow risk for many areas compared to average.

Note 1: Large scale blocking with easterly types seem to only be reliably forecastable about two weeks ahead.

Comment: Good indication for above average temperatures but any hints at nearer normal or cooler values were misleading. Signal for wetter than average rainfall was good for the southern half of UK as was the hint at drier for NW Scotland later.

Scoring will attempt to state good, fair, poor or no signal for the 3 month period (not individual months).
Revised order
1. Russia (WMO): Temp fair. PPN good.
2. USA – CFS2 : Temp good. PPN poor.
3. UKMO Contingency: Temp fair. PPN fair.
4. UKMO : Temp good. PPN good.
5. USA – IRI : Temp fair. PPN poor.
6. KMA APCC : missing .
7. JMA : Temp good. PPN good. PMSL fair
8. NMME : Temp good. PPN poor .
9. WMO multi : Temp good. PPN good.
10. BCC : Temp good. PPN fair.
11. NASA : Temp v good. PPN mostly good .
12. CanSips : Temp fair. PPN fair.
13. Copernicus Temp good. PPN fair. PMSL fair
14. CMCC Temp good. PPN poor. PMSL poor
15: DWD Temp good. PPN fair. PMSL fair
16. EC Temp good. PPN poor. PMSL fair
17 JMA Temp good. PPN fair. PMSL poor
18 UKMO Temp good. PPN poor. PMSL poor
19. MF Temp good. PPN good. PMSL good
20 NCEP Temp good. PPN good. PMSL fair
21 ECCC Temp: fair. PPN fair. PMSL fair

WMO low res data:
BoM Temp good. PPN poor.
Can Temp fair. PPN good.
DWD Temp poor. PPN good.
KMA Temp good. PPN good.
MOSC Temp fair. PPN poor.
WASH Temp good. PPN good.
CMA Temp good. PPN fair.
ECMWF Temp good. PPN fair.
UK Temp good. PPN poor.
JMA Temp good. PPN good.
MF Temp good. PPN good.
CMCC Temp good. PPN poor.
CPTEC Temp fair. PPN good.

D: Text Forecast for SW England

Remainder of Spring 2024 (May).

Temperature is likely to be above average by around 1 degree Celsius .

Rainfall for SW England is most likely to be near normal but with a 30% chance of above normal. A drier than average May (suggested by Russia, Indian, NMME and NASA output) is roughly a 20% chance.

May climate: 1981-2010 average mean temperature 11 or 12°C. Average May rainfall roughly 70mm but 150mm over moors and 40mm in drier East of region.

Summer 2024 (June July August) limited data.

Temperature expected to mean about 1 or 2 degrees Celsius above climatology. Rainfall totals likely to be near average, although there are again hints at longer drier spells in July and/or August. Very localised thunderstorms can increase the rain totals so perhaps a below average number of rain days might be a better indication than the rainfall total.

Summer climate: 1981 to 2010 average daily mean temperature 14 or 15°C in many areas to 16 or 17°C in main urban areas also locally east of the moors and more widely in Somerset. Maximum temperatures average 19 to over 21°C in similar areas. July often warmer than August. Average 1981 to 2010 rain 300mm over the moors, typically 200 to 250mm in many coastal and eastern areas. June often drier than July and July drier than August.

Autumn 2024 (September October November) limited data

Milder/warmer than average. The start of Autumn could be wetter than average but the second half drier..

Autumn climate: 1981 to 2010 average mean temperature 11 or 12°C but nearer 10°C in rural areas. Maximum temperatures average 14 to 16°C. November normally colder than October which is colder than September. Average 1981 to 2010 rain 300 to 400mm, 600 to 800mm over the moors but east of the moors and in lowland Somerset more like 200 to 300mm. September often drier than October or November.

Winter (December 2024 January and February 2025) minimal data

Milder than normal winter overall although January and February may be nearer average. Precipitation above average for the season but with a chance of nearer normal values in January and February. Snow probably near average so perhaps some days with snow accumulation at low levels.

Winter Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East. Rainfall; Dec and Jan typically wetter than February. 1981-2010 Autumn average 300-400 mm lowlands but 200-300 mm areas to E of Dartmoor. Snow climatology less than 5 days lying snow over lowland areas, 5 to 10 days over hills around or above 200 metre elevation – one in three years have no lying snow on low ground.

E: Caution.

Experimental Long Range Forecasts do not have a good success rate, especially with regards to precipitation. The models are good at predicting above average values but not for picking out a one off colder month. The data used for the above forecast summary can be seen at here.

The attempt at a Regional Forecast for SW England aims to test whether such a forecast of temperature and rainfall variation from average can be made using numerical model data available on the internet. The forecast should not be used for any other purpose. A brief verification summary for the UK and Eire is routinely published at http://www.weather-info.co.uk/wxsvc/Verification.html or Click here for the Teignmouth and Dawlish summary

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

GLOFAS Acknowledgement: Data were provided by the Global Flood Awareness System – GloFAS (http://www.globalfloods.eu/) of the European Commission Joint Research Centre and the European Centre for Medium-Range Weather Forecasts.
Reference: Alfieri, L., Burek, P., Dutra, E., Krzeminski, B., Muraro, D., Thielen, J., and Pappenberger, F.: GloFAS – global ensemble streamflow forecasting and flood early warning, Hydrol. Earth Syst. Sci., 17, 1161-1175, doi:10.5194/hess-17-1161-2013, 2013.

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. February 2024.

Published 20 February 2024

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies across the North Atlantic remain warmer than climatology for the middle of February. Areas around the UK, Europe, Mediterranean show 1 or 2 Celsius positive anomalies. Pacific ocean anomalies along the equator show an established El Nino state and the Atlantic looks to have similar anomalies to those in December.

The Tropical Atlantic sea temperature anomalies are warmer than average and are forecast to maintain positive anomalies into Summer 2024. (see Met Office graphic below).

Tropical Pacific Sea Surface Temperatures (Nino3.4) are in an El Nino state and forecast to become neutral during Spring. Indication are for the formation of a strong La Nina in the second half of this year.

The North Atlantic Oscillation index (500hPa index shown below) became negative in early January 2024 then turned positive except for a short dip in early February. The forecast trend is towards a neutral state by early March. A positive NAO reflects a more mobile westerly type but neutral conditions are inconclusive.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Tropical storms etc: (Data from Wikipedia)

Southern Indian 2023-2024. Tropical cyclones 3, intense cyclones 2. Fatalities 25.

South Pacific Ocean 2023-2024. Tropical cyclones 4, severe cyclones 2. Fatalities 2.

Australia region 2023-2024. Tropical cyclones 4, severe cyclones 3. Fatalities 1. Damage 675million USD.

UK Named storms:

January 19th, Storm Isha centre moved across the fat N of Scotland but brought gale or severe gale winds to many areas, including SW England where Amber and Yellow warnings were in force. January 22nd storm Jocelyn followed quickly but this depression passed further to the north of Scotland with strong to gale winds for SW England.

Details of the storms can be found on the Met Office Storm web page: https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-storm-centre/index

3. Recent Climatology

SW England: The mean temperatures has been two or three degrees about the February long term average and rainfall has also been well above average. This is illustrated by the temperature anomaly for the period 4th to 10th February and rainfall total for the same period as shown below.

Reservoir levels, according to SW Water, are above the long term average across SW England as of 11th February 2024.

UK October November December 2023, January 2024

Met Office provisional Temperature and Rainfall anomalies for 2023 November and December and January 2024 are shown below. You can see the effect of an increase in average temperatures in the 1991 to 2020 period (right hand mini pictures) when comparing the images for the different 30 year averaging period. Temperatures in most areas were above average for the three month period thanks to a much milder December when compared to the recent 30 year average. Rainfall was notably above average in the S and E of the UK whereas W Scotland had below average precipitation.

River flows and ground water levels in January 2024 can be found in the Hydrological Summary

The Global Flood Awareness System – GloFAS – forecast from February 1st 2024 to end of May 2024. Although the map does not shown any enhanced flood risk across Southern England a look at individual rivers suggest higher than average flows are more likely than below average flow over the months ahead. Flash flooding, from for example thunderstorms, is not covered by this system.

Europe Climate:

Copernicus, European sourced temperature and rainfall anomalies for January 2024 and the 12 months to the end of January compared with the 30 year periods 1991-2020 (left) and 1981-2010 (right) shown below:

B: Forecast data:

1. Stratosphere:

According to the “Tokyo Climate Center”, a second (minor) stratospheric sudden warming (SSW) event started at 30 hPa level in the Northern Hemisphere around 14 February 2024.

The North Polar Stratospheric Vortex weakened or a period due to a significant warming and then redeveloped. The current warming has displaced the vortex and a series of ongoing warming events may lead to the early demise of the winter vortex as shown in the forecast sequence below.

The median date for “summer vortex” when winter stratospheric polar vortex breaks down and switches semi-permanently from westerly to easterly winds is April 12th. The latest final warming (FW) on record occurred 11 May 1981.

Current guidance indicates that a FINAL WARMING might occur around 7th March, which is about 4 weeks earlier than average. The earliest date on record occurred in 2016 on March 5th which was also a strong El Niño winter. The demise of the westerly stratospheric flow over the Atlantic/Europe could mean that a cold spell may develop in March due to reduced Atlantic mobility OR it could mean an early Spring is possible – something that has already started in SW England.

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) and NMME anomaly (lower row) for 2024 March April May. Charts may suggest reduced Atlantic mobility.

3. Lower Troposphere:

A selection of model solutions for February March April 2024 using January data are shown below. The full set can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

March to May 2024

Data from WMO:

Three month average anomaly followed by March April May 2024. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution.

Data shown is multi model anomaly probability charts except for Pune, India Met Department which shows deterministic mean anomaly.

Individual members of the WMO super ensemble are shown below. (Beijing missing).

C: Comparing previous output for UK area:

NOTE: 30 year period 1981-2010 no longer available from UKMO web site now using newer 30 year period 1991 to 2020 which has higher temperature averages. 1961-1990 shown for comparison.

Review of details looked for in seasonal forecast for November 2023 to January 2024r, using October 2023 data.

Observed data

Temperature. Overall above average for the three month period mostly due to December. November and January near the 1991-2020 average but each month above the 1961-1990 average.

Rainfall. NW/W Scotland below average for the three month period elsewhere above averahelargely due to wet December.

Sunshine. Wales below average elsewhere mostly above average

Pressure. Below average despite January being slightly above average

Original Summary -171023.

Temperature for the three month period all models suggest the mean is likely to be above average although a few models suggest reduced anomalies and hint at near normal in the south of UK in December and / or January. Rainfall, main theme is for above normal rainfall, especially in western and southwesterly parts. The N or NW of the UK may have normal or below normal winter rainfall. Some indication of longer drier spells but detail inconsistent. Snowfall probably below normal in south but normal in the north. Dominant theme is for unsettled westlery types and below average pressure but does not preclude a colder anticyclonic period some time in December and or January.

Note 1: Large scale blocking with easterly types seem to only be forecastable about two weeks ahead.

Comment: 030324, overall indication of above average temperature anbd rainfall was good and hint a drier colder spell for December and or January turned out ok for January but not December which had the higher positive anomalies. Good signal for below averaghe rain in NW of UK but less good for W of UK alough SW and S England was above average except in January.

Scoring will attempt to state good, fair, poor or no signal for the 3 month period average not individual months.
Revised order
1. Russia (WMO): Temp Missing .
2. USA – CFS2 : Temp good . PPN fair .
3. UKMO Contingency: Temp fair . PPN good .
4. UKMO : Temp good . PPN good . PMSL good
5. USA – IRI : Temp good . PPN good .
6. KMA APCC : Temp missing
7. JMA : Temp good. PPN good . PMSL good
8. NMME : Temp good . PPN good.
9. WMO multi : Temp good . PPN good .
10. BCC : Temp good . PPN good .
11. NASA : Temp good . PPN poor .
12. CanSips : Temp good . PPN good.
13. Copernicus Temp good . PPN good . PMSL good
14. CMCC Temp good . PPN good . PMSL fair
15: DWD Temp good . PPN good . PMSL fair
16. ECMWF Temp good . PPN good . PMSL fair
17 JMA Temp good . PPN good . PMSL good
18 UKMO Temp good . PPN good . PMSL fair
19. MF Temp good . PPN fair . PMSL poor
20 NCEP Temp good. PPN good . PMSL fair
21 ECCC Temp: good . PPN good . PMSL good

WMO low res data: 3 month period. Temperature UKMO hinted at higher anomalies in December but overall models were a little warm. Rainfall CMCC CPTEC and BoM had the wetter anomalies in December and lower ones otherwise.
BoM Temp good. PPN good .
Can Temp good. PPN good .
DWD Temp good. PPN good .
KMA Temp good. PPN good .
MOSC Temp good. PPN good/fair .
WASH Temp good. PPN good .
CMA Temp good. PPN good .
ECMWF Temp good. PPN good .
UK Temp good. PPN good .
JMA Temp good. PPN good
MF Temp good. PPN good .
CMCC Temp good. PPN good .
CPTEC Temp good. PPN fair.

D: Text Forecast for SW England

Spring 2024 (March April May).

Temperature for the season likely to be above average although there is a chance that March, after a mild start, could turn colder and be nearer normal or even a little colder than average. This colder theme might also extend into early April but cold spells are unlikely to be prolonged.

Rainfall for SW England is likely to be above average for the the Spring period although this may be largely due to a wet May. March could well see near average rainfall totals and above average incidence of snow (and frost) for short period during the month, probably after mid March. Rainfall in April probably near average across with May wetter than average.

Spring climate: 1981-2010 average mean temperature 9 or 10°C but a few degrees cooler over the moors. Roughly Mar 7 or 8°C Apr 8 or 9°C May 11 or 12°C. Average 1981 to 2010 rain 200 to 300mm lowest values in E Devon and over parts of Somerset.

Summer 2024 (June July August) limited data.

Temperature expected to mean about 1 or 2 degrees Celsius above climatology. Rainfall totals likely to be near average, perhaps drier early and wetter later in the summer. Very localised thunderstorms can increase the rain totals so perhaps a below average number of rain days might be a better indication.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. December 2023.

Published 19 December 2023

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies across the North Atlantic remain warmer than climatology for the middle of December. Areas around the UK, Europe, Mediterranean and the Baltic show 1 or 2 Celsius positive anomalies. Ocean anomalies along the equator show an established El Nino state in the Pacific and warmer than average values across the Atlantic.

The Tropical Atlantic sea temperature anomalies are warmer than average and are forecast to maintain positive anomalies through Spring 2024. (see Met Office graphic below).

Tropical Pacific Sea Surface Temperatures (Nino3.4) are in an El Nino state and forecast to remain so until late Spring 2024. This may help push average global temperature to new records for both 2023 and 2024.

The North Atlantic Oscillation index (500hPa index shown below) became positive on the 7th of December but is forecast to become neutral and perhaps negative in early January 2024. If westerlies are suppressed, as in the case of a negative NAO, the temperature across Europe can be more extreme suggesting colder temperature in mid-winter across Europe. Blocked patterns are typical but depending where the high pressure block forms a location can be in the “high” or in the associated slow moving “low” pressure zone. Neutral states are inconclusive.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

Arctic November sea ice extent remained below the average and well below the 1981-2010 average as shown in the lower of the two images below.

2. Tropical storms etc:

Final data for the Atlantic Hurricane season of 2023. There have been twenty tropical storm strength systems and seven hurricanes three of which were CAT 3 or stronger. Fatalities to date at least 16* (*updated since November) with total damage estimate more than 4.19* billion USD. (Wikipedia). Atlantic tracks and timeline shown below.

Updated figures for the East Pacific has had 10 hurricanes and over 64* known fatalities with estimated damage of 16.8* Billion USD. The West Pacific has had 10 typhoons (4 super typhoons) 191* known fatalities and damage estimated at 18.5* Billion USD.

Northern Indian Ocean to date 6* cyclonic storms, 5* severe storms and 4 extremely severe storms equalling the record set in 1999 and 2019. There were 523* attributed fatalities and damage estimated at 2.47* billion USD. The increase here probably due to Severe Cyclonic Storm Michaung which approached the east coast of India on 4th December. India’s meteorological department issued a red alert for the region. Heavy rain and strong winds battered the coastal areas. Persistent rains caused widespread flooding and inundation in Chennai, the capital of Tamil Nadu. Rivers including Cooum and major lakes overflowed in Chennai causing further water logging in the low-lying areas along the banks. At least 17 people were killed, and more than 41,000 people were evacuated and temporarily relocated, including 32,158 in Tamil Nadu and 9,500 in Andhra Pradesh. Power supply was cut off by the government in flooded areas in Chennai as a preventive measure to avert electrocution.

2023/24 South Pacific cyclone season starts officially 1st November. First storm 19th October 2023. Two severe tropical cyclones to date with 2 fatalities but no damage estimate.

2023/24 Australian cyclone season starts officially 1st November. First storm 4th December – Jasper ongoing event major flooding in NE Australia / Cairns area. Known fatalities 1 no damage estimate yet. Record rainfall reported.

SW England storms and floods:

Wikipedia stated “conditions in early December resulted in 50 flood warnings across the UK. In Dorset, the River Frome flooded in the village of Stratton near Dorchester. The warnings spanned along the Jurassic Coast from Bridport to Chideock and Charmouth and also Dorchester, Maiden Newton and Beaminster. In Somerset, roads were flooded. The A358 road near Ilminster became unpassable in both directions.….”

BBC source: December 4th Somerset 67mm in 24 hours caused flooding of road network as well as some property flooding. 7th December Cornwall and Devon also affected by flooding and road closures and rail lone flooding near Exeter.

Named storms:

Storm Elin and Fergus occurred on the 9th and 10 December 2023 and detail can be found on the UK Storm page click here for pdf from UK Met Office

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

3. Recent Climatology

According to Copernicus Climate Change Service/ECMWF November 2023 was the warmest November on record globally, with an average surface air temperature of 14.22°C, which follows on from a record October.

Copernicus, European sourced temperature and rainfall anomalies for November 2023 and the 12 months to the end of November compared with the 30 year periods 1981-2010 (lower row) and 1991-2020 (upper row), are shown below:

UK: Autumn 2023.

Met Office provisional Temperature and Rainfall anomalies for 2023 September October and November are shown below. You can see the effect of an increase in average temperatures in the 1991 to 2020 period (right hand mini pictures) when comparing the images for example in September where anomalies are shown as a darker red when using the earlier 1961-1990, 30 year period as the base. Temperatures in most areas were above average for the three month period. October was unusually wet in Eastern areas of England and Scotland as well as parts of N Ireland making the season wet overall except for parts of W Scotland.

River flows and ground water levels in November 2023 can be found in the Hydrological Summary

Reservoir levels, according to SW Water, are above the long term average across SW England as of 17th December 2023.

The Global Flood Awareness System – GloFAS – forecast from December 1st 2023 to end of March 2024 shows a slightly enhanced flood risk across Southern England – does not cover flash flooding from for example thunderstorms.

SW England

December through to 18th had an average temperature ranging from around 9 C in the west and 7 C in the East. For many areas that was 1 to 2 Celsius above average. Rainfall was above average with many places already recording totals reaching the average for the whole month. Sunshine was probably near or a bit below average.

Example of changes to 30 year average. Teignmouth December (UKMO data) :

1981-2010: 9.8C 4.4C 3.6 60.4 102.9 12.7

1991-2020: 10.4C 4.6C 3.0 59.2 101.3 13.4

B: Forecast data:

1. Stratosphere:

The North polar vortex has established in the winter mode. GFS 19/06UTC December analysis at 10hPa is shown below along with forecast charts for the 23rd and 26th of December and 4th January 2024. The forecast chart show stratospheric warming moving over Canada and extending across the Atlantic. A few seasonal forecast models are hinting at a temperature change to colder types in late January or in February but this is by no means certain as not all stratospheric warming events lead to colder easterly types at the surface across Europe.

In the southern hemisphere the Ozone column minimum has been at record lows for the time of year as shown by the graphic below:

The stratospheric Southern Hemisphere Ozone “hole” is now filling.

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) and NMME anomaly (lower row) for 2024 January, February and March. Hints at upper level ridging in February.

3. Lower Troposphere:

A selection of model solutions for January February and March 2024 using December data are shown below. The full set, including available graphics for Spring 2024 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

January to March 2024

Data from WMO:

Three month average anomaly followed by January February and March 2024. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution.

Data shown is multi model anomaly probability charts except for CMCC which shows deterministic mean anomaly.

Individual members of the WMO super ensemble are shown below.

Spring 2024 WMO multi model chart can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

C: Comparing previous output for UK area:

NOTE: 30 year period 1981-2010 no longer available from UKMO web site now using newer 30 year period 1991 to 2020 which has higher temperature averages. 1961-1990 shown for comparison.

Review of details looked for in seasonal forecast for Autumn, August 2023 data.

Observed data

Temperature. Above normal although Scotland near normal October and November (below normal compared to most recent 30 year average)

Rainfall. W Scotland normal or below normal elsewhere above normal. Wettest month October especially in E of UK.

Sunshine. Wales below normal elsewhere a little above normal

Pressure. below normal (SW)

Forecast data

Original Summary -180823 –

Temperature: Available models, apart from Russia (which tends to a little colder than other models), suggests above normal for the season and for each month although a few models suggest nearer normal in the south in September and more widely in November.
Rainfall: THREE Month summary: Uncertain mixture of solutions for the season based on some above and some below normal ending up near normal. Month to month data also lacks consistency but the strongest indication for above normal looks to be for western and southern areas of UK and Ireland. Normal or below normal perhaps more likely in the north. Month to month data hint at September having the highest change of being drier than average and October the higher chance of wetter than average. November Eire and western half of UK more likely to be wetter than average.

Comment: Temperature forecast for above normal good, September hint at nearer normal poor but OK for November. Rainfall good steer for the less wet areas and for the wetter months and good for above average overall away from the W Scotland.

Scoring attempts to state good, fair, poor or no signal.
Revised order
1. Russia (WMO): Temp poor. PPN poor.
2. USA – CFS2 : Temp good. PPN poor.
3. UKMO Contingency: Temp good. PPN poor.
4. UKMO : Temp good . PPN fair . PMSL good
5. USA – IRI : Temp good. PPN poor .
6. KMA APCC : Temp good. PPN good .
7. JMA : Temp good . PPN fair . PMSL
8. NMME : Temp good . PPN fair .
9. WMO multi : Temp good . PPN poor .
10. BCC : Temp good . PPN fair .
11. NASA : Temp good . PPN fair
12. CanSips : Temp good. PPN fair .
13. Copernicus Temp good. PPN fair PMSL poor
14. CMCC Temp good. PPN fair PMSL poor
15: DWD Temp good. PPN poor PMSL poor
16. EC Temp good. PPN poor PMSL poor
17 JMA Temp good. PPN poor PMSL poor
18 UKMO Temp good. PPN good. . PMSL good.
19. MF Temp good. PPN poor PMSL poor
20 NCEP Temp good. PPN poor PMSL fair
21 ECCC Temp: good. PPN fair PMSL fair

WMO low res data:
BoM Temp good. PPN fair. (Wetter OCT)
Can Temp good. PPN fair.
DWD Temp good. PPN poor.
KMA Temp good. PPN poor.
MOSC Temp poor. PPN poor.
WASH Temp good. PPN poor.
CMA Temp missing .
ECMWF Temp good. PPN poor.
UK Temp good. PPN good.
JMA Temp good. PPN poor.
MF Temp fair. PPN poor.
CMCC Temp good. PPN fair.
CPTEC Temp good. PPN poor.

D: Text Forecast for SW England

Remainder of Winter (January and February 2024)

January probably above average but bay turn near or below average late in the month and / or in February for a time before milder types return later in February (uncertain cold spell in an otherwise milder than average winter period. Rainfall average or above for the season but with a chance that February could see longer drier spells and Eastern parts of the region may have nearer normal values. Snow probably again below average in January but increasing risk of snow and ice for a time late January and/or in February which could lead to above average snowfall across the district, not just for the moors (uncertain and low confidence) .

January and February Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East similar for both months. Rainfall; January typically wetter than February. 1981-2010 January average 100-150 mm lowlands but over 200-300 mm over the Moors. February average 80-100mm for lowland areas, less in the east and a little more in the west. Moors over 150mm. Winter snow climatology less than 5 days lying snow over lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow for lower ground

Spring 2024 (March April May) limited data.

Temperatures likely to be above average although small risk that March could start colder. Rainfall for SW England above average for the period but perhaps near average later on.

Summer 2024 (June July August) minimal data.

Temperature expected to mean about 1 degree C or so above climatology. Rainfall totals likely to be above average especially in August. Chance of drier July and near average June. Despite above average rain totals the number of “rain days” may not be above average.

E: Caution.

Experimental Long Range Forecasts do not have a good success rate. especially with regards to precipitation. The models are good at predicting above average values but not for picking out a one off colder month. The data used for the above forecast summary can be seen at here.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. September 2023.

Published 19 September 2023

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies in most of the North Atlantic remain warmer than climatology for the middle of August. Areas around the UK, western Europe, western Mediterranean and the Baltic show 1 to 3 Celsius anomalies. Cold paths in the Atlantic due to recent hurricane activity, the larger area due to Hurricane Lee. Colder area in the Med off Libya due to storm Daniel.

Ocean anomalies along the equator show an established El Nino state. The extent of the cold anomaly to the west of North America is similar to values in August.

Atlantic Hurricane season 2023 has seen fifteen tropical storm strength systems and six hurricanes three of which were CAT 3 or stronger. Fatalities to date at least 14 with total damage estimate 2.29 billion USD. (Wikipedia). Atlantic tracks and timeline shown below.

The East Pacific has had seven hurricanes but only thee known fatalities. The West Pacific has had 8 typhoons (3 super typhoons) 167 known fatalities and damage estimated at 15.8 Billion USD.

Indian Ocean to date 3 cyclonic storms, 2 severe to extremely severe storms, with 480 attributed fatalities and damage estimated at 1.6 billion USD.

The recent storm in the Med (Daniel) which affected Greece, parts of Türkiye and later contributed to the disaster in Libya has resulted in 2023 being the costliest European windstorm season on record. Greece, Bulgaria, Turkey, 15 deaths. Libya, at least 11,300 people have died and another 10,100 are missing from the coastal city of Derna. An estimated 170 people have been killed as a result of the flooding elsewhere in the country.

Below: 10/0300UTC sat image, 24 hour rainfall estimate map to 10th 0600UTC and multi model forecast rain accumulation to 11th 1200UTC.

Below: Sat image 11/0300UTC and 24 hour rainfall map to 11th 0600UTC showing estimates of over 200mm accumulation.

The Tropical Atlantic sea temperature anomalies are warmer than average and are forecast to maintain positive anomalies through Winter 23/24. (see Met Office graphic below).

Tropical Pacific Sea Surface Temperatures (Nino3.4) are in an El Nino state and forecast to remain so until Spring 2024. This may result in a higher global average temperature for 2023 and 2024 and there are suggestions that over the next few years the global temperature average will set further new records.

The effects of the El-Nino may be difficult to predict due to the excessive heat in water around coastal western Europe. A statistical link between El-Nino and rainfall suggests near normal rainfall for the winter 2023/2024, the higher probs being in eastern areas.

The North Atlantic Oscillation index (500hPa index shown below) became negative in mid September and is forecast remain neutral or negative for the next few weeks. If westerlies are suppressed, as in the case of a negative NAO the temperature across Europe is more extreme in summer leading to heat waves and colder temperature in winter across Europe.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

Following the global hottest ever June, Nasa announced that July 2023 had the highest global temperature recorded for that month since 1880. It was also the warmest month on record. In the UK however July was wet with nearer normal temperatures. August 2023 ranks as the second warmest month ever recorded in the European C3S ERA5 reanalysis dataset by a large margin, after July 2023.

SW England

Up until mid month September 2023 was sunnier, very much warmer and drier than average. Although there were thunderstorms on the night of the 9/10th the storms of the early hours of the 17th and those later in the day were of a different order. Rainfall became extremely heavy with 35mm to 90mm falling in a short space of time leading to significant flooding in parts of the SW, especially South Devon.

RADAR image 17/0200UTC and 1230UTC

The river gauge in Dawlish shows how quickly river levels rose. It should be noted that this was not a record level. The record level back in 2012 was associated with days of heavy rain rather than short period violent rainfall.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2023 June July August and then combined summer period, are shown below. You can see the effect of an increase in average temperatures in the 1991 to 2020 period when comparing the image for July where anomalies are shown as negative when compared to the newer thirty year period. Temperatures in most areas were above average. Due to the wet July rainfall ended up near or above average in many places but below average for the three months in SE England, parts of Wales and Scotland. Changes in rainfall are less clear cut but suggest slightly higher rainfall in the most recent 30 year average.

Copernicus, European sourced temperature and rainfall anomalies for August 2023 and the 12 months to the end of August compared with the 30 year period 1991-2020, are shown below:

River flows and ground water levels in August 2023 can be found in the Hydrological Summary

River flows across SW England were average or above in August 2023. River flow data for the 18th September from the UK Water Resources Portal shows mostly normal flows but the blue dots east of Exeter are due to the recent heavy rain.

Reservoir levels, according to SW Water are above the long term average across SW England as of 10th September 2023. The long standing hosepipe bans remain in force across Cornwall and much of Devon until the 25th September when all restrictions are due to be lifted according the SW Water.

The Global Flood Awareness System – GloFAS – forecast from September 1st to end of December 2023 shows a “normal” flood risk across SW England – does not cover flash flooding from for example thunderstorms.

B: Forecast data:

1. Stratosphere:

The polar vortex remains in summer mode as shown by the GFS 18/0001UTC analysis at 10hPa

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) and NMME anomaly (lower row) for October November December 2023. Hints at strong jet flow hence more mobility especially in CFSv2 for December

3. Lower Troposphere:

A selection of model solutions for October November December 2023 using September data are shown below. The full set, including available graphics for Winter 2023/24 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

October to December 2023

Data from WMO:

Three month average anomaly followed by October November December 2023. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution. Note rainfall anomalies show cancellation between wetter and drier solutions in some of the multi model ensembles.

Data shown in multi model deterministic anomaly (probability charts not available)

Individual members of the WMO super ensemble are shown below.

WMO super ensemble for Winter 2023/24

C: Comparing previous output:

NOTE: 30 year period 1981-2010 no longer available from UKMO web site now using newer 30 year period 1991 to 2020 which has higher temperature averages. 1961-1990 shown for comparison.
Review of details looked for in seasonal forecast.

Observed data

Temperature.
Summer overall above average thanks mainly to June with July and August mostly near average or slightly above.

Rainfall. Most areas wetter than average summer except for NE Scotland and parts of E of England. Main thing to look for is drier June and wetter July with nearer normal August.

Sunshine. Summer near average, local indications for Teignbridge suggest below average.

Pressure. Below average (WSW)

Forecast data

Original Summary – Summary – 190523
Overwhelming indication for above average temperatures for the season and each month although some models suggest Scotland could be nearer normal and some models hint at nearer normal values in June which looks unlikely. Rainfall very little consistency month to month except for Scotland where normal or below normal rainfall seems most likely. Elsewhere for the season hints at above normal in places but uncertain as to whether this is more wet days or just shorter spells of heavier rain with fewer wet days compared to average. Suggestion of E/SE being more likely to be below normal but unreliable.
Pressure more likely to be above average in the north with risk of below average in the south. 200hPa anomalies suggest drier start to season and possibly wetter end (thundery showers).

Comment: Overall signal for above average summer temperature was good but month to month detail unreliable. Hints at less wet in parts of E/SE England and parts of Scotland were OK as was the overall indication for above average rainfall. Teignbridge indications show there were more dry days than average despite above average rainfall but elsewhere in SW England there looks to have been fewer dry than average.

Scoring will attempt to state good, fair, poor or no signal for the three month period as a whole.
Revised order
1. Russia (WMO): Temp good. PPN poor.
2. USA – CFS2 : Temp good. PPN fair but reasonable sequence.
3. UKMO Contingency: Temp good. PPN fair.
4. UKMO : Temp good. PPN poor. PMSL poor
5. USA – IRI : Temp fair. PPN no signal .
6. KMA APCC : Temp missing
7. JMA : Temp good. PPN fair. PMSL fair
8. NMME : Temp good. PPN fair.
9. WMO multi : Temp good. PPN poor.
10. BCC : Temp good. PPN poor.
11. NASA : Temp good. PPN poor.
12. CanSips : Temp good. PPN poor.
13. Copernicus Temp good. PPN poor. PMSL poor
14. CMCC Temp good. PPN poor. PMSL poor
15: DWD Temp good. PPN poor. PMSL poor
16. EC Temp good. PPN poor. PMSL
17 JMA Temp good. PPN good. PMSL good
18 UKMO Temp good. PPN poor. PMSL poor
19. MF Temp good. PPN poor. PMSL poor
20 NCEP Temp good. PPN poor. PMSL poor
21 ECCC Temp fair. PPN good. PMSL good

WMO low res data:
BoM Temp good. PPN poor.
Can Temp good. PPN poor..
DWD Temp good. PPN poor.
KMA Temp good. PPN poor.
MOSC Temp good. PPN poor.
WASH Temp good. PPN fair.
CMA Temp good. PPN poor.
ECMWF Temp good. PPN poor.
UK Temp Missing.
JMA Temp good. PPN fair.
MF Temp good. PPN poor.
CMCC Temp good. PPN poor.
CPTEC Temp good. PPN poor.

D: Text Forecast for SW England

Remainder of Autumn 2023 (October November)

Temperature: A milder than average period is most likely, consistent across models. Each month likely to be above average with anomalies of around 1 C.

Rainfall: October and November likely to be wetter than average although some models suggest near normal values for October.

Autumn climate: 1981 to 2010 average mean temperature 11 or 12°C but nearer 10°C in rural areas. Maximum temperatures average 14 to 16°C. November normally colder than October. Average 1981 to 2010 rain 300 to 400mm, 600 to 800mm over the moors but east of the moors and in lowland Somerset more like 200 to 300mm.

Winter (December 2023 January and February 2024)

Milder than normal winter overall although February may be nearer average. Rainfall average or above for the season but with a chance that February could see longer drier spells and Eastern parts of the region may have nearer normal values. Snow probably again below average so any accumulations more likely to be across the moors.

Spring 2024 (March April May) limited data.

Temperatures likely to be above average although some hints at a colder May but mainly in the north of UK. Rainfall for SW England above average though perhaps near average in May.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. August 2023.

Published 18 August 2023 delayed due technical issues until 24 August 2023

A: Overview

1. Influences.

Changes in sea temperature

Ocean anomalies along the equator show an established El Nino state. The extent of the cold anomaly to the west of North America has markedly decreased in size.

Atlantic Hurricane season 2023 has seen nine tropical storm strength systems but only one hurricane and only one known fatality. The East Pacific has had six hurricanes and five known fatalities. The west Pacific has had 6 typhoons (2 super typhoons) 163 known fatalities and damage estimated at 15.6 Billion USD.

Time line to late August shown below (Wikipedia).

Potential new developments as stated by NOAA on the 18th August.

The Tropical Atlantic sea temperature anomalies are warmer than average having exceeded the forecast issued in June. Sea temperature in the tropical region are forecast to maintain positive anomalies through Winter 23/24. (see Met Office graphic below).

Tropical Pacific Sea Surface Temperatures (Nino3.4) are in an El Nino state and forecast to remain so into 2024. This may result in a higher global average temperature for 2023 and 2024 and there are suggestions that over the next few years the global temperature average will set further new records.

The effects of the El-Nino may be difficult to predict due to the excessive heat in water around coastal western Europe. A statistical link between El-Nino and rainfall suggests a slightly increased probability for a wetter than average autumn.

The North Atlantic Oscillation index (500hPa index shown below) became negative in early July through to mid August and is forecast to remain neutral or negative for the next few weeks. If westerlies are suppressed, as in the case of a negative NAO the temperature across Europe is more extreme in summer leading to heat waves which in 2023 has led to record high temperatures across many parts of Europe.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

There have been two named storms in August so far.

SW England

August to the 18th has been rather mixed with near average temperature (17 C) slightly above average rainfall and near or a little below average sunshine.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2023 May June July are shown below. You can see the effect of an increase in average temperatures in the 1991 to 2020 period when comparing the image for July where anomalies are shown as negative when compared to the newer thirty year period. Temperatures in most areas were above average. Due to the wet July rainfall ended up near or above average in many places but below average for the three months in SE England, parts of Wales and Scotland. Changes in rainfall are less clear cut but suggest slightly higher rainfall in the most recent 30 year average.

Copernicus, European sourced temperature and rainfall anomalies for July 2023 and the 12 months to the end of July compared with the 30 year period 1991-2020, are shown below:

K River flows and ground water levels in July 2023 can be found in the Hydrological Summary

River flows across SW England were average or above in July 2023. River flow data for the 13th August from the UK Water Resources Portal shows mostly above normal flows.

Reservoir levels, according to SW Water are above the long term average across SW England as of 13th August 2023. Despite this hosepipe bans remain in force across Cornwall and much of Devon.

The Global Flood Awareness System – GloFAS – forecast from August 1st to end of November 2023 shows a “normal” flood risk across SW England – does not cover flash flooding from for example thunderstorms.

B: Forecast data:

1. Stratosphere:

The polar vortex remains in summer mode as shown by the GFS 17/1200UTC analysis at 10hPa

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) and NMME anomaly (lower row) for September October November 2023.

3. Lower Troposphere:

A selection of model solutions for Autumn 2023 using August data are shown below. The full set, including available graphics for Winter 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

September to November 2023

Data from WMO:

Three month average anomaly followed by September October November 2023. Top row temperature anomaly and lower row precipitation anomaly.

Individual members of the WMO super ensemble are shown below (Beijing China missing)

WMO super ensemble for Winter 2023/24

C: Comparing previous output:

May to July 2023 – based on April 2023 data.

NOTE: 30 year period 1981-2010 no longer available from UKMO web site now using newer 30 year period 1991 to 2020 which has higher temperature averages. 1961-1990 shown for comparison.

Review of details looked for in seasonal forecast.

Observed data

Temperature. Despite a cooler/near average July values were above average for season.

Rainfall. Difficult to fully quantify but looks like the wet July more than offset the previous drier months in some places. More clear cut in the 1961-1990 averages. Scotland and Wales below average but England and N Ireland above. Did models suggest wet July?

Sunshine. Above average sunshine for the three months despite cloudier July.

Pressure. Three month average above normal but July was well below normal

Forecast data

Original Summary – 18April2023
Consistent forecast for above normal temperature but hints at nearer normal in May and strong signal for above normal in June and / or July. Rainfall forecast rather messy with wetter models cancelling drier output. Hint at wetter than average or normal but with slightly stronger signal for drier than average in the south in June.
Notes: 1: Large scale blocking with easterly types seem to only be forecastable about two weeks ahead.

Comment on summary: Signal for warmer June good not so clear for July, overall above average good signal. Rainfall overall above average good as was drier June in south.

Scoring will attempt to state good, fair, poor or no signal.
SCORE based on THREE MONTH AVERAGE
1. Russia (WMO): Temp fair . PPN fair .
2. USA – CFS2 : Temp good . PPN fair .
3. UKMO Contingency: Temp fair . PPN fair .
4. UKMO : Temp good . PPN good . PMSL fair
5. USA – IRI : Temp fair . PPN poor .
6. KMA APCC : Temp good . PPN poor .
7. JMA : Temp good . PPN poor . PMSL poor
8. NMME : Temp good . PPN poor .
9. WMO multi : Temp good . PPN fair .
10. BCC : Temp good . PPN poor.
11. NASA : Temp good . PPN fair.
12. CanSips : Temp good . PPN poor.
13. Copernicus Temp good . PPN fair. PMSL fair
14. CMCC Temp good . PPN poor . PMSL good
15: DWD Temp good . PPN poor . PMSL good
16. EC Temp good . PPN poor . PMSL good
17 JMA Temp good . PPN poor . PMSL good
18 UKMO Temp good . PPN good . PMSL fair
19. MF Temp good . PPN poor . PMSL fair
20 NCEP Temp good . PPN poor . PMSL good
21 ECCC Temp: fair . PPN fair. PMSL fair

Only Canada got the monthly sequence best for temperature but perhaps a little cool.
WMO low res data:
BoM Temp GOOD . PPN poor.
Can Temp GOOD . PPN fair.
DWD Temp GOOD . PPN poor.
KMA Temp GOOD . PPN fair.
MOSC Temp poor . PPN fair .
WASH Temp GOOD . PPN fair .
CMA Temp GOOD . PPN good .
ECMWF Temp GOOD . PPN poor .
UK Temp GOOD . PPN good .
JMA Temp GOOD . PPN poor
MF Temp GOOD . PPN fair .
CMCC Temp GOOD . PPN poor .
CPTEC Temp poor . PPN fair.

D: Text Forecast for SW England

Autumn 2023 (September October November)

Temperature: A milder than average Autumn is most likely, consistent across models.

Rainfall: Probably wetter than average for the season. Month to month detail unreliable but hints at a drier start and wetter end to the season can still be found.

Winter (December 2023 January and February 2024)

Milder than normal winter overall although February may be colder than average. Rainfall average or above for the season but with a chance that December and / or February could see longer drier spells which is consistent with July data. Snow probably again below average so any accumulations more likely to be across the moors.

Winter Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East. Rainfall; Dec and Jan typically wetter than February. 1981-2010 Autumn average 300-400 mm lowlands but 200-300 mm areas to E of Dartmoor. Snow climatology less than 5 days lying snow over lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. July 2023.

Published 19 July 2023.

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies in most of the North Atlantic remain warmer than climatology for the middle of July. Areas around the UK, western Europe, western Mediterranean and the Baltic show 1 to 3 Celsius anomalies with the Mediterranean area 3 to 5 Celsius above average.

Ocean anomalies along the equator show an established El Nino state. The extent of the cold anomaly to the west of North America has again increased in size a little.

(Error in June edition spell checker changed to Adriatic should read read Arabian Sea)

Atlantic Hurricane season 2023 has seen some tropical storm strength systems but not a full hurricane. (Wikipedia)

Western Pacific and Indian Ocean tracks are shown below along with the time line.

According to Wikipedia Northern Indian Ocean storms have contributed to 480 fatalities and a cost of 1.5 Billion US dollars. Western Pacific storms have led to 11 fatalities and a cost of $137million although it is too early to assess the effects of the recent storm Talim which produced some damage and flooding in southern China.

The effects of the El-Nino may be difficult to predict due to the excessive heat in water around coastal western Europe.

The North Atlantic Oscillation index (500hPa index shown below) became negative in early July and are forecast to turn to neutral state over the next few weeks. Affects on the UK area are inconclusive for a neutral state.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

See wiki pages with regards to heat waves:

https://en.wikipedia.org/wiki/2023_European_heat_waves

https://en.wikipedia.org/wiki/2023_heat_waves

In addition to a record breaking June there have been a lot of new all time temperatures records broken in July across parts of southern USA and Southern Europe as well as in Asia.

SW England

July to 17th 2023, has been cool than of late although temperatures have still been marginally above average. Rainfall has largely reached or exceeded the full month total and sunshine looks to be slightly below average to mid month.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2023 April May June are shown below. Temperatures in most areas were above average. Rainfall was above average. in most places hence it is shocker that hosepipe bans are require although there has been climate data showing increased run off rather than retention of water in the soils.

Due to the ongoing rise in temperatures over the last 60 years, 30 year averages used for comparisons have increased hence what appears to be average as in April 2023 when using to 1991 to 2020 values would have been above average using the 1961 to 1990 values. Changes in rainfall are less clear cut but suggest slightly higher rainfall in the most recent 30 year average.

Copernicus, European sourced temperature and rainfall anomalies for June 2023 and the 12 months to the end of June compared with the 30 year period 1991-2020, are shown below:

UK River flows and ground water levels in June 2023 can be found in the Hydrological Summary

River flows across SW England were below average in June 2023. River flow data for the 14th July from the UK Water Resources Portal shows mostly above normal flows following the recent wet weather although North Devon and North Cornwall seem to have nearer normal flows

Reservoir levels, according to SW Water are approaching the long term average across SW England as of 16th July 2023. Despite this hosepipe bans remain in force across Cornwall and much of Devon.

The Global Flood Awareness System – GloFAS – forecast from July 1st to end of October 2023 shows a “normal” flood risk across SW England – does not cover flash flooding from for example thunderstorms.

B: Forecast data:

1. Stratosphere:

The polar vortex remains in summer mode as shown by the GFS 19/1200UTC analysis at 10hPa

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (lower row) for August September October 2023.

3. Lower Troposphere:

A selection of model solutions for August to October 2023 using July data are shown below. The full set, including available graphics for Autumn 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

August to October 2023

CFSv2 E3 data (below)

NMME data (below)

ECMWF (below)

NASA (below)

Data from WMO:

Three month average anomaly followed by August September October 2023. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution. Note rainfall anomalies show marked cancellation between wetter and drier solutions in some of the multi model ensembles. Due to problems with the host web site WMO means are shown rather than the probability charts.

Individual members of the WMO super ensemble are shown below (Beijing China missing)

C: Comparing previous output:

April to June 2023 – based on March 2023 data.

Observed data.

Temperature: above average for season.

Rainfall: mostly below average for season although April was wetter in places and a few places may have been near average overall.

Sunshine: above average all of UK due to sunny June

Pressure: above average for season and each month

Original Summary – 190323 Temperature: for the three month period above average most likely. Most models suggest slighly larger anomalies for the second half of the period with a chance of near normal values early in the forecast period, perhaps more especially in the south. Rainfall: Overall near normal for the period. Some hints at above average early in period and below average later. Lots of uncertainty but slightly more models have drier rather than wetter June. Pressure: near normal with hint at above normal. Caution: 1: Large scale blocking with easterly types seem to only be forecastable about two weeks ahead.

Comment on summary: Good temperature forecast and trend through season, only fair for location of near average early in season.
Rainfall signal for drier June was good as was wetter start to season. Overall forecast of near normal less good. Indication for above average pressure was good.
Scoring will attempt to state good, fair, poor or no signal.
Revised order
1. Russia (WMO): Temp fair . PPN fair .
2. USA – CFS2 : Temp good . PPN fair .
3. UKMO Contingency: Temp good . PPN good .
4. UKMO : Temp good . PPN good . PMSL good
5. USA – IRI : Temp fair . PPN poor .
6. KMA APCC : Temp missing . PPN missing .
7. JMA : Temp good . PPN fair . PMSL good
8. NMME : Temp good . PPN fair .
9. WMO multi : Temp good . PPN poor .
10. BCC : Temp good . PPN poor .
11. NASA : Temp good . PPN poor .
12. CanSips : Temp fair . PPN fair .
13. Copernicus Temp fair . PPN fair . PMSL poor
14. CMCC Temp good . PPN fair . PMSL poor
15: DWD Temp good . PPN fair . PMSL poor
16. EC Temp good . PPN fair . PMSL fair
17 JMA Temp good . PPN fair . PMSL poor
18 UKMO Temp good . PPN fair . PMSL fair
19. MF Temp good . PPN fair . PMSL poor
20 NCEP Temp good . PPN fair . PMSL poor
21 ECCC Temp: good . PPN fair . PMSL poor

ECMWF mnthely graphics good signal for drier June but not widespread enough.

WMO low res data:
BoM Temp fair . PPN fair .
Can Temp fair . PPN poor .
DWD Temp fair . PPN fair .
KMA Temp good . PPN fair .
MOSC Temp poor . PPN poor .
WASH Temp good . PPN fair (good June signal) .
CMA Temp fair . PPN poor .
ECMWF Temp good . PPN fair .
UK Temp good . PPN fair .
JMA Temp good . PPN fair
MF Temp good . PPN fair .
CMCC Temp good . PPN fair .
CPTEC Temp fair . PPN poor.

D: Text Forecast for SW England

Remainder of Summer 2023 (August)

Temperature: Anomalies suggest around 1 deg C above normal, virtually all models above normal.

Rainfall: Highest probs are for near normal rainfall, suggestion of above normal for northern and western pasrts of the region.

August climate: 1981 to 2010 average daily mean temperature 16 or 17°C in main urban areas also locally east of the moors and more widely in Somerset, 13 to 15 Celsius elsewhere. Average 1981 to 2010 rain 40 to 80mm but over the moors, typically 125-150mm.

Autumn 2023 (September October November) limited data.

Temperature: A milder than average Autumn is most likely, consistent across models.

Rainfall: Probably wetter than average for the season. Month to month detail unreliable but hints at a drier start and wetter end to the season..

Winter (December 2023 January and February 2024) limited data

Milder than normal winter overall although December could see near normal temperatures. Rainfall average or above for the season but with a chance that December and / or February could see longer drier spells. Snow probably again below average so any accumulations more likely to be across the moors.

Winter Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East. Rainfall; Dec and Jan typically wetter than February. 1981-2010 Autumn average 300-400 mm lowlands but 200-300 mm areas to E of Dartmoor. Snow climatology less than 5 days lying snow over lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. June 2023.

Published 20 June 2023.

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies in most of the North Atlantic remain warmer than climatology for the middle of June. Areas around the UK, western Europe, western Mediterranean and the Baltic show 3 to 5 Celsius anomalies. Pacific Ocean anomalies along the equator show established El Nino state. The extent of the cold anomaly to the west of North America has increased in size a little. Temperatures in the NE of the Adriatic sea show a cold anomaly following the very severe cyclonic storm storm Biparjoy which brought flooding to parts of N India over recent days.

Biparjoy made landfall on June 16 near Naliya, India, with sustained winds of 95 km/h (60 mph) having weaken prior to landfall but continued to produced heavy rains as the weakening storm moved east for several days. Almost 180,000 people in Pakistan/India were evacuated. Final damage and casualty numbers are not yet available but so far 17 fatalities have been recorded.

The Atlantic Hurricane season for 2023 is just starting and there are currently two systems being monitored for development (Bret and 93L)

Confirmed tracks so far in 2023 are shown below. (Wikipedia)

Timeline: Arlene became a tropical storm but not a Hurricane. Bret and 93L are forecast to be tropical storms but it is not certain they whether one or both will develop further.

The Tropical Atlantic sea temperature anomalies are warmer than average, also at the higher end of the ensemble forecast from last month. Sea temperature in the tropical region are forecast to maintain similar anomalies through Autumn 2023. (see Met Office graphic below).

Ttropical Pacific Sea Surface Temperatures (Nino3.4) are in an El Nino state and forecast to remain so into 2024. This may result in a higher global average temperature for 2023 and there are suggestions that over the next few years the global temperature average will set a new record.

The effects of the El-Nino may be difficult to predict due to the excessive heat in water around coastal western Europe.

The North Atlantic Oscillation index (500hPa index shown below) became positive again around the 17th of June forecast to turn to neutral state over the next few weeks. Affects on the UK area are inconclusive for a neutral state.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

Recent WMO publication “State of the Climate in Europe 2022” shows how Europe has been warming twice as much as the global average since the 1980s, with far-reaching impacts on the region’s socio-economic fabric and ecosystems. In 2022, Europe was approximately 2.3 °C above the pre-industrial (1850-1900) average used as a baseline for the Paris Agreement on climate change.

SW England

June to the 19th the average temperature was between 16 and 18 Celsius, that’s 2 to 3 degrees Celsius above average. Rainfall was largely below 10mm in most places but overnight rain 19/20th and heavy thundery showers across northern parts of SW England will have locally increased totals.

Afternoon radar image 20th + show thunderstorms.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2023 March April May are shown below. Temperatures in most areas were above average. Rainfall was above average. in most places hence it is shocker that hosepipe bans are require although there has been climate data showing increased run off rather than retention of water in the soils.

The 1981-2010 anomalies are no longer available on the Met Office site so will be using 1991-2020 graphics in future. Note that due to the rises in temperature decade on decade the April value shows as above average compared to 1961 to 1990 but near average when using the higher averages in the 30 years to 2020. Rainfall shows a similar trend suggesting rainfall amounts (30 year average) have increased decade on decade so that averages are higher and hence above average values harder to achieve at least early in the 30 year comparison period (assuming increases continue).

Copernicus, European sourced temperature and rainfall anomalies for May 2023 and the 12 months to the end of May compared with the 30 year period 1991-2020, are shown below:

UK River flows and ground water levels in May 2023 can be found in the 2023 Hydrological Summary

River flow across SW England were above average in May 2023. River flow data for the 15th of June from the UK Water Resources Portal shows well below normal river flows following the recent dry and hot weather.

Reservoir levels, according to SW Water remain below the long term average across SW England as of 15th June 2023 mainly due to Colliford and Roadford being only 70% full despite above average rainfall over Winter and Spring!. Consequently hosepipe bans remain in force across Cornwall and much of Devon.

The Global Flood Awareness System – GloFAS – forecast from June 1st to end of September 2023 shows a “normal” flood risk across SW England – does not cover flash flooding from for example thunderstorms.

B: Forecast data:

1. Stratosphere:

The polar vortex remains in summer mode as shown by the GFS 19/0600UTC analysis at 10hPa

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (lower row) for July August September 2023.

3. Lower Troposphere:

A selection of model solutions for July to September 2023 using June data are shown below. The full set, including available graphics for Autumn 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly. Lower row precipitation anomaly

July to September 2023

NASA EU area not available.

Data from WMO:

Three month average anomaly followed by July August September 2023. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution. Note rainfall anomalies show marked cancellation between wetter and drier solutions in some of the multi model ensembles.

Individual members of the WMO super ensemble are shown below.

Russia

Copernicus C3S multi model ensemble. Less models than used in the WMO version but at higher resolution. data is available on a month by month bases but this detail often proves unreliable especially with regards to precipitation so here just the three month average anomalies are shown. The C3S is the combined multi model ensemble.

C: Comparing previous output:

March to May 2023 – based on February 2023 data.

Observed data.

Temperature. above average when compared to 1961-1990 but near average 1991-2020 period

Rainfall. above average

Sunshine. above average except N Ireland

Pressure. near normal or slightly above, Below normal in March otherwise mostly above normal and strongly so in May.

Original Summary – 160223 –
Temperature : Strong indication for above average temperature values for Spring, although the size of the anomaly is less clear and values may be only slightly above average. Some hints at near average values in March due to possible colder spell for the S of England around Mid March but this is uncertain.
Rainfall: Slightly more models suggest below average rainfall for Spring but with a hint of above normal across the NW. Large spread of solutions with some suggest a wet March across the S and W of the UK. In the WMO superensemble works out near average as the wetter solutions cancel out with the drier ones.
Caution:
1: Due to large scale stratospheric warming out of the polar vortex there is increased uncertainty for the second half of March.
2: Large scale blocking with cold easterly types seem to only be forecastable about two weeks ahead.

Comment: Above average temperature forecast good (three month average). Rainfall poor buut suggestion of wetter March in south was good.

Scoring will attempt to state good, fair, poor or no signal.
Note du3 to averaging period in models hindcast being below closer to the 1991-2020 period this new period will after this period be used for verification.
1. Russia (WMO): Temp good . PPN poor.
2. USA – CFS2 : Temp good . PPN fair.
3. UKMO Contingency: Temp good . PPN fair.
4. UKMO : Temp good . PPN fair . PMSL fair
5. USA – IRI : Temp good. PPN poor .
6. KMA APCC : Temp good . PPN poor .
7. JMA : Temp good PPN fair . PMSL good
8. NMME : Temp good . PPN poor.
9. WMO multi : Temp good . PPN poor..
10. BCC : Temp good . PPN fair. .
11. NASA : Temp good . PPN poor .
12. CanSips : Temp good . PPN poor .
13. Copernicus Temp good . PPN poor . PMSL poor
14. CMCC Temp good . PPN poor . PMSL fair
15: DWD Temp good. PPN fair . PMSL fair
16. EC Temp good. PPN fair . PMSL fair
17 JMA Temp good. PPN poor . PMSL fair
18 UKMO Temp good . PPN fair . PMSL fair
19. MF Temp good. PPN poor . PMSL fair
20 NCEP Temp good . PPN fair . PMSL fair
21 ECCC Temp: poor . PPN poor . PMSL fair

WMO low res data:
WMO low Temp good . PPN poor .
BoM Temp good . PPN fair .
Can Temp good. PPN poor .
DWD Temp good. PPN fair .
KMA Temp good. PPN poot .
MOSC Temp fair . PPN fair .
WASH Temp good . PPN poor .
CMA Temp good. PPN poor .
ECMWF Temp good . PPN fair .
UK Temp good. PPN poor .
JMA Temp good. PPN poor
MF Temp good. PPN fair .
CMCC Temp good. PPN poor .
CPTEC Temp good. PPN poor.

D: Text Forecast for SW England

Remainder of Summer 2023 (July August)

Temperature: Overwhelming indication for above or well above average temperatures for the season and each month.

Rainfall: Mixed signals. Above average more likely than below average in northern and western parts of SW England, elsewhere normal perhaps below normal but could be made above normal by local thunderstorm rainfall. Uncertain as to whether above average rain relates to more wet days or just shorter spells of heavier rain with fewer wet days compared to average.

Autumn 2023 (September October November)

Temperature: Milder than average Autumn is most likely, consistent across models. Slightly reduced anomalies in November.

Rainfall: Probably wetter than average for the season. Month to month detail unreliable but suggestion of drier start and wetter October/November.

Winter (December 2023 January and February 2024) limited data

Milder than normal for the season and each month. Average or above average precipitation in December and then average perhaps below. Overall wetter than average season. Snowfall likely to be below average.

Winter Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East. Rainfall; Dec and Jan typically wetter than February. 1981-2010 Autumn average 300-400 mm lowlands but 200-300 mm areas to E of Dartmoor. Snow climatology less than 5 days lying snow over lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. May 2023.

Published 20May 2023.

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies in most of the North Atlantic remain warmer than climatology for the middle of May. Parts of the Adriatic and central Mediterranean Sea are cooler due to recent cyclonic activity which brought floods to parts of Italy. Pacific Ocean anomalies along the equator have warmed as part of the transition towards El Nino state and the extent of the cold anomaly to the west of North America has reduced in size a little. Temperatures in the Bay of Bengal show a cold anomaly following MOCHA the CAT 4/5 storm.

Storm MOCHA 9th to 15th May 2023. CAT 5 storm, sea temperature in Bay of Bengal prior to storm over 30C. Advance forecast of over 10 days for the development of the storm. Provisional death toll 463 over 100 missing.

Myanmar: More than 78,250 people evacuated from at-risk areas, including 18,800 internally displaced persons in Rakhine. The nation’s government preparations shelter stockpiled to accommodate 100,000 people. The World Food Programme (WFP) in Myanmar said it was preparing food and relief supplies to support over 400,000 people in Rakhine and nearby areas. According to the United Nations Office for the Coordination of Humanitarian Affairs (OCHA), Mocha was anticipated to reach Myanmar’s Rakhine state and northwest region, where six million people require humanitarian assistance and 1.2 million are displaced. The World Health Organization has positioned 500,000 water purification pills in Myanmar, along with additional supplies.

Bangladesh: By 14 May, approximately 1.27 million people evacuated from Cox’s Bazar and over 100,000 from Chittagong.

https://en.wikipedia.org/wiki/Cyclone_Mocha

The Tropical Atlantic sea temperature anomalies are warmer than average, also warmer than forecast, and are now forecast to maintain similar anomalies through Autumn 2023. (see Met Office graphic below).

Forecasts suggest that tropical Pacific Sea Surface Temperatures (Nino3.4) are now in an El Nino state and forecast to move to strong El Nino condition during the summer and autumn. This may result in a higher global average temperature for 2023 and there are suggestions that over the next few years the global temperature average will set a new record.

The North Atlantic Oscillation index (500hPa index shown below) became positive around the 12th May but is forecast to return to neutral or negative over the next few weeks. Affects on the UK area are inconclusive for a neutral state.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

SW England

May to the 19th average temperature between 12 and 13 Celsius, about 0.5C above average. Rainfall between about 50 and 70 mm (although thunderstorms locally brought 25mm or so across eastern parts of SW England on the 19th) which was above average for most places. (Drier weather for the latter parts of May could return this to average). Sunshine 90 to 120 hours has been slightly below average so far.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2023 February March April are shown below. Temperatures in most areas were above average. The very dry February was offset to some extent by the wetter March and in the south of the UK also the wetter April.

Storm Noa on 12 April 2023 was the second named storm of the 2022/2023 storm season. The storm was named by Meteo-France and brought widespread gusts of over 50Kt around coastlines of England and Wales. This was an unusually severe storm for the time of year; the most significant April wind storm to affect England and Wales since April 2013.

The 1981-2010 anomalies are no longer available on the Met Office site so will be using 1991-2020 graphics in future. Note that due to the rises in temperature decade on decade the April value sho2s as above average compared to 1961 to 1990 but near average when using the higher averages in the 30 years to 2020. Rainfall shows a similar trend suggesting rainfall amounts (30 year average) have increased decade on decade.

Copernicus, European sourced temperature and rainfall anomalies for April 2023 and the 12 months to the end of April compared with the 30 year period 1991-2020, are shown below:

UK River flows and ground water levels in April 2023 can be found in the 2023 Hydrological Summary

River flow across SW England were above average in April 2023. River flow data for the 16th of May in the UK Water Resources Portal shows normal to above normal river flows

Reservoir levels, according to SW Water remain below the long term average across SW England as of 14th April 2023 mainly due to Colliford and Roadford being only 70% full despite above average rainfall over winter. Consequently hosepipe bans remain in force across Cornwall and much of Devon.

The Global Flood Awareness System – GloFAS – forecast from May1st to end of August 2023 shows an enhanced flood risk across SW England, S and SE England.

B: Forecast data:

1. Stratosphere:

Stratospheric warming event ended on 21st March 2023. The polar vortex remains very weak and is in summer mode as shown by the GFS 19/1200UTC analysis at10hPa

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) NMME anomaly (lower row) for May June July 2023. Anomalies suggest above normal heights and reduced Atlantic jet flow through May to July.

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (lower row) for June July August 2023. Inconstant anomalies between CFS and the NMME ensemble suggest problems with rainfall forecast.

3. Lower Troposphere:

A selection of model solutions for June to August 2023 using May data are shown below. The full set, including available graphics for Autumn 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly and lower row precipitation anomaly

June to August 2023

NASA EU not available.

Data from WMO:

Three month average anomaly followed by June July August. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution. Note also rainfall anomalies show marked cancellation between wetter and drier solutions. (UKMO data missing).

Individual members of the WMO super ensemble are shown below.

Temperature:

Precipitation:

C: Comparing previous output:

February to April 2023 – based on January 2023 data, for the UK.

Observed data.

Temperature. above average (March and April near normal but above normal compared to earlier 30 year periods).

Rainfall. Scotland below elsewhere normal or above (Feb dry other months wet)

Sunshine. Below average

Pressure. above average (below in March)

Original Summary – 190123 – Main theme is for above average temperatures for the three months taken together. There is a hint that March could have nearer normal values. Precipiation near normal overall with a chance of below average in parts of south and above in parts of the N. However, February probably wetter than average esepecially in western exposures (hill snow especially in N), March could see more areas near or below average except perhaps the N. April uncertain probably near average. Caution: 1: Due to large scale stratospheric warming out of the polar vortex there is increased uncertainty for the second half of February and for March. At present the indications are for a mostly mild and unsettled period which could lead to an early Spring. 2: Large scale blocking with cold easterly types seem to only be forecastable about two weeks ahead.

Comment: Temperature forecast good. Precipitation forecast fair overall but did not get very dry (February) or very wet (March) months, again month to month detail unreliable.

Scoring will attempt to state good, fair, poor or no signal.
Revised order
1. Russia (MHC+MGO): Temp good . PPN poor .
2. USA – CFS2 : Temp good . PPN poor .
3. UKMO Contingency: Temp good . PPN poor.
4. UKMO : Temp good . PPN poor. PMSL fair
5. USA – IRI : Temp poor . PPN poor. .
6. KMA APCC : Temp good . PPN poor.
7. JMA : Temp good . PPN poor PMSL poor
8. NMME : Temp fair . PPN poor but good in NW .
9. WMO multi : Temp good . PPN fair.
10. BCC : Temp good . PPN poor.
11. NASA : Temp good . PPN poor.
12. CanSips : Temp good . PPN poor.
13. Copernicus Temp good . PPN fair . PMSL poor
14. CMCC Temp good . PPN fair . PMSL poor
15: DWD Temp good . PPN fair. PMSL poor
16. EC Temp good . PPN poor. PMSL poor
17 JMA Temp good . PPN fair . PMSL good
18 UKMO Temp good . PPN fair . PMSL poor
19. MF Temp good . PPN fair . PMSL poor
20 NCEP Temp good . PPN fair . PMSL poor
21 ECCC Temp: good . PPN poor. PMSL poor

WMO low res data:
BoM Temp good . PPN poor .
Can Temp good . PPN poor .
DWD Temp good . PPN poor .
KMA Temp good . PPN poor .
MOSC Temp poor . PPN poor .
WASH Temp good . PPN poor .
CMA Temp good . PPN poor .
ECMWF Temp good . PPN poor .
UK missing .
JMA Temp good . PPN poor
MF Temp good . PPN poor .
CMCC Temp good . PPN poor .
CPTEC Temp good . PPN good .

D: Text Forecast for SW England

Summer 2023 (June July August)

Temperature: Overwhelming indication for above average temperatures for the season and each month although some models suggest Scotland could be nearer normal and some models hint at nearer normal values elsewhere in June which looks fairly unlikely.

Rainfall: Very little consistency month to month. Slightly mod models suggesting above average rainfall across SW England than below average. Uncertain as to whether this is more wet days or just shorter spells of heavier rain with fewer wet days compared to average. Hint that July could have the higher rain totals.

Autumn 2023 (September October November) limited data.

Temperature: Milder than average Autumn is most likely, consistent across models.

Rainfall: Probably wetter than average for the season. Month to month detail unreliable.

Winter (December 2023 January and February 2024) very limited data

Winter Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East. Rainfall; Dec and Jan typically wetter than February. 1981-2010 Autumn average 300-400 mm lowlands but 200-300 mm areas to E of Dartmoor. Snow climatology less than 5 days lying snow over lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. April 2023.

Published 21April 2023.

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies in most of the North Atlantic remain warmer than climatology for the middle of April. Pacific Ocean anomalies along the equator have warmed as part of the transition towards El Nino state and the area of sea to thw west of North America has become relatively colder than average. The cold area to the NW of Australia probably stems from the recent CAT 4 storm in that area.

The Tropical Atlantic sea temperature anomalies remain slightly warmer than average and are forecast to maintain similar anomalies through to at least Autumn 2023. (see Met Office graphic below).

Forecasts suggest that tropical Pacific Sea Surface Temperatures (Nino3.4) are moving towards a strong El Nino condition. This may result in a higher global average temperature for 2023.

Met Office El Nino impact chart.

The North Atlantic Oscillation index (500hPa index shown below) has been trending negative recently and forecasts suggest a negative outlook through to the end of April. Negative values imply WEAKER westerly winds across the Atlantic towards Europe although a neutral or weak signal is inconclusive.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

SW England

Temperatures to 20th are running a fraction above average in western parts of the region and a fraction below in eastern parts. Rainfall has also been a little above average so far. Pressure has been a little higher than average with sunshine not far from average.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2023 January, February and March are shown below. The higher rainfall in places during January and the very wet March period did go some way to recovering reservoir levels but clearly not yet enough for parts of Cornwall and Devon.

Copernicus, European sourced temperature and rainfall anomalies for March 2023 and the 12 months to the end of March compared with 30 year period 1981-2010, are shown below:

UK River flows and ground water levels in March 2023 can be found in the 2023 Hydrological Summary

River flow data is only available to the 10th of April in the UK Water Resources Portal, hence a recent graphic has not been included.

Reservoir levels, according to SW Water remain below the long term average across SW England as of 16th April 2023. Some of the reservoirs are at 100% capacity except in the N and W of the region, for details check SW Water website.

Due to low reservoir levels at Colliford and Roadford the hosepipe ban in Cornwall continues and is being extended to parts of Devon from the 25th April (see map below) despite the September to March rainfall being above average across most of SW England.

The Global Flood Awareness System – GloFAS – forecast from April 1st to end of July 2023 shows no enhanced flood risk.

The Global Flood Awareness System – GloFAS – forecast from March 1st to end of June 2023 shows neutral or reduced river flood risk.

B: Forecast data:

1. Stratosphere:

Temperature in the upper stratosphere over the N Pole at 30hPa and 10hPa are shown below.

Stratospheric warming event ended on 21st March 2023. The polar vortex is now very weak as shown by the GFS 21/0600UTC analysis at10hPa

3. Lower Troposphere:

A selection of model solutions for May to July 2023 using April data are shown below. The full set, including available graphics for Summer 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly and lower row precipitation anomaly

May to July 2023

NASA missing.

Data from WMO:

Three month average anomaly followed by May June July. Top row temperature anomaly and lower row precipitation anomaly.

Individual members of the WMO super ensemble are shown below.

Exeter UKMO

Temperature:

Precipitation:

WMO super-ensemble for Summer 2023:

C: Comparing previous output:

January to March 2023 – based on December 2022 data, for the UK.

Observed data.

Temperature. Above normal overall and each month except for N Scotland which was colder in March.

Rainfall. For the UK as a whole rainfall was a tiny fraction below average, largely due to N Ireland and Scotland being drier on aggregate and Wales and England wetter.

Sunshine. Was slightly above aveage despite a cloudier than average March.

Pressure. on aggregate pressure above average (SW flow) due to High pressure in February which did not offset lower pressure in March.

Original Summary – 191222-

The overall signal for the three month period is for above normal temperatures, although some models suggest near average or slightly above. Met Office contingency, issued 19th, has a slightly increase in below average solutions for January although the majority are near average. Several other models hint at near average temperatures in January so another cold snap is possible before a milder end to winter. Precipitation very mixed indication with the wetter than average solutions balanced against the drier than average. Probably a drier (and colder spell in January) then near normal precipitation but with a chance of above in western exposures.

Comment: Temperature forecast was good for the three month average. Rainfall forecast of near average was good but did not indicate the very dry February and in the south the very March.

Scoring will attempt to state good, fair, poor or no signal for the three month overall.

Brazil and DWD made a stab at the drier Feb and wetter March also Moscow WMO hinted that way but given the very dry and very wet observed data these events were not reflected by the mean anomalies.
Non of the models got the colder March in N half of Scotland

1. Russia (WMO): Temp good . PPN fair .
2. USA – CFS2 : Temp good . PPN fair .
3. UKMO Contingency: Temp fair . PPN good .
4. UKMO : Temp good . PPN good . PMSL fair
5. USA – IRI : Temp good . PPN fair .
6. KMA APCC : Temp good . PPN no signal .
7. JMA : Temp good . PPN poor . PMSL fair
8. NMME : Temp good. PPN fair .
9. WMO multi : Temp good . PPN fair .
10. BCC : Temp good . PPN fair .
11. NASA : Temp good . PPN poor .
12. CanSips : Temp good. PPN fair.
13. Copernicus Temp good . PPN fair . PMSL fair
14. CMCC Temp good . PPN fair . PMSL poor
15: DWD Temp good . PPN fair . PMSL good
16. EC Temp good . PPN fair . PMSL good
17 JMA Temp good . PPN fair . PMSL fair
18 UKMO Temp good . PPN fair . PMSL fair
19. MF Temp good . PPN fair . PMSL fair
20 NCEP Temp good . PPN fair . PMSL fair
21 ECCC Temp: good . PPN fair . PMSL poor

WMO low res data:
BoM Temp good . PPN poor .
Can Temp good . PPN fair .
DWD Temp good . PPN good .
KMA Temp good . PPN poor .
MOSC Temp poor/fair . PPN fair .
WASH Temp good . PPN poor .
CMA Temp good . PPN poor .
ECMWF Temp good . PPN poor .
UK Temp good. PPN fair .
JMA Temp good . PPN poor
MF Temp good . PPN poor.
CMCC Temp good . PPN poor .
CPTEC Temp good . PPN fair.

D: Text Forecast for SW England

Remainder of Spring 2023 (May)

Temperature: Strong indication for above average temperature values.

Rainfall forecast very uncertain overall suggestion of average or above average. Above average more likely in western parts of the region. Number of models suggesting above average similar to those suggesting below.

Caution:
1: Large scale blocking with easterly types seem to only be forecastable about two weeks ahead.

May climate: 1981-2010 average mean temperature 11 or 12°C. Average May rainfall roughly 70mm but 150mm over moors and 40mm in drier east each month.

Summer 2023 (June July August)

Temperature: Likely to be above average for the season and each month.

Rainfall: Slightly more models suggest a drier than average season rather than a wetter than average season. Rainfall totals may be above average but with more dry days than average. Month to month data unreliable.

Autumn 2023 (September October November) limited data.

Temperature: Milder than average Autumn is most likely, consistent across models.

Rainfall: Probably wetter than average for the season. Month to month detail unreliable.

Winter (December 2023 January and February 2024) very limited data

Milder than normal with average or above average precipitation.

Winter Climate: 1981-2010 average temperature values for lowland areas 7°C in the West and 5°C in the East. Rainfall; Dec and Jan typically wetter than February. 1981-2010 Autumn average 300-400 mm lowlands but 200-300 mm areas to E of Dartmoor. Snow climatology less than 5 days lying snow over lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

Climate review and Experimental Long Range Forecast for SW England. March 2023.

Published 19 March 2023.

A: Overview

1. Influences.

Changes in sea temperature

Sea temperature anomalies in most of the Northern Hemisphere remain warmer than climatology for the middle of March. Pacific Ocean anomalies have warmed along the equator as the La Nina decays and transitions towards El Nino state. The South China Sea along with the West coast of North America show below normal anomalies.

The Tropical Atlantic sea temperature anomalies remain slightly warmer than average and are forecast to maintain similar anomalies through Spring and Summer 2023. (see Met Office graphic below).

Forecasts suggest that tropical Pacific Sea Surface Temperatures (Nino3.4) are moving towards El Nino conditions as previously forecast. This may aid higher global average temperatures for 2023.

The North Atlantic Oscillation index (500hPa index shown below) has been neutral recently and forecast to remain neutral through March. Negative values imply WEAKER westerly winds across the Atlantic towards Europe although a neutral or weak signal is inconclusive.

See https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

2. Recent Climatology

SW England

Up to the 18th of February, the average temperature has been around 7.5C which is near or slightly below average. Rainfall has been above average for the month so far with totals 50 to 90mm, most of which fell after the 7th. Sunshine has been bellow average.

UK:

Met Office provisional Temperature and Rainfall anomalies for 2022 December, 2023 January and February are shown below. The higher rainfall in places during the November to January period did go some way to recovering reservoir levels at least in parts of the SW but the low rainfall in February has not helped further recovery. December was the only colder than average month of 2022 and for southern areas since August 2021.

Copernicus, European sourced temperature and rainfall anomalies for February2023 and the winter period December to February compared with 30 year period 1981-2010, are shown below.

“In February 2023, most of western Europe experienced below-average soil moisture, reaching more than 4% below average in many regions, and more than 8% below average in parts of Spain and Türkiye. Although not as low in magnitude as for Spain and Türkiye, the soil moisture levels in parts of Ireland, UK and France, were lower than in any previous February in the ERA5 soil moisture record from 1979 onwards.

The pronounced lack of precipitation along with above-average temperatures that led to such conditions was related to persistent anticyclonic conditions shielding the affected areas from weather disturbances.

According to the UK MetOffice, England had its eighth driest February in a series which goes back to 1836, and its driest since 1993, with an average of 15.3mm of rain. Météo France reported over 30 days without precipitation after the 21st of January for France; a record in a dataset going back to 1959. The current dryness of soils in France is untypical for February and rather expected in mid-April. Further evidence of the severity of the drought comes from the European Drought Observatory which, for the second 10-day period of the month, issued a warning based on the impact of the precipitation deficit on soil moisture for France, Belgium, most of the UK and Ireland, and an alert to highlight the fact that vegetation was also being affected, for much of Ireland and regions of Spain and Türkiye.” Source Copernicus.

UK River flows and ground water levels in February 2023 can be found in the 2023 Hydrological Summary

The exceptionally dry February resulted in very low river flows data on the 16th March reflects the recent wetter weather.

Reservoir levels, according to SW Water remain below the long term average across SW England as of 12th March 2023. Some of the reservoirs are at 100% capacity except in the N and W of the region, for details check SW Water website.

The Global Flood Awareness System – GloFAS – forecast from March 1st to end of June 2023 shows neutral or reduced river flood risk.

B: Forecast data:

1. Stratosphere:

Temperature in the upper stratosphere over the N Pole at 30hPa and 10hPa are shown below. Stratospheric warming has occurred and the polar vortex is now very weak.

Very weak polar stratospheric vortex, not quite summer mode as shown by GFS 10hPa plot 18th March 2023

2. Upper troposphere:

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle row) NMME anomaly (lower row) for and April May June 2023. Anomalies suggest above normal heights and reduced Atlantic jet flow through May and June.

3. Lower Troposphere:

A selection of model solutions for April to June 2023 using March data are shown below. The full set, including available graphics for Summer 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

Top row temperature anomaly and lower row precipitation anomaly

April to June 2023

CFSv2 E3 data (above)

NMME

ECMWF

NASA

Data from WMO:

Three month average anomaly followed by April May June. Top row temperature anomaly and lower row precipitation anomaly.

WMO super ensemble (below) is a mean of data supplied by National Meteorological organisations across the globe. Because of the amount of data the output is a low resolution.

WMO super-ensemble

Individual members of the WMO super ensemble are shown below.

BCC China

BOM Australia

CMCC (Southern Europe)

CPTEC Brazil

DWD Germany

ECMWF low resolution

Canada CMA

Russia Moscow

Seoul KMA Korea

Tokyo JMA

Toulouse France

UKMO Exeter

Washington USA

WMO super-ensemble for Summer 2023:

Graphics for Summer 2023 can be found at https://www.weather-info.co.uk/wxsvc/seaslatest.html

C: Comparing previous output:

December 2022 to February 2023 – based on November 2022 data, for the UK.

Observed data

Temperature. Despite colder December the season had average or above average temperatures

Rainfall. Despite the exceptionally dry February some parts of the UK had above average rain although balanced by the larger area with below average

Sunshine. above average in S, elsewhere near average but below in N Ireland

Pressure. below normal in December but overall above average for season. H over S in February

Original Summary -18NOV2022 –
Temperature:
The main indication remains for above normal temperatures through the season and probably for each month. There are, however, a few more models suggesting nearer normal values in December (most likely in England) and recent Met Office monthly forecasts suggest a colder spell in December. The Met Office seasonal forecast issued late October also hinted at some colder spells but the most recent forecast indicates above normal values. Output from Russia (via WMO) suggests colder than average across England later in the winter but earlier Russian output (from Russian Met Service) was for above average. A caution is that over recent years models have not picked out a colder spell more than about two or three weeks ahead.
Precipitation: Forecast suggest below average in the south and perhaps above in the north but are not consistent month to month and are less reliable than temperature forecast. December and to a less extent February, have the biggest chance of being below average in the south. Snow risk likely to be lower than average for most areas except high ground.
Sea level pressure probably above average.

Comment: Good steer for above average overall and also the hints at a colder December. Rainfall signal for some areas drier than average and hint at drier February but not that strong a signal. Pressure forecast good.
Models did not pick out exceptionally dry February.

Scoring will attempt to state good, fair, poor or no signal for the three month averages.
Revised order
1. Russia (WMO): Temp fair. PPN fair .
2. USA – CFS2 : Temp good . PPN fair .
3. UKMO Contingency: Temp fair . PPN good .
4. UKMO : Temp good . PPN good . PMSL good
5. USA – IRI : Temp no signal . PPN no signal.
6. KMA APCC : Temp fair . PPN no signal .
7. JMA : Temp good. PPN fair . PMSL fair
8. NMME : Temp good . PPN fair.
9. WMO multi : Temp good. PPN good .
10. BCC : Temp fair. PPN fair .
11. NASA : Temp fair. PPN poor .
12. CanSips : Temp good . PPN fair.
13. Copernicus Temp good . PPN fair. PMSL good
14. CMCC Temp good . PPN fair. PMSL good
15: DWD Temp good . PPN good. PMSL good
16. ECMWF Temp good . PPN good. PMSL good
17 JMA Temp good . PPN fair. PMSL good
18 UKMO Temp good . PPN good. PMSL good
19. MF Temp good . PPN fair. PMSL good
20 NCEP Temp good. PPN fair . PMSL poor
21 ECCC Temp: good . PPN fair. PMSL good

WMO low res data:
BoM had the best shot at the drier February
BoM Temp good . PPN good .
Can Temp good . PPN good .
DWD Temp good . PPN fair .
KMA Temp good . PPN good .
MOSC Temp poor. PPN fair .
WASH Temp good . PPN poor .
CMA Temp good . PPN fair .
ECMWF Temp good . PPN good .
JMA Temp good . PPN fair
MF Temp good . PPN fair .
CMCC Temp good . PPN good .
CPTEC Temp good . PPN fair .

D: Text Forecast for SW England

Remainder of Spring 2023 (April May)

Temperature: Strong indication for above average temperature values with higher anomalies in May than in April.

Rainfall forecast very uncertain overall suggestion of average or above average,

Caution:
1: Large scale blocking with easterly types seem to only be forecastable about two weeks ahead.

Spring climate: 1981-2010 average mean temperature 9 or 10°C but a few degrees cooler over the moors. Roughly Apr 8 or 9°C May 11 or 12°C. Average 1981 to 2010 rain similar totals in April and May roughly 70mm but 150mm over moors and 40mm in drier east each month.

Summer 2023 (June July August) Limited data

Temperature: Likely to be above average for the season and each month.

Rainfall: Slightly more models suggest a drier than average season rather than a wetter than average sesason. Rainfall totals may be above average but with more dry days than average. A hint that August less likely to be a drier than average month though usually month to month detail unreliable.

Autumn 2023 (September October November) very limited data.

Temperature: Milder than average Autumn is most likely, consistent across models.

Rainfall: probably wetter than average for the season but some indication of a drier October, though monthly detail unreliable.

E: Caution.

F: References.

SST anomaly NOAA Remote Sens. 2014, 6(11), 11579-11606; doi:10.3390/rs61111579

IRI statistics: Mason, S.J. and L. Goddard, 2001: Probabilistic precipitation anomalies associated with ENSO. Bull. Amer. Meteor. Soc., 82, 619-638.

UK climate details see: http://www.metoffice.gov.uk/public/weather/climate/

NMME information: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00050.1

CFS2 info

‘Copernicus Products’ as listed in the C3S or CAMS Service Product Specification or any other items available through an ECMWF Copernicus http://climate.copernicus.eu

International seasonal monthly data from WMO

Climate data from The Met Office UK and NCEP USA

Contains public sector information licensed under the Open Government Licence v3.0.

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