Review and Experimental Long Range Forecast for SW England. March 2021.

Published 18 March 2021.

GDPR statement: Please note that the author of this blog does not set cookies but the host “wordpress.com” sets multiple cookies which are outside of the authors control. You can view their cookie policy here. 

1. Influences.

Changes in sea temperature

Atlantic sea temperatures are generally warmer than climatology as are waters of the North Sea. Norwegian Sea, Baltic Sea and the Med. The tropical North Atlantic is forecast to remain slightly warmer than average through Summer 2021 (See Met Office graphic below).

Colder sea temperatures in the East Pacific, just south of the equator, show a weakening La Nina with further noticeable warming having occurred in the East. Forecasts suggest that Pacific Sea Surface temperatures may remain in a La Nina or Neutral state through the remainder of 2021.

The North Atlantic Oscillation index (500hPa index shown below) has been slightly positive recently and is forecast to remain slightly positive for a short time before becoming uncertain.

The positive NAO phase represents a stronger than usual difference in pressure allowing winds from the west to predominate. The position of the jet stream enables stronger and more frequent storms to travel across the Atlantic bringing more frequent milder and wetter weather types for NW Europe which in summer results in cooler temperatures.

For Met Office information about the NAO see https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

Recent Climatology –  SW England

Up to the 17th temperatures averaged out around 7 Celsius which is slightly below the March average. There has been about 40% of normal rainfall and 60% of sunshine. High pressure was over the UK to start the month before becoming unsettled and at times windy in the second week of March, followed again by a spell of High pressure..

CPC graphic 7th to 13th March showing temperature anomalies and total rainfall in this period.

Looking back at the last three months Winter temperatures were a little colder than average across SW England and there was above average rainfall.

River flows and ground water levels in February 2021 were well above normal across SW England. Details can be found in the February 2021 Hydrological summary PDF 

UK based data is available in The Hydrological Outlook which provides an insight into future hydrological conditions across the UK.  Detail can be found at http://www.hydoutuk.net/

River flow from climate forecast

Global Flood Awareness (updated) System. February forecast for the period February to May indicates slightly above normal flood risk for SW England.

Glofas March forecast for March to June 2021. Blue above normal flood risk which probably mostly reflects the current above average ground water levels.

Atmosphere: Predictions.

A:  1: Stratosphere

Major warming in the stratosphere (see N Pole temperatures below) in January 2021 caused a reversal of the westerly flow across North America and a significant re-location of the polar stratospheric vortex towards Norther Russia. The SSW was deemed to have ended on 13th February.

The polar stratospheric vortex has strengthened into normal winter mode. Below the ECMWF 10hPa and 30hPa for 17/1200UTC and 27th March show the strong vortex relocating poleward and remaining stronger than climatology.

A: 2: Upper Troposphere

CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle) and NMME (lower row) for April to August 2021 hint at a less mobile patterns across the Atlantic for April and June but more cyclonic patterns near the UK for July and August.

B: Lower Troposphere:

Selection of April to June solutions using March 2021 data are shown below, top row temperature anomaly and lower row precipitation anomaly.

CFSv2 April to June
NMME April to June
NASA April to June
ECMWF April to June
UKMO April to June
WMO super ensemble April to June

The full set of graphics can be seen at http://www.weather-info.co.uk/wxsvc/seaslatest.html

Selection of Summer (June to August) solutions using March 2021 data are shown below, top row temperature anomaly and lower row precipitation anomaly.

CFSv2 SUMMER 2021 note there looks to be a cold bias in temperature across the N Sea in summer.
NMME SUMMER 2021
NASA SUMMER 2021
ECMWF SUMMER 2021
WMO super ensemble for SUMMER 2021
Beijing for SUMMER 2021
Australia BoM for SUMMER 2021
Germany DWD for SUMMER 2021
Canada for SUMMER 2021
Korea KMA for SUMMER 2021
France for SUMMER 2021
UKMO for SUMMER 2021

C: Comparing the output of seasonal models for 2020 December, 2021 January and February based on November 2020 data for the UK and Ireland.

For graphics and details see Verification review 2020 Dec 2021 January February

Review of details looked for in seasonal forecast.


Temperature. The North, mainly Scotland, was colder than average elsewhere mostly near average. The colder January mostly off set by above average December and February.

Rainfall. NW Highlands ended with below average rain but elsewhere values were mostly above average for the season.

Sunshine Northern areas had above average sunshine but southern areas had cloudier skies.

Pressure. Below normal for the season but above normal in N Scotland in Jan and Feb.

Temperature forecast was a little warm but got the idea of a milder February but not the cold January. Moscow output (WMO) which is often on the cold side got the idea of a colder January with near normal other months and some other models had January with smaller anomalies hinting at less mild. The colder than average season in Scotland was not indicated although the idea of above average snow in the north was correct. Above average rainfall was correct but the month to month detail was poor.

Models affected by the cold January and the lack of ability to forecast cold conditions.

Scoring for the three month season will attempt to state good, fair, poor or no signal. (E.O.E.)

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

2: Forecast.

Remainder of Spring  (2021 April May)

The overall indication for the April and May is for slightly above average temperatures with the strongest indication for above average values is in April.

Rainfall uncertain, probably near average overall but with some hints that April could be drier.

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 2021  (June July August)  

Temperature above average for the season with June possibly seeing the warmest anomalies and August the lowest, with values closer to the average.

Rainfall for the season uncertain but probably above average rain totals. Higher rain rates are typical of a warming atmosphere but may not imply an increase in the number of days with rain. Suggestion of one month being drier than average but no agreement as to whether it could be June or August. Slightly reduced indication for a wetter August.

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 2021  (September October November).

Milder than average overall but perhaps near average, or even cooler than average, in November. Wetter than average Autumn with little agreement which month if any might be 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 2021 /22 (December January February) very limited data.


Milder overall and also wetter than average especially early in the winter but February drier and possibly colder than 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.

3. Caution.

Experimental Long Range Forecasts do not have a good success rate. 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

4. References.

SST anomaly NOAA Remote Sens. 20146(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

Stratospheric Diagnostics from Japan Met Agency and ECMWF via  Free University Berlin

Climate data from The Met Office UK and NCEP USA

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

By Master0Garfield – Created using WikiProject Tropical cyclones/Tracks. The background image is from NASA [1]. The tracking data is from the National Hurricane Center’s Atlantic hurricane database, Public Domain, https://commons.wikimedia.org/w/index.php?curid=90697173

Review and Experimental Long Range Forecast for SW England. February 2021.

Published 19 February 2021.

GDPR statement: Please note that the author of this blog does not set cookies but the host “wordpress.com” sets multiple cookies which are outside of the authors control. You can view their cookie policy here. 

1. Influences.

Changes in sea temperature

Atlantic sea temperatures are mostly warmer than climatology apart from slightly cooler than average values around the UK. Norwegian Sea and Baltic Sea temperatures also remain above climatology despite the recent cold spell. The tropical North Atlantic is forecast to remain slightly warmer than average through Summer 2021 (See Met Office graphic below).

Colder sea temperatures in the East Pacific, just south of the equator, show a well established La Nina although some noticeable warming has occurred in the East. Forecasts continue to suggest that Pacific Sea Surface temperatures may remain in a La Nina state through to 2021 although may be near neutral for the Spring.

The North Atlantic Oscillation index (500hPa index shown below) turned turned slightly negative early in December 2020 and has recently turned slightly positive and is forecast to remain slightly positive through the remainder of February.

The positive NAO phase represents a stronger than usual difference in pressure allowing winds from the west to predominate. The position of the jet stream enables stronger and more frequent storms to travel across the Atlantic bringing more frequent milder and wetter weather types for NW Europe

For Met Office information about the NAO see https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

Recent Climatology –  SW England

The recent cold and largely dry spell between the 5th and 14th has resulted in temperature averages being slightly below normal although this made be offset by milder SW which look like continuing until nearer the end of February when High pressure and a change in wind direction is likely. Rainfall to the 19th has been near or slightly above average and sunshine somewhat below average.

CPC graphic 7th to 13th February showing temperature anomalies and total rainfall in this period.

Looking back at the last three months, despite the colder January, temperatures have been near or a little above average across SW England and rainfall above average despite the drier November.

River flows and ground water levels in January 2021 were well above normal across SW England. Details can be found in the January 2021 Hydrological summary PDF 

The forecast changes in the next month and three months can be viewed at Hydro UK http://www.hydoutuk.net/latest-outlook/

The reservoir levels in the SW of England were above the normal level as of February 7tht 2021.

Global Flood Awareness (updated) System. February forecast for the period February to May indicates slightly above normal flood risk for SW England.

Glofas February forecast for Feb to May 2021. Blue above normal flood risk.

UK based data is available in The Hydrological Outlook which provides an insight into future hydrological conditions across the UK.  Detail can be found at http://www.hydoutuk.net/

River flow from climate forecast

Further graphics from the February outlook are available http://www.hydoutuk.net/archive/2021/february-2021/further-information-february-2021/

Atmosphere: Predictions.

A:  1: Stratosphere

Major warming in the stratosphere (see N Pole temperatures below) in January 2021 caused a reversal of the westerly flow across North America and a significant re-location of the polar stratospheric vortex towards Norther Russia.

JMA North pole observed temperature changes at 10hPa and 30hPa

Since then the polar stratospheric vortex has re-formed and strengthened into a normal winter mode. Below the ECMWF 10hPa and 50hPa show only limited stratospheric warming although a further weakening of the flow is evident across western Europe at 50hPa in the forecast for 28th Feb.

A: 2: Upper Troposphere

CFsv2 200hPa contours (top row) and anomaly (lower row) for March to May 2021 hint at a less mobile patterns across the Atlantic for April and May.

B: Lower Troposphere:

A selection of  March to May solutions using February 2021 data are shown below, top row temperature anomaly and lower row precipitation anomaly. 

NMME Spring 2021
CFSv2 Spring 2021
ECMWF Spring 2021
NASA Spring 2021

A selection of  WMO sourced March to May solutions using February 2021 data are shown below, top row temperature anomaly and lower row precipitation anomaly. 

WMO super ensemble 11 models combined
Beijing Spring 2021
BoM Australia Spring 2021
Brazil Spring 2021
DWD Germany Spring 2021
ECMWF Spring 2021
Canada Spring 2021
Korea Spring 2021
Japan Spring 2021
France Spring 2021
UKMO Spring 2021
USA CFS2 Spring 2021

A selection of  June to August solutions using February 2021 data can be seen at http://www.weather-info.co.uk/wxsvc/seaslatest.html

C: Comparing the output of seasonal models for 2020 November December and 2021 January based on October  2020 data for the UK and Ireland.

For graphics and details see Verification review 2020 Oct Nov Dec

Review of details looked for in seasonal forecast.
Temperature. Three month season slightly above normal except Norther Ireland slightly below. Nov and DEC above normal but January as much below normal as November was above. Look for colder January following milder Nov and Dec in most areas.

Rainfall. Scotland marginally below elsewhere above normal for the season. Look for November drier and then wetter.

Pressure. Overall below normal (WSW) but above normal in November, well below in December and slightly below in January except in NW Scotland were slightly above.

Comment: DWD and Tokyo had the correct temperature sequence milder start colder end. Washington, UKMO, DWD and Canada had the rainfall trend OK but were not “wet” enough with near normal suggested rather than above normal.

TABLE below is for 3 month data only. Scoring will state good, fair, poor or no signal for the three month season.
1. Russia: Temp no signal. PPN fair.
2. USA – CFS2 : Temp good . PPN good .
3. UKMO Contingency: Temp good . PPN poor .
4. UKMO : Temp fair. PPN fair . PMSL poor
5. USA – IRI : Temp no signal . PPN poor .
6. KMA APCC : Temp good . PPN no signal .
7. JMA : Temp good . PPN poor . PMSL poor
8. NMME : Temp good . PPN poor .
9. WMO : Temp good . PPN poor .
10. BCC : Temp good . PPN poor .
11. NASA – Temp fair . PPN poor .
12. Brazil: Temp good . PPN poor .
13. CanSips : Temp good . PPN fair .
14. IMME : Temp good. PPN fair .
15. Copernicus Temp fair . PPN poor. PMSL poor
16. CMCC Temp fair . PPN poor. . PMSL poor
17: DWD Temp fair . PPN poor. . PMSL poor
18. EC Temp fair . PPN poor. . PMSL poor
19 UKMO Temp fair . PPN poor. PMSL poor
20. MF Temp poor . PPN poor . PMSL poor
21 NCEP Temp fair. PPN poor . PMSL poor
22 JMA: Temp fair. PPN poor . PMSL poor
23 ECMWF (monthly) Temp: poor. PPN poor .

2: Forecast.

Spring  (2021 March April May)

The overall indication for the Spring Season is for above average temperatures. March could well see some colder spells and could turn out to be near average. The strongest indication for above average values is in April although May is also likely to be warmer than average.

Rainfall uncertain, probably near average for the season but with some longer dry periods quite likely. There is a risk that March could be wetter than average with even a little snow over the moors but this could be followed by a drier April and near normal May.

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 2021  (June July August)  

Temperature above average for the season with June possibly seeing the warmest anomalies and August the lowest, with values closer to the average.

Rainfall for the season uncertain but probably above average rain totals. Higher rain rates are typical of a warming atmosphere but may not imply an increase in the number of days with rain. June possibly drier than average but with a risk of above normal rainfall in July and/or August.

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 2021  (September October November)  limited data.

Milder than average but with near average rainfall.

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.

3. Caution.

Experimental Long Range Forecasts do not have a good success rate. 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

4. References.

SST anomaly NOAA Remote Sens. 20146(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

Stratospheric Diagnostics from Japan Met Agency and ECMWF via  Free University Berlin

Climate data from The Met Office UK and NCEP USA

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

By Master0Garfield – Created using WikiProject Tropical cyclones/Tracks. The background image is from NASA [1]. The tracking data is from the National Hurricane Center’s Atlantic hurricane database, Public Domain, https://commons.wikimedia.org/w/index.php?curid=90697173

Review and Experimental Long Range Forecast for SW England. January 2021.

Published 19 January 2021.

GDPR statement: Please note that the author of this blog does not set cookies but the host “wordpress.com” sets multiple cookies which are outside of the authors control. You can view their cookie policy here. 

1. Influences.

Changes in sea temperature

Atlantic sea temperatures are mostly warmer than climatology apart from slightly cooler than average values to the SW of the UK and Ireland. North Sea, Norwegian Sea and Baltic Sea temperatures also remain above climatology. The tropical North Atlantic is forecast to remain slightly warmer than average through to at least Summer 2021 (See Met Office graphic below).

Colder sea temperatures in the East Pacific, just south of the equator, show a well established La Nina and forecasts continue to suggest that the La Nina will remain active until at least Spring 2021 possibly trending towards neutral conditions for the summer months.

The North Atlantic Oscillation index (500hPa index shown below) turned turned slightly negative early in December 2020 and currently has about a 30% chance of turning positive at the start of February.

The negative NAO phase represents a weaker than usual difference in pressure North to South across the North Atlantic. Winds from the east and north-east are more frequent, bringing with them cold air, while the adjusted position of the jet stream leads to weaker and less frequent storms. As a result Europe is more likely to experience colder, less windy and drier winters during persistent El Nino conditions.

The positive NAO phase represents a stronger than usual difference in pressure allowing winds from the west to predominate. The position of the jet stream enables stronger and more frequent storms to travel across the Atlantic bringing more frequent milder and wetter weather types for NW Europe

For Met Office information about the NAO see https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

The more blocked patterns during a negative phase can produce cyclonic or anticyclonic patterns over the UK depending on where such features become slow moving.

Recent Climatology –  SW England

The first ten days of January were rather cold with frequent frosts but fairly dry. After the 10th it became less cold but with some rain. To the 19th of January temperature means across SW England are about 1 to 1.5C below the longer term average and rain totals to the 19th January are only about a third of average. Sunshine hours have been close to average. This can be seen in the snapshot for the period 3rd to 9th showing widespread below average temperature and rain/snow

Looking back at the last three months, temperatures have been near or a little above average across SW England and rainfall above average despite the drier November.

Looking back at 2020 for SW England the year was warmer, wetter but also sunnier in places. It very much looks like that when rain occurred it was “heavier”. For example in the Dawlish and Teignmouth area data suggests there were more dry days than average but also more days with 10mm or more of rain.

River flows and ground water levels in December 2020 were well above normal across SW England. Details can be found in the December 2020 Hydrological summary PDF 

The forecast changes in the next month and three months can be viewed at Hydro UK http://www.hydoutuk.net/files/3916/1054/7577/2021_01_HO_Summary.pdf

The reservoir levels in the SW of England were above the normal level as of January 10th 2020.

Global Flood Awareness (updated) System. January forecast for the period January to April (shown left below) indicates slightly above normal flood risk for SW England. The image on the right shows a forecast for river flow based on the North Atlantic Oscillation (NAO) implying normal to above normal river flows across parts of the SW. For details see Outlook from NAO Analogues (hydoutuk.net)

Atmosphere: Predictions.

A:  1: Stratosphere

Major warming in the stratosphere (see N Pole temperatures below) has caused a reversal of the westerly flow across North America and a significant re-location of the polar stratospheric vortex towards Norther Russia. Although further warming is expected to continue forecasts suggest the vortex may return towards the N Pole and redevelop for a time before perhaps splitting the vortex in two weeks time.

ECMWF 50hPa and 10hPa analysis 17th and forecast for 27th Jan
JMA North pole observed temperature changes at 10hPa and 30hPa

NW Europe NCEP forecast temperature anomaly forecast have been trending to colder values in February and possibly March over recent days and the stratospheric warming may well be part of the reason.

A: 2: Upper Troposphere

CFsv2 200hPa contours (top row) and anomaly (lower row) for Feb to May 2021 hint at a more cyclonic February across the UK the less mobile patterns for March to May.

B: Lower Troposphere:

A selection of  February to May solutions using January 2021 data are shown below, top row temperature anomaly and lower row precipitation anomaly. 

Many models seem to have a problem forecasting colder than average values so the increase in the number of models showing near normal values might imply colder values in February and perhaps early March.

NMME
CFS2
ECMWF
NASA

A selection of  WMO sourced March to May solutions using January 2021 data are shown below, top row temperature anomaly and lower row precipitation anomaly. 

UKMO
WMO super ensemble
Beijing China
BoM Australia
Brazil
Germany
Canada
Korea
France

A selection of  June to August solutions using January 2021 data

NMME
NASA

C: Comparing the output of seasonal models for October November and December based on September  2020 data for the UK and Ireland.

For graphics and details see Verification review 2020 Oct Nov Dec

Review of details looked for in the seasonal forecast.
Temperature. above average for season with November strongest for above normal after normal October. Rainfall. above average for season with November below average except N Ireland and W Scotland. Oct and Dec wet in S and E especially. Pressure. below average for season, November above average but Oct and Dec below.

TABLE below is for 3 month data only. Scoring will state good, fair, poor or no signal for the three month season.

1. Russia: Temp good . PPN mainly no signal Scotland and N Ireland good .
2. USA – CFS2 : Temp fair . PPN fair . (CFS2 monthly E3 suggested drier Nov)
3. UKMO Contingency: Temp fair . PPN no signal .
4. UKMO : Temp good. PPN poor . PMSL poor
5. USA – IRI : Temp no signal . PPN good .
6. KMA APCC : Temp poor . PPN poor .
7. JMA : Temp good – a little cool . PPN poor . PMSL poor (mean direction good)
8. NMME : Temp good. PPN fair .
9. WMO : Temp fair . PPN poor .
10. BCC : Temp fair . PPN poor .
11. NASA – Temp good . PPN poor .
12. Brazil: Temp good . PPN good . PMSL good
13. CanSips : Temp fair . PPN fair .
14. IMME : Temp good. PPN poor .
15. Copernicus Temp fair. PPN poor . PMSL poor
16. CMCC Temp fair. PPN poor . PMSL poor
17: DWD Temp fair. PPN poor . PMSL poor
18. EC Temp fair. PPN poor . PMSL poor
19 UKMO Temp fair. PPN poor . PMSL poor
20. MF Temp fair. PPN poor . PMSL poor
21 NCEP Temp good. PPN fair . PMSL fair
22 JAMSTEC: no data
23 ECMWF (monthly) Temp: fair . PPN good

Remainder of Winter (February 2021).

February may well start near normal or even slightly milder than average but there is a moderate risk of a change to be colder than average values – overall the month ending up near or slightly below average.. Rainfall is likely be near or above normal to start the month but trending drier, overall near normal totals for the month are possible. Increased risk of snow IF the change to colder types occurs.

Winter Climate: 1981-2010 February average temperature values for lowland areas 6 or7°C in the West and 5 or 6°C in the East. Rainfall; February. lowland areas 80-100mm but 60-80mm in east. Around 200mm over moors. Snow climatology  for December to February less than 5 days lying snow in lowland areas 5 to 10 hills, say hills around 200 metre elevation – one in three years have no lying snow. February possibly around 2 days on average with lying snow for low ground.

Spring  (2021 March April May)

After a colder than average start Spring temperatures are likely to trend above average for May. April could see values close to normal. Overall above average values are likely for the three month season.

Rainfall uncertain but probably near or a little below average for the season. There is however a risk that March could be wetter than average followed by a drier April and near normal May.

Possibly some snowfall on the moors in March.

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.

Early indication for Summer 2021  (June July August)  limited data (data from eight global systems)

Temperature slightly above average for the season although Cornwall could be near average. Rainfall for the season uncertain but majority suggest close to average values although some models have wetter/drier than average.

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.

3. Caution.

Experimental Long Range Forecasts do not have a good success rate. 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

4. References.

SST anomaly NOAA Remote Sens. 20146(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

Stratospheric Diagnostics from Japan Met Agency and ECMWF via  Free University Berlin

Climate data from The Met Office UK and NCEP USA

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

By Master0Garfield – Created using WikiProject Tropical cyclones/Tracks. The background image is from NASA [1]. The tracking data is from the National Hurricane Center’s Atlantic hurricane database, Public Domain, https://commons.wikimedia.org/w/index.php?curid=90697173

Review and Experimental Long Range Forecast for SW England. November 2020.

Published 18 November 2020.

GDPR statement: Please note that the author of this blog does not set cookies but the host “wordpress.com” sets multiple cookies which are outside of the authors control. You can view their cookie policy here. 

1. Influences.

Changes in sea temperature

Apart from a cooler area, centred near 55 North 40 West, Atlantic sea temperatures are mostly warmer than climatology as is the area around the UK, Norwegian Sea and Baltic.

The tropical north Atlantic is forecast to remain slightly warmer than average through to at least Spring 2021 (See Met Office graphic below).

Wikipedia states that “The 2020 Atlantic hurricane season is the most active season in terms of tropical depressions and named storms and has equalled or broken a number of records. It has been the second season after 2005 to use the Greek-Alphabet, the latest in season forming Category 5 hurricane on record (Iota). Record-breaking most storms to have formed before August through November. Most active September on record with 10 named storms. Record breaking most landfalls in the United States and Louisiana with 12 and 5, respectively. Record-tying 2 named storms in May, and 5 named storms in July. Record-breaking 6th straight season with at least one pre-season storm.

Wikipedia track map so far in 2020

 Colder sea temperatures in the East Pacific just south of the equator show the La Nina is well established and forecast suggest the La Nina will remain active until at least Spring 2021.

The North Atlantic Oscillation index (shown by a 500hPa index in the image below) turned positive in late October but there is about a 30% chance of the index turning negative by December 1st.

Why could a change in the NAO phase be important?

The positive NAO phase represents a stronger than usual difference in pressure between the two regions. Winds from the west dominate, bringing with them warm air, while the position of the jet stream enables stronger and more frequent storms to travel across the Atlantic. These support mild, stormy and wet winter conditions in northern Europe

The negative NAO phase represents the reverse with a weaker than usual difference in pressure. Winds from the east and north-east are more frequent, bringing with them cold air, while the adjusted position of the jet stream leads to weaker and less frequent storms. As a result Europe is more likely to experience cold, calm and dry winters.

For Met Office information about the NAO see https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

Recent Climatology –  SW England

November to the 18th has been fairly mild with an average temperature around 11 Celsius, which is around two degrees or so above 1981-2010 mean for the month and rainfall has been near or a little above average so far.

Temperatures since summer have been near average with rainfall, taking September and October together, probably a little below average although this follows a “wet summer”.

Copernicus.eu climate data for month of October 2020 and year from November 2019 to October 2020

River flows in October 2020 were above normal across SW England and groundwater levels were also near or a little above normal in the eastern parts of SW England. Details can be found in the October 2020 Hydrological summary PDF 

The reservoir levels in the SW of England were above average as of November 8th 2020.

Global Flood Awareness System. November forecast for the period November to February (shown below) indicates above normal flood risk for much of the UK and Ireland but near average risk in the south. In the river flow image there is just a hint of above average flows in the Exe estuary.

Atmosphere: Predictions.

A:  1: Stratosphere

Data from November 16th shows polar vortex established at 50 and 30hPa. The temperature trace below indicates that temperature in the stratospheric polar region is close to the cold values required for Polar Stratospheric Cloud formation which is implicated in Ozone depletion. This year has seen increased Ozone depletion in the Antarctic Polar Stratosphere and this may be something to watch out for in the North polar region next Spring. http://www.weather-info.co.uk/ozone.html

A: 2: Upper Troposphere

CFsv2 200hPa contours (top row) and anomaly (lower row) for Dec Jan and Feb hint at a more cyclonic February across the UK area and may suggest low centres could be steered further north than normal in the early part of winter.

B: Lower Troposphere:

A selection of  December to February (Winter) solutions using November 2020 data are shown below, top row temperature anomaly and lower row precipitation anomaly. 

NMME DJF (tends to be overly warm)
CFS2 10 day mean (E3) data DJF. Tends to be overly warm.
ECMWF DJF
NASA DJF

WMO data. Three month average than separate months

WMO super ensemble (11 models) DJF
BoM Australia DJF
Brazil DJF
Canada DJF
UKMO Exeter DJF
Moscow DJF (tends to be cold)
Japan DJF
France DJF
Germany DJF
South Korea DJF

SPRING (March April May) 2021

NMME Spring 2021
WMO Spring 2021

C: Comparing the output of seasonal models for August September October, based on July  2020 data.

For graphics and details see Verification review 2020 Aug Sep Oct

Temperature for the three month mean was correctly indicated as above average but few models got the month to month trend correct – EC and the WMO super ensemble perhaps did best. Rainfall forecasts were poor despite above average being indicated there was little indication for a drier September after a wetter August.

TABLE below is for 3 month data only:
Scoring will attempt to state good, fair, poor or no signal based upon
temperature being normal (fair) or above average (good). Rainfall above average and pressure below average. Errors and omissions excepted.
1. Russia: Temp mostly no signal. PPN no signal.
2. USA – CFS2 : Temp fair . PPN poor .
3. UKMO Contingency: Temp good . PPN good .
4. UKMO : Temp good . PPN no signal. PMSL no signal.
5. USA – IRI : Temp no signal. PPN no signal. .
6. KMA APCC : Temp good . PPN no signal..
7. JMA : Temp good . PPN poor. PMSL poor
8. NMME : Temp good . PPN poor .
9. WMO : Temp fair. PPN poor .
10. BCC : Temp good. PPN poor .
11. NASA – Temp good . PPN fair .
12. Brazil: Temp fair . PPN poor .
13. CanSips : Temp fair . PPN poor .
14. SAWS: : no data
15. Copernicus Temp no signal . PPN no signal . PMSL no signal
16. CMCC Temp no signal . PPN poor . PMSL poor
17: DWD Temp no signal. PPN no signal . PMSL no signal
18. EC Temp fair. PPN poor . PMSL poor
19 UKMO Temp good. PPN no signal. PMSL no signal
20. MF Temp no signal . PPN no signal . PMSL no signal
21 NCEP Temp no signal. PPN no signal. PMSL no signal
22. JAMSTEC: no data
23 ECMWF (monthly) Temp: fair. PPN poor
24 IMME Temp: fair . PPN poor

2. Forecast. SW England.

Winter (2020 December 2021 January February).

For the Winter season the mean temperatures is likely to be above average. That said there are some indications that the first half of the Winter could see near average values with some colder than average periods – the latter perhaps most likely in December. There is some agreement between models that February could be significantly milder than average.

Rainfall indications for the Winter season are rather mixed with a similar number of models showing below or above average values. There is a signal that December could be drier than average, January roughly 30% chance of wetter and 40% chance of near normal and February has a 60% chance of being wetter and possibly much wetter than average. The total number of days with measurable rain could end of below average though this is very uncertain.

Below average snowfall seems likely – snow most likely confined to higher 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.

Spring  (2021 March April May) limited data.

Milder than average temperatures seem likely for the season although March and April could see values closer to normal and May could be significantly milder than average.

Rainfall near or a little below average for the season although March could be wetter than average. The driest month varies between April in May is some of the models.

Possible a little snowfall on the moors in March.

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.

Early indication for Summer 2021  (June July August)  very limited data from China, Japan and Canada

Temperature and rainfall for the season near average but perhaps drier than average in August.

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.

3. Caution.

Experimental Long Range Forecasts do not have a good success rate. 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

4. References.

SST anomaly NOAA Remote Sens. 20146(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

Stratospheric Diagnostics from Japan Met Agency and ECMWF via  Free University Berlin

Climate data from The Met Office UK and NCEP USA

Review and Experimental Long Range Forecast for SW England. October 2020.

Published 19 October 2020.

GDPR statement: Please note that the author of this blog does not set cookies but the host “wordpress.com” sets multiple cookies which are outside of the authors control. You can view their cookie policy here. 

1. Influences.

Changes in sea temperature

Atlantic equatorial sea temperatures remain warmer than climatology as is the area area around the UK, Norwegian Sea and Baltic.

Colder sea temperatures in the East Pacific just south of the equator show the La Nina has strengthened.

The tropical north Atlantic is forecast to remain slightly warmer than average through to at least March 2021 (See Met Office graphic below).

Wikipedia states that “The 2020 Atlantic hurricane season is an ongoing tropical cyclone season which has featured tropical cyclone formation at a record-breaking rate. So far, there have been a total of 27 tropical or subtropical cyclones, 26 named storms, 9 hurricanes, and 3 major hurricanes.[nb 1] With 26 named storms, it is the second most active Atlantic hurricane season on record, behind only the 2005 Atlantic hurricane season. It is also only the second tropical cyclone season to feature the Greek letter storm naming system, with the other season also being 2005.

Wikipedia track map so far in 2020

The most recent storm (October 5th to 12th) Hurricane Delta was the record-tying fourth named storm of 2020 to strike Louisiana, as well as the record-breaking tenth named storm to strike the United States. “

A new storm shown “Epsilon” is likely to track near to Bermuda on the 23rd/24th of October 2020.

In the Pacific, sea temperatures continue to trend towards cooler / La Nina conditions which may now last until early Summer Spring 2021 before returning to neutral conditions.

The North Atlantic Oscillation index (shown by a 500hPa index in the image below) turned negative in near the end of September but is forecast to below positive before the end of October.

The positive NAO phase represents a stronger than usual difference in pressure between the two regions. Winds from the west dominate, bringing with them warm air, while the position of the jet stream enables stronger and more frequent storms to travel across the Atlantic. These support mild, stormy and wet winter conditions in northern Europe and eastern US. Conversely, northern Canada, Greenland and southern Europe are prone to cold and dry winter conditions.

For Met Office information about the NAO see https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/north-atlantic-oscillation

Recent Climatology –  SW England

October to the 18th: Temperatures have been averaging around 11 Celsius or between 0.5 and 1 Celsius BELOW the 30 year average. Rainfall shows between 50 and 80% of the average, thanks mostly to the four wet days at the start of the month and mainly the 2nd and 3rd. Sunshine has so far been and near or slightly below average.

This follows drier than average September and a wetter summer with generally near normal temperatures.

River flows in September 2020 were near or slightly below normal across the SW and groundwater levels were also near normal in the eastern parts of SW England. Details can be found in the September 2020 Hydrological summary PDF 

The reservoir levels in the SW of England (16th August) were above average as of the 11th of October.

Global Flood Awareness System. October forecast for Oct to Jan has above normal flood risk for much of the UK and Ireland. (Orange below normal Blue above).

Details of soon to be implemented improvements to the system can be found the the following URL https://www.ecmwf.int/en/about/media-centre/news/2020/new-upgrades-deliver-step-change-improvements-flood-forecasting

Atmosphere: Predictions.

A:  1: Stratosphere

Stratosphere polar vortex is forecast to strengthen towards winter mode as shown by the ECMWF 30hPa height and temperatures for October 18th 1200UTC and forecast chart for 28th October 2020.

A: 2: Upper Troposphere

October 6th data for CFSv2 200hPa contours for November 2020 to January 2021  shown in top row along with the anomalies from CFS (middle row) and the NMME anomalies (lower row). Forecast is for above normal heights but with an increase in jet flow during January.

B: Lower Troposphere:

A selection of  November solutions using October 2020 data are shown below.

Top row temperature anomaly and lower row precipitation anomaly. 

CFS2 NASA ECMWF NMME for November 2020
WMO ensemble data for November 2020 : WMO BoM CMC and DWD
WMO ensemble data: Beijing Moscow Exeter and Toulouse 

A selection of  December to February (winter) solutions using October 2020 data are shown below.

Individual months, top row temperature anomaly and lower row precipitation anomaly. 

NMME DJF
NASA DJF
ECMWF DJF
CFS2 E3 data DJF
WMO super ensemble DJF
Beijing
BoM Melbourne
DWD Germany
Montreal Canada
UKMO
Toulouse MF
Korea KMA

C: Comparing the output of seasonal models for July August September 2020, based on June  2020 data.

For graphics and details see Verification review 2020 Jul Aug Sep

Temperature forecast for the three months had the correct idea even the suggestion of the colder and warmer areas

Rainfall: The idea that the south could see one wetter month was correct and there were hints to wetter than average in places but overall not an especially helpful forecast

Models monthly:
Temperature: ECMWF BOM CMC TOKYO and Washington(WMO) had some idea of the cold July and warmer August.
Rainfall: NMME UKMO and CMC had hints at parts of the correct sequence

Scoring for three month season (from text if available) will attempt to state good, fair, poor or no signal.

Despite some models scoring good few had the monthly sequence anything light right.

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

2. Forecast. SW England.

Remainder of  Autumn 2020 (November) 

Temperatures are likely to be near or slightly above the 30 year average (1981-2010)

Rainfall more likely to be slightly below normal than above across SW England (confidence low)

November climate: 1981 to 2010 average mean temperature 8 or 9C°C.  Average 1981 to 2010 rain 60 to 100mm East of the moors, 100-200mm west of the moors but over 250mm over the moors.

Winter (2020 December 2021 January February).

A milder than average Winter in indicated as well as each month being near normal or milder than average in most of the data. There is, however, a chance that December could be very close to average and a smaller risk that February could be a little colder than average.

Mixed rainfall indications with some of the wetter model solutions being cancelled out buy the drier ones in the WMO super ensemble. Overall though it seems more likely that total Winter rainfall may end up above average. There is a signal for the first half of Winter to be drier than average but the latter part could be much wetter than average and this may lift the overall winter total to be above average although the number of rain days could be below average. Below average snowfall seems likely – snow most likely confined to higher 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.

Spring  (2021 March April May) limited data.

Milder than average temperatures seem likely for the season although March and April could see values closer to normal and May could be significantly milder than average.

Rainfall near or a little below average for the season although March could be 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.

3. Caution.

Experimental Long Range Forecasts do not have a good success rate. 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

4. References.

SST anomaly NOAA Remote Sens. 20146(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

Stratospheric Diagnostics from Japan Met Agency and ECMWF via  Free University Berlin

Climate data from The Met Office UK and NCEP USA

Review and Experimental Long Range Forecast for SW England. September 2020.

Published 19 September 2020.

GDPR statement: Please note that the author of this blog does not set cookies but the host “wordpress.com” sets multiple cookies which are outside of the authors control. You can view their cookie policy here. 

1. Influences.

Changes in sea temperature

Atlantic equatorial sea temperatures remain warmer than climatology as is the area area around the UK, Norwegian Sea and Baltic. Higher than average sea temperatures in the Gulf of Mexico, apart from the cool area near the NW coast of Florida (due to storm Sally) may aid the development of current potential storm “Beta”

Colder sea temperatures in the East Pacific just south of the equator show the La Nina has strengthened.

The tropical north Atlantic is forecast to remain slightly warmer than average through to at least February 2021 (See Met Office graphic above).

Wikipedia states that “The 2020 Atlantic hurricane season is an ongoing tropical cyclone season that has featured tropical cyclone formations at an unprecedented rate. So far, it has featured a total of 24 tropical cyclones, 23 named storms, eight hurricanes, and two major hurricanes.[nb 1] With 23 named storms, it is the second most active Atlantic hurricane season on record, behind only the 2005 Atlantic hurricane season. It is also only the second tropical cyclone season to feature Greek letter named storms, with the other season again being 2005.

Wikipedia track map
Images and time line from Wikipedia

In the Pacific sea temperatures continue to trend towards cooler / La Nina conditions which may now last until mid to late Spring 2021 before returning to neutral conditions.

The North Atlantic Oscillation index (shown by a 500hPa index in the image below) turned positive at the start of August and heralded the drier and warmer weather. The index turned negative in mid August a forerunner of more unsettled and cooler weather. The positive phase is forecast to come to an end by in the last week of September as Atlantic mobility returns.

Recent Climatology –  SW England

September to the 19th: Temperatures have been averaging around 16 Celsius or between 1.5 and 2 Celsius above the 30 year average. There has been above average sunshine and rather low rain totals – typically less than 10mm recorded so far.

This follows an average to slightly warmer summer – June and August were warmer but July was slightly colder than average. It was also a very wet summer in terms of rain total, although July was drier in SW England.

River flows in August 2020 were above normal across the SW and groundwater levels were also above normal in the eastern parts of SW England. Details can be found in the August 2020 Hydrological summary PDF 

The reservoir levels in the SW of England (16th August) were above average as of the 13th of September.

Global Flood Awareness System. August forecast has above normal flood risk for the UK except perhaps inn the south. (Orange below normal Blue above).

Atmosphere: Predictions.

A:  1: Stratosphere

Stratosphere is transitioning towards winter mode as shown but the ECMWF 50hPa height and temperatures for 18th 1200UTC and forecast chart for 28th September.

A: 2: Upper Troposphere

CFSv2 200hPa contours for October to December 2020  shown in top row along with the anomalies from CFS (middle row) and the NMME anomalies (lower row). Forecast of above normal heights more especially in the over western Europe in November and indication of stronger contrast in the north Atlantic in December.

B: Lower Troposphere:

A selection of  October to December solutions using September 2020 data are shown below. Three month season and individual months, top row temperature anomaly and lower row precipitation anomaly. 

NMME
ECMWF
CFS2
NASA

Selection of WMO data including the WMO super ensemble. Full set from http://www.weather-info.co.uk/wxsvc/seaslatest.html

WMO super ensemble probability
UKMO
BoM Australia
BCC China
Brazil
Tokyo
Moscow

For the Winter period December 2020 to February 2021.

NMME
CFS2
ECMWF
NASA
WMO super ensemble

For Spring 2021, March 2021 to May 2021.

NMME
NASA

C: Comparing the output of seasonal models for May June July 2020, based on April  2020 data.

For graphics and details see Verification review 2020 Jun Jul August

Comment: 040920 The idea that June and August would have the higher warmer anomalies in the south was correct, but the rain forecast was poor except perhaps for August in the south.

Scoring attempts to state good, fair, poor or no signal for the three month as a whole.

Comment 040920: Monthly data did not imply the correct temperature sequence in any model – several models got the idea of less rain in the south in July.
Season: Temp: To be correct near normal but above across Midlands and E/SE England and parts of W Scotland. Rain: needed to show above average rain except N Scotland and SE England.
1. Russia: Temp poor. PPN fair.
2. USA – CFS2 : Temp fair. PPN poor .
3. UKMO Contingency: Temp good . PPN fair .
4. UKMO : Temp fair . PPN Good for N and SE elsewhere poor . PMSL poor
5. USA – IRI : Temp good . PPN fair .
6. KMA APCC : Temp good . PPN poor/no signal .
7. JMA : Temp good . PPN poor . PMSL poor
8. NMME : Temp good . PPN poor .
9. WMO : Temp good . PPN poor .
10. BCC : Temp good . PPN poor .
11. NASA – Temp good . PPN fair .
12. Brazil:
13. CanSips : Temp good . PPN poor .
14. SAWS: :
15. Copernicus Temp good . PPN poor . PMSL poor
16. ECMWF Temp good . PPN poor . PMSL poor
17. MF Temp good . PPN poor . PMSL poor
18. JAMSTEC: Temp good . PPN poor .
19:
20: CMCC Temp poor . PPN poor . PMSL poor
21: DWD Temp fair . PPN fair . PMSL poor

2. Forecast. SW England.

Remainder of Autumn 2020 (October November) 

Temperature are likely to be near or slightly above the 30 year average (1981-2010) October could see values closer to the average than in November.

Rainfall forecast lately have been poor and continue to be split for this period between drier and wetter solutions roughly 40% wetter/drier and 20% near normal. The start of October seems likely to be unsettled and rainfall for the month may well be near normal (wetter in the N of UK). November also probably near or a little above normal rainfall.

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. Autumn 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. October and November have similar number of rain days and totals range from around 70mm east of the moors to over 200mm over the moors.

Winter (2020 December 2021 January February).

A milder than average Winter in indicated as well as each month being near or milder than average. Caution models tend to be poor at picking colder types.

Mixed rainfall indications but Winter probably having above average rainfall and below average snowfall. There is a stronger signal for December being wetter than average compared to other months but February could also be wetter than average which is at odds with the data a month ago and illustrates the uncertainty. Below average snowfall seems likely – snow most likely confined to higher 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.

Spring  (2021 March April May) limited data.

Milder than average temperatures seem likely for the season although March and April could see values closer to normal. Rainfall possibly below average in March but above in other months, hence above average for the season.

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.

3. Caution.

Experimental Long Range Forecasts do not have a good success rate. 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

4. References.

SST anomaly NOAA Remote Sens. 20146(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

Stratospheric Diagnostics from Japan Met Agency and ECMWF via  Free University Berlin

Climate data from The Met Office UK and NCEP USA

Experimental Long Range Forecast for SW England July 2016 issue.

Published 19 July 2016.

Potential influences that might affect the forecast:

SEA TEMPERATURE.

anomnight.7.18.2016

NOAA Night time sea surface temperature anomaly 18 July 2016

The cooler than normal North Atlantic sea temperature area has expanded towards the UK again due to more frequent W or NW winds. This may impact on day time temperatures in some western parts of Eire and the UK. Note though that sea temps to the SW of UK remain above normal so winds from SW or S probably warmer/milder than average. (Sea Temperature in the west Atlantic including the tropical areas are above normal and this may impact rainfall amounts through late summer and Autumn).

El Nino/La Nina conditions are neutral at present with La Nina conditions predicted to develop over the next few months.

figure1

IRI/CPC probability of occurance

ECMWFNina

ECMWF forecast sea temperature anomaly Nino 3.4 location

The duration and strength of the La Nina is uncertain consequently the potential impact on the rainfall as shown by the IRI statictical relationship may be unreliable at the start of Autumn. Consequently the drier than normal signal could be much weaker than shown in Graphic 1: below.

SONnina

Graphic 1: IRI probability for drier/wetter/normal during La Nina event September to November

For the winter months the relationship is not so clear as in Autumn, slightly favouring normal to below normal rainfall across much of SW England apart from N Devon and Somerset which have similar probabilities of each category..

DJFnina

Graphic 2: IRI probability for drier/wetter/normal during La Nina event December to January

MODEL OUTPUT.

A text summary of the seasonal model output from the UK, various USA, Canada, China, Japan, Russia, Korea, Brazil and South Africa can be seen in the UK and Eire summary at www.weatherservice.co.uk

200hPa heights predicted by CFS2 and NMME to be above normal but hints at enhanced zonal pattern in September and October but not in November. This may steer rain bearing weather systems further north and away from SW England. There is some support for this from other models.

200SON

September, October and November 2016 200 hPa. Top CFS2 anomaly. Middle NMME anomaly. Bottom CFS2 mean. Data 7 July 2016.

200nmmeDJF

December January and February 200hPa CFS2 and NMME anomaly and CFS2 ensemble mean

The anomalies suggest lower than normal heights during February, perhaps hinting at slow moving low pressure centres across or near the N of UK.

Looking at the NMME near ground level output for Autumn and Winter a trend to mild conditions is shown but with a hint of less mild temperatures in February. Rainfall anomalies favour less wet conditions in parts of the S and E of England compared to elsewhere.

NNMESON

NMME September October and November top Temp anomaly Bottom Precipitation indicator

DJFNNME

NMME December January February Top temperature anomaly Bottom PPN indication

 

Forecast:

Remainder of Summer (August and possibly into September) 2016:

In summer the  main risk of heavier rain can come from showers or thunderstorms. These can give locally high rain totals but may not be widespread across a region. Despite this risk it seems more likely than not that August and parts of September will see some long dry spells. The S and E of the Region in particular may have below normal rainfall compared to nearer normal elsewhere.

In most parts the temperature for August and for a time in September is probably going to be  above normal although some western parts may be  nearer normal.

(1981 to 2010 average mean temperature  15°C  to 17°C or more 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. Average 1981 to 2010 rain for August 100-150mm over the moors, typically 60-100mm but locally E of Dartmoor and inland in Somerset 40 to 60mm)

Autumn  (most of September, October and November) 2016:

The temperature for the season probably above normal. September probably a little warmer than normal, October nearer normal and November is expected to be especially mild.

Rainfall probably near normal for the season as a whole but parts of SE  Devon and Dorset below  normal. September and some of October possibly drier than normal but with a wetter than normal November for Cornwall, N and W Devon but perhaps not in SE and E parts of the Region.

La Nina conditions expected to become established in the Pacific in the Autumn which may start to influence global weather patterns. For the SW of England this implies drier than normal conditions may develop through the Autumn which is consistent with at least some of the model forecasts.

 (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  (2016 December 2017  January and February – :

A mild winter is most likely, although February may see temperatures nearer normal. Near normal rainfall across the SW is more likely, especially in the N and W but with a chance that SE and E parts of Devon and Dorset might be a little drier than normal for the season as a whole. There is a chance that February may see above normal precipitation totals across the region. Below normal snowfall is more likely than above normal which means just a little snow accumulation over the moors but not much elsewhere.

(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)

Caution:

Experimental Long Range Forecasts do not have a good success rate. The data used for the above forecast summary and brief verification of previous Long Range Forecast summaries can be seen at   http://www.weatherservice.co.uk

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

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/

Stratospheric images prepared by Freie Universität Berlin using European Centre for Medium Range Weather Forecasting data supplied by Deutscher Wetterdienst

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

CFS2  info

 

 

Experimental Long Range Forecast for SW England

Published 19 March 2016 (layout change – Forecast then influences) .

The remainder of Spring (April and May) 2016:

April is likely to have unsettled/changeable weather with spells of rain or showers and shorter drier intervals, hence above normal rainfall accompanied by near or a little above normal temperature. For May a less clear signal, though rainfall is again more likely to be above normal than below normal. This does not rule out some drier spells and parts of Dorset and SE Devon probably near normal rainfall rather than above normal. The temperature in May probably a little above normal.

(1981-2010 average mean temperature roughly Apr 8 or 9°C  May 11 or 12°C but a few degrees cooler over the moors. Average 1981 to 2010 monthly rain April and May 60 to 80mm locally up to 150mm over the moors but 40-60mm around Exeter and widely across Somerset levels.)

Summer  (June July August) 2016:

Probably a typical summer with rather mixed weather, with no strong indication for a long dry summer despite some signs of above average pressure. Rainfall near normal or a little below normal in June and July  (a little more likely to be below normal in July than June) but above normal in August. There is chance that July may see some longer drier spells.

Temperature near or a little above normal in parts of E Devon, Somerset and parts of Dorset but cooler than normal Atlantic sea temperatures may result in near or below normal temperatures elsewhere. This could be due to reduced day time maximum temperature rather than overnight minimum temperatures. July may be a slightly warmer month than June or August compared to the average, which is not unusual.

(1981 to 2010 average 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  (September October November) 2016 with limited data:

Overall temperature for the season near normal, perhaps a little below at first then becoming above normal. Rainfall near normal for the season but in September a higher risk of above normal rain than below normal.

La Nina may conditions may become established in the Pacific by Autumn which may start to influence global weather patterns. For the SW of England this implies drier than normal conditions may develop. The onset of this potential impact is very uncertain.

 (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)

Caution:

Experimental Long Range Forecasts do not have a good success rate. The data used for the above forecast summary and brief verification of previous Long Range Forecast summaries can be seen at   http://www.weatherservice.co.uk

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

Potential influences that could affect the forecast.

Sea temperature.

SST170316

NOAA/NESDIS night time sea surface temperature anomaly 17 March 2016

Typically the coldest time of the year for sea temperatures around the UK but note the further cooling of North Atlantic temperatures relative to normal. Long range forecast systems tend to retain a colder than North Atlantic right through the summer months, much like last year. The impact of this is a likely reduction in temperatures, especially maximum temperatures, in at least the western half of the UK – assuming winds from a westerly direction predominate.

The strong El Nino in the Pacific continues but forecast systems tend to weakening this by summer with potential La Nino conditions for the Autumn and Winter 2016/17 as shown by the graphic below.

ENSO0316

Nino 3.4 Sea Surface Temperature Anomaly prediction comparison

Rainfall probabilities linked to El Nino.

IRIelninoAMJ

IRI rainfall probabilities during El Nino for April May and June (Dry Wet Normal left to right)

The El Nino linked probabilities for April May and June suggest above normal rainfall most likely but nearer normal in parts of Devon, roughly Torbay and eastwards, also in Dorset.A graphic for the summer months is not included due to the weakening El Nino.

There is a chance that La Nina conditions develop in the Pacific later this year. The graphic below shows the Autumn rainfall probabilities based on IRI research for a well established La Nina.

SONnina

IRI rainfall probabilities if strong La Nina develops in time for Autumn – not very likely.

Changes in the Stratosphere.

The anticipated Sudden Stratospheric Warming arrived too late to influence the winter pattern with a major warming event starting during the first week of March, roughly at the same time as High pressure developed across the UK. The 50hPa analysis for the 17th March is shown below for comparison with earlier publications.

50hpa170316

ECMWF 50hPa analysis by FU Berlin

200hPa predicted anomalies.

z200com0316

200hPa CFS2 mean and anomaly

NMME mean not available. CFS2 suggests above normal heights over UK area except perhaps in April. A slightly enhanced westerly jet is predicted in the NW Atlantic in May but with ridging over the UK area.

Conflicting model output.

nmme0316

NMME March 2016 1 deg GRIB data.

The North American Multi Model Ensemble (NMME) which includes CFS2 data, suggests slightly above normal temperatures for SW England and a drier than (model) normal June and July. CFS2 is not so clear cut, some output did suggest drier in SW England in July but the set shown below implies near normal rain although better agreement for April. The data for CFS2 used in the NNME had June drier in the SW. Temperature anomalies show below normal across SW England in the summer month otherwise near average +/-0.5C which is not far from the NNME anomalies. Other models to indicate a risk of cooler summer temperatures include UK Met Office and Beijing Climate Centre and these centres also suggest that slightly wetter than normal is more likely than below normal.

Many long range forecast models seem fairly poor at picking drier than normal months.

 

CFS20316

CFS2 averaged 6 to 16th March. Left temperature anomaly. Right precipitation anomaly.

 

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/

Stratospheric images prepared by Freie Universität Berlin using European Centre for Medium Range Weather Forecasting data supplied by Deutscher Wetterdienst

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

CFS2  info

 

UK Autumn 2015 and Winter 2015/16 weather outlook

Can the weather for SW England be forecast for Autumn 2015 and Winter 2015/16?

Many International National Weather organisations issue experimental long range forecasts for up to a year ahead using some of the most powerful computers available.

Are the forecasts any good? The answer is not very good but improving. Combining output from many sources led to the conclusion that summer 2015 would be drier in June and then turn wetter and that temperatures would be near normal. This forecast turned out to be a good guide.

For the coming Autumn and Winter there are two complicating factors.

1: The El Nino, in the Pacific Ocean, is likely to last into the middle of 2016 and can impact on Global weather. The International Research Institute for Climate and Society (IRI), a joint USA project between Columbia University and National Oceanic and Atmospheric Administration (NOAA), has published research which implies that SW England may have normal or above normal rainfall this winter (see map).

Featured image

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

2: Unusually cold North Atlantic Sea Temperature – shown by the sea temperature anomaly map below. The forecast models tend to hold on to these cold ocean temperatures well into winter. This implies that winds from the west or northwest may be cooler than in typical years.

Featured image

NOAA USA National Environmental Satellite Data and Information Service (NESDIS).

Experimental Forecast based on available August 2015 data.

The forecasts, which should take account of the above factors, suggest that the weather for SW England may be quite unsettled in Autumn and for the start of Winter.

Temperatures on average are likely to be near normal or above normal through to January 2016. Consequently, snow risk is reduced until nearer the end of winter, which is not unusual. This does not mean there will be no frost but suggests less frequent frost.

Rainfall is likely to be above normal for Autumn and Winter, although September and February may have less precipitation. The forecast for above normal rain agrees with the statistical El Nino probabilities as published by IRI.

Prepared August 2015 weatherservice.co.uk