Published 18 May 2022.
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A: Overview
1. Influences.
Changes in sea temperature

Sea temperatures in the Northern Hemisphere Atlantic, North Sea, Baltic, Mediterranean and Gulf of Mexico are warmer than climatology for mid May. Parts of the Eastern Pacific are colder than climatology although other areas continue to be warmer.
The Tropical Atlantic sea temperature warmed more than expected in April but are forecast to be near or slightly cooler than average through to Autumn 2022 which is slightly less cool than the forecast issued last month. (see Met Office graphic below).

Forecasts suggest that tropical Pacific Sea Surface Temperatures (nino3.4) are likely to have similar anomalies through the remainder of Spring 2022 with weak La Nina conditions forecast to persist through the remained of 2022.

The North Atlantic Oscillation index (500hPa index shown below) turned negative in late April and for the first week of May but then turned positive. Weakly positive are forecast to continue over the next two weeks. Positive values imply weaker westerly winds across the Atlantic towards Europe or a reversal to easterlies more typical of blocked weather patterns although a weak signal is inconclusive.

2. Recent Climatology
SW England:
To the 18th temperatures have been a little above average despite below average sunshine and rainfall has been slightly below average in the South and East of the region but near average in the North and West.
UK:
Met Office provisional Temperature and Rainfall anomalies for February to April 2022 are shown below:

Copernicus, European temperature and rainfall anomalies and global temperature anomaly for April 2022. (30 year period 1981-2010). Spain in particular was wetter and colder than average during March.
UK River flows and ground water levels in April 2022 reflected the drier weather and were below average. Details can be found in the March 2022 Hydrological Summary

Global Flood Awareness System – GloFAS – flood risk for May to August suggests the river flood risk is near or below average across the UK. This does not include “flash” floods caused by thunderstorms.
Reservoir levels, according to SW Water, slightly below the long term average across SW England as of 8th May 2022.

B: Forecast data:
1. Stratosphere:
The stratosphere remains in “summer” mode.
2. Upper troposphere:
CFSv2 200hPa contours (top row) and CFSv2 anomaly (middle) and NMME (lower row) for summer (June July August) 2022, although hints at a transition to lower heights for August. Suggestion of reduced zonal flow in the Atlantic west of the UK early in the summer but less so later. The higher than average heights forecast could be due to higher than average temperatures in depth through the atmosphere?.

3. Lower Troposphere:
Selection of model solutions for summer June July and August 2022 using May data are shown below.
May graphics can be viewed at http://www.weather-info.co.uk/wxsvc/seaslatest.html
Top row temperature anomaly and lower row precipitation anomaly




Source Data WMO low resolution super ensemble for June to August 2022 based on April data. Full data at http://www.weather-info.co.uk/wxsvc/seaslatest.html
Top row temperature anomaly and lower row precipitation anomaly. Left image three month mean then individual months.

Individual members of the WMO super ensemble.













Limited graphics for Autumn (September October and November) available at http://www.weather-info.co.uk/wxsvc/seaslatest.html
C: Comparing previous output:
February to April 2022 – based upon January 2022 data.
Summary – 200122 –
All models suggest above normal temperature values for the three month average. A few models have March and/or April near normal. Precipitation forecasts (often more variable and less reliable) suggest above average values across the North or NW and below average across the south or SE of the area (UK and Ireland). The strongest signal for above average precipitation is in February for western and northern areas and the strongest indication of drier than average is in March and in a few models April. The drier signal is associated with higher than average pressure.
Review of details looked for in seasonal forecast based on observations.
Temperature: Above normal but April nearer normal
Rainfall: N Scotland above or near average elsewhere wetter Feb largely offset by drier March and especially April
Sunshine: mostly above normal due to sunnier March and near average other months..
Pressure: Slightly above average (SW) but N Scotland below in Feb.
Comment on summary: Overall a good summary hinting at above average pressure and some skill pointing to the wetter and drier months. WMO did fairly well with rain sequence.
Scoring will attempt to state good, fair, poor or no signal.
Evaluation for 3 month anomalies.
1. Russia (WMO): Temp mostly good. PPN fair .
2. USA – CFS2 : Temp good. PPN fair .
3. UKMO Contingency: Temp good. PPN poor .
4. UKMO : Temp good. PPN fair . PMSL fair
5. USA – IRI : Temp good. PPN poor .
6. KMA APCC : Temp good . PPN fair .
7. JMA : Temp good . PPN fair . PMSL good
8. NMME : Temp good. PPN fair .
9. WMO multi : Temp good . PPN fair .
10. BCC : Temp good. PPN good (monthly data good).
11. NASA : Temp good. PPN poor .
12. Brazil: Temp poor . PPN poor .
13. CanSips : Temp fair. PPN fair .
14. IMME part of Copernicus no longer included.
15. Copernicus Temp good . PPN fair . PMSL fair
16. CMCC Temp good . PPN poor . PMSL good
17: DWD Temp good . PPN poor . PMSL fair
18. EC Temp good . PPN poor . PMSL fair
19 JMA Temp good . PPN fair . PMSL fair
20 UKMO Temp good . PPN fair . PMSL fair
21. MF Temp good . PPN fair . PMSL fair
22 NCEP Temp good . PPN fair . PMSL fair
23 ECCC Temp: good . PPN good . PMSL good
D: Text Forecast for SW England
Summer 2022 (June July August)
Temperatures likely to be above average for the season and possibly each month. Typical forecast anomalies are around 1 C above average. This suggests more warm days compared to an average summer but not necessarily hot.
Rainfall forecasts are inconclusive suggesting near normal rainfall for the summer overall with perhaps a majority hinting at drier than average over N France and parts of the S of England. Suggestion that July is the most likely month to be drier but a risk that June and August could be wetter more especially in western parts of SW England than in the East. Summer rainfall can be in form of thundery showers which can lead to rainfall totals being very uneven across a district. Should local rain totals be above average due to thundery showers it may not lead to an increase in the number of “wet days”.
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 2022 (September October November).
Good indication for above average temperatures with the strongest signal being for September but with a weaker signal for November. Rainfall probably above average for the season, especially in October but drier than average in November.
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 2022/23 (December January February). Very limited data.
Temperature forecasts suggest near or above average values. Rainfall forecast is for above average rainfall early in Winter and below average later. Snowfall like to be below average which means little if any snow for lower ground but some snow over 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.
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
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
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.