SW England Experimental Long Range Forecast

SW England Seasonal Forecast January 2016 to May 2016 and first look at Summer 2016 – published 17 December 2015.

This attempt at a Regional Forecast for SW England is based on long-range experimental forecasts for the period January through to May 2016 plus some of the earliest data for Summer 2016. This has been prepared using  available data up to 17 December 2015. The summary forecast aims to test if any usable regional forecast can be made from internet model data. The forecast should not be used for any other purpose. A brief verification summary is routinely published at http://www.weather-info.co.uk/wxsvc/Verification.html

Changes to Atlantic Sea Temperature


NOAA/NESDIS night time sea temperature anomaly 14 Dec 2015

The cold sea temperature anomaly in the North Atlantic remains although has reduced around 45 to 50 Deg N with above normal values near the UK. Long range models continue predict a cold anomaly is likely to last well into 2016 perhaps mostly north of 55 Deg N. The strong El Nino is shown clearly in the Pacific. The nino3.4 area is predicted by models to cool to neutral conditions in mid 2016.

Statistical rainfall probabilities during El Nino.


IRI January to March precipitation probabilities for drier, wetter and normal during an El Nino event


IRI Spring (March to May) precipitation probabilities for drier, wetter and normal during an El Nino event.


Pressure patterns Jan to May 2016.

NMME 200hPa ensemble mean output was not available at the time of writting but available data hints at return to normal rather than enhanced strength jet flows from some time in January. There were hints of above normal 200hPa heights developing over the N Atlantic. Some output suggests lower than normal 500hPa heights over Central and Northern Europe.

Sea Level Pressure output suggest higher than (model) normal pressure on average to the SW of the UK but with lower pressure to the N and E especially over central and N Europe hence reducing the probability of a long period of cold easterlies. Not clear how suggested above normal pressure to the SW of UK in some model output fits in with the above normal rain.


Experimental forecast for SW England.

Remainder of Winter (January and February 2016):

Mostly unsettled, perhaps less frequent bands of rain and gales in February than in January.

The mild weather in December looks like continuing into the start of January. Temperatures then probably trending nearer normal for a time but with a risk of colder spells later in January and Early February before milder types return (confidence in this detail is not high). Rainfall is expected to be above normal, especially in January perhaps less so in February. The main risk of snow is chiefly for the moors during the possible colder spell later Jan and early Feb. There is no strong indication from the models for an unusually cold end to winter and the risk of February being colder overall has reduced.

(Typical winter 1981-2010 average mean temperature values for lowland areas 7°C in the West and 5°C in the East.  Dec and Jan typically wetter than February on average. 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 2016 (March April May):

On average temperatures are likely to be above normal overall, but perhaps only slightly. There remains a suggestion that April may see nearer normal values and hence be a colder month.

Precipitation near or above normal for the season seems most likely which fits with the statistical relationship between El Nino and a wetter than normal Spring across parts of SW England. There continues to be some indication of above normal precipitation in March and April and near or below normal rainfall in May.

(1981-2010 average mean temperature 9 or 10°C, roughly Mar 7 or 8°C Apr 8 or 9°C  May 11 or 12°C. Average 1981 to 2010 rain 200 to 300 mm.)

Summer 2016 (June July August) limited data:

Temperatures above normal, most likely in June and July and less likely in August. Rainfall near or above normal. No strong indication for a drier or colder than normal summer.

(1981 to 2010 average mean temperature 14 or 15°C in many areas to 16 or 16°C in main urban areas, locally east of the moors and more widely in Somerset – average max temps 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)


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 foreecast summaries can be seen at   http://www.weatherservice.co.uk


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


250hPa wind climatology source IRI maproom.

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


UK climate details see: