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).

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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.

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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

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