Europe Summer 2017 Forecast

This seasonal forecast for the upcoming June-August 2017 period is based on past, present and forecasted atmospheric, oceanic and ground conditions.

There are 3 main aspects I have looked at when compiling this forecast. 1) Past winter and current spring rainfall distribution. 2) sea surface temperature anomalies, particularly in the Atlantic and Pacific. 3) Current and forecasted ENSO (El Nino Southern Oscillation Index) state.

Winter rainfall distribution and anomaly is important but it becomes more important during the spring months as the amount of soil moisture content can determine level of atmospheric pressure and water vapour through soil-atmosphere feedback.

Winter 2016-17 was the UK’s driest in over 20 years.

Credit: Met Office

April 2017 was considerably drier than normal.

The UK landmass is small compared to surrounding waters and so warm and cold SSTA’s have an even greater influence on the atmosphere so we combine soil moisture with SSTA’s with the ENSO thrown into the equation to draw a potential outlook.

Note cool waters across the north North Atlantic but warmer across the central-north Atlantic extending into and around the UK caused by persistent storms south of Greenland (upwelling), high pressure nearer the UK (less disturbed).

Based on a DRIER than normal soil, currently neutral ENSO but lean towards weak El Nino LATE summer into autumn and a cold North Atlantic, warm UK SSTA configuration, I believe a drier and therefore warmer first half to summer 2017 looks likely. As is 95% of the case, rainy, cooler days can and will occur but June through mid-July should see drier, warmer days dominating thanks to higher than normal pressure both at the surface and aloft.

The CANSIPS model indicates a moderate central Pacific based El Nino but it’s peak doesn’t come till December.

Credit: Tropical Tidbits

The June-July period could resemble 2013 and possibly 2014 but to the extreme of 2006? That remains to be seen. A reminder, 2013 saw the most persistent dry, warm late June-July weather UK-wide since 2006 and 2014 hosted more persisted dry, warm weather with Glasgow’s warmest day since 2005.

A dry UK extending east into central and northern Europe suggests the strongest heights compared to normal should be Northwest and Northern Europe including northern France, Low Countries and UK and this region could see significant heat late June into July where as we could see slightly wetter, cooler conditions down into Iberia and through the Med. That doesn’t mean Spain, Portugal, across the Med Sea won’t get very hot days because they will but not in the same prolonged fashion as last year.

JUNE-AUGUST BREAKDOWN

JUNE

Based on the past, current and forecasted rain pattern and current dry ground, I expect June to still host perhaps week’s worth of cool, cloudy, wet days (spaced out) but I do expect a dominant ridge to set up shop near or over the UK or near continent (Low countries) for a week or more once or twice which could see great summer weather from Glasgow down to Paris eastwards to Berlin up into Stockholm and southern Scandinavia.

Heat is likely to be short lived over eastern Europe due to persistent blocking high pressure over western and or northern Europe.

JULY

July may see a week or more of ‘heat wave’ conditions with day after day of 23-26C and a peak near 30C across many parts of Scotland, southern England and Wales widely 25-30C but a peak of 34 or 35C in favoured south-central and southeast parts of England. Paris could near 40C.

Intense heat can be directly attributed to dry conditions and stronger than normal upper ridging. This of course is based on a dry May.

Eastern Europe may see cool, wet conditions in response to a strong, dominant western Europe high.

AUGUST

August is a more tricky month and in recent years has tended to be wet, especially on the heels of the decent June-July of 2013, 2014. The timing of any potential development of the El Nino could well determine a significant pattern chance. If there was to be an El Nino come on during say June or July, my hunch would be a cooler, wetter or at least wetter August but if it held off, I would lean towards the continuation of a warmer, drier theme.

CFSv2 June-August 2017

500mb height anomaly

Credit: Tropical Tidbits

Precipitation anomaly

Credit: Tropical Tidbits

Temperature anomaly

Credit: Tropical Tidbits

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