Europe December Outlook (Includes Video)

Written by on November 23, 2015 in Autumn 2015, Rest of Europe, United Kingdom & Ireland with 0 Comments

Despite the current cold blast with snow for some, frost for most, November 2015 will wind up well above normal temperature and precipitation wise, a complete flip from September and October’s tranquility.

This turnaround in November was forecasted here since back in late summer as I strongly stated that the same drivers in summer, provide a different weather pattern during autumn and different again come winter.

Europe temperature anomaly to date.

Credit: Michael Ventrice

Credit: Michael Ventrice

Notice how the -NAO/AO summer of 2015 along with a colder-than-normal North Atlantic helped bring a cool/wet Ireland and UK summer but one of the warmest across much of continental Europe. When we entered the transitional autumn period, the NAO/AO flipped positive and this presented a warmer, drier signal across Europe including the UK and Ireland for September and October.

total_obs

The NAO/AO after briefly returning negative, providing our first cold blast, will go positive into early December and that means the return of seasonable temperatures and wetter conditions.

ao_fcst

nao_fcst

A warm and wet December?

Long range modelling tends to contradict and is quite often a very poor tool for long range forecasting. You only have to look at the late October precipitation forecast for November off the CFSv2. The CFSv2 had, like September and October, a drier than normal November.

The only thing this model got right was the warmth which by the way coincides well with the global warming we’re seeing with this year’s strong El Nino. Strong El Ninos tend to produce very mild autumn’s, we saw that in 2006 and 2009. Big difference however between those years is we saw a very warm, wet winter in 06-07 but the opposite in 09-10.

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Based on all the factors and indexes and forecast projections into early December, including polar stratospheric temperature, strength and position of polar vortex, NAO/AO trend and the long range models combined, I believe an average to warmer/wetter than normal December is likely over much of Europe including the UK and Ireland with a mild and wet first half which may extend towards the 20th and week of Christmas but there’s a question mark over the period 17-22nd where there may be a major pattern change. By that I mean strat warming, Greenland blocking and colder Europe.

As is often the case during the winter months, Atlantic lows tend to drag Greenland air in on their backside and so brief cold shots along with lowering snow levels can be expected once the cold fronts. With clear sky and cool air in place once the low passes, it turns cold with frost a given during the long dark nights.

The above NAO/AO going strongly positive coincides well with the projected 50hpa stratospheric temperature profile through the next 10 days.

Day 7

gfs_t50_nh_f168

Day 10

gfs_t50_nh_f240

What to look for in the above two charts for the 50hpa level is where the warmer than normal and colder than normal is positioned. When there’s warming on the Asian side, you typically support more trough near Iceland and a +NAO but a warming in, over the pole and nearer Greenland tends to support above normal heights near Greenland and Iceland and a negative across Europe.

For Western Europe, a conducive stratospheric temperature profile and NAO/AO connection doesn’t typically kick in until mid and late winter, especially during El Nino years.

So, I’m looking at a generally mild, strong westerly/Atlantic influence on much of Europe through at least December 15th but there’s a possibility of a shift come the week prior to Christmas as the atmosphere transitions into a more winter state and the atmosphere has better response to the ocean below.

There’s a chance that December 2015 may reflect closely with December 2009 which was mild and wet through December 17th and then we saw a sudden stratospheric warming event.

Current global SSTA’s (sea surface temperatures) aren’t overly dissimilar to this time back in 2009. For cold outbreaks into Europe and especially Western Europe… YOU WANT TO SEE WARMER THAN NORMAL SST’S NORTH OF THE UK AND AROUND GREENLAND INCLUDING THE DAVIS STRAIT BETWEEN CANADA’S BAFFIN ISLAND AND WEST COAST GREENLAND. We have that!

Now

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Same time back in 2009

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Biggest difference is the much colder North Pacific and stronger El Nino. Cold pool in the Atlantic is larger than 2009 but waters are warming around and north of the UK. This is all being taken into consideration…

Notice though a cooling beginning to show on the western edge of the N Pacific warm pool! That may be significant late winter!

CFSv2 and Canadian long range shows a warm, wet December.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Canadian is the same.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

For more on the overall winter, see Winter 2015-16 Forecast

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