Official UK & Europe Winter 2016-17 Forecast

Today’s winter forecast is based on all current global atmospheric/oceanic drivers in place, their current status and model projection.

Following the record tying strongest El Nino in history last winter in which global temperature has been at record levels for some 16 months as a consequence, the ENSO is back NEUTRAL although record warmth is still be felt.

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Background Behind The Forecast

Coming off a super el nino = weak polar vortex = persistent high latitude blocking = record low arctic sea ice = fast siberian snowcover growth…

Powerful El Nino’s create a sharp rise in global temperature and like heating up a house, once it’s warm and you turn off the heat source, it takes time for it to cool. However, there is evidence which shows a sharp drop in global temperature once the ENSO flat lines. Are we seeing the trend reverse already?

The polar stratosphere has been unusually weak this autumn and slow to cool, so much so that we’ve seen a rare split October in the polar vortex circulation.

Credit: chorleyweather.com

Credit: chorleyweather.com

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This has made for a strongly negative Arctic Oscillation. This slowed the reformation of Arctic Sea Ice and so we’ve observed widespread and strong high latitude blocking which has helped Siberia become snow covered unusually early and fast.

Credit: AER

Credit: AER

Interesting to see the reflective cold over that growing snow cover, especially given the global warmth of the last 16 months! Top (high latitude) down (low latitude) cooling?

Credit: AER

Credit: AER

Arctic sea ice remains record lowest extent for the end of October.

n_daily_extent_dthumbn_stddev_timeseries_thumb

Note the incredible expanse of open water on the Eurasia side of the ocean, likely due to persistent blocking above.

The Super El Nino occurred following the peak of solar cycle 24 which is well off the maximum and below the half way point to the minimum which should occur around 2020.

Credit: NASA

Credit: NASA

Sunspot activity this year is said to be quietest since 2010.

What’s interesting is that Eurasian snow cover is at the greatest land coverage for late Oct/Nov in some 40 years.

Atlantic & Pacific Sea Surface Temperature Anomaly

While all the above is positive factors to a cold winter, my concern is with the North Pacific and Atlantic sea surface temperature anomaly which hasn’t changed all that much over the last 3 years. In saying that the warmth in the North Pacific and cold in central North Atlantic is less aggressive but this SSTA profile isn’t particularly favourable for bringing a cold pattern right to Western Europe.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Warmth surrounding the UK and cold south of Greenland supports an Atlantic trough, UK ridge.

CFSv2 Dec-Feb 2017 forecast

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The exceptional warmth over the Gulf of Alaska back in 2013/2014 was likely the primary driver to a cold Central/Eastern US, Canada winter but this enhanced the Atlantic jet stream which kept Western Europe mild and stormy. Less warmth in the Gulf of Alaska and less cold in Atlantic may help us out and may have less low pressure/trough influence over the Atlantic this year.

So what can we expect?

Well for one, I expect to see strengthening of the polar vortex and regrouping over the pole during November but not to anywhere near the same levels as last year. I believe a less cold stratosphere will be easier to break and with slow ice build up on the Eurasia side of the Arctic Ocean along with high Siberian snow cover, this should favour a more negative Arctic Oscillation supporting frequent high latitude blocking and cold into Europe.

This year’s SSTA profile may not be perfect in the northern end of the oceans but other factors including that lack of sea ice, weak PV which is more likely to trigger a ‘sudden stratospheric warming event’, could all override the feedback potential of the ocean and drive a strong -AO/NAO which drives bitterly cold Siberian/Arctic air all the way to Ireland this winter.

Europe overall

Given all of the above, I see Europe enduring a colder-than-normal winter with several significant blasts of Arctic/Siberian air. This has the potential of rivalling some of the cold experienced over the continent back in 2011-12 and 2012-13 which was when we last saw a true SSWE. The UK and Ireland largely missed out in both winters 2011-12 and 2012-13 except for a 10 day stretch in January 2013 following the SSWE.

With a lot of cold expected to dam over the heart of the continent, I expect a southerly diverted storm track which could see a rather stormy, turbulent winter for Iberia, southern Europe and the Med with significant mountain snows as a warm Med meets incoming Siberia/Arctic air.

UK/Ireland

As for the UK and Ireland, I believe we may be leaning more on the cold side of average but the Atlantic could come and go more often than we would like. Yes I cannot ignore the possibility of a frigid Europe but mild UK with a blocking high sitting over the UK while a trough shivers our neighbours on the other side of the North Sea like seen in winter 2012-13.

The CFSv2 monthly is going for a warm winter. Would take the below with a big pinch of salt!

December 2016

Credit: Tropical Tidbits

Credit: Tropical Tidbits

January 2017

Credit: Tropical Tidbits

Credit: Tropical Tidbits

February 2017

Credit: Tropical Tidbits

Credit: Tropical Tidbits

3-month mean 2m temperature anomaly.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Month-by-month breakdown

Timing cold spells this far out is impossible but in the below monthly breakdown I will attempt to do just that.

December

Following a pullback of the AO/NAO and strengthening of the polar vortex in November, we could see the return to a negative in early to mid December following a warming of the stratosphere. Significant cold across much of Europe including the UK is expected before Christmas.

January

Will much of Europe remains cold with snow covering a large proportion of the continent, the UK may see a milder Atlantic spell through early to mid January. The second half of the month however could see a major push of Siberian/Arctic air westwards reaching the UK in response to a major sudden stratospheric warming event.

February

The influence of a sudden stratospheric warming event would likely continue into February with a prolonged spell of cold following heavy snowfall for much of Europe INCLUDING the UK and Ireland.

All in all I believe the second half of winter 2016-17 will be worst and February is likely to be the coldest month.

See today’s video.

Feel free to add your comments and let me know your thoughts!

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