Signs Of Arctic Blocking And Colder Times Ahead For UK & Western Europe

Written by on December 22, 2013 in Rest of Europe, United Kingdom & Ireland with 0 Comments

Well it would appear we may have a much anticipated hemisphere wide pressure shift on the way as modelling, the NAO/AO and stratospheric temps all showing colder times ahead. North America has taken the brunt of the mid-latitude cold over the past month with far less over Europe but that may be about to change as we head towards January with the Arctic Oscillation going negative for the first time since mid-November and that was brief and barely noticeable on the chart.

This fits well with my long range outlook with a colder trend towards Christmas although the storminess has held on a tad longer than expected but only by about a week. The storminess in more recent times has trended colder, particularly on the backside of the lows, drawing air in from Greenland. Sleet and snow has affected Northern Ireland as well as parts of the UK in the last 36 hours and it continues to do so tonight as colder air gets entrained into the backside flow of the latest low.

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As we head towards New Year, the storminess continues with brief mild surges ahead of lows, followed by a colder backlash but it’s once we enter January that things should get more interesting with a slackening off of jet stream winds as pressures build over the high latitudes while they lower underneath.

Check out the latest GFS  ‘AO’ ensemble.


Importantly for a trough position over WESTERN Europe, the NAO is also showing a negative trend.



Notice that both indices haven’t really been all that negative over recent months yet the US and Canada has been very cold. Other players have taken charge such as the EPO and WPO and as we head into true winter, so the NAO/AO will play a bigger role and thus may reinforce an already cold North America pattern. What a difference compared to last year when the front end of winter was very mild.

Here’s the CFSv2 which shows strong blocking building over the pole down into north, central Greenland which suggests lowering heights and eventually and pooling of cold (arctic) air Western Europe with ridging in the east.

Week 1-2


According to the CFSv2, notice that it’s the period after Dec 29 when the block really sets up. These passing lows by the way, are helping lower heights between North America and Europe. This hype active storm train is laying the ground work for a colder pattern in January for sure.

In week 3-4 below, there’s a good high latitude block set up with ridging hooking up between Alaska, Greenland and eastern Europe which traps the cold pools over Western Europe and Eastern North America.

Week 3-4


As a confirmation. Check out the very latest stratospheric temperatures.

Here’s the initial which shows a nice circular and strong polar vortex centred directly over the arctic.


By 240 hrs there is strong warming over Siberia which forces the vortex to stretch, most certainly dislodges at least pieces of arctic air south but as time progresses, it will be interesting to see whether this strong warming at 10mb begins to push towards the pole. Even this warming around the edges which affects the vortex, backs up the colder trend. Another thing to keep in mind is that 240 hrs away in still 10 days out and usually when we get a stratospheric warming event, there’s a 10 day lag before the arctic air rushes into the mid-latitudes. Point is, we should turn colder by New Year but this may support a longer term cold trend.


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