UK: Cold or no cold?

Written by on November 14, 2018 in Rest of Europe, United Kingdom & Ireland with 0 Comments

I have to admit that I’m struggling with the pattern and shifts over the next week or so. I’m very conflicted but here’s what I wrote in a post earlier today….

In the short 6-10 day range, cold spells are possible for the British Isles but when looking at the bigger picture and longer 2 to 3 week range, I’m doubtful about a sustained cold spell for NW Europe. In fact a very stormy spell looks more likely to me if I base the forecast on projected 10mb temperatures (stratosphere).

My reason for stormy rather than cold is fairly simple. Purely based on the forecast modelling and yes they do chop and change I know, the projected warming at 10mb within the stratosphere does potentially favour a prolonged cold spell into the mid latitudes but it’s aimed at eastern North America, not NW Europe. That’s IF we see stratosphere to troposphere coupling.

There has been a lot of noise regarding a weakening vortex but the weakening and stretching has to take a certain shape.

10mb temp now vs Nov 29th

Credit: wxcharts

Credit: wxcharts

If this warming turns out different, then my thoughts would change.

2013-14 as a prime example of what I feel could develop but I may be wrong.

A wave of warmth travelling from Siberia to Alaska draws a highly anomalous ridge up the NA west coast, into Alaska and across the WESTERN Arctic. This forces a displacement/stretching of the polar vortex towards Greenland and Scandinavia with a piece dropping into the central and eastern US.

As the polar plunge drives south over E NA, the thermal gradient between Caribbean and E USA tightens enhancing the trans Atlantic jet. The reflective downward cooling from from strat to trop over Iceland only enhances the Icelandic low and drives a very active storm train across the British Isles.

These thoughts coincide with my winter forecast and the front end (December). BUT, I do see a shift towards Christmas which could make for a very wintry January, February and even March. Remember 2009? Wet Nov, early Dec but cold run up to Christmas. Low solar years with modoki El Ninos do have a tendency to bring cold, snowy back ends to winter.

HOWEVER, check out the AO/NAO forecasts below which kind of contradict all of the above! Maybe I should throw the whole polar vortex/stratosphere thinking out the window, perhaps there’s more driving a potential period of winter and I’m missing it all together…

Here’s a great 500mb pattern for cold both sides of the pond…

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

I shall revisit this topic in a few days.

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