There’s a fight that’s becoming more pronounced these days. That’s between the Atlantic trough and Eurasian ridge. It appears that high starts to win as we head towards December with the slowing and possible shut down of the westerlies and that means more stagnant or easterly flow.

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We continue to see the strat warming and over the next 2-4 weeks, we may or may not see the seal break and the burst of warming over top which would result in a ‘highly likely’ cold outbreak for not just Europe but the UK also.

As shown in today’s ‘must see’ video, it’s a building process, it doesn’t happen overnight and note the two most recent ‘major SSWE’ (1985 and 2009) we saw record cold here as a result.

However what’s important to note. These didn’t occur straight away and during late autumn (now) but they were triggered by an early buildup of Siberia/Eurasian snow cover and strat warming up above in response. Constant pressure put on the PV through November into December eventually triggered to SSWE but that in both examples didn’t occur until mid or late December. SSWE’s result in a bursting of warmth.

We’ve been seeing that now since October. It still may not happen but I think the chances are growing.

What’s interesting though is it appears modelling is starting to show something. Notice the BUILD-UP of heights into late November/early December over Northern Europe. This may or may not be an early indication of an SSWE coming on. In fact it may just be part of the pattern and there’s no linkage. It’s difficult to say but there does appear to be warming at the more crucial 50mb level over the next 10 days and the building of heights in more northern latitudes may be the lower atmosphere responding or ‘seeing’ this warming above.

Now

144 hrs

240 hrs

ECMWF surface

While the westerly flow becomes slowed down and the flow reverses. We are unlikely to see anything particularly cold until there’s warming at 50 to 30mb up above which then forces the Europe high and Siberian high to shift.

In all most major SSWE’s I notice a common thread. High pressure which starts over Europe with core focusing north and northeast of the UK backs WNW while cold builds over Siberia then gets forced west underneath the expanding high.

This remains theory but I’m trying to show you what I’m seeing here.

We now have a textbook North Atlantic tripole in place with warmest anomalies surrounding Iceland and coastal Greenland. Favours blocking in the key position for cold making it to the UK and Ireland.

The AER and Chinese models see this in the Dec through Feb analog/forecast.

The AER is based on an analog package.

UPDATE:

Check out this 360 hour 500mb height anomaly.

Here’s Jan 6, 1985 following the sudden strat warming event. Looks similar to the above right? This far out is fantasy but you see where I’m going with this right?

See this morning’s video for discussion.

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Tags: arctic oscillation, north atlantic oscillation, polar vortex, scandinavian high, stratospheric warming, sudden stratospheric warming event