The very low that’s set to usher in the first true autumn chill to the UK is bringing a near white out to parts of NW Iceland this evening while further west, clear, cold high pressure has settled over Greenland in the wake of the low. That low is playing a large role in the weather across a vast area.

Here’s the current scene out of Iceland’s West Fjord region this evening. Rather bleak and cold. Note the current air temp is -2C.

Check out the beautiful sunset over central Greenland. The temperature here has now dipped to -45C and may hit -50C overnight.

It’s the calm before the cold wind here this evening but you’ll notice winds picking up and it turning colder if you live in Scotland and Northern Ireland. I’ve made mention several times now and will do so again. This is a taste of reality, not the extreme and I don’t want to appear as though I’m hyping this up. It’s going to be a shock for sure given how mild it’s been.

Here’s the GFS chart by tomorrow. Winds will blow at gale or severe gale-force across northern Scotland with low level gusts of 70 mph on exposed northern coasts but get above 3-4,000ft in an exposed NW ridge and winds will comfortably gust beyond 90-100 mph tomorrow with precip falling as snow. Yes, the first blizzard conditions are likely over the higher peaks.

Here’s the 850mb temps Thursday. Note the nice tongue of cold diving south over the UK in the wake of the low. Nothing like what Greenland is having in the wake of the same low right enough.

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The models are now trending towards an increasingly interesting scenario for the se4cond half of the month. The NAO/AO signal is set to tank once again but the PNA is set to go positive rather than neutral like it has been. That suggests we get our more typical cold signal here rather than warmth and ridging like we got with the last -NAO/AO.

Here’s the 500mb chart by the 15th (next Tue) which shows the building of heights from the UK up to Greenland with arctic air driving into eastern Europe.

By 240 hours or Fri 18th, note the classic Greenland block set up with height falls now over the UK with train tracks laid down for the arctic air to run along.

Here’s the 850mb temps for 240 hrs.

As for the indexes vs models, all I can say is that they match up beautifully!

The key is held by the PNA (Pacific North America Pattern) which has been stuck in negative territory and with this holding a western North America trough, so there is an eastern ridge and thus the typical -NAO signal doesn’t work BUT as you can see (below) the signal is shifting towards positive during the second half of the month and with both NAO and AO going back into the tank, so one must consider a more likely WESTERN, not eastern Europe trough. -AO suggests that with that trough comes ARCTIC air. Long way off but this is a real possibility and I feel happier seeing the PNA trending positive because even though the trough rather than ridge is thousands of miles away, it has a ripple effect. One out of place piece means the whole thing is out of line.

See tonight’s video!

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