The Enforcer

I was thinking earlier that the models don't seem to 'like' a synoptic pattern where the UK is in this sort of no-mans land, where it is cold, but in a slack rather than direct feed, so not excessively cold or snowy compared with historical precedents. They seem hellbent on breaking this pattern at the first available opportunity, usually with an extreme solution - hurricanes, spanish plumes at one extreme and chunks of polar vortex from the Arctic/Siberia at the other end of the spectrum. A model may run with variations of the same extreme for a few runs, so seemingly it starts to gather support within its ensembles and some credence. This appears to come to an abrupt halt when the proximity to current data eventually makes the model's extreme solution impossible at which point it shows the preservation of the existing pattern for a bit longer, with an alternative exterme change being introduced a couple of days later.

Consistently inconsistent.

If you chuck in ICON as well that will be four contrasting D8 solutions. There are plenty of ideas about how Week 2 might pad out, but there can be no conclusions at the moment.

Down to around -6.3 when I went to bed and didn't get below -7C, due to crappy cloud, was -0.6C when I woke up, but managed to drop to -1.6C even in daylight. Maximum not above 2C in spite of that disruption and already back down to -2.5C.

Jasper Carrott: "In Antartica its -50 C and they've got bloody tons of the stuff!!"

As of 22:20 there is the first significant incursion of precipitation into mainland England (Yorkshire/Nottinghamshire/Derbyshire): What did the hi-res short-range models predict? NMM T+10 - underplayed: UKMO T+10 - non-existent: Arpege T+10 - skirts the coast: ICON T+4 - underplayed: Conclusion: it doesn't matter if the models suggest it is going to remain dry. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4757829

What did todays UKV runs look like?

Gold star for UKV at T+28: only 4 hours too early.

Good luck against those elephants.

As of 22:20 there is the first significant incursion of precipitation into mainland England (Yorkshire/Nottinghamshire/Derbyshire): What did the hi-res short-range models predict? NMM T+10 - underplayed: UKMO T+10 - non-existent: Arpege T+10 - skirts the coast: ICON T+4 - underplayed: Conclusion: it doesn't matter if the models suggest it is going to remain dry.

Just reached -5C, almost 3C colder than the equivalent time yesterday evening.

Max here was about +0.7. Already down to -3.9C, was about -2.0C this time yesterday, but barely dropped for the next three hours.

Only according to GEFS that I have seen. Tail wagging dog.

Probably why MOGREPS cuts off when it does, to avoid becoming too chaotic to be of any real use.

Yes there is a trend. Is it worrying? Not really. A. It begins 9 days from now; B. It's GFS and the above is an example of how that model runs with an idea for a bit at such range then has a complete change of heart; and C. MOGREPS still plotting a steadier overall picture in an 8-day timeframe, even though there are clear synoptic differences emerging between models/runs in the details well within that period.

Got below -5C overnight. Currently -0.7C.

And then a 0.7C drop to -3.0C within the hour.

UKV Boss: Are you sure this is what was generated? UKV Model: Well there might have been a few more snow showers and not so many pink elephants...

Is there any historical precedent for that Low to the east to move over the UK?

For some reason it's only reached -2.3C, almost three hours later under clear skies. Go figure.

Already ahead of you there.

Which one is 'GEM'?

It was the ICON 12z chart above. I referenced it earlier, but it's not directly visible in that post. It's stretching the wishbone effect to breaking point. Don't say what you see.

You're better off saying 10 white runs (representing extreme cold) and 10 black ones (representing Spanish plume). The mean would be grey (average temperatures) even though no run actually shows that scenario.

Is there any scenario under which the Low to the east could track westwards over the UK?