At 9 days range and beyond this is technically just for fun, but it reflects recent trends very nicely as LP is neatly into the North Sea by day 8 and LP to the SW is turned down, while the western N. Atlantic low is slower moving, allowing for a reasonable Greenland High and weak mid-Atlantic ridge:
Snow likely for the northern half of the UK on Christmas Day while Boxing Day could produce snow showers just about anywhere though The South could have to wait until evening. Taking this run at face value of course!
An interesting channel low followed by day 12/13 breakdown brought about by LP behaving quite strangely... far from convincing really.
It then finishes with what might be a nod to the ECM 12z control run of yesterday, as LP dives into Europe and the cold starts to think about coming back in from the NE or E (below-left):
Meanwhile the parallel GFS still brings through a bothersome LP from.he SW but while it delays the cold by two days, the outcome is more dramatic (above-right). The low goes on to invade Europe with the properly cold N'rly veering NE'rly and persisting to 29th December.
Apologies to mobile users for taking up so much space with a single GFS run well outside the reliable - I just couldn't resist as it's been so long since I got to stare at NWP output of this nature i.e. full of cold potential and some realisation from day 8 through to day 16
I think the biggest development on these 12z GFS and GFSP runs is low pressure getting down into Europe in the later stages. It represents a big shift from the 'return of the extended Euro High' that kept cropping up over the past few days, and is the best way to extend the cold spell while setting up a decent pattern going into the New Year.
Definitely the highlight of the NWP watching so far this season - now will ECM trash the party? gulp
A quick glance at UKMO shows a day 6 setup that would go on to be closer to GFS than GFSP i.e. without the LP from the SW.
On that note, which would you rather have, GFS or GFSP? Cast your votes
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T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
Keep Calm and Forecast On