Nick F

It's like children in a candy shop who've been told by the owner they can help themselves to as many sweets as they want in here. Sugar rush over day 10+ charts showing deep cold and snow. Maybe after watching and discussing the models for 20+ years I've got a bit weary of the excitement of cold and snowy nirvana past day 7. I'll join in when it's still showing below 7 days.

I'm not getting too excited yet, we are still talking day 10 and the -10C line is arriving across northern Scotland on 12z GFS. A lot can change before then, though granted the models are being consistent!

Well, Greece and Turkey get in on the deep cold before we do on 12z GFS

Oh dear, the annual comparisons to 62/63 being uttered. Got my tin hat ready in case it goes Pete Tong But not often you see such a strong +height anomaly over Greenland at T+300, as below on 12z EPS Same time Europe in the freezer looking at T2m mean anomaly NOAA CPC 8-14 day heights look similar Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4994151

Oh dear, the annual comparisons to 62/63 being uttered. Got my tin hat ready in case it goes Pete Tong But not often you see such a strong +height anomaly over Greenland at T+300, as below on 12z EPS Same time Europe in the freezer looking at T2m mean anomaly NOAA CPC 8-14 day heights look similar

Going against my wisdom to look too far ahead, but @Mike Poole analogy of a nice starter next week, but the mains to follow could be even better ...

It often snows with high pressure at the surface, so long as there is not a strong ridge aloft with subsidence, just need cold air advection over relatively warm sea (eg North Sea) to produce thick enough cloud for flurries / showers. SE / E England best chance for some flurries / showers with deeper cold air advection and lower heights closer to the upper low over the near continent.

What if there is only one course on offer, any subsequent courses may not leave the kitchen, too far out to know for sure Cheeky little streamer for our SE contingent on Monday on ICON.

Yes, still far enough out for some 'upgrades' to cold into early next week. Can't imagine the models have an accurate handle on the position of the developing high - given the upper trough still has to dig into Europe later this week then disrupt into a cutoff upper and surface low over the Med over the weekend for the high to build. 12z ICON could be a more extreme solution for cold air advection, but can't rule out this depth of cold

UK Severe Convective & Storm Forecast - Issued 2023-12-30 09:45:57 Valid: 30/12/2023 0900 - 31/12/2023 0600 SEVERE CONVECTIVE WATCH - SAT 30TH DEC 2023 Click here for the full forecast

Good to see a deep Genoa Low on the GFS, always a good omen for coldies, though it's not in the reliable yet.

Uh oh, the 06z GFS op has gone rogue from it previous runs and ensembles - maybe playing catch-up with the ECM colder trend? Still a waiting game to see if this blocking signal to the NW has mileage, but seems a good signal from EPS for now.

00z EPS have trended a little colder than the 12z run yesterday. GEFS seem much less enthusiastic in any colder trend. Lets hope EC is leading us the right way! 12z yesterday 00z today

00z EPS H500 and T850 mean anomaly at day 10 will please coldies

Not really until into the 2nd week of Jan does the 12z EPS mean get all the UK cold / below average temps. But it has been looking like that the last few days anyway, jet doesn't get far enough south to bring the cold to all before then. Patience as always, fingers crossed it's not another false dawn like the late Dec promise that failed in the end. This time the trop drivers are lining up more favourably for the right pattern change, even without a SSW.

I'm not the only one concerned that the jet stream struggles to get far enough south in recent winters, because of the sub-trop high pressure belt expanded northwards, even when high lat blocking is signalled. It hampers cold air getting further south than Scotland. Lets hope we get a greater push south of high latitude blocking in January, as at the mo it's not coming into reliable.timeframes. Always beyond 7-10 days.

Trend GIF for last 4 EC high res runs for 12z 1st Jan show the shift south overnight of the jet stream & consequently track of lows towards NW Europe for 1st few days of New Year. That wedge of +ve heights suddenly appears to the SE of Greenland on 00z run:

Quite a big change from the models for the 1st few days of the New Year, was looking rather mild with long-draw SWly winds, but the models this morning have pulled the jet stream further south, with that low moving up from the Azores underneath that wedge of +heights over the far North Atlantic. Something stirring ...

12z UKMO offers up a 'wedge of hope' this time next week, with wedge of high pressure building to the NE on back of low moving SE into near continent pulling in cold air briefly Probably won't be continued though!

Blog looking at the increasing probability from weather models for a Sudden Stratospheric Warming in early January, which could bring colder and wintry weather, especially if there is a split in the polar vortex following the SSW. View the full blog here

The stratospheric polar vortex is currently displaced towards northern Europe and has brought very cold temperatures in the stratosphere above the UK and Ireland, leading to nacreous clouds which have been sighted as far south as Kent. View the full blog here

Got some nacreous cloud here in Caterham-on-the-hill in Surrey Not seen them this far south before.

Yes, I've recently become unconvinced by the whole solar min = cold winters / solar max = mild winter idea. So much so, I didn't include it in my current winter forecast for Netweather. Jan/Feb 1979 was very cold and snowy, yet there was a solar cycle max that year, albeit in December. Winter 1968-69 had cold Dec and Feb (Feb had CET of 1C) despite solar max in Nov 1968. Then we had solar min on Dec 2019 - look how that winter turned out. Winters of 1974-75 and 1975-76 were mild, despite a solar min in March 1976. There are mentions out there over the years that just after a solar min is when colder winters are more likely, like 2009-10 / 2010-11. But it doesn't stack up for other solar cycles. Back to the models, at least it doesn't look too mild on Xmas Day on 12z EC, especially up north in the strong NWly: Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4980323

Yes, I've recently become unconvinced by the whole solar min = cold winters / solar max = mild winter idea. So much so, I didn't include it in my current winter forecast for Netweather. Jan/Feb 1979 was very cold and snowy, yet there was a solar cycle max that year, albeit in December. Winter 1968-69 had cold Dec and Feb (Feb had CET of 1C) despite solar max in Nov 1968. Then we had solar min on Dec 2019 - look how that winter turned out. Winters of 1974-75 and 1975-76 were mild, despite a solar min in March 1976. There are mentions out there over the years that just after a solar min is when colder winters are more likely, like 2009-10 / 2010-11. But it doesn't stack up for other solar cycles. Back to the models, at least it doesn't look too mild on Xmas Day on 12z EC, especially up north in the strong NWly:

I'm not holding my breath for the ECM, it's been very conservative this winter so far in terms of any half-exciting set-ups for coldies, but unfortunately it's normally been right. If we didn't have GFS, it be quieter/more subdued in here I guess! True>>>