There speaks a man who doesn't have to drive to London tomorrow

martin

The ECM 00z show a similar pattern, with op run well outside the confidence limits in the latter part of the run and a significant spread over southern parts showing a range of options on the table clearly. 

Well, it’s just as well I decided to zip through the model output before checking the comments here. What I see is a complex picture with a clear trend away from milder options. 

In the reliable timeframe it’s about the same message as my last post: mild Monday/Tuesday and Thursday/Friday then unclear but now quite clearly trending colder next weekend.

Jet  stream operating in fits and starts, something more organised across England for Chriatmas Day; after that signs of a much more S-ly jet developing across N Africa. The extreme cold LP in New England recently (see Extreme Weather thread) doesn't appear to have influenced the jet.

GFS Op shows a general pattern of LPs moving NE-wards close to/over Scotland and merging with LP N of Norway ( 965mb off NI Tue 20th, 990 mb Central Belt Scotland Sat 24th, 980mb Rockall Tue 27th) . Mostly SW-lies as they approach, N-lies as they leave, the N-lies affecting Scotland more than S England. Brief HP New Year's Eve sinking S and introducing a W-ly spell.

ECM similar to GFS though the LP 27th is more of an elongated N-S trough than localised over Rockall.

GEFS in the S mild (Mon 19th and Fri 23rd) and cool by turns with heavy rain associated with the mild spells. After Christmas Day (most ens members dry, normal temps) there is little agreement - probably drier, perhaps a cooler few days, op run on its own, really cold Fri 30th. In the N, the first mild spell is most marked, and dry, but after that increasingly cold to Mon 26th with pptn (good chance of snow) on Christmas Eve.  The op there also has a very cold loop.  N England more like Scotland  than S England but not as cold.

It’ll go down as a ‘nice pre-Christmas’ seasonal chill here, although I know for others have it’s been more memorable (OT).

https://www.theweatheroutlook.com/twodata/gefs.aspx?run=na&lg=850&lglocation=dublin&charthour=006&chartname=ps_500hpa&chartregion=na-region&p=1&charttag=PS%20500hPa%20(GPDM) 

Interesting spread in the GFS ensembles between Dublin and London(and presumably relevant to other locations North and West of London. Considerably colder in Dublin post Christmas than London. Not sure if this is a trend or not. However, it does show the possibility of colder conditions for some parts at least. 

Perhaps I’m clutching at straws but I’ll be hoping that things correct southwards as we often see. I think right now, some festive cold during the key Christmas Eve/Christmas Day/Boxing day period would be a delight for many.

Yes, if your benchmark is evidence of ‘a robust return nationwide’ then that’s pretty much right. But I think equally there’s no ‘robust’ signal for any particular pattern just now; it all looks very messy and unclear, but into next weekend trending cooler, maybe colder.

It will have to correct south or north ward fully, not possible for UK a small landmass to have forever dividing line, only happened in the larger continent areas.  See the USA map how from very cold north to warm south in a 3000miles landmass all winter long.  So for here will be all out mild or cold everywhere.

Yes, hopefully. However, I do think that the Dublin ensembles show that things are still finely balanced and there will almost certainly be corrections,  hopefully good ones!

All very messy, but the little we can get to fathom from all the noise is that no real set in mildness is on offer over the next 10 days, and really anything from a major Arctic outbreak to just chilly, benign conditions are on the table at this point: (Christmas Day forecast chart)

Nothing to show warm weather

Milder (and wet) interludes from South West and West

Colder incursions from North

Rather a battleground that will change every day or two, but clearly the further north you are, the higher the proportion of colder days exceeding the milder wet days

If start cherry picking charts from multiple models, can illustrate any of the above, but only one won’t find is warm/hot weather, milder couple of days at best.

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=gfs&var=2&run=0&time=144&lid=AVG&h=0&mv=0&tr=6#mapref 

Still looking very messy with the increasing risk of colder weather for Scotland in particular as we head towards Christmas. Less so further south. 

Theres no point analysing the ECM into FI as it’s so out of kilter with the ensemble set, so will wait for the 12z.

MetO T+168 shows up the snow risk I talked about yesterday for central parts, it even picks up on lying snow for quite a widespread area of Ireland.

https://www.wetterzentrale.de/maps/UKMHDOPEU00_168_1.png 

The MOGREPS postage stamps for Christmas Eve are quite interesting. The vast majority are pretty mild for the south but much colder as you head further north. 

Christmas weekend won’t be nailed for a few days yet. 

Better news for the Scottish skiing industry though, so not all bad. 

And it’s been a wonderful cold spell here and for many in the SE. Lots of snow still lying here a week after a huge fall. Can’t be too greedy.

For the Cambridge area in a week from now the MOGREPS postage stamps show: 6 cold (including the control), 8 around average and 5 mild.  Cold being 5c or lower, mild being 10c+

If you’re talking about London and south of the infamous M4 corridor then there are just 3 cold options and rather more mild ones.  But surely the message from that is how finely balanced it is?  

If you pull back from the minutiae and think about what the computer models are trying to resolve here, what we have are two very large, contrasting air masses swirling around with much of the UK currently being modelled to sit in that complicated, moving boundary.  

If you think you can detect to within 200-300 miles where these air masses will lie in a week’s time then you have a rare talent.

https://www.wetterzentrale.de/en/show_diagrams.php?model=gfs&lid=ENS&var=2&bw=1&geoid=49069 

Those useless 100% on models cannot work out to move LP or HP freely as Earth rotates but go back to the past newspapers, Ceefax and TV forecasts would simply say it move down to the south anyway after entering Scotland.  No way it can't be stuck forever in same place for a very small landmass.  

Newspapers : Snow moving in Scotland and rain in the south, this will move down and turning to snow while clearer weather in Scotland.

Ceefax ;  Green rain England, white snow Scotland, next page white England and blue or yellow Scotland for clearer weather.

TV forecast.  Snow and rain sysbol change over.

Models on 21st Centrey - Crap and cannot work out at all so they decided to stick the LP in same place even with Earth rotates it should move to other country.  Window watching the way to go sadly as there no other source to know what will happen.

www.wetterzentrale.de/maps/GFSOPNA06_192_2.png

I’m looking at a much bigger area than that. South of say the river Tees it’s looking mild and largely forgettable to my eye. Things could shift as next weekend is a fair time away. But I’d say mild for the vast majority of the UK population is very much the form horse.