Progressive and zonal GFS, occasional PM  colder shots for the North.

Yup, can't argue with that.

Chance that the jet will dig further South and also a chance that heights might increase enough to the North to keep it cold, at least for the North of the UK.

Rather more extensive Pm than that, but certainly a mobile pattern once the high pressure recedes later next week.

Meanwhile the ECM 12z remains keen on a northerly plunge for days 9 & 10.

It could be a December a bit like that of 2017, if the models at the moment are proved right. That December saw a few cold shots that came from a N/NW direction.

The likely PV displacement may yet lead to a split, but that's pure speculation at this point. What does look favourable is LP setting up in Scandi, which would allow for noses of HP to try and establish to the west of that from the Arctic into Greenland (as per model output currently in the mid- to long-term). That would always provide a ready connection from Atlantic ridging, which would as you say provide semi-regular N'ly or NNW'y outbreaks as we go into mid December. Such outbreaks likely to be quite transitory until when and if any more stable blocking might take hold.

All-in-all, a more than usual interest to be maintained into that mid-December period.

Something like this? ECM mean:

Yep, that about sums it up Gandalf 

London ECM 12z ensembles show the 3-day mild blip and then the quite consistently signalled return to colder conditions. The signal is stronger than it was in the 00z but the usual cautionary note applies (that ensembles are not foolproof and can flip)

Another day, another GFS picture, and less wintry than yesterday. 

HP over the UK or close to the south through to Thu 12th (just a brief rush of cold air down the N Sea on the 9th) but after that Arctic-sourced LPs get more active with cold air over the whole country by Tue 17th as per WM's post above. (and FWIW my experience is that if we are to get cold weather for Xmas, it's more likely to come from the N rather than the E, the E is for later on).

Jetstream matches this but I'm not sure whether jetstream predictions inform the GFS or vice versa. Anyway, the Jetstream is uncertain of itself for the coming 10 days or so, with loops and branches, so no clear prediction there, but then settling back to a position south of the UK which should allow cold air and unsettled weather to come in behind.

ECM similar but has its cold incursion on the 9th more pronounced.

Ens keeping to dry weather until 7th, temps rising to above seasonal  average but then with sharp fall; recovering for a bit, then most runs below average out to 15th and some pptn, but not a lot. Snow row totals well down on yesterday for the S, but holding up in Scotland and to some extent in N England 

Yes, decent summary: still that signal for a slide into cold zonality. Still too much mobility and no signal for blocking.

The jet stream forecast is just one of the elements of the model, nothing more or less.

ECM 00z ensemble for London:



Similar to yesterday's 12z but the signal for the period of cold zonality has lessened slightly overnight.  Still looking like a rather cold period with options either side.

 Definitely a trend now that there is a southerly tracking low between 11th and 13th Dec:

Big call from the owner of the site then,going for a mild winter.
Nothing looking particular mild in the models though,and we have just come off the back of two below average months in a row,which is unusual in recent years.

Looks more like a good chance of  colder than normal winter,rather than milder.
Time will tell ..

Its a decent call IMO but all the time we’re seeing pressure in the PV from persistent warming at 10hPa then there’s a chance that blocking may appear ‘unmodelled’ so to speak.

As for an election snowstorm, it’s as certain or uncertain as the result at this range.

just think it would be Sod’s law so whoever loses could blame the weather - research would favour conservatives winning in a bad weather polling day

Any 3 month weather forecast for the UK is a big call IMO 

almost futile, so a big thumbs up to anyone who has had the balls to offer a coherent and well reasoned approach. Gav and Brian always back up their thoughts so credit to them both. 

Indeed- just ask the MetO for starters.

This time last week there was a brief flurry of excitement when it looked like (in terms of model output) that a cold NE'ly flow would set in today with showers filtering in off the North Sea. With 850's on some of the 12z output suggesting -7c to -8c the words 'wintry showers' were rightly being touted.

In reality the models have been virtually spot on with the pattern here in the extreme SE but further north HP has moved across quicker cutting off the flow.

The first showers filtered in at 3pm with almost faultless precision. What didn't verify so well was the depth of cold of this NE'ly flow that has been scaled back to a 9 hour -5c (850Hpa) event.

The first rain shower came through with a temperature of 7.7c after a max of 8.3c.

A word of caution when it comes to getting excited with the prospects of cold weather....as if we didn't already know that. 

Closer to 100 hours of sub -5 850s up here and lots of very welcome dry but cold conditions.(Wintriness never looked overly likely IMO).

The 12z output is following the same trend as previous sets. With unsettled conditions in the medium to longer term. The GFS 12z op “FI” section looks very much on the stormy side at times.