Isolated Frost

GFS 18z and CMA = real Arctic blast. First NNW, then N and then the cold pool advects slowly westward... huge ridge building with a 1060mb high o/ Greenland shown in later frames. Hell of a late output. For those in Scotland and much of Northern England/Northern Ireland, the best of the winter. Nothing beats arctic northerlies (and nor'westerlies/nor'easterlies).

Plenty of snow/wintry shrs for northern areas, and some southern hills with this. WAA up W Greenland- favourable stalled amplified trough off NE Canada w/ associated jet energy- retrogressive ridge SSE-NNW, not quite SE-NW yet, but it's a very positive set-up+ 552dm moving into Greenland It may not be the mystical easterly some set out for, but it would be some cold NW/N'lies with the chance of a NE downstream as the upper trough builds energy in C Europe and advects the cold pool W/SW.. Some very pleasing synoptics from the north in the output.. that may not favour some certain areas but us up north will be very pleased..

EC 0z analysis- -25c t850s into the US via a northerly at D9. Yesterday's 12z analysis- comparison will be the D9 from the upcoming output- here's hoping we manage a stalled, intensified and most importantly amplified trough... SSE-NNW would do nicely- see if the EC can provide any notable retrogression...

Writing it off after Feb 1st- gosh some are fickle... Wait for the next 4 weeks and then we'll talk! Very optimistic still for the conveyor belt of seaboard heights to stall and intensify, w/ amplification, the polar jet- retrogression gets a few attempts it seems and there is a developing cold pool associated with the upper troughing over Central Europe. Patience.

February 11th, 3am

Blimey! Bloody hope not It's very interesting that Arctic Amplification still exists and is possibly worsening, whilst the rest of the world is, despite various inter-yearly fluctuations, remaining around stable in terms of temperature. Isn't the polar jet likely to push further into more 'sub-tropical' climes as the current situation worsens?

What I see from a rather outsider-ish POV, is that the Earth is warming, generally due to the fact that the areas which are warming, are warming faster than the areas cooling... Arctic Amplification a good example of this. But it's at this when I become lost. Is cycles like the PDO or NAO weather, or climate. There is a real link between the PDO and weather in Western Europe- so, what is the PDO? Is it a climatic phase which we may be in for at least 10-20 years? Or is it weather patterns altering and changing, with a bias at this moment in time to a negative phase? One thing I am concerned about is the Arctic, the losses there have been so consistent it is truly scary. A question is... what changed in 2004-2005 in the Arctic for such a drop in summer ice area? What factors have changed since the 1980s have caused the global temperatures to increase? I am sceptical to whether it is man or nature, I like to keep an open mind... I'm not exactly sure if it's either at the moment! There is no doubt CO2 emissions are rising, but the global temperatures have fluctuated in the timeframe shown above, so surely the current phase cannot be attributed to carbon emissions, or at least not completely to carbon emissions?

90% here as well... day 13 of snow cover in a row tomorrow at 0900? I don't think it can last the night though. EC looks fun- here's hoping we get a NNE/NE'ly from Scandinavia and the Arctic instead of the grim (but wintry) SElies! I'm sure NickR agrees with me there

Not quite full retrogression on the EC suite- but as touted previously, a lot of mid-atlantic highs being spawned off the Eastern Seaboard- and the stalling, amplified trough to the west at 240 is bingo.. Advancing cold pool and -ve anomaly set in place for C Europe, here we go !

Hopefully some sun!

Best since Dec 2010. Not that great though, despite having 6 inches lying for quite a while- the snow became hard and turned to slush after the 22nd, there was no deep cold (no ice days, no sharp frosts) and most importantly no sunshine. A ESE wind with a layer of low cloud and light to moderate snow characterised this spell, with a few frontal exceptions and the very fun convective days of the 14th/15th and 18th. Good for snow, but the lack of fresh snow, sunshine and cold made it quite monotonous in the end.

55-45 in favour of a plus 3c not sub 3c month? About 3.3c before corrections seems likely- about 3c/3.1c after them.

Compared with Nov 22 to Dec 8 (7.6/10) Snow 9/10 Cold 7/10 Sun 7/10 Severity 8/10 Longevity 7/10 Dec 16 to Dec 26 2010 (6.6/10) Snow 4/10 Cold 9/10 Sun 10/10 Severity 5/10 Longevity 5/10

11 Jan to 26 Jan ratings Snow 6/10 Cold 3/10 Sun 2/10 Severity 3/10 Longevity 8/10 On mobile so will explain why later , overall rating 4.4/10.

16cm here, 4cm added since this time yesterday- 12 days of snow lying in a row 18 so far this winter (incl October), so we are now above the average and have half a foot !

When we are looking at the retrogressive motion due to a stalled jet trough in E Canada/NE USA- we must look for the SW-NE tinted Atlantic high, with heights moving in the same direction- we want to see the 552dm line moving SW to NE into W Greenland.. This is the important aspect of building any potential cold spell... There is a trend in recent modelling to build this 'positive retrogression' with an anomalous Atlantic high around D9 or thereafter.

Light snow - vis over 1km Snow flurry - very brief light snow Mod snow - 0.5km to 1km vis Heavy snow - under 0.5km vis Snow storm - steady or prolonged heavy snow Blizzard - heavy snow and sustained wind, frequent gusts over 50km/h No fake reports now then !

Snow intensity is measured on visibility and only visibility. Some low visibility at times here, but its not been heavy for long, mostly light to mod. I'll dig up the scale

It's only weather! The areas getting the highest intensity for the most part got MUCH less than us in Nov 10 and probably have less right now ! I'm sure you are quite happy and stating the facts- but we all know the south/midlands is in a better position for tonight's event; I'm just concentrating on what's outside

Just checked, 4cm added and still snowing. And stop moaning, the snow we got on the 26th Nov was immense and the heaviest I'd ever seen. We have good accumulations here, and the others deserve some intense stuff - we usually have it all!!

Heavy snow here, about 2 inches added since 0900.

Light mod snow, with heavy bursts- about an inch or 2 added today

And if by magic, the 18z catches on with the retrogressive theme in its provided operational suite. D12- after a progressive subtropical ridge latches on to the UK, it retrogresses and pushes up to create a large east Atlantic ridge- the succession of atlantic lows is stopped, and then, a subtropical low enters the circulation, prompting more retrogression towards D14- this time the upper heights build more SE-NW (v favourable) and create a 'hotspot' of Southern Greenland. The jet then digs in southwards... once the Norwegian upper ridge retrogresses back into the flow, we have one hell of a N/NE'ly coming post D16. Interested in whether the ENS will step up the case of positive retrogression after a upper ridge from the SW enters the UK around D9/D10.

Wouldn't mind this.

Do you think this in turn could provide the Siberian vortex with some space to move W/SW in the 15-25 day period ?