That siberian high has been consistently forecasted for days.

Getting the cold air into Eastern Europe seems likely now. Its just a case of getting it as far as the UK. If that canadian cold pool fires up the jet it could end up being pushed towards Greece/Turkey instead.

Yes, it does reach us (albeit not for nearly two weeks) with -15c 850s tantalisingly close to the east coast... I wonder what it would take to get the -25c, or even -30c, 850s over Eastern Europe?

A slightly different position of the siberian high.

The 12Z had -32C uppers over E europe. The connection was broken a little later than with the 18z which has a warmer cold pool as a result.

Keep a watch on the ensembles, I'm sure we will see a few -20Cs over the UK in the coming days.

Wouldn’t that be colder than the heights of the infamous Jan 1987 spell?

This is an example of a less ideal one. The siberian high has already split cutting off the truly cold air from E siberia. The later the 'pinch off' happens the colder the uppers that get into E europe.

People may think I'm being a little bit ridiculous in talking about the siberian high cutting off cold air because regardless its going to be cold in the UK if the scandi high sets up (and if it doesn't none of this matters).

However since we are talking early march now, this is the difference between -10C and -15C uppers eventually reaching the UK. And -10C uppers did very little for me in the last cold spell, so I definitely need the -15s now its March!

Something brewing in GFS FI I wonder? The 18z Op and Control follow the trend of the 12z op with a pressure build to our NE as we head into March. A quick look at the 18z ENS doesn't offer much support though as they're all over the shop.

Looks a bit of a long shot at this stage I'd say, but certainly of interest.

GFS chart has a continuous picture of LP centres to NW or occasionally N and HP lurking somewhere to the S. Thus winds mainly from W or SW throughout. HP more dominant in week beginning Mon 1st but Atlantic LP returns after. No sign of the fabled E-ly shown in GFS as recently as yesterday

GEFS shows mild to Sat 27th (v. mild in S) then mostly around seasonal norm though op has another mild peak Tue 2nd and with the control a hint of something colder at end of run Sun 7th. Very dry in SE, wettest in N & W esp around Sat 20th, Wed 24th and Mon 1st. 

ECM like GFS at first, but builds the HP over the UK from Sat 27th to become centred over UK 1035mb Mon 1st

Looked at that ENS graph- saw the GFS Op, Para and Control and thought yep, bring it on! - we are in for another cold spell - BFTE or colder snap at the very least only to find out that it was last nights 18z. Having said that the ENS mean in FI has trended colder despite milder GFS Op & Control runs. 

Siberian high not really present on the 0Z at all, so no real suprise there is a lack of easterlies deeper into FI.

Wonder if this is the odd man out run, because the siberian high has been quite consistent until now.

I noticed that it is between now and March 1st that the 850's long term mean is pretty much at its lowest -3C. Of course coincides with our mild spell ! A an aside I see Jerusalem has seen its first snow for six years.

As is often the case in these scenarios, much of France is set to bask in spring like sunshine and warmth over the next few days. 19C in Paris over the weekend, 21C in central France next week. Let's hope we get some of that sun and are not stuck under cloud and drizzle. 

Lack of siberian high on the 6Z.

Still the conditions have clearly been there for it to form, lets see if the 12z flips back.

Good news: Siberian high is back

Bad news: Its much weaker than it was yesterday and in a much less ideal position.

Its alot better than the 06Z and 00Z runs.

The polar vortex over canada is further NW which is great.

Its still nowhere near as good as yesterday though. Notably because there is a strong trough in the way between the UK and the siberian high that we have to clear away first. Also its further North which positions it over the Eastern arctic. This has the effect of weakening the cold by cutting off airflow to eastern siberia and also making it take longer to build an anticyclone over scandi.

Upshot is, cold will be weaker and take longer to arrive.

However on this 12z I do expect to see some cold charts.

Its, and I need to keep enphasising this, so so much better than the 6z and the 0z though. They didn't have a siberian high at all.

T850s kinda illustrate some of the issues by T+252h

Siberian cold pool split in half, western half is impressive but its a shame to lose the connection so early on.

The deepest cold asociated with the canadian polar vortex is safely in the south canadian arctic. However there is also a secondary pool of cold air that is getting dangerously close to the atlantic. That could ruin everything.

For an upgrade (say on the 18Z). I want both the eastern and western cold pools not to split. And for the cold over Canada to join the northern one, and the cold over E siberia to join the western one.

Bank it.

The positioning of the siberian high can change though, the main thing is that this feature is now back. Which means the cold spell can't be written off for the first week of March yet.

Yeh I can tell its going to get there, but it will take longer and be weaker.

Expect some insanely cold ensembles though that do get the siberian high position right, and don't have the polar vortex over canada break up.

GFSP is alot better than the GFS

By 228 we already have the scandi high. This is what happens when the positioning of the siberian high is better.

This is not a perfect run though, because that canadian polar vortex has spilled into the Baffin. That will cause issues.

What we want is the positioning of the siberian high minus the annoying lobe of polar vortex from canada.

This one will also get there though. Just less ideal.

Consequence of that Canadian polar vortex going into the baffin.

Siberian airflow pinched off, and just a normal scandi high type affair.

Expect some good ensembles though. Both the GFS and GFSP has most of the elements there, just not quite everything together.

A scenario that sends the candian polar vortex to the south canadian arctic and has the siberian high in the same position as the GFSP would be perfect, and send -16C uppers to our shores.

EDIT: The fact the GFSP probably gets to the siberian airflow via a greenland retrogression is a bit irrelevant imho. We are talking 2nd week of March by then and cannot rely on that.

full image: https://i.ibb.co/N7hF9Rb/siberianhighsteps.png

How to get a beasterly in the first week of March in 3 easy steps. 

GEM has the siberian high in roughly the right position but it is far too weak to do anything useful

However it does keep the canadian polar vortex lobe far away. So again it has some of the elements right.

6 Q posts in a row!

Meanwhile, it looks like a renewed cold spell is elusive and Spring of sorts is the favoured option in the next 10 days