Model output discussion - deep cold inbound?

[Ice Day]

The Control continues the theme of moving the low slightly south east.  Very similar to the 6z.

Very positive signs at the moment, I would say anywhere north of the Wash you're on 'Easy Street'.  Those further south, there's still much to be resolved, but today's trends are getting me twitchy..... in a good way!

[Anthony Burden]

Morning all latest GFS beginning to show stronger northern blocking keeping the very cold/cold

north easterly going.My take after initial low pressure to the southeast on Sunday bringing some 

snow,a mostly dry Cold/very cold period with Atlantic lows forced further south due to increased 

pressure rise to the north.

[kev238]

I think there can be increasing confidence for the majority of the UK of a bitter spell laden with Eastern Promise.  It really would take a shift Of monumental proportions for it to go wrong now 

And pressure looks low so quite unsettled with it too 

 

[kold weather]

1 minute ago, Speedbird said:

could be a quick and soggy end for the south, hopefully the Atlantic lows take a more ESE path

I think the south would be mighty unlucky to somehow evolve out of this without snowfall I've got to say, especially the further east you go given the set-up on Sunday looks increasingly good.

That being said the 06z GFS shows how it could happen, would only need a weaker warm front that takes longer to form over the south or stays a little further south at 156-168hrs and we'd end up with nothing from the 2nd attack either.

Rainy end to the cold spell across a big chunk of the country at 180hrs, but to be honest that really is way too far out to have any sort of idea on.

 

 

[MattStoke]

The GFS has been atrocious at handling low pressure over and around the U.K. in the short term but you can bet some people will get hung up on it showing low pressure bringing milder air into the south way beyond the reliable timeframe

[Blessed Weather]

A few posts showing/discussing Met Office weather warnings have been moved over to the Winter Chat thread. Thanks.

[high ground birmingham]

I highly doubt that the low at 168 will barge through the block like that. The models always overestimate lows at that timeframe and beyond. Would expect the low to slide.

Also re precipitation, it’s the same story every cold spell when people say it “looks cold but dry”. Higher res models closer to the time will pick up on convection activity, troughs etc so it won’t be dry

[TSNWK]

Just now, MattStoke said:

The GFS has been atrocious at handling low pressure over and around the U.K. in the short term but you can bet some people will get hung up on it showing low pressure bringing milder air into the south way beyond the reliable timeframe

Still be nice.  And I actually expect for this run to be top of pack from day 7ish

[Timmytour]

16 hours ago, DCee said:

Hi Tim,

I would very much enjoy a cold and snowy time, and of course I do hope I am wrong more than anyone. But, alas, I am not usually wrong im afraid (no matter how much I want to be).

When you have money in the game it helps removes the bias, believe me!

So much can go wrong and prevent the lows from moving south, the three sisters at 120h need to be just right...a phase here or missed phase there and its game over. The ECM tends to keep them together then slip under and around, quite a feat.

The models appear to be in remarkable agreement this morning over a cold to very cold spell hitting the UK.... they are aligned for such a real winter bit of whether as I have rarely ever seem before

 

But things can still go wrong.  Despite all the models being in agreement, it worries me that they seem to run contrary to what some who come on here and post  - and who tell us they are not usually wrong - are saying will happen

[Battleground Snow]

I know it's hard not to worry about the milder air creeping in past 168 on runs, but take a look at the difference from yesterday 06z run to today's for the same time period...

The most important thing is the really cold air should get in by 72-96 now, almost the reliable timeframe.

History tells us that low pressure tends to struggle against a cold stagnant air mass and it usually takes a few attempts to break it down.

 

[kold weather]

Just now, MattStoke said:

The GFS has been atrocious at handling low pressure over and around the U.K. in the short term but you can bet some people will get hung up on it showing low pressure bringing milder air into the south way beyond the reliable timeframe

In all fairness there is strong support for a push from the SW on most models, how much success it has is very much in the air but all major models have that push from the SW to some extent between Weds-Thurs. 

Besides a bit of milder air isn't a disaster if we can keep the airflow from the SSE/SE direction. We can afford a certain uplift at 850hpa in that scenario, which at the moment does appear favoured.

Some of the GFS models are being very progressive and even trying to push one into the SW on Tuesday, though I think thats probably much too fast!

[Don]

11 minutes ago, kold weather said:

I think the south would be mighty unlucky to somehow evolve out of this without snowfall I've got to say, especially the further east you go given the set-up on Sunday looks increasingly good.

 

I hope to see some snow at some point next week but my location I think still looks to be too knife edge ATM to get excited, especially as I'm not that far east?  What's your take?

Edited February 3, 2021 by Don

[Eagle Eye]

Morning everyone, 

Just the one post for this morning here,

That cold air creating the heay snow across the US East Coast is expected to bulldose it's way across the way across the Atlantic and strengthen near land, I still haven't woken up properly so this will make no sense but basically that's where this weekends stalling front is expected on the boundary of that air mass and the one that's come south from the East which means that this isn't the Beast and could still be a few weeks before the Beast fully arrives.

Xander

[East_England_Stormchaser91]

Wondering if the Mediterranean low could link up and engage with the chunk of PV over NW Russia, and then shove the brutally cold air further west.  I’ve been slowly watching it get corrected further towards us over the days, so you never know. 

If we see further corrections south of that pesky low, then more of us could be seeing the white stuff as early as Saturday evening. 

[Ice Day]

8 minutes ago, WINTRY WALES said:

It’s not nation wide tho ...looks dry for western side of England and all of wales

Yes, fair point, there are still some areas to the south west and Wales that need to be brought into the fray.  However, with the current trends (see @carinthianpost earlier), it's possible that these areas could end up colder than this run shows.  

 

[Cleeve Hill]

21 minutes ago, chris55 said:

Proper undercut, potential for a classic south west blizzard!

 

YES, these are classic charts for the South West. I remember seeing these in the 80's I reckon. Snow drifts would last for weeks !! 

[MJB]

Decent enough mean 126h

[kold weather]

Just now, Don said:

I hope to see some snow at some point next week but my location I think still looks to be too knife edge ATM to get excited, especially as I'm not that far east?

I suspect even I may end up just a little too far SW unless a rock solid streamer manages to set-up, so yeah it may well prove tricky as far west as you are to get too much across, though even for us I suspect there will be some, it will just be scattered in nature I reckon.

Our best chance will come from any attack from the SW. 

[sheikhy]

4 minutes ago, East_England_Stormchaser91 said:

Wondering if the Mediterranean low could link up and engage with the chunk of PV over NW Russia, and then shove the brutally cold air further west.  I’ve been slowly watching it get corrected further towards us over the days, so you never know. 

If we see further corrections south of that pesky low, then more of us could be seeing the white stuff as early as Saturday evening. 

That exactly what ive been watching as well over the last few days mate!!bit more disruption into europe to curve round into the cold pool across russia and boom it could head straight for us!!

[Don]

Just now, kold weather said:

I suspect even I may end up just a little too far SW unless a rock solid streamer manages to set-up, so yeah it may well prove tricky as far west as you are to get too much across, though even for us I suspect there will be some, it will just be scattered in nature I reckon.

Our best chance will come from any attack from the SW. 

Yes, as long it doesn't introduce too much mild air we could indeed do very well!  Knife edge high risk/high reward scenario?!

[Robbie Coldrain]

6z has slight shift east, which would help the SE. 

[kold weather]

Something to take note of on the 06z GFS ensembles is that they are becoming increasingly progressive with the LP in the Atlantic between 96-120hrs.

It doesn't have to be a problem away from the far south possibly, as I suspect any push on that low is going to be well south of the UK, but its worth just keeping an eye on in case it gains any traction on the models within the next few suites. 

Edited February 3, 2021 by kold weather

[Valleyboy]

18 minutes ago, kold weather said:

The set-up at 168hrs screams of the precipitation ending up staying over the channel and the cold staying embedded over most of the UK bar perhaps the very far south where an onshore flow will raise temperatures.

Following on from that a stronger attack from the SW gives front edge snow for the south and probably much more sustained snow to the Midlands northwards.

Too far out to look at snow chances.  Places that look primed now will change in the coming days.  Remember what the uk met are saying, fronts making little progress into the UK.  At the moment, and based on history, I would suggest southern and western England and South Wales are favoured areas, but best to get the cold in first.  Snow chances will change from output to output.

[SqueakheartLW]

After such doom and gloom from GFS 00z, 06z and 12z yesterday with the 3 least cold averages so far that I have featured for the up coming colder snap/spell did yesterday's 18z and today's 00z fare any better?

18z GFS

The peak of the colder spell on yesterday's 18z came at 144 hours away. These are the average charts for that timeframe

A decent quite beasterly looking average pressure setup showing on the first chart but is this a sign that the 850hpa temperatures are going to reflect this. Good news is that the 18z was the coldest on average of the 4 GFS runs of yesterday with an 850hpa temperature of -8.7 at the peak of the cold spell which is -4.4 below the long term mean and -1.7 colder than the 06z was. Is this a sign that GFS is coming back more on board again or is it a one off blip before the backtrack continues?

00z GFS

After the GFS recued itself somewhat yesterday with the 18z average of -8.7 will the 00z keep this going or will it go back down in the dumps again. The peak of the colder spell on the 00z came in at 132 hours away

Another easterly showing up on average again but that pesky spoiler low pressure area has crept further north again. This is reflected in the 850hpa temperature on the 00z which is -8.5 which is -4.2 below the long term mean and a slight downgrade of 0.2 compared with the 18z. The anomaly chart at least is pushing that Europe mild further and further away from us now.

00z GEM

The GEM has generally been more on board with the colder spell for some time compared with other models and today is no exception to this with an 850hpa temperature of -8.9 at the peak of the colder spell which is -6.3 below the long term mean. The peak today happens at 126 hours away. This is a tiny downgrade of 0.1 compared with the 12z so not really much difference between them.

GFS Extended

The main bad news of this update comes with the GFS Extended which has seen a massive downgrade compared with yesterday.

Although it is still showing an average easterly the 850hpa temperatures have downgraded a lot since yesterday's extended run. Today the peak of the cold spell comes in at an average of 6.5 which is -4.0 below the long term mean. A full 4.0 warmer than yesterday at the peak of the colder spell. The anomaly chart also reflects this with much less deep blues showing compared with yesterday's extended run and that milder region is getting too close to the SE for comfort too.

Mildest doom and gloom chart from the GFS Extended

For a balanced view I will show this first and it is the mildest chart I have featured so far from GFS or GFS Extended

Member 24     +840 hours     850hpa temp 12.4

Very early start to spring here with those warm uppers under that high pressure. Would only be welcome if we had had a big freeze winter from December to February and needed a break from it or if we'd had a total washout and needed some dry and warm weather

Coldest fantasy chart from the GFS Extended

This is a chart that all cold fans will really want to see due to the 850hpa temperatures for early March

Member 5     +744 hours     850hpa temp -18.1

That is one beasterly showing there for 5th March. Would be great if this one came off as shown when the time comes

[Ice Day]

1 minute ago, Frosty Winter said:

The ensemble mean is an improvement out to t126 with colder uppers across the majority of the UK with a slightly more notable surface ridge over Scandinavia as well.

 

Indeed, at 138 you can compare the 850's mean vs the 0z - a shift south of 100 miles I'd say.