Model output discussion - deep cold inbound?

[Valleyboy]

1 hour ago, P-M said:

Morning all. Well after a really bleak year for me (and everyone else) and getting over Covid for a second time in November I can finally start to be happy! 

All I would add to the brilliant posts already on here is that those snow depth charts don't really take into account convective snow showers well IMO. Although the models are showing disruptive snow for the south and SE, the North and East and Eastern side of the UK looks likely to get pummelled with convective showers which can quickly accumulate even right down to the coast. 

 

Either way an exciting time for model watching and I for one can not wait to stock the fridge up and start radar watching from the weekend! 

 

 

I would advise caution all around with snow depths.  I would suggest less snow will fall due to lake effect not being maximised.  If the uppers were lower, then yes, we would see more snow.

[Gustywind]

13 minutes ago, nick sussex said:

Hi Anthony

There’s a decent chance of that verifying. 

In these situations the trend is important because it’s like a domino effect going forward , if the first attempt by the Atlantic fails then the chances of the second failing also increase .

To be honest I’m just made up that this cold spell will land for my coldie friends in the UK and Ireland . In terms of any potential breakdown I’m now going to be looking at that in more detail .

My interest now moves to the Cold Extension ! 

Where could this still all go wrong Nick? Looks pretty much cast iron guaranteed up till Thursday, just the possible breakdown  after that which is uncertain. Is that how you see it or is there still doubt over the initial Easterly?

[Battleground Snow]

The OP is not even an outlier at any point in the run.

[Tim Bland]

3 minutes ago, Battleground Snow said:

The OP is not even an outlier at any point in the run.

And it’s 3c above the mean at the end for the south!!!

[markw2680]

So the last few days I wake up and see over 200 posts, today there was 186 so I’m thinking a slight downgrade!! I look and quite simply WOW.

THE MIND BOGGLES!

hope these upgrades keep on coming we are going to be in for a shock ladies and gentlemen 

[AWD]

4 minutes ago, Battleground Snow said:

The OP is not even an outlier at any point in the run.

Definitely at the colder end of the spectrum;

A lot of spread from Wednesday onwards, more so the further south and west you are.  The above are for the West Country.

[Tim Bland]

UKV has a lot of snow in the south east early Sunday (as it’s closest to the. Low) but all eastern areas having regular snow showers ..

[Neilsouth]

12 minutes ago, Valleyboy said:

I would advise caution all around with snow depths.  I would suggest less snow will fall due to lake effect not being maximised.  If the uppers were lower, then yes, we would see more snow.

Especially as ECM was very bad with the snow depths of recent snow falls, and also it depends what directions those winds are this weekend/week. If they are more to the ESE less people will be in the game

[MattStoke]

1 minute ago, Neilsouth said:

Especially as ECM was very bad with the snow depths of recent snow falls, and also it depends what directions those winds are this weekend/week. If they are more to the ESE less people will be in the game

ECM overdoes frontal snow accumulations but doesn’t pick up showers well at all. Expect a lot more shower development than the models currently show.

[Tim Bland]

Just now, Neilsouth said:

Especially as ECM was very bad with the snow depths of recent snow falls, and also it depends what directions those winds are this weekend/week. If they are more to the ESE less people will be in the game

I actually think ECM has done quite well with the forecasted precip amounts and locations at short range. I agree it didn’t do to well with the ‘snow depths’ but this was more to do with it showing all falling snow accumulating. Last Sunday for example it showed 5cm of snow for some areas but what they got is 7-10mm of sleet. Next week is different, with low uppers and low DP etc there is nothing marginal about it so Almohad to all snow will accumulate. Not saying it’s 10 day forecasted snow depth is anywhere near right as it’s very extreme but it’s not a bad model to look at for a rough guide of snow depths 2-3 days out. 

[mb018538]

Most models also tend to underestimate convective shower penetration inland - ie they fizzle them out too quickly. Don’t be surprised to see more snow showers than models show. 

[johnholmes]

Looking at the ECMWF outputs I use then the maximum cold, re 850's looks to be next Wednesday with a move then for the lowest values to recede back into Scotland by about 12 th Friday. The flow remains throughout next week, into the weekend, from an easterly point, with the zero to -5 C line running from the Thames to the Bristol Channel.

On the anomaly charts there is so little contour flow in the UK area that they offer little solid advice on what the UK weather is going to be in the 6-14 day period in my view. Other than there seems little prospect of any really mild air getting into pretty much anywhere away from the far SW at times.

The post above from AWD showing the meteogram from EC sums up the picture with the milder air moving in to the far SW. I doubt, if you posted the meteogram from the Midlands north it would show anything like that temperature rise.

I think this is the meteogram for Sheffield, not tried these before so I may be wrong!

ECMWF Forecasts

WWW.ECMWF.INT

 

Edited February 4, 2021 by johnholmes

[Battleground Snow]

Nice to see the icon trending pressure higher again in this region, possibly this is the MJO influence.

[Bristawl Si]

18 minutes ago, AWD said:

Definitely at the colder end of the spectrum;

A lot of spread from Wednesday onwards, more so the further south and west you are.  The above are for the West Country.

Nice! Battleground West Country

[ALL ABOARD]

Icon at 120 is fantastic.

Scandi surface high forming as the cold becomes entrenched. 

Bitterly cold with snow showers packing into the east, frontal systems diving and the possibility of significant snow as they nudge in. 

No wonder why the met aren't sure wether the even colder air will make its way towards us. 

[goosey007]

8 minutes ago, Tim Bland said:

I actually think ECM has done quite well with the forecasted precip amounts and locations at short range. I agree it didn’t do to well with the ‘snow depths’ but this was more to do with it showing all falling snow accumulating. Last Sunday for example it showed 5cm of snow for some areas but what they got is 7-10mm of sleet. Next week is different, with low uppers and low DP etc there is nothing marginal about it so Almohad to all snow will accumulate. Not saying it’s 10 day forecasted snow depth is anywhere near right as it’s very extreme but it’s not a bad model to look at for a rough guide of snow depths 2-3 days out. 

Agree Tim at T48/36 found it to be fairly accurate it said 7cm for me on 22nd Jan on 24th I had exactly that .not always that accurate but I can only say as I found it last time out.  Obvs the amounts we are seeing now for a weeks time is based soley on that outcome happening it will change 10/15 times before then...so really JFF and an idea of what coudl happen.

[snowblizzard]

GFS 00Z colder 850's never really get into South/South East before Atlantic starts pushing in!

Adjustments South likely?

Edited February 4, 2021 by snowblizzard

[Don]

Well, another relief this morning and good to see the potential breakdown being pushed back a bit.  Almost there now!

[Speedbird]

2 minutes ago, snowblizzard said:

GFS 00Z colder 850's never really get into extreme South/South East!

Adjustments South likely?

-7 / -8 widely across the SE - not as cold as those further north but would still ensure anything that falls from the sky will be white and provide impetus for convective snowfall

[MattStoke]

ICON pushes fronts further north over the weekend. Raining turning to snow as it crosses England and Wales, Saturday night into Sunday. Marginal for south eastern areas (At that stage).

 

During Sunday morning, further snow pushes into the South East, where it’s then less marginal.

Edited February 4, 2021 by MattStoke

[goosey007]

8 minutes ago, snowblizzard said:

GFS 00Z colder 850's never really get into extreme South/South East!

Adjustments South likely?

GFS only came fully on board 24 hrs ago or so...think its still playing a bit of catch up. Not really performed that well for this upcoming cold spell all things considered .....to see it 10 days out then to drop it at day 6 when the others come of board is not really acceptable to have any great confidence in it currently. Much rather what the ECM did and pick it up at day 6 and stick with it.

Overall ECM has proven again to be king model in my mind. UKMO deserves a mention as well very good performance in this particular scenario.

Edited February 4, 2021 by goosey007

[bluearmy]

1 hour ago, radiohead said:

And even with the less cold upper air over the south, it's still cold all the way out to 240 at the surface due to the snowfields.

 

not really relevant because it won’t happen like that but Dp’s remain sub zero down to the south coast whilst uppers are above zero south of the M4 - that’s a wide area of freezing rain falling onto lying snow ..... whilst not at this timeframe over this locale, this set up may well happen where the milder air rises up above the entrenched surface cold - the last thing the country  needs at the moment is a widespread freezing rain event - better it stays all as snow ! 

 

 

[Neilsouth]

Rain quickly turns to snow across the SE on Saturday night and meanders around throughout Sunday morning before gradually being restricted to the coast

WWW.METEOCIEL.FR

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Meteociel propose de manière régulière le modèle à maille fine de WRF-NMM 0.05x0.05° (5km) sur 5 zones (France, Nord-Ouest, Nord-Est, Sud-Ouest, Sud-Est) et l'Italie, Royaume-Uni, Espagne et Allemagne

 

[East_England_Stormchaser91]

27 minutes ago, Tim Bland said:

UKV has a lot of snow in the south east early Sunday (as it’s closest to the. Low) but all eastern areas having regular snow showers ..

What a chart already!

With parts of the Netherlands and N Germany forecasted to get below -10c, you can see how readily showers are developing as soon as that frigid air hits the North Sea. Watch out for sudden disturbances cropping up over Sunday evening, into the early part of the week. 

[bluearmy]

1 minute ago, goosey007 said:

GFS only came fully on board 24 hrs ago or so...think its still playing a bit of catch up. Not really performed that well for this upcoming cold spell all things considered .....to see it 10 days out then to drop it at day 6 when the others come of board is not really acceptable to have any great confidence in it currently. Much rather what the ECM did and pick it up at day 6 and stick with it.

Overall ECM has proven again to be king model in my mind. UKMO deserves a mention as well very good performance in this particular scenario.

I think that’s pretty disingenuous. Gfs was the model that sniffed the Iberian low pushing quickly northeast to engage our sinking low over the Low Countries. It just made a mess of that interaction and had it a little too far west.  The experience watchers on here dismissed the mess it was making of the meeting of the two air masses but were cautious about ignoring it completely. and they were right to do that.