Model thread discussion - cold spell looming

[stodge]

11 minutes ago, East_England_Stormchaser91 said:

As expected, the ECM is calling for an extension already of the cold. Would not rule out more snow events to the SW before next weekend is out, given the volatility, and how much tomorrow and Sunday’s Synoptics are drastically correcting. 

It's fair to say since Tuesday the models have been struggling with the mid range which is effectively T+144 tonight.

The Atlantic LP faces off against the Scandinavian heights. Oddly enough, both lose - the HP sinks south and becomes a mid-latitude HP while the trough fills in situ as the Atlantic quietens down suggesting more opportunities for upstream amplification in the second half of the month. 

We need the Scandinavian HP to orient more favourably to draw in a new feed of ESE'ly air to keep the cold going (less chance of snow). Denmark's weather service is keeping them very cold through next weekend for example.  

The modelling has moved a lot since Tuesday - I wouldn't rule out seeing a few OP tomorrow or Sunday which keep heights to the north east and get more out of the cold spell - it's the direction of travel but we aren't there yet.

[MJB]

1 hour ago, ICE COLD said:

Wow freezing still . They’ll be 7 to 8 days straight of ice days

That's at midnight 

[Hammer50]

Low pressure now called Storm Darcy by the Dutch.

[icykev]

1 hour ago, nick sussex said:

I’d love to see that happen as it was part of the conclusions of the Crunchy Snow and Ice Day Committee from a few days back !

Thats the best chance for those areas with a shortwave approaching and ahead of it changing the flow to a more ese.

Any thoughts for the Irish contingent regarding the breakdown/battleground scenario Nick?

I know its a little imby but my back yard has been NW Kent,(Rochester) for thirty odd years. But have been working in Leinster since November. Wish I could have flown back tbh.  Had some great spells at the top of the downs

So a little jealous but looking at Met Eireanns outlook, seems they are predicting a disruptive spell of snow later this week.

What do Met Eireanns forecast take on board, have read a little about ACCORD. Is this operational yet or are they using ECM/UKMO/HIRLAM?

Hope your well and the floods in SW France are subsiding?

Sorry mods it is model related though.

Thanks

 

Edited February 5, 2021 by icykev

[icykev]

JFF GEM control +384

Control

Promising signs from another model. . . 

Big outlier in the ensembles but you never know

Edited February 5, 2021 by icykev

[Matthew Gill]

Just having a look at the winter of 1963 charts 

 

14th Feb 1963 vs 11th Feb 2021

[Premiere Neige]

6 minutes ago, icykev said:

JFF GEM control +384

Control

Promising signs from another model. . . 

Big outlier in the ensembles but you never know

FWIW.....the JMA is showing a return to cold after a brief interlude of less cold weather. 

[Don]

2 minutes ago, Premier Neige said:

FWIW.....the JMA is showing a return to cold after a brief interlude of less cold weather. 

Is the JMA now behind a paywall?

[icykev]

2 minutes ago, Premier Neige said:

FWIW.....the JMA is showing a return to cold after a brief interlude of less cold weather. 

Hopefully following the control on GEM

If only . . .

 

 

[Premiere Neige]

3 minutes ago, Matthew Gill said:

Just having a look at the winter of 1963 charts 

 

14th Feb 1963 vs 11th Feb 2021

That didn't look too promising for a continuation of the cold (63 chart) did it?! And higher pressure over Greenland and Scandinavia on the 2021 chart. I'm not convinced yet that a breakdown next week is nailed on at this time.

[Don]

1 hour ago, Mike Poole said:

The key time is the T144, the middle column.  There are differences in the way that Atlantic low is handled, does it disrupt,  does it stall in place, or what?  I think this in FI for the moment, but will be firmed up in the next day or two, and could have a big impact on the next months weather.

What March?! 

On a more serious note, you think what shows in the next day or two could be make or break for the second half of February i.e mild or cold?

Edited February 5, 2021 by Don

[Premiere Neige]

2 minutes ago, Don said:

Is the JMA now behind a paywall?

I'm not sure to be honest. I watched it on Gavs Weather Vids this afternoon while I was "working" from home. I tried to find it over Christmas but without success. 

[Battleground Snow]

Icon at 120 v 126, moderate increase in heights to the north. The interest lies 24 hours ahead from here though.

 

[SqueakheartLW]

Both 12z's look promising for the cold spell itself and both the 12z GFS and GEM set a new cold low for the peak of the colder spell. The GFS dipped into the -11's territory this time at -11.1 850hpa temperature whilst GEM set a new low too of -10.3 at 850hpa. However my updates are now about when the cold spell comes to an end and how mild the milder spell could be and like with previous updates of this variety I hope for the milder period to either be pushed back or watered down but preferably both.

12z GFS

The latest 12z GFS puts the end of the colder spell at 162 hours away. This is an exact match to both the 00z and 06z so like with the 06z we gain another 6 hour extension to the colder spell so another tick for the GFS

As can be seen a common theme showing up here at transition period with low pressure out to the west throwing up a front with transitional snow along it and milder air behind it. The 850hpa chart clearly shows the different air masses. The anomaly chart shows this up even more with the blues in the N and E and the yellows in the S and W.

The peak of the milder spell on the 12z comes in at 222 hours away. This is in comparison to 252 hours away on the 06z. Allowing for the 12z and it's 6 hours later this is a bad signal as the milder spell has been brought forwards by 24 hours compared with the 06z.

A doom and gloom setup here on the average mild peak charts. All those milder uppers showing too and the anomaly chart makes it look all the more grim really with those oranges over the UK.

12z GEM

The end of the cold spell on the 12z GEM comes in at 162 hours, matches the GFS now but this is a shortening of the cold spell on GEM by 6 hours so a big x for the GEM on this count at least. The peak of the milder spell comes in at 234 hours away which matches the 00z so at least GEM delays the really mild air and has given a 6 hour extension to the getting milder phase.

[Griff]

Just now, Battleground Snow said:

Icon at 120 v 126, moderate increase in heights to the north. The interest lies 24 hours ahead from here though.

 

You beat me to it, heights remind me of the ECM, but this is sooner, trend? 

(icon being icon?) 

[Mike Poole]

4 minutes ago, Don said:

What March?! 

On a more serious note, you think what shows in the next day or two could be make or break for the second half of February?

No, not make or break, there’s the possibility of a return to cold shown already after the current mild spell which the models are showing end of next week.  It is more the question of whether there will be any significant mild spell at all.  And the implications of that which would be significant if there wasn’t.  No evidence for that on the current output, but as I said, I’d like to see what the models are saying in a day or two once the cold is in place, it might be harder to shift...this has happened in the past.  

We will see...

Edited February 5, 2021 by Mike Poole

[Tim Bland]

11 minutes ago, Don said:

Is the JMA now behind a paywall?

It’s on Meteociel http://www.meteociel.fr/modeles/jma.php

 

[Griff]

Before I forget, a week ago I posted this chart for tonight (this is the 12z from earlier) and received the usual heckle of "that's 10 days away", it wasn't it was 7...

Now happening off the north of Scotland. 

Whatever happens and whatever your luck, enjoy

[Battleground Snow]

2 minutes ago, Griff said:

You beat me to it, heights remind me of the ECM, but this is sooner, trend? 

(icon being icon?) 

Latest data so it must be more accurate

Looking more closely that is a notable increase, if we can just get some greens in that area we would have  a great chance of maintaining the easterly

[nick sussex]

Looking at the NCEP discussions for the USA.

Two areas of uncertainty impact the possible breakdown .

First is how quickly the PV departs from southern Canada and the level of shear as that happens .

The second is shortwaves running east and exiting the east coast .

So in terms of the PV that effects how much energy will spill east invigorating the flow into the Atlantic .

The shortwave uncertainty impacts the main low to the west which tries to bring the breakdown , that runs into that and phases. 

 

[sheikhy]

17 minutes ago, Battleground Snow said:

Icon at 120 v 126, moderate increase in heights to the north. The interest lies 24 hours ahead from here though.

 

Thats a big change towards ecm mate!!!

[chionomaniac]

1 hour ago, Paul said:

The GFS 18z may be a bit delayed tonight, ncep having data dissemination problems again.

Anyone else drumming their fingers.  Now up to T+6 for me lol.  Must be a great pub run coming up with a renewed Scandi high! We wish. 

[john mac1]

2 minutes ago, chionomaniac said:

Anyone else drumming their fingers.  Now up to T+6 for me lol.  Must be a great pub run coming up with a renewed Scandi high! We wish. 

I reckon a short term upgrade for the SE for Sunday’s event. 

[Jason M]

Scandi high has been building run by run over the last 24 hours but as always its just about getting that final extra bit of build or westwards movement. Probably still a 'close but no cigar' situation but might be worth waiting till the morning just in case!

Edited February 5, 2021 by Jason M

[Tim Bland]

Something for the south west?  Are there any here or did they all give up ? Where is @BARRY?