Model output discussion 24/01/21

[Battleground Snow]

GEFS flapping around like a fish, but they are still showing a lot of blocking post 300..

Mean is hinting at Greenland rises. P11 is the pick of the bunch.

 

[Snowman.]

18z OP is probably the worst of the entire bunch in terms of blocking/potential. Probably the most zonal member.

 

[Severe Siberian icy blast]

Mixed feelings, 

A fantastic 96h chart from the UKMO, weak wedge of hights, with cold air moving back over the UK, in the following 24hrs it removes the hights and its down hill, but as we know its 4 days limit atm, everythings changing within 3-4 days. 

But id say the chances of a battle ground snow fall are quite high still moving into the weekend, it's all about timing and keeping just enough pressure up north to deflect the fronts south as the are doing.. 

As blue said, get the wkend cold and next wk will be aswel. 

[feb1991blizzard]

30 minutes ago, Severe Siberian icy blast said:

Mixed feelings, 

A fantastic 96h chart from the UKMO, weak wedge of hights, with cold air moving back over the UK, in the following 24hrs it removes the hights and its down hill, but as we know its 4 days limit atm, everythings changing within 3-4 days. 

But id say the chances of a battle ground snow fall are quite high still moving into the weekend, it's all about timing and keeping just enough pressure up north to deflect the fronts south as the are doing.. 

As blue said, get the wkend cold and next wk will be aswel. 

Thomas  schafernaker disagrees, he thinks it will get mild again next monday, i think it will but it maybe short lived mild looking at these.

 

[sheikhy]

Torrid charts this morning and im not talkin about after days 9 or 10 cos they are always nice and rosy at that timeframe and seem to stay there!!charts look good at 96 hours then implode!it really aint looking good in the reliable timeframe!!!winter slipping away slowly but surely!!

[mountain shadow]

Poor overnight runs with an Atlantic driven profile. Very wet.

Subtle signs of an Atlantic ridge in the +10 day timeframe, but that's about it.

 

[kev238]

Well.. one thing is looking pretty evident on all models . That the weather is going to be very wet ( Infact potentially exceptionally so) in the next 10 days. The chance is there that some precipitation could be wintry but floods re-emerging could be the major story

[Guest]

Continuing theme of the winter really, Chilly/Cold at times with short lived wintry blasts, nothing in the models to suggest anything but rinse and repeat atm!

Although the Atlantic has been relatively quiet compared to previous Winters. its still had enough influence to scupper any long term blocking!

[bluearmy]

those who say that we aren’t seeing the strat affecting the trop should perhaps check out where the spv and tpv currently reside and where the spv and tpv currently don’t reside 

btw, at day 10 ec has the spv over Greenland ..... no prizes for guessing where the tpv is (and the strat ridge matches too into Alaska) 

               
 

the movement of the vortex is never a good thing for blocking as it generally brings mobility to the Atlantic sector .....so we rely on wedges until later in week 2 
 

 

[Nick F]

A chance of another snow event on Sunday, a week after many central, southern and western areas saw some snow.

00z EC shows snow to rain event on Sunday, as Atlantic frontal system bumps into cold wedge of HP ahead of it - but with a positive tilt to trough and no undercut front edge of front snow turns to rain eventually as milder air wins out.

However, 00z GEM shows low pressure being forced to undercut the cold HP wedge, so greater chance of all snow event next Sunday. But without support for this scenario from EC, GFS or UKMO.

00z ICON brings the Atlantic low at more negative tilt against the wedge, attempts at a brief undercut, but goes wrong way in the end.

It's the outsider the undercut, but wouldn't rule it out, sometimes models underestimate blocking cold surface highs, even a small wedge.

Not great viewing in the medium range from GFS and EC, trop PV re-organises over Greenland and generally over the arctic, BUT, so much chopping and changing of the arctic flows since the SSW, that not sure models can be trusted with mapping heights over arctic at the moment. 

Edited January 26, 2021 by Nick F

[bluearmy]

1 hour ago, Severe Siberian icy blast said:

Mixed feelings, 

A fantastic 96h chart from the UKMO, weak wedge of hights, with cold air moving back over the UK, in the following 24hrs it removes the hights and its down hill, but as we know its 4 days limit atm, everythings changing within 3-4 days. 

But id say the chances of a battle ground snow fall are quite high still moving into the weekend, it's all about timing and keeping just enough pressure up north to deflect the fronts south as the are doing.. 

As blue said, get the wkend cold and next wk will be aswel. 

Not quite - the next big low has to disrupt se  and keep most of any split  flow into Europe - see gem 00z as an example.  The other models not so keen. Gfsp not a bad effort and ec had a go before giving in. Certainly a better picture than the 12z runs but is this the edge of the envelope or a gradual trend emerging ? 

[Griff]

Gem and ecm... 240 nobody else think the models are in flux rather than settling on something certain yet? 

Hard to make any conclusions when FI is a couple of days away surely? 

Edited January 26, 2021 by Griff

[Drifter]

Yes, another fantastic GEM. Is there any chance it has got the upcoming pattern nailed? 

[Vikos]

8 minutes ago, Griff said:

Gem and ecm... 240 nobody else think the models are in flux rather than settling on something certain yet? 

Hard to make any conclusions when FI is a couple of days away surely? 

If things go that way then it is game over. The cold block shifted its position towards Canada, igniting the North Atlantic cyclogenesis. Endless autumn goes on. Very bad morning runs!

[Roger J Smith]

The ten-day ECM didn't look all that bad, could use a few isobars anywhere between the North Sea and the North Pole to make it more interesting, but at least it is trying to advect cold -- hard to do with a 5 knot gradient all over the northern half of Europe though. That's okay for when the cold already got here. 

The overall look of the model runs is weak domination by mild being challenged increasingly after Friday. Would not surprise me if some model runs in the near future start to emphasize deeper cold. Nature abhors a vacuum. 

[carinthian]

2 minutes ago, Nick F said:

A chance of another snow event on Sunday, a week after many central, southern and western areas saw some snow.

00z EC shows snow to rain event on Sunday, as Atlantic frontal system bumps into cold wedge of HP ahead of it - but with a positive tilt to trough and no undercut front edge of front snow turns to rain eventually as milder air wins out.

However, 00z GEM shows low pressure being forced to undercut the cold HP wedge, so greater chance of all snow event next Sunday. But without support for this scenario from EC, GFS or UKMO.

00z ICON brings the Atlantic low at more negative tilt against the wedge, attempts at a brief undercut, but goes wrong way in the end.

It's the outsider the undercut, but wouldn't rule it out, sometime models underestimate blocking cold surface highs, even a small wedge.

Not great viewing in the medium range from GFS and EC, trop PV re-organises over Greenland and generally over the arctic, BUT, so much chopping and changing of the arctic flows since the SSW, that not sure models can be trusted with mapping heights over arctic at the moment. 

Good summary @Nick F. The team over here still think post weekend remains up for grabs. I think your best bet to retain a longer spell of cold is for the undercut scenario to develop. The out parameter results for the snow computer has flagged up some snow depths of 10cm + for parts high ground in the North of England on Saturday with what appears some convective snow rates for a time . However, that is still along way off. What interests me is the now forecasting period over the next 3 to 4 days. The wedge of cold between Scotland and Iceland tries to hold ground.

C

[saintkip]

13 minutes ago, Griff said:

Gem and ecm... 240 nobody else think the models are in flux rather than settling on something certain yet? 

Hard to make any conclusions when FI is a couple of days away surely? 

Aren’t they always in flux. Probably the worst looking models for sone time 

[Severe Siberian icy blast]

18 minutes ago, bluearmy said:

Not quite - the next big low has to disrupt se  and keep most of any split  flow into Europe - see gem 00z as an example.  The other models not so keen. Gfsp not a bad effort and ec had a go before giving in. Certainly a better picture than the 12z runs but is this the edge of the envelope or a gradual trend emerging ? 

Oh I agree, the point been is the models continue to underestimate and disregard these wedges, iv a sneaky feeling it will show its hand more compelling in the next 24hrs

[IDO]

The gefs still have a few hold outs moving to the undercut, but the writing is on the wall now post-d5 so very likely a less-cold 7-days as a whole incoming from tomorrow IMBY:

London> 

Turning cooler from d8-d10 and then the gefs still working out from there. The mean and gefs suggest the most likely scenario aound d10 is the jet NW>SE and the UK in the confines of the euro trough:

d11 mean>

This is cool and wet with maybe snow for the usual suspects but much like previous versions, not going to do it for hardcore cold and snow lovers down south. But, from around d11 the gefs scatter in synoptic in our region and there is no signal to garner ATM. Is that conflicting data re MJO signal and/or combination of enso and strat? See where the models take us for February but with the underlying repeating pattern it seems this SSWE has been not as productive for snow/cold that we hoped for in the south?

[Griff]

5 minutes ago, Vikos said:

If things go that way then it is game over. The cold block shifted its position towards Canada, igniting the North Atlantic cyclogenesis. Endless autumn goes on. Very bad morning runs!

 

1 minute ago, saintkip said:

Aren’t they always in flux. Probably the worst looking models for sone time 

ECM seems to have been very fickle since December, in terms of following rather than leading. Not sure anyone has been lording gem day 10 charts as guaranteed, so absolutely nothing to convince me that this morning's output will be backed up this time tomorrow, and no doubt different again come Wednesday. 

The only consistency is a range of options being shown. 

Yet again we've entered a model discussion loop. Saying with certainty how the dice will fall when events in the strat are ongoing seem a tad premature. 

Yeap models are always in flux, so the notion that this will count down as shown seems very questionable given short term unreliability. 

[sebastiaan1973]

14 minutes ago, Vikos said:

If things go that way then it is game over. The cold block shifted its position towards Canada, igniting the North Atlantic cyclogenesis. Endless autumn goes on. Very bad morning runs!

They are in line with the general theme the models are hinting at for days.

[sebastiaan1973]

 

[Vikos]

7 minutes ago, sebastiaan1973 said:

They are in line with the general theme the models are hinting at for days.

So? We are reaching the bottom of the candle...

[sebastiaan1973]

EC46 shows we have to wait for the second week of February. Matt Hugo seems to point in that direction as well. Altough the signal seems to be rather weak at the moment.

 

Edited January 26, 2021 by sebastiaan1973

[Radiating Dendrite]

13 minutes ago, Vikos said:

So? We are reaching the bottom of the candle...

Still waiting for it to be lit - the SSW seemingly put it out.