Model output discussion 24/01/21

[Man With Beard]

13 minutes ago, That ECM said:

The charts JH and mushy use should start to reflect this in the near future you would think.

I think they're already on the way - the thing about a Scandi High in winter is it as often doesn't go that warm at 500mb, so sometimes it doesn't show quite as distinctly as other highs on the 500mb chart - this doesn't mean it's a weak high but rather it has very cold air at the centre. But on last night's NOAA 8-14 day chart there's already a small ridge to our north:

[Tim Bland]

Those further soothe are still in the game looking at the Arpege and UKV... 

[Griff]

3 minutes ago, Tim Bland said:

Those further soothe are still in the game looking at the Arpege and UKV... 

This will really hinder my log delivery!  

[sheikhy]

3 minutes ago, Tim Bland said:

Those further soothe are still in the game looking at the Arpege and UKV... 

My only concern with the high reso models is ecm and gfs did one on all of em last sunday!!considering they are higher resolution they really did perform poorly!!the global models did well all the way through!!im sticking with ecm and gfs on this one again!!!

[sheikhy]

Ecm has multiple snow events between saturday and tuesday!!!!

[TSNWK]

1 minute ago, sheikhy said:

Ecm has multiple snow events between saturday and tuesday!!!!

Leicester by any chance

[nick sussex]

I think Nick F covered things very well in his post so not much to add . I’ll be much happier to see that Genoa Low agreed on between the models .

Another issue later on , it’s quite rare for a huge block to deliver the deepest cold , the last time that happened was in 2018 and that was truly extraordinary in terms of cold .

As you can see from the outputs there’s that pinch point highlighted by that shortwave between the high pressure lobe  over Scandi and the Arctic high , we need that smoothed out with the former orientated more ne sw.

If we’re going to get this blocking why settle for -10 uppers when there’s that lovely bank of sub -20 to the ne ! 

Edited January 28, 2021 by nick sussex

[Anthony Burden]

Some very interesting weather coming up according to the charts,possible snow event in the south

again and some very cold air pushing across the U.K. from Scandinavian high pressure bringing 

Russia to are shores.Lots to get your head around all in relatively short notice as Matt Hugo

states on Twitter.

[sebastiaan1973]

Latest plume De Bilt. Lovely Control -again-

Average EC 240h shows an Iberian low as well.

[MattStoke]

13 minutes ago, sheikhy said:

My only concern with the high reso models is ecm and gfs did one on all of em last sunday!!considering they are higher resolution they really did perform poorly!!the global models did well all the way through!!im sticking with ecm and gfs on this one again!!!

I was about to say similar. The UKV and Aperge were really poor last weekend. They had the front far too far south right up until the last minute.

[sheikhy]

2 minutes ago, MattStoke said:

I was about to say similar. The UKV and Aperge were really poor last weekend. They had the front far too far south right up until the last minute.

Honestly matt considering they are higher reso than gfs and ecm the global models crapped all over them!!i still think it may move a little further south but not by much!!

[Sky Full]

The charts at 168h are just outside the usually reliable frames but are worth studying as they are full of potential for the days to follow...

                                    500s                                                           850s

ECM        

GFS       

GEM    

If the models continue to show this pattern by the 4th February then a cold week is very likely to follow.

[winterof79]

17 minutes ago, sheikhy said:

Ecm has multiple snow events between saturday and tuesday!!!!

And if the first doesn't transpire the rest probably won't as the colder air wins

[username home]

15 minutes ago, TSNWK said:

Leicester by any chance

every else yes. leicester just misses out. 

in all seriousness, it does look like the stars are aligning and that we're in for something special in the next few weeks.....

[Anthony Burden]

23 minutes ago, Nick F said:

Morning

Looks like we are on the cusp of tapping into the deep cold lurking to the northeast, the The Beast is ready to pounce, but the usual obstacles in the way, as is par of the course in recent winters. First of these obstacles is getting low pressure to the NW to sink SE rather than south, as a cut-off low off Iberia will pump heights across mainland Europe holding up the deep cold from spreading south. 00z EPS mean does push troughing / low heights further east across the Med in the extended. We really need that Genoa low, rather then ridge there! Secondly, getting heights to rise to our North and ideally NE too. There are probably more obstacles, but these the main two IMO.

GFS has the Genoa low at day 10

EC has Iberian low at day 10

But as they both similarly get the ridge building NE over NE Atlantic  towards GIN corridor at day 10 is a good signal, so long as we get those low heights / troughing the Med, worry is EC would cut of the low over Iberia and that would allow milder air over southern Europe to get mixed into any easterly flow. 

Great deal of uncertainty even in the near time, but more on the mesoscale differences on how far north frontal systems advance over the weekend against cold air trying to push back south. 03Z UKV has the two frontal systems pushing in from the SW on Sat morning then later on Sunday, but further south than other models, which have snow/rain divide over N Wales/Midlands rather than UKV across S Wales and S England.

Saturday morning

Sunday evening

Hi Nick,

great Synoptics in regards to possible outcome,very informative as you say still different options 

on the table but great watching regarding charts how they handle this possible very cold spell.

[winterof79]

13 minutes ago, sebastiaan1973 said:

Latest plume De Bilt. Lovely Control -again-

Average EC 240h shows an Iberian low as well.

An outlier too I see. 

Iberian low? 

 

Edited January 28, 2021 by winterof79

[sheikhy]

18 minutes ago, TSNWK said:

Leicester by any chance

Leicester well in the snow zone for both saturday and sunday!!10 to15cms!!

[SqueakheartLW]

Good agreement at around 340 to 350 hours from two ensembles members of both the GFS 00z and GEM 00z

GFS Member 16

GEM Member 6

I know its cherry picking but I couldn't help it

[nick sussex]

Last weekend and this weekend are quite different set ups and need to be viewed in that context .

Last weekend the shortwave formed to the nw within the overall UK troughing and then headed se .

The weekend shortwave low is developing in the sw and then moving ene and then east and coming up against that wedge to the north.

 

[johnholmes]

45 minutes ago, Man Without Beard said:

I think they're already on the way - the thing about a Scandi High in winter is it as often doesn't go that warm at 500mb, so sometimes it doesn't show quite as distinctly as other highs on the 500mb chart - this doesn't mean it's a weak high but rather it has very cold air at the centre. But on last night's NOAA 8-14 day chart there's already a small ridge to our north:

Possibly, I'll do a post but not sure when I will have time today

[Purga]

Pure X rated stuff from P18

[Battleground Snow]

Icon has a better wedge forming, which should force that trough south east faster and allow the colder uppers to reach us more quickly.

A pattern that keeps occuring this week is the low pressure gets squeezed and slides South East, we need that to happen the final big one.

If the 00z runs are usually the least appealing for coldies, I'm looking forward to the rest of todays output!

 

[Purga]

V good ECM mean chart again for D9

Edited January 28, 2021 by Purga

[mountain shadow]

43 minutes ago, sheikhy said:

Honestly matt considering they are higher reso than gfs and ecm the global models crapped all over them!!i still think it may move a little further south but not by much!!

Confirmed. The snow we received here last week in Northern Ireland was not predicted by Arpege. In fact the GFS was the best would you believe.

We have a similar scenario this time with Arpege giving nothing to NI yet the 0z had continuous snow on Saturday.

Lets see what the 6z does.

[CameronWS]

So the models mainly bring in the cold quite a lot earlier than the Met suggest. Anyone expect either a backdown/slowdown from the models today or a change in the Met’s long-term forecast at 4?