Model output discussion - deep cold inbound?

[Tim Bland]

2 minutes ago, TSNWK said:

do we think -5/-6 uppers on the 144 will introduce a rain risk - thiking on the -7 and rain streamer early January?

No, DP and thickness will be low so -5 is not an issue. Think we had -3 / -4 in jan and DP was too high as continent was warmer and air was sourced from an abnormally warm Eastern Europe, This is much different 

[Phil Blake]

8 minutes ago, SqueakheartLW said:

          

How can we be seeing this kind of chart when the NAO forecast doesn't even reflect the -NAO setup on the GFS chart. Doesn't that show classic -NAO with high pressure near Greenland and Iceland and lower pressure further south?

It's the way nao is measured. Something to do with the anomaly of heights between Iceland and the Azores. Of course I could be wrong

[Captain Shortwave]

Two crucial parts really, firstly the residual heights to the north holding in place and now we begin to bring severe cold into Northern Europe (sub -15c 850s)

That channel low should continue east until it hits that bitterly cold airmass and potentially stall and pivot. I wouldn’t rule out seeing most of the south having disruptive snow stretching from Cornwall to Kent/East Anglia as the low curves around the south of England. In the meantime the north continues to see showers packing in from the North Sea.

Really good agreement in regards to the cold fully penetrating the U.K. by Sunday (day 4), slight differences in time and also how precipitation manifests itself, again the north sees showers but further south there might be organised areas of precipitation involved but this depends on how the complex low behaves.

Edited February 3, 2021 by Captain Shortwave

[kold weather]

Lots of instability on that 12z run, though as noted the profile becomes mighty marginal for the SE but hopefully it will still be just about cold enough should that warm sector get wrapped around like that. Unfortunately the 00z ECM had that and it was rain for the SE, so its a very realistic risk for us down here in the SE. With that being said the SE winds may allow us to get away with it, its close call.

Still no denying its a pretty cold run, with lots of precipitation around with the majority of it being snow.

[Tim Bland]

Just throwing GEM into the mix....

[radiohead]

Early days, but colder uppers on the 12Z GEM at 96 hours than it's previous run.

[Djdazzle]

Great runs, and the UKMO uppers will be low enough for snow everywhere. But I would expect them to be lower that what is being shown, given the setup.

ICON uppers are lower.

[ITSY]

Just now, Tim Bland said:

Just throwing GEM into the mix....

Not light years away in terms of south/central impact from the current BEEB graphics or the midnight GFSP which I've only just seen. 


 

[ICE COLD]

T96 on the Gem Beautiful

[Tim Bland]

Just now, ITSY said:

Not light years away in terms of south/central impact from the current BEEB graphics or the midnight GFSP which I've only just seen. 


 

Yes and usually the ECM follows this is Yesterday’s GFSp run though 

[ICE COLD]

T108 Gem . I love it  

[nick sussex]

A pretty straightforward forecast for northern areas but still a lot to be resolved further south.

The depth of cold varies between runs especially further south and so convection is effected by that .

Frontal snow relies less on that.  The duration of the cold and snow potential looks at this point to be a minimum 5 days which is very good .

 

[supernova]

Don't show @sheikhy the GEM. V snowy in his manor! 

Edited February 3, 2021 by supernova

[Chrisover93]

1 minute ago, nick sussex said:

A pretty straightforward forecast for northern areas but still a lot to be resolved further south.

The depth of cold varies between runs especially further south and so convection is effected by that .

Frontal snow relies less on that.  The duration of the cold and snow potential looks at this point to be a minimum 5 days which is very good .

 

Yes, but its all looking very good for everyone on the map and southerners as everly as sundya

[feb1991blizzard]

2 minutes ago, Drifter said:

What is that purple stuff across Europe?

 

Given its a long a front by the looks of it, freezing rain perhaps??  Thats my guess.

[sheikhy]

Peeps the gfs mean is just ridiculous at 120 hours!!its just a constant stream of either persistant snow or in the form of showers from pretty much every model this evening!!ecm shall complete these dreamy charts in a while!!

Edited February 3, 2021 by sheikhy

[Jason M]

9 minutes ago, Drifter said:

No chance

- lower dew points

- colder source of air

- colder seas

- more embedded cold 

Will be fine. Totally different airmass type. It was essentially a modified tropical airmass and this will be completely different.

[Snowboy111]

Desperate for that low to sink further south for us in the Channel Islands. Even a 70 mile correction would do. I know we nicked all your snow back in 2013 but please don’t be cruel to us ! Looking marginal atm. We don’t need anymore rain, we’re submerged as it is. 

[Day_9]

1 hour ago, Ice Day said:

Actually, this Icon run is turning into a stunner out to day 7

  

The plucky little ICON

[weirpig]

wow that gem  blows all the showers from the east coast through to wales    

[kold weather]

Both GEM and the GFS are starting the usual strengtheing of precipitation.

Very impressive amount of preciptation on both of these models, GEM is very snowy indeed!

ICON is very snowy as well, it even shows some inland convection, which is amazingly rare for those that follow!

[phil nw.]

13 minutes ago, feb1991blizzard said:

Think you can pretty much bin anything from now onwards on the GFS, is it really going to blow up that low in the Atlantic shown like that?

I think we are getting to the point where can count this down on the ukmo raw and fax's and similar near time models now feb.Ok we can monitor further out but it's the s/r models that will have the best handle on the ever shifting detail.

I have seen this before  with easterly set ups how once the models recognise the depth of cold and blocking to the north they can upgrade the severity.This will likely apply to snow fall as well,As many of us know a minor disturbance in an unstable easterly creates short term  snow warnings.

[Matt H]

The best part of the the GEM 12z is that it keeps the easterly winds going for longer than the 00z run. What an absolute beauty out to t138!

[ICE COLD]

Gem is a snorter at T144 for everyone 

[Jason M]

Just now, weirpig said:

wow that gem  blows all the showers from the east coast through to wales    

Oddly, South Wales often does better in an easterly than the SE, so that is actually quite a normal and likely scenario.