Cold hunt - models and chat

[Mr Frost]

GFS 6z delivers the goods for all the UK and Ireland - plenty of snow possibilities roaring through from start to finish. 

Very cold run with plenty of precipitation - what is not to love!? 

[Methuselah]

So there we have it...16 days' worth of abundant snow opportunities. Marginal? At times, yes. But, hey, we live in the UK!

Sid says: ROCK ON!

Edited January 24, 2019 by Ed Stone

[weirpig]

Upto 144h on the control  very similar  snow opportunities  More so  on Tuesday fro those further south

[IDO]

The GEFS have covered every possibility for that trigger low at D6:

From past experience maybe D4 before we can be sure how it develops?

[shaky]

Control looks even better at 144 hours!!

[Nick F]

Been a bit too busy to post much lately … but I'm finding the outlook rather fascinating and quite exciting to watch evolve. Fairly unusual to have such a long stint at cold northwesterlies that actually bring snow risk even in the south.

Despite a lot of model uncertainty over the track of lows after the weekend, it looks a generally cold picture and at times snowy picture with the UK staying on the cold side of the jet most of the time.

IMO arctic ridging via Alaska is tanking the AO and pushing the low heights / upper cold air over this side of the North Pole, so in turn forcing the jet further south.

Potential for some wintriness in the strong northerly wake of that deep low clearing the east Sunday, which incidently GFS redeepens a little to around 980mb across SE England early Sunday before it clears, northerly gales in the west.

Another low dropping SE toward N Sea Tuesday, with another surge of cold polar air from the NW behind associated weather systems bringing plenty of sleet and snow showers perhaps

Mid-week been earmarked for a while for another low to drop in from the west, however, uncertainty how far north or south it may track, but likely to bring snow on its northern flank

Further on, signs of amplification working through from upstream, perhaps in response to MJO forcing as it moves through 6 towards 7 - which may allow mid-Atlantic ridging, but uncertainty over how quickly the Canadian Vortex will try and flatten out the ridging again.

[Daniel*]

27 minutes ago, northwestsnow said:

Some of the temps next week on 6z are really really cold...!!

tues 9pm

thurs 9am.. look at SCOTLAND temps!!

 

I think its fair to say next week is looking COLD!!

GFS 2m temps are rubbish too low resolution ECM has some extremely cold nights in Scotish highlands..

[Jonathan Rhodri Roberts]

1 hour ago, kold weather said:

Yeah.

For those who don't know, to work out thicknesses you need to find out the geopotenial heights (that would be the colours on the meteociel charts for example, same with wetterentrale), lets say 528 for example here of the top of my head.

Then for you either add or subtract from that based on the pressure above or below 1000mbs.

So for example, with a low pressure of 970mbs, that actual thickness is 558, which would actually be high. In contrast if the surface pressure is 1020, the thickness would be 508, which would actually be very cold. Broadly anything below 520 is going to be snow in all but the most exceptional chances. 533 will be rain, except again in exceptional circumstances.

I remember reading that 528 dam is the snow line, is that true? 

[weirpig]

Short ensembles for Central England   Cold and snowy    

[Weathizard]

Control run 

[kold weather]

Control run is a edge bit further south on this run, which brings more of the south into a pure snow set-up rather than snow-rain like the operational run.

We probably won't have a more solid grip on that low track though until 96hrs out, and even then could be quite sizeable differences right down to 12hrs out...so we have an awful long way to watch it and it could still very easily trend way too far north...or much further south.

[Chertseystreamer79]

35 minutes ago, kold weather said:

Very cold day there Frosty, not surprising given the low thicknesses and also the probable fairly widespread snow cover by that point which will help hold back temperatures. Indeed the wrap around low drops quite a lot of snow, sweet spot would be S.Midlands/ Home counties on this run.

But now you say...barely nothing for home counties 3 posts later........unless I missed something?

 

Don't get me wrong....your work rate is admirable!

[northwestsnow]

1 minute ago, weirpig said:

Short ensembles for Central England   Cold and snowy    

Excellent GEFS !!

[feb1991blizzard]

Just now, northwestsnow said:

Excellent GEFS !!

Yes, snorter - miles better ridges at 192, going to make huge differences by 240 onwards, better UK trough.

[kold weather]

I'd also say the control run looks more realistic for that PV over E.Canada, maybe a touch underdone but much more realistic IMO.

PS, there are some extreme snowfall solutions in the ensembles, with a VERY tight gradient between the snow-rain.

Still, a heck of a lot of disagreement on that track of the low, and don't expect any real clarity for some time yet, for good or ill.

[Jonathan Rhodri Roberts]

13 minutes ago, Daniel* said:

GFS 2m temps are rubbish too low resolution ECM has some extremely cold nights in Scotish highlands..

If the Scottish highlands are very cold and shown in dark red then what are those purples across Cornwall & far south of Southern Ireland? Little confusing for me as it looks like land temperatures will be warmer than the seas, something you'd expect to see from late Spring 

Edited January 24, 2019 by Jonathan Rhodri Roberts

[bluearmy]

1 hour ago, kold weather said:

Yeah.

For those who don't know, to work out thicknesses you need to find out the geopotenial heights (that would be the colours on the meteociel charts for example, same with wetterentrale), lets say 528 for example here of the top of my head.

Then for you either add or subtract from that based on the pressure above or below 1000mbs.

So for example, with a low pressure of 970mbs, that actual thickness is 558, which would actually be high. In contrast if the surface pressure is 1020, the thickness would be 508, which would actually be very cold. Broadly anything below 520 is going to be snow in all but the most exceptional chances. 533 will be rain, except again in exceptional circumstances.

No idea if any pedants our there corrected the detail Kold but you need to multiply the slp by 0.87 (rather than 1) to give you the actual number to subtract/add from the heights 

[Disco_Stu]

Well I'm convinced, what could possibly go wrong! I'm off to tell everybody that I know!!! 

[northwestsnow]

GEFS mean MILES better than the 00z mean at day 9

[SMU]

2 minutes ago, bluearmy said:

No idea if any pedants our there corrected the detail Kold but you need to multiply the slp by 0.87 (rather than 1) to give you the actual number to subtract/add from the heights 

Here we go from my account in 2005 

14 years ago

The Sunglasses smiley is an 8

So its 0.8 

[Jackski4]

Seems like all the models are giving good run after good run right now..☺ 

 

Imagine if we get some brilliant 12zs later!!

[shaky]

And a fantastic parallel aswell!!just 2 and a half days before our next cold and snowy spell lol!!

[weirpig]

Up we go on the Para?.

[Weather of Mass Disruption]

1 hour ago, chionomaniac said:

This chart is truly unbelievable. Off the scale cold into the heart of the USA. ( >-35C 850 hPa  temps)

I love and really admire your input on here Chino, but have to admit I get seriously fed up with the yanks getting all the action every year. Definitely considering a relocation across the pond to Chicago, Wisconsin or anywhere else that has such unbelievable models that do actually verify! 

[Weathizard]

Looks like a rapidly developing situation now, if I was midlands north I would be getting very excited about this setup up potential, SW and the south I would say knife edge, but as has been said these features CAN trend south as we get nearer so nothing done yet.

Thats if we get past the first few hurdles.