Model Output Discussion. 3/12/2022. How cold will it get?

[Guest]

Yeah the ECM run is great but with respect, anyone putting any credence to ppn charts for next week is clinically insane

It's cold, cold, cold!

[Johnp]

I suspect snow for the south at day 10?

[radiohead]

2 minutes ago, LRD said:

ECM is a great run for cold. Not sure abut snow but I'm sure that will take care of itself if the forecast patterns become a reality

Snow charts change dramatically with every run after about 120 hours. Especially in this set up with the high uncertainty of low pressure running up against the cold air. Great run for extended cold.

[Anon90]

This run remains cold for the most part, longer term not so good if look at it from the Northern hemispheric view. Vortex looks to be getting it's act together......

[Liam Burge]

I love cold as much as the next person, but these temperatures would just be ridiculous and dangerous. -6c with a feels like temp of -11c. I know this is unlikely to happen but it just goes to show the true potential that this cold spell may have. Bear in mind, this is in Bridgwater which is very far south, so cities more north could expect to see temperatures much lower than we are being forecast.

[Tim Bland]

3 minutes ago, Johnp said:

I suspect snow for the south at day 10?

South Ireland perhaps . It’s like the ECM is taunting us with “how can I stay really cold but avoid snow for in” it’s all  just for fun at this range though. Will change with every run, that part of the fun

[Harsh Climate]

5 minutes ago, radiohead said:

Snow charts change dramatically with every run after about 120 hours. Especially in this set up with the high uncertainty of low pressure running up against the cold air. Great run for extended cold.

I would say they change dramatically even down to <24 hours. Just look at what gfs is showing for tomorrow evening/night (almost nothing for northern england)

Yet bbc look north for yorkshire just predicted a couple cm in places..

Edited December 7, 2022 by Harsh Climate

[Mike Poole]

12 minutes ago, Anon90 said:

This run remains cold for the most part, longer term not so good if look at it from the Northern hemispheric view. Vortex looks to be getting it's act together......

It can get its act together all it likes over there!!

It is fine NH synoptics!

Edited December 7, 2022 by Mike Poole

[LRD]

1 minute ago, radiohead said:

Snow charts change dramatically with every run after about 120 hours. Especially in this set up with the high uncertainty of low pressure running up against the cold air. Great run for extended cold.

Agreed. Not worried about a forecast lack of snow at this stage. As I say, get the pattern in and snow will sort itself out

Transition from 2016 to 240 on ECM - a moot point discussing detail at that range but I did give a wry smile when everything went from negatively tilted on Day 9 to positively tilted on Day 10 with Iberian heights becoming a risk again. Irrelevant of course as it won't look like that but there you go

[sheikhy]

Boy i will take that ecm any day!cold locked and loaded all the way to the end!!!brilliant end to the evening!!no horrible southerlies like ecm 12z from yesterday!!

[Linda]

4 minutes ago, Liam Burge said:

I love cold as much as the next person, but these temperatures would just be ridiculous and dangerous. -6c with a feels like temp of -11c. I know this is unlikely to happen but it just goes to show the true potential that this cold spell may have. Bear in mind, this is in Bridgwater which is very far south, so cities more north could expect to see temperatures much lower than we are being forecast.

You don’t remember 2010 when temps didn’t go above -7 during the day and dropped to around -14 during the night for over a month here in the northwest 

[Southender]

In my opinion the best spells of snow have a period of proper cold preceding it. Get the cold locked in first then anything can happen.

[Anthony Burden]

Evening all,ECM showing the low heading around the channel area or a little further south ie Brest still lots to change  as we get closer to next week.Before this possible threat of snow to the south of the U.K. later next week some very cold days after severe frosts over night,as I mentioned in my previous blog keep an eye on the Fax Charts for more accuracy on that positioning of the low pressure,very exciting weather watching it has been a long time coming enjoy.

[DOdo]

Thiis Low Pressure is proving to be  a real nightmare for forcaster. Here in Ireland they are forcasting tempertures not to go above freezing over the weekend and on monday. The question how cold can it get between now and Christmas. 

[weatherguy]

We'll take 72h as the starting point here, GFS/ECM both show the cold trough over us, with a Griceland high and MAR blocking off the atlantic, while that storm tracks eastwards gradually. Also worth mentioning that we can expect some snowfall anytime from Thurs-Sat due to features popping up in the unstable air - nothing particularly significant showing up as of yet though.

By 120h:

The GFS edges the trough westwards, while the LP stalls and starts to disrupt SE.  The ECM is similar, but extends the trough further westwards.  Another notable difference is the energy present over western Greenland on the GFS, which nudges the Griceland high further to the east.  This has consequences further down the line.

At 168h:

  

Due to the placement of the high to our north, the GFS blocks the route of a "cold reload" from the north and instead builds a new scandy high, while the ECM allows the cold to come down the NE with the HP instead renewing itself around Greenland. 

Throughout, both models show the LP disrupting against the block and there would be cold conditions with a chance of some major snowfall.  It is clear that we need the forecast time to come down to resolve these differences - namely where the energy may go both over Greenland and in terms of the approaching LP to our west (how exactly it interacts with the cold dense air as it approaches, and how exactly it will disrupt), but what is encouraging is that "all roads lead to cold" at the moment.  The GFS shows a riskier evolution, but with the potential for more major battleground scenarios (and followed by a lovely easterly I must add), while the ECM shows perhaps less PPN but a brutally cold setup within which snow would surely come.  The tPV is not in a healthy state into the medium term, that's for sure!

Take your pick, enjoy what's on offer!

 

Edited December 7, 2022 by weatherguy

[icykev]

30 minutes ago, Liam Burge said:

I love cold as much as the next person, but these temperatures would just be ridiculous and dangerous. -6c with a feels like temp of -11c. I know this is unlikely to happen but it just goes to show the true potential that this cold spell may have. Bear in mind, this is in Bridgwater which is very far south, so cities more north could expect to see temperatures much lower than we are being forecast.

-6 is well within the envelope at night, met eireann predicting -4 tonight for my location freezing fog and severe frosts predicted this weekend, all combined with the shortest days of the year!! ❄❄ I believe it will be progressively colder than the models are predicting in the next week.

Where is @tight isobarwith a great unique  ramp?? Hope you're

good bro

Edited December 7, 2022 by icykev

[Stuie]

This looks like sorting that SW LP out...

[terrier]

Wow what a great Ecm this evening. For anyone worried about snow don’t be. As the old saying goes wedges make sledges . Locked the cold in and the snow will follow at some point. Once the cold does break down and the Atlantic try’s and makes some inroads they could be some spectacular snowfalls across the U.K. 

[ANYWEATHER]

11 minutes ago, icykev said:

-6 is well within the envelope at night, met eireann predicting -4 tonight for my location freezing fog and severe frosts predicted this weekend, all combined with the shortest days of the year!! ❄❄ I believe it will be progressively colder than the models are predicting in the next week.

Where is @tight isobarwith a great unique  ramp?? Hope your good bro

Well it's already minus 3c/27f here barely 7.30 pm....

[Met4Cast]

Ignoring the short-term patterns for a moment there is something perhaps encouraging about the longer term too.

Weak easterly anomalies are continuing to appear in the higher latitudes and the AAM has now levelled off around neutral following a return to +ve MT. 

This suggests to me that an abrupt pattern change back to a westerly dominated flow is unlikely in the next couple of weeks, although an argument can be made that we'll see a gradual transition back to westerlies later on in the month. It was hoped that the MJO would cycle back around into the maritimes & help to re-support a waning block however current forecasts on this are incredibly uncertain;

Expert discussion earlier today did suggest a likelihood of a return to phases 5-6-7 albeit weaker than the event we've seen more recently. The strat remains disrupted & looking at forecasts I can't see any reason to believe we'll see a rapid strengthening downwelling into the lower stratosphere for a little while yet.

With that in mind;

- On going risk of blocking/colder outbreaks through the second half of December, albeit likely becoming "riskier" in terms of a weaker block/perhaps more west based -NAO with time. 

- December as a whole likely to be a below average winter with 

- No sign of raging zonality/very mild weather.

[MATTWOLVES 3]

General theme from Mogreps is it stays cold..A few straddlers towards London but further North especially it stays cold!!

[andy989]

Seems to be an inversion going on. I live 1000ft asl and it doesn’t feel as cold up here as it did down in the village (around 400ft). Clear skies too. I suspect it will get colder at my height as the days go on and any milder air is mixed out as the cold spell goes on. 
Mountains have a nice covering of snow from about 1400ft upwards. 

[shawty1984]

21 minutes ago, Harsh Climate said:

I would say they change dramatically even down to <24 hours. Just look at what gfs is showing for tomorrow evening/night (almost nothing for northern england)

Yet bbc look north for yorkshire just predicted a couple cm in places..

That shows snow for Yorkshire?

[Harsh Climate]

1 minute ago, shawty1984 said:

That shows snow for Yorkshire?

Read my post again  

[bluearmy]

Three major population centres of the NH prone to extreme cold anoms looking cold days 11/16