[Model Output Discussion - Colder but how cold and for how long?]

Just now, Met4Cast said:

If the models aren't getting blocking right at days 3/4, why do people expect them to be right at days 9/10? 

What’s been shown is the means are king! 

They have been rock solid in the face of some odd runs, shortwaves, bulges in the ops. But the closer we have got the more the ops have firmed up on what was showing 10 days ago!

 

This cold spell has some legs to go yet! 
 

1-0 GDSM on this years chases!

[Model Output Discussion - Colder but how cold and for how long?]

5 minutes ago, Cheshire Freeze said:

Your poor dog will be checking the outputs more than the snow starved members on here.

Hahahahaha that’s hilarious

[Model Output Discussion - Colder but how cold and for how long?]

1 minute ago, Allseasons-Si said:

The control and mean are both an upgrade at 120,...keep the upgrades coming,....pleeeeaaaaase

18z v's 12z

short gefs ens.

 

Look at those ensembles between -10 and -15 around the 15th 16th I’ve not seen that on the ensembles yet!

Very interesting!!!!

[Model Output Discussion - Colder but how cold and for how long?]

Remembering that surprises crop up at VERY short notice I’d advice us to use the HI res models on Saturday to corner Monday which is the first day with low enough uppers and low enough heights. Then each day going forward. Sunday for Tuesday and so on! 
 

I’ll eat my dog and I love my dog! If there isn’t a disturbance that throws up snow next week!

[Model Output Discussion - Colder but how cold and for how long?]

4 minutes ago, Derecho said:

Probably irrelevant at this stage but good to see shallow heights to the north and a disrupting low out west ahead of the cold over the UK. 

Edit: doesn't look like it's coming to anything this time round but trough disruption and shallow highs to our north are what we want to see if northern blocking is to wane...

Just posted the same thing off the back of a glaam state that is still high this is the possibility before more amplification into Iceland and or Scandi

[Model discussion highlights]

The wedge isn’t probably prominent enough on this run but if you look where the black arrow is pointing you can see where the residual elements of inertia have created a wedge. Run it back and forward and you’ll see the trough west of Greenland breaking up and sliding. 
 

This is what could potentially extend our spell. I’d like to see the ensembles move over the next 3 days then it’s game on!

Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007854

[Model Output Discussion - Colder but how cold and for how long?]

The wedge isn’t probably prominent enough on this run but if you look where the black arrow is pointing you can see where the residual elements of inertia have created a wedge. Run it back and forward and you’ll see the trough west of Greenland breaking up and sliding. 
 

This is what could potentially extend our spell. I’d like to see the ensembles move over the next 3 days then it’s game on!

[Model Output Discussion - Colder but how cold and for how long?]

1 minute ago, sebastiaan1973 said:

It is hard to say things in a way everybody understands and makes the right conclusions. Thanks for sharing your thoughts.

EC46 shows a return of a block at the northern part of the Atlantic Ocean. 

 

The 29th - 5th chart is encouraging. Not hard to see that evolve into an Icelandic/Scandinavian high. I’m encouraged again for round 2 around this 29th date. February if anything has more potential than January in my opinion with uppers at their lowest this month to the east of us. It’s sad that I prefer a 3 week chase to a 1 week chase getting some snow weather geek alert!!!

[Model Output Discussion - Colder but how cold and for how long?]

1 minute ago, Bricriu said:

Well I hope she is right, but the form horse looks a return to milder weather.  What we don't want is a tepid return to milder  weather, either let's at least have a massive snow dump from a frontal  event or a good unstable northerly airflow,  but I am not confident  of either happening now. If this is the case then it's a big anticlimax after what seems  like one of the longest chases ever 

Tbh it’s too premature to write off any snow it’s just too far out and too premature to predict mild when a lot of signals point to blocking wedges keeping the jet south. Sometimes it’s good to second guess the models if you don’t feel it fits in with the predicted atmosphere and never take them at face value until inside 96hours. We don’t need to be down beat it’s a watching scenario still for both length and level of snowcover

[Model Output Discussion - Colder but how cold and for how long?]

3 minutes ago, SilverWolf said:

Not nationwide, but the fairly substantial snow I had in Dec 22 wasn’t predicted 12 hours before! I’ll always remember that when scenarios like next week are probably upcoming…

Yeah I remember that event and your right it’s prime example of why it’s too premature to forecast it being dry. It’s a fact the at this range snow can’t be predicted by todays science so best to get the cold in then daily check arome wrf arpege models for any disturbances

[Model Output Discussion - Colder but how cold and for how long?]

Just now, mountain shadow said:

Next week doesn't look anything special snow wise at all now away from the North East.

Bits of snow here and there then a quick return to wet and windy with some transient snow as the mild moves back in.

Still time for change of course, but it all looks a bit meh to me despite the positivity of the background teleconnections. 

Snow can’t be forecast until 48hours before the models don’t have the resolution to pick up disturbances so to say it’s dry now is a lesson we learnt years ago in these spells. Best bet is your hi res models 48hours out

[Model Output Discussion - Colder but how cold and for how long?]

1 minute ago, Bricriu said:

Well that is a big ask, despite the suggestion from some  that cold may hang on past next weekend it doesn't seem likely now whether we have a frontal event or not, but I agree it could lead to a big dump of snow more widely  for a lot of people who will likely  be dry otherwise.

If you read Tamara’s take there are wedges that won’t be picked up until 120s. I agree the end back mild winning at day 9 but I wouldn’t put my mortgage on it if wedges send low pressure into Europe and keep us on the right side of the jet. That’s something to keep an eye on and until I see it I have to go with the ensembles atm and say I agree mild “should” be coming in 9 days time. Just watch this space….

[Model Output Discussion - Colder but how cold and for how long?]

1 minute ago, Metwatch said:

Very true, but frontal clashes with cold air will almost always be better in terms of being widespread, so more are in with a chance of snow, especially central areas. I know which one myself and those in Midlands prefer, but those living close to coastal areas prefer the latter which I still respect.

The issue with frontal clashes is it tends to be a day of snow then mild air coming in 48 hours later. I prefer to keep the cold in and get several troughs shortwaves in a flow for a week or two. But each. To their own I guess!

[Model Output Discussion - Colder but how cold and for how long?]

Just now, Metwatch said:

Better than nothing for sure, but only if we assume it doesn't trend any more south.

 

Looks like another Cumbria streamer event where some areas could really get pasted.

Thursday the interest is back, too far out but shows little features like these can develop no problem!

 

Yeah and many more features will pop up for sure! We won’t know till Saturday at the earliest for Monday - Wednesday

[Model Output Discussion - Colder but how cold and for how long?]

It does look dry atm but with the low heights and warm seas in place small features have a chance of popping up within 48 hours. The same is said every cold spell 2010 was dry 144 hours out then look what happened. I’d rather the low go to the south keep hold of the cold air for longer and get disturbances.

[Model Output Discussion - Colder but how cold and for how long?]

Just now, That ECM said:

Old news.

we need the date of the next one.

Posted it yesterday mate.

29th of January 

[Model Output Discussion - Colder but how cold and for how long?]

Deep cold bang on cue on “that day”!

Boom!

[Model Output Discussion - Colder but how cold and for how long?]

5 minutes ago, IanT said:

 

Too early for that! Clearly plenty here who are still looking/hoping for a good lynching opportunity

 

my doors are locked!

[Model Output Discussion - Colder but how cold and for how long?]

4 minutes ago, feb1991blizzard said:

Remember though, the eps are dumping a fat PV over Greenland in the extended as well.

Yeah that’s true and there’s no doubt there will be a period where the jet is forced north due to a fall in AAM and MJO Phases 4/5 but with some inertia left in the system if we can get wedges a little further east than Greenland we may stay on the cold side of the JET. *MAY* we have sets still working this out at this range. I suspect even if it does flatten out the very end of Jan into Feb looks ripe for High lat blocking to dominate once more anyway

[Model Output Discussion - Colder but how cold and for how long?]

44 minutes ago, Tamara said:

Two things:

The energy distribution on UKMO is much more separated upstream than GFS and hence tendency towards a more split flow/ sub tropical jet is emphasised.

Also the -ve inertia (-ve zonal wind pockets) at higher latitudes is modelled much more and the amplification inertia within the extra tropics has less low AAM bias than GFS - which piles all into the polar jet and ends up with the scribble in the extended period that it does. It sees a brick wall but models/simulates attempting to drive straight through it anyway.

One of the best posts ever made about GFS bias! It’s something that should absolutely be taken into account when the whole set up is extremely sensitive to the AAM balance!

[Model Output Discussion - Colder but how cold and for how long?]

52 minutes ago, Mike Poole said:

850s, nice, we can live with that!  Puts us in a great place for the chaos when the block does fail.

I think the models are sneakily extremely slowly coming full circle back to the extended long cold spell we expected in last weeks models. Looking at the ensembles it’s now stretched at a push to the 21st of January for cold 

[Model Output Discussion - Colder but how cold and for how long?]

Another morning another load of daft over reactions to a jaffa cakes poor GFS and then comes the ECM to tell people to relax the winter cold is coming and always has been coming! See you for the 12z

[Model Output Discussion - Colder but how cold and for how long?]

1 minute ago, jonboy said:

All the extra water vapour due to hunga tonga will show its hand in shear intensity of any snow fall as I said back in November.  Get your very large shovels ready!!

It’s a bit off topic but I’ve read some papers and the amounts of atmospheric rivers 2023 going into the start of this year has been unprecedented so I can sort of see what you are saying without having seen any solid solid evidence. It needs studying more I think 

[Model Output Discussion - Colder but how cold and for how long?]

9 minutes ago, Kasim Awan said:

Edit: not engaging in this, bit of a silly comment, if you want to contest what I am saying then use logic and evidence not bullying tactics.

Agree that was a bit uncalled for that I had the same last night Kasim just ignore it or ignore the poster there are some childish comments sometimes on here. It’s really not on

[Model Output Discussion - Colder but how cold and for how long?]

7 minutes ago, Jamie M said:

Wouldn't really say 1881 lol, very doubtful there'd be 24 inches of snow on the Sussex coast and 34 inches of snow on the Isle of Wight lol? It sure does look like a proper snow dump for someone but wouldn't say 1881 

Well the chances are it will not be that extreme!! Obviously I’m not forecasting that hahaha but it has the same ingredients! What it will be if it plays out is widespread 20cm+ in my opinion