model discussion Model output discussion - closing in on Winter

[jmp223420]

I must say here in Glasgow on my daily morning walk to the shop I saw something in the sky that I havent for nearly a year-con trails!  A real abundance of them and I know roughly air temp must be -50c for them to form...so in the mid trop it's certainly cooling--I have went a few walks in the last weeks with a clear sky and surface temps around 5*--no contrails.  Forgive my ignorance but what chart gives temps for Fl30-40? Glad to be riding the winter train again with you all...eight years ago I'd be waking up a hungover student with a banging headache having if lucky, ridden something else   How time changes you!

Would good to see the MJO get into phase 8, I believe there to be a fair prospect of this happening.

 

[jmp223420]

2 hours ago, Ed Stone said:

Good morning, folks. And welcome to another day of 'will it snow in. . ?'. Well, the GFS 00Z operational run looks to remain amplified. But the question is: will that amplification be in the desired

And take a look at all those temporal/thermal shifts within the GEFS ensembles? Are they not enough to make even the pros want to 'sit on the fence'?

   

Looking at the above ensembles, from about 30/11 it's impossible to draw any conclusions right now.  I am certainly sitting on the fence, leaning to the colder and snowier than average winter end given the signals we have had from multiple indicators in the run up to today.    (This is my answer to the above quote, I have no idea how to separate my comments from the quote-thats why I put it in bold. I am using the app, if that helps)

 

Edited November 22, 2021 by jmp223420

[mountain shadow]

23 minutes ago, northwestsnow said:

I'm not liking the direction of travel either.

 

Indeed, a portion of the purple Trop PV of doom looks like heading to NE Canada, never a good sign.

[Met4Cast]

I do understand the more pessimistic tone in here this morning, but I don't think things are quite as bad as they seem. 

Looking at the 06z GEFS postage stamps for T+240 there isn't all that much support for a flat zonal pattern, an argument could possibly be made for cold zonal but broadly winds are NWerly rather than a milder SWerly. 

The ECM mean is similar at the same timeframe, a northerly displaced azores ridge. The GFS mean at 240 is very flat but given the range of solutions above, it's difficult to discern anything from that.

The ECM clusters are singular beyond day 10 suggesting the model doesn't have a clue which direction of travel to go in. As Matt Hugo said in the earlier posted tweet, anything beyond days 6-7 may as well not exist, too messy, no clear signal. 

Keep an eye on the MJO signal, that'll be important.

[mushymanrob]

1 hour ago, Met4Cast said:

Models are trying to resolve the Atlantic wave break & following jet extension across the Pacific, we've already seen the ensembles push back a return to average from the 30th November to the 4th/5th December, I'd be cautious re: watching individual det runs too closely, best to stick to the ensemble means/ensemble charts rather than taking runs in isolation. 

In short, models don't currently have a scooby doo.

To be fair though, the cold was pushed back too, it should have been here by now and all we have is normal cold..

 

[sheikhy]

On a more positive note its currently  2 degrees here with frost in the shade!so it might not be as cold as it was meant to be but boy can you tell the difference today!!❄

[bluearmy]

24 minutes ago, mushymanrob said:

To be fair though, the cold was pushed back too, it should have been here by now and all we have is normal cold..

 

We are in the post cold front pattern and - it’s just that the flow becomes split around the dumbbelling high which makes it less potent (although originally any deeper cold was always progged around 26th )

not sure about the back end of the chilly period being put back either - there has never been a convincing end to it shown in the extended ens. 
 

[Methuselah]

So, we have yet more average (give or take) late autumn/early winter fayre on offer. But, once one's subtracted all the hyperbole, is this any great surprise? Isn't a December increase in Atlantic influence a common feature of British winters? Am I bothered? Can I predict the weather six-weeks hence? Am I the CFS!

    

    

    

And, anyway, one thing about 2021 has been the relative impotence of Atlantic incursions? Over-analysis could be the death of us all!

[knocker]

1 hour ago, Met4Cast said:

I

The ECM clusters are singular beyond day 10 suggesting the model doesn't have a clue which direction of travel to go in. As Matt Hugo said in the earlier posted tweet, anything beyond days 6-7 may as well not exist, too messy, no clear signal. 

 

I am surprised you need MH to tell you that when the ecm is quite explicit t192-20

"When the ensemble distribution is sufficiently homogeneous the cluster algorithm cannot partition the ensemble in a meaningful way, for these cases the ensemble member that better represents the ensemble mean is shown".

[SLEETY]

Looking at gfs ensembles, it obviously hasn't a clue after a few days, huge scatter, 20c difference between the runs. 

So as mentioned earlier after 5 days might as well bin the output 

[TSNWK]

On 22/11/2021 at 13:27, SLEETY said:

Looking at gfs ensembles, it obviously hasn't a clue after a few days, huge scatter, 20c difference between the runs. 

So as mentioned earlier after 5 days might as well bin the output 

Where was the op against the pack please? Sorry I cannot find spaghetti plots

[Methuselah]

Well then, here are the GEFS 06Z ensembles, and I agree with @SLEETY. Though I suspect the same will apply to all the NWP models? Is there a hint of an upcoming pattern change, I wonder?

    

[throwoff]

It is all looking distinctly 'average' at the moment. 

However after the past few years rain I will take average with a bite in the air.

[damianslaw]

As others have said reliable timeframe perhaps 120hrs tops at present, as often the case. At this range UKMO showing low pressure digging deeper south into Europe and tilting winds to the NE slightly.. if it's right heights would struggle thereafter to topple SE.. and further renewed NW flow resumes. This is picked up by ECM as well. Its subtle changes positioning of trough that may indicate direction of flow further ahead. Lower heights into Europe suggests base state remains highly amplified. 

[tight isobar]

The disparity/ conflict is there in form @ GEFS /@ Eps 500s . What’s more note worth, is the obvious wave construction into the pole.. along with a very complex- mindful upper hemisphere pattern overall.. we keep an eye firm

[TSNWK]

On 22/11/2021 at 14:07, damianslaw said:

As others have said reliable timeframe perhaps 120hrs tops at present, as often the case. At this range UKMO showing low pressure digging deeper south into Europe and tilting winds to the NE slightly.. if it's right heights would struggle thereafter to topple SE.. and further renewed NW flow resumes. This is picked up by ECM as well. Its subtle changes positioning of trough that may indicate direction of flow further ahead. Lower heights into Europe suggests base state remains highly amplified. 

At micro level within our part of the world I agree there is scope for uncertainty.. my real concern is the signal for the vortex to start cranking up to our north west.. ultimately overiding and ebbs and flows in our neck of the woods. 

Edited November 22, 2021 by TSNWK

[Eskimo]

So some places getting snow, largely to highest ground with cooler than average temps and a brisk wind everywhere else. Perhaps sleet in places 150m+ but low ground exclusively seeing rain.

Seems very normal for the time of year. Standard PM incursions (for now). 

Edited November 22, 2021 by Eskimo

[Geordiesnow]

It's ashame any ridges could not be sustained so whilst we remain on the cold side of the jet, it's not going to be cold enough for anything too significant in terms of cold. 

As per ever with the details though, they will vary so would not rule out in time things setting up to bring cold enough air for snowfall but it won't be in the short to medium term.

[TSNWK]

Ukm keeps it chilly and wet over the weekend.  Looks thoroughly miserable for the while nation.. duvet and box sets..

I say it would be looking to flatten beyond 144 but there are some very weak heights towards eastern Baltic.. 

[Staffmoorlands]

12z GFS/UKMO going for a wintry spell from Thursday onwards with sleet/snow in the usual places for this setup

[weirpig]

Havnt seen any runs for a while  but the 12z isnt without interest  snow showing up at the weekend for Wales Northern England  maybe parts of the North Midlands and Scotland.  Not to be bad if short lived

[Methuselah]

Well (and I'm nae ramping!) the GFS 12Z looks better for the weekend. More of the country under -6C Uppers?

    

[Ali1977]

An upgrade for Saturday on the GFS, colder uppers and chances of snow are on the up

[Mapantz]

Certainly a feature on the 03Z UKV and FAX charts

  

Some snow possible, down to around 100-150masl.

[Ali1977]

A closer look and everything looks good for some white stuff anywhere on Sat

850s  

528 dam  

Dew point  

Precip tick  

Edited November 22, 2021 by Ali1977