Model output discussion - deep cold inbound?

[ICE COLD]

The control out to day 8 is brilliant. If you want the next attempt at more cold whilst still being cold all the way . 

[Valleyboy]

27 minutes ago, DCee said:

Could be a memorable event this one. The extension of cold is all to play for I would say. What a rare treat, be like Japan for a while!

Well, northern Japan, you don’t want the south.  

[Cloud 10]

96 and 120 fax charts are out.

 

There are many troughs.

 

[radiohead]

For the east coast, the op had milder uppers than the mean all the way out, from day 3 onwards (out to 192 so far).

A 0Z GFS upgrade looks very possible.

 

[Captain Shortwave]

Just for a bit of a comparison, for all that is worth the snow on Sunday and into the new week delivers over 40cm of snow across the north sea in the Netherlands.

Normal caveats apply, but this is an example that shows the wintry risks that could occur. One singular snow event contributes this and some parts of the UK are at risk of being stuck under that same frontal system. The model then brings sub -15C minima when the skies clear. 

We are a long way from sorting out where gets snow, but everywhere across the UK will turn cold or very cold and there is the risk of significant or even disruptive snow. Just the details to sort.

 

 

Edited February 3, 2021 by Captain Shortwave
Fixed everything, probably should go to sleep

[TallPaul]

4 hours ago, Daniel* said:

Spot the pattern over the last 3 runs from ECM regarding Sunday further south....

No idea...still showing all green to me...

[chionomaniac]

I would just like to say that anyone who wants to discuss the model aspect of the upcoming cold spell, then that is fine.

If anyone also wants to discuss a possible model breakdown of the possible cold spell that hasn’t occurred yet, then that is fine also. 

If it is model related, then it is on topic.

 For those who don’t want to discuss the possible upcoming cold spell, then don’t.

For those who don’t want to discuss the breakdown or longevity of any possible cold spell, then don’t.

But please let everyone have the freedom to discuss any part of the models they wish.  Discuss, fine. Diss, not fine.

[pages]

9 minutes ago, pages said:

Of course the breakdown is showing as the models have been showing phantom Greenland high for next week and still showing downgraded heights there 100hr+

Met office never mention heights next week to the north west i.e no Greenland heights.

Met office mention height rises to north and it being dry apart from snow showers in east

Expect over next few runs that higher pressure over Greenland to disappear and be replaced by wedges of heights between Iceland and Scotland just strong enough to send the approaching lows into France.

The increased heights over UK limiting convection.

 

Para starting to see the picture, not there yet.

Now cold spell nailed on, next thing to look for on future runs is that wedge south of Iceland.

Met office outlook suggests that will be further east and a tad stronger then easy to see where there cold but mainly dry outlook comes from. 

Scotland and north to be left very cold within high pressure and rest of country with slacker easterly end of next week.

[damianslaw]

3 minutes ago, Cloud 10 said:

96 and 120 fax charts are out.

 

There are many troughs.

 

Convergence lines rather than troughs, these are the streamers.

[ICE COLD]

2 minutes ago, radiohead said:

For the east coast, the op had milder uppers than the mean all the way out, from day 3 onwards (out to 192 so far).

A 0Z GFS upgrade looks very possible.

 

I just went through every ensemble at 192 and I make it 17 of 30 that keep the cold over us . That’s an upgrade longer term

[matty40s]

6 minutes ago, TallPaul said:

No idea...still showing all green to me...

Green snow is better than yellow snow.

[pyrotech]

7 minutes ago, Don said:

A good post pyrotech.  Do you think it's a case of the favourable MJO vs a strong jet stream courtesy of brutal cold coming out of the USA and seeing which gains the upper hand moving forward?

Yes i think thats what some of the model runs are showing, but  some runs have a less effect East North Atlantic ( UK) so its intriguing how those models are handling the contrast in air temperature, the resulting jet stream and the low.  I would hope a seasoned forecaster with vast experience like John Holmes would pop in and give his thoughts. (There are quite a few others on here too)  I need to look at 500mb charts to see what is driving the data correctly or incorrectly. 

There could be some interesting warnings pop up over the weekend  (for next week) if MET output remains same, but that changes like the other models by run to run, especially 5 day plus. Interesting as in where they are !

[sunnijim]

47 minutes ago, DCee said:

If that monster low can slide it'll bring the house down. Just need some lower heights in Iberia and voila you've got winter wonderland for a good while.

It won't be a monster low by the time we reach that date,I would put my house on that.

 

[UKSupercell]

7 hours ago, MATTWOLVES said:

Well folks I'm sure the excitement is now starting to build for the upcoming cold spell...Many of those ensembles show whatever is going to be falling out of the sky will be off snow.

On a lighter note I had just pointed this out to Family but have kept tight lipped over snow risks for obvious reasons...when my mother said...Matthew you've always been obsessed with the weather, who on earth do you follow! It came flooding back to me...8 or 9 years old and I was watching all TV forecasts religiously!! Even drawing up my own weather charts over Atlas maps...with the boundaries of colder and milder airmasses....and the funny bit was phoning up all the latest local forecasts around the country in the early 1980s...I just said ohh mom,happy days...she said yeh until the phone bills come for 100 quid...

Enjoy the upcoming cold and snow,and make sure your kids enjoy it too..it all makes more great memories further down the line.

Great post Matt, really enjoyed reading that. I read this on lunch at work earlier and just had to respond! 

Your tales of being a kid and taking a huge interest in the weather, particularly the part about watching the forecasts religiously, really struck a chord in me. I've got to be honest I didn't quite go to the lengths you did with atlas annotations and ringing up all the forecasters (that's brilliant!) but I did become known as the "weatherman" in year 10.....

Appreciate this is not model-related and I'll try to keep this short as pos, mods! But it all started when I was about 13/14.... Used to visit grandparents every boxing day, when they lived in a small village just outside Cambridge. I can remember one year, literally praying for snow. It got really cold before Christmas and I think that year perhaps we visited on Xmas eve. Driving back south it was clear and starry with a hard frost. Instinctively I didn't think it would snow but I had so much hope. I think there were easterlies and light snow showers drifted in to affect Scotland and the NE. We didn't get snow that time (in the Chilterns) but I became almost obsessive watching the BBC interactive forecasts thereafter....John Hammond, Peter Gibbs, Alex Deakin, Helen Willets, Darren Bett, Phil Avery....etc! From then on started buying weather books, always loved thunderstorms, and used to compare online forecasts in school etc. 

Anyway, don't want to waffle on, but always enjoy reading posts like this. I did once meet John Hammond on the train to London Marylebone, nice guy! 

Maybe we should have a thread about what got people interested in weather, sure there's more great stories.

Fingers crossed for all you in Kent and elsewhere in SE/SW esp that ain't seen much. Got a good feeling about this impending cold, good luck all!  


 

[Tim Goffer]

26 minutes ago, Frosty Winter said:

ECM 12z was suggesting lows of around -13C across the snow fields in the Midlands on Thursday next week.

Wow! I’m gonna have to insulate the pipes!

[londonblizzard]

 

For london thats the best short ens set in a while! For monday onwards the mean gets as low as -8.9 and a big cluster of members appearing in the -10 to -12 region.

[Singularity]

Something to consider in terms of snow accumulation - most models are putting nothing down from very light snowfall despite subzero dew points and not especially dry air. This seems counterintuitive and may account for a cm or two of underestimation in areas where such light snow is shown for many hours.

On top of this there should be at least one or two disturbances in the flow providing some heavier snow further inland anyway. This being almost entirely missed by most global models currently.

[Geordiesnow]

5 minutes ago, Singularity said:

Something to consider in terms of snow accumulation - most models are putting nothing down from very light snowfall despite subzero dew points and not especially dry air. This seems counterintuitive and may account for a cm or two of underestimation in areas where such light snow is shown for many hours.

On top of this there should be at least one or two disturbances in the flow providing some heavier snow further inland anyway. This being almost entirely missed by most global models currently.

Well Sunday does have higher thicknesses so I can understand the PPN charts looking a little underwhelming. I believe higher thicknesses mean higher lapse rates therefore a lid on convection. Next week does see lower thicknesses so convection should increase as the air is more unstable. 

Of course details like that will be subject to change for sure. 

[TallPaul]

1 hour ago, Tim Bland said:

Don’t forget though mate that there’s a lot of people in the south who haven’t seen a single flake so far this winter and this maybe their last chance, Northern areas have seen a lot of snow this winter, even if it was transient at times. Charts like this are very rare (perhaps once in every 3 years) in the south ...

"Once in every 3 years" Tim? Add a zero on to that....

[Scott Ingham]

59 minutes ago, Griff said:

//180 grinding to a halt? 

This reflects my own opinion on the likely way forward

Put simply in this period we have 1 force competing against two.

In the mild corner (1)- The SPV wants to chuck a lobe of the vortex over America and the atlantic firing up the jet

In the cold corner (2) We have a stangnant highly amplified signal in phase 7 which eventually moves to phase 8 of the MJO AND we have a spike im AAM due to peak around the 13th of the month.

Option 1 is flat option 2 encourages further height rises both over Griceland and Scandi.

All winter the models have showm to underestimate momentum and tropical signals until within 120.

Its around 168-210 the breakdown is shown to occur.

If my own logic is correct in two days time friday 12z i expect to see models prolonging the cold and either strong wedges or heights pushing the atlantic energy under prolonging the easterlies or creating battlegrounds in a favourable manner

[kold weather]

Interesting little thing I've noted on the GFS ensembles which are still flip-flopping all over the place.

The reason why they are trending colder again is quite a few of them are pushing that low much further east and weaker, which allows ironically us to go back to a cleaner unstable easterly flow.

It'd be funny after all this drama about the LP if it does end up going further east and stays away from the UK!

There does seem to be a trend SE with the frontal shield over Sunday today though, so perhaps thats not impossible.

[ScottSnow]

Looking at the 18z, from experience this winter we have seen the Atlantic struggle to make inroads north and east and Scotland has been cold since before Christmas with lots of snow in the Highlands, I can’t see the Atlantic breaking through so quickly when it hasn’t all winter.

I expect to see the cold spell lengthened in the coming days especially for northern and eastern parts.

Certainly going to be some high snow totals for eastern areas.

I for one cannot wait. Certainly a positive for snow lovers in such depressing times !

[pyrotech]

Hi res is showing precipitation to west of Ireland Tuesday turning to snow, 100 miles out to sea. Thats a good indication that anything trying to push in will be readily falling as snow, The Southwest approaches has precipitation the same.

Can i add, slightly off topic The latest BBC (stav  Danaos) only went as far as Sunday. I compared the graphics and they very much showed the UK Met output. Not ECM.  They will do paid services for forecasts when the weather is potentially disruptive ( i believe). 

[Snowman31]

ROUND 2

[pyrotech]

10 minutes ago, Scott Ingham said:

This reflects my own opinion on the likely way forward

Put simply in this period we have 1 force competing against two.

In the mild corner (1)- The SPV wants to chuck a lobe of the vortex over America and the atlantic firing up the jet

In the cold corner (2) We have a stangnant highly amplified signal in phase 7 which eventually moves to phase 8 of the MJO AND we have a spike im AAM due to peak around the 13th of the month.

Option 1 is flat option 2 encourages further height rises both over Griceland and Scandi.

All winter the models have showm to underestimate momentum and tropical signals until within 120.

Its around 168-210 the breakdown is shown to occur.

If my own logic is correct in two days time friday 12z i expect to see models prolonging the cold and either strong wedges or heights pushing the atlantic energy under prolonging the easterlies or creating battlegrounds in a favourable manner

A well put post that highlights the conundrum. I agree that MJO is the most likely to overwhelm the SPV, but any ideas why the models have such a poor comprehension regarding this battle. I would suggest MJO influence is not accountable in output and the models are at times reverting to "normal" intensification with out the MJO effect or they believe that the contrast is great enough to displace the blocking MJO would normally build with strength.