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Paul

Model output discussion - here comes the beast!

Paul

Please only post model discussion in this thread 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

We also have a special post SSW cold spell discussion open here:
https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

Thank you!

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1 minute ago, radiohead said:

Up to 9cm of snow in Kent by 192 hours according to Weather.us charts.

 

I think those charts are in inches?

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Now getting upset over the ECM run I cannot understand. So much snow potential in that precisely because we have avoided the much colder uppers. Why would anyone want -20c uppers if it meant it was dry?

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Well the ECM pretty much takes the previous output and probably raises the stakes further. Temperatures likely to be close to freezing by day before that low moves in and then colder still after this with brutal cold moving in. Week 2 sees winds ease but showers would continue to drift into eastern areas in particular with the continued risk of more organised areas of snow. The ECM would develop severe frosts in any clearer slots later on (minus double figures even in the south). 

Another variation on the general theme of seeing the coldest weather move in at the start of next week with the risk of snow coming from distrubances in that cold pool as it crosses the UK.

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All this fuss about downgrades - 'chill' out !

Looking at two runs 24 hrs apart so examine the same time stamp - from last night's 12z to tonight with a helpful Polar Bear diagram included. 

Capture.thumb.PNG.e2ae5fa45e1b6d8b0dd2c3378095ba5b.PNG

As you can see the Polar Bear still on course to arrive, just a slightly less ferocious looking bear this evening..

 

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I must admit I had my toys / pram ready early on with the ecm lol....

The rest of the run is superb! !      Can we dream the dream😆

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1 minute ago, Snowy L said:

Now getting upset over the ECM run I cannot understand. So much snow potential in that precisely because we have avoided the much colder uppers. Why would anyone want -20c uppers if it meant it was dry?

Simply put with atmospheric temperatures that low it wouldn't be dry. At that range though it's all rather pointless trying to surmise snowfall.

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The Ecm 12z is stunning, it turns into an absolute snow fest with snow just about everywhere as pressure gradually falls during the run and deep siberian sourced cold becomes entrenched..wherever you are in the uk, the Ecm 12z would deliver!..next week is going to be Epic i think and not dry with sunny spells as BBC say!!!:D:cold-emoji:

Edited by Frosty.

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The apparent horror snow of GFS would still be impactful in eastern/southern/central parts while for a much shorter time compared to ECM, which again is phenomenal and COBRA run.

tempresult_qez1.gif

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It would be nice to see the actual track this little low takes on the ecm. I'm sure more surprises to come 

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1 minute ago, lorenzo said:

All this fuss about downgrades - 'chill' out !

Looking at two runs 24 hrs apart so examine the same time stamp - from last night's 12z to tonight with a helpful Polar Bear diagram included. 

Capture.thumb.PNG.e2ae5fa45e1b6d8b0dd2c3378095ba5b.PNG

As you can see the Polar Bear still on course to arrive, just a slightly less ferocious looking bear this evening..

 

Don't take this the wrong way Lorenzo but your Photoshop skills don't quite match your weather postings! :D

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10 minutes ago, Panayiotis said:

Not really sure why people are concerned with this ECM run:

Easterly flow from tomorrow for the foreseable dropping dew points

Sunday onwards sees 850hPa temps dropping to below -10C with a sustained easterly feed embedding the cold over U.K. 

With those 2 features in place, I wouldn't be surprised to see snowfall with 850hPa temps at -2C/-3C (if the flow is from the continent). 

Given that the ECM has the shortwave moving east to west (maintaining the flow from the continent) and 850hPa temps of less than -8C, anything that falls from the sky will be snow.

Hang on a minute...I haven't seen anyone moan about the ECM run (unless of course they are on my block list, in which case I'll give myself a pat on the back 😆).

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Are the lapse rates different depending on air mass?   Ecm uppers of -8 would normally give +3/+4 at 2meters wouldn't they?   This would make snowfall marginal.

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Model output for next week looks a bit more messy this evening. To be expected at this range. We've had days of very consistent output. So wobble is expected, but there is no change to the general theme of prolonged, deep cold and snow potential.

Edited by MattStoke

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2 minutes ago, Deep Snow please said:

I think most of the country would be happy with the 13th member by the 3rd March

 

 

Edited to include graph

Ideal.PNG

What’s the 22.8 ? Feet 😂 ❄️ 

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How strong will inland convection be if you have -14C 850hpa in combination with late February sun? 

I recall past late February northerlies being more inland convective than say an early January one. The 13th March 2013 easterly brought sunshine and snow showers, with the 19th February 1996 NEly, clouds erupted spectacularly that afternoon with snow showers and great cloudscapes.

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16 minutes ago, nick sussex said:

Because of the shortwave discrepancy to the nw at T120hrs and T144hrs I’d be wary of taking any detail past that point with much confidence .

Wait till the outputs agree on that as it does have a bearing on the high set up.

 

Nick,nooooooooo,take your shortwave and stic.....................lol

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3 minutes ago, weirpig said:

It would be nice to see the actual track this little low takes on the ecm. I'm sure more surprises to come 

It dives SW from the wash and exits probably around the Brighton area.

If it does happen, expect the models to steadily upgrade this feature and make it stronger, that is what happens typically.

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Just now, Fender.. said:

Are the lapse rates different depending on air mass?   Ecm uppers of -8 would normally give +3/+4 at 2meters wouldn't they?   This would make snowfall marginal.

There is already embedded cold and DP' s well below freezing the air temp would be neaer 0-1! Snow and temps arent black and white 

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16 minutes ago, radiohead said:

Up to 9cm of snow in Kent by 192 hours according to Weather.us charts.

Would be more than that, snow accumulation charts are nonsense IMO

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Just now, MattStoke said:

Model output for next week looks a bit more messy this evening. To be expected at this range. We've had days of very consisten output. So wobble is expected, but there is no change to the general theme of prolonged, deep cold and snow potential.

Bar the GFS (which is actually quite a boring run in the context of what we have been seeing lately), the modelling has introduced an element of high risk high reward early next week.

The GEM shows what can go wrong in such circumstances i.e the coldest flow is terminated to our E as a disturbance spins up and heads more N then W than direct W. This allows all sorts of phasing issues to take place.

The ECM, on the other hand, shows the flip side of the coin...we get a discrete feature heading due W in the flow which ushers in even colder 850s.

Given the evidence tonight I'd suggest that AT PRESENT a disturbance of some sort is likely to form. ECM probably more on the money here than the GEM but the atmosphere is a dynamic entity so we'll see a state of flux RE this over the next day or two.

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