Model Output Discussion - A cold start to Spring?

[winterof79]

51 minutes ago, DAVE_ALLEN said:

So much information to digest on the fax chart for next Friday. Whoever does the week ahead forecast for the Met office today. Will have a lot to include this week  

On the chart blueline shows an approximate limit of the snow coming south. 
The Midlands looks to be particularly wet with possibly some very high rainfall totals. If  that warm front waves over that region for long. This in part due today huge difference in temperatures to the north and south of the front.
 

After probable heavy fall of snow, in southern counties of England, on Wednesday and Thursday, there could be a great deal of fog and a rabbit thaw , if the warm front moves north into northern England, as shown on the fax chart. 
The incoming low over Biscay has some very warm air behind the warm front, possibly up to 15 C. So there could be a particularly warm day one day this weekend down south.

And finally, the low with a purple arrow could develop into something of a beast, as the jet is still to the south, and the low will be developing in the colder air close by the UK. If this happens, there could be some very stormy conditions along the south coast and in the south western parts. 
 

All of that follows the snowfall that we see in the days beforehand. If you check the radar this morning, you will see, see it is already falling across parts of Surrey and the borders to Sussex and there has been some wet snow passing close to Cambridge, and heading towards Suffolk and Essex. 

Well that's sorted the southern part of Uk out then.

 

Substantial snowfall remains a realistic probability from the North midlands ,maybe just south, northward.

My view of the North Midlands being Derby /Nottingham not Manchester/Leeds.

Edited March 6, 2023 by winterof79

[TEITS]

Im struggling to figure out the next 24hrs let alone midweek.

At the moment there seems to be some disagreement with the possible snow during tonight into tomorrow morning for S England/Midlands. Some runs have the front weaken whereas others seem to re-intensify the band of precip. The next disagreement is for the far SW/S England during Tuesday night/Wed. The GFS only brings light precip into these areas whereas the UKMO/ECM indicate a decent snow event.

My main issue is normally I prefer UKMO/ECM over other models. However that is not the case when it comes to precip predictions within the +48 timeframe. Im also struggling to understand the Met O warnings for snow showers across E parts for tomorrow. Any showers appear to only skim the E coast with the exception of locations such as N/E Scotland.

By this time next week my location could see max temps of 17C or 0C!! 

[Tim Bland]

I wouldn’t say it’s a done deal for this to be over in the south by the end of the week. This is the latest ECM for Saturday morning ..

[throwoff]

1 minute ago, TEITS said:

Im struggling to figure out the next 24hrs let alone midweek.

At the moment there seems to be some disagreement with the possible snow during tonight into tomorrow morning for S England/Midlands. Some runs have the front weaken whereas others seem to re-intensify the band of precip. The next disagreement is for the far SW/S England during Tuesday night/Wed. The GFS only brings light precip into these areas whereas the UKMO/ECM indicate a decent snow event.

My main issue is normally I prefer UKMO/ECM over other models. However that is not the case when it comes to precip predictions within the +48 timeframe. Im also struggling to understand the Met O warnings for snow showers across E parts for tomorrow. Any showers appear to only skim the E coast with the exception of locations such as N/E Scotland.

By this time next week my location could see max temps of 17C or 0C!! 

Completely agree, we say it time and time again that snow can be nowcasting, this really is.. 

It is plausible the entire UK gets snow, it seems equally plausible from other models that it is a nothing except Scotland!!

[DAVE_ALLEN]

10 minutes ago, TEITS said:

…..By this time next week my location could see max temps of 17C or 0C!! 

[That ECM]

The only accurate model this week.

[Mike Poole]

HARMONIE has light snow for most of the south Tuesday - here starting from midnight:

[throwoff]

Just now, Mike Poole said:

HARMONIE has light snow for most of the south Tuesday - here starting from midnight:

I have seen great accumulation from 'light' before now. 

It is a window watch situation. 

[DJ Fart]

1 hour ago, Man With Beard said:

Just to give some idea of the problems in forecasting next weekend's weather, here are the snow charts from a few ECM ensemble members for Saturday evening:

 

 

If I was a betting man, I'd be doing a combination tricast on numbers 2, 6 and 7, knowing our luck in England! 

[mushymanrob]

Those snow depth charts..... cant see it myself. The ground isnt cold, the uppers are dodgy and the 528DAM contour isnt far enough South for my liking.. So whilst im sure we will see snow, and where its heavy itll settle... but not for long. March snowfalls away from high ground are often slushy messes... i just cannot see laying snow lasting long..

[nick sussex]

The latest GEM 06 hrs run to T84 hrs drops the deeper low and increases the snow signal compared to the earlier 00hrs run to T90 hrs .

00hrs run to T90 hrs .                                  06hrs run to T84 hrs.

 

[Man With Beard]

The GFS 06Z take on snow cover by tomorrow morning:

 

[Scandinavian High.]

4 minutes ago, mushymanrob said:

Those snow depth charts..... cant see it myself. The ground isnt cold, the uppers are dodgy and the 528DAM contour isnt far enough South for my liking.. So whilst im sure we will see snow, and where its heavy itll settle... but not for long. March snowfalls away from high ground are often slushy messes... i just cannot see laying snow lasting long..

Even if it doesn’t last I think most will be happy to see snow falling  there hasn’t been much around I was lucky in December south east snow fall.

[Alexis]

Just a demonstration showing how poorly Harmonie is doing...

[MidnightSnow]

Just now, Man With Beard said:

The GFS 06Z take on snow cover by tomorrow morning:

 

Would snow cover tomorrow, help with snow chances for the rest of the week? With it being fairly marginal, could the cold ground make the difference?

[Man With Beard]

And here's the AROME for tomorrow morning in the southern half. Now AROME has been pretty good at nailing snow areas in recent months:

@MidnightSnow ... not sure, I think snow cover would need to be more extensive to have a significant extra cooling impact.

Edited March 6, 2023 by Man With Beard

[Stuie]

6 minutes ago, Man With Beard said:

And here's the AROME for tomorrow morning in the southern half. Now AROME has been pretty good at nailing snow areas in recent months:

@MidnightSnow ... not sure, I think snow cover would need to be more extensive to have a significant extra cooling impact.

0z Alaro 4k also showing EA snow.

[Guest]

FWIW, GFS 06z takes Friday's low further north with milder air quicker to move in, even Scotland is losing the deeper cold now - here's 102hrs:

Edited March 6, 2023 by Guest

[Alexis]

8 minutes ago, Man With Beard said:

And here's the AROME for tomorrow morning in the southern half. Now AROME has been pretty good at nailing snow areas in recent months:

@MidnightSnow ... not sure, I think snow cover would need to be more extensive to have a significant extra cooling impact.

Except Arome shows Yorkshire being bone dry as I type this. It's lashing it down in Scunthorpe for example!

[throwoff]

13 minutes ago, Man With Beard said:

The GFS 06Z take on snow cover by tomorrow morning:

 

That's a fascinating option, if there is lying snow, regardless of depth, at 10am and then we get either more light snowfall or rain for the day it could be treacherous out there.

[Chesil View]

1 hour ago, Tim Bland said:

I wouldn’t say it’s a done deal for this to be over in the south by the end of the week. This is the latest ECM for Saturday morning ..

At this rate the Atlantic won't be making much in roads at all we've got 4 days of further correction before then  

[DAVE_ALLEN]

14 minutes ago, Man With Beard said:

The GFS 06Z take on snow cover by tomorrow morning:

 

Is that a figure of 13139cm in the highlands ???

[Rain All Night]

39 minutes ago, Mike Poole said:

HARMONIE has light snow for most of the south Tuesday - here starting from midnight:

Hey Mike, I thought of you when I noticed that the WetterZentrale site has the outputs from Denmark's instance of HARMONIE, which has twice the resolution and twice the number of daily runs as the Dutch one, and its domain reaches further west into the Atlantic; with the downside being that WZ's charts are not half as pretty as Meteociel's.

https://www.wetterzentrale.de/en/topkarten.php?map=20&model=hardm&var=43&time=3&run=6&lid=OP&h=0&mv=0&tr=1

After finding this I had a look to see whether any sites have the outputs from Ireland's instance of HARMONIE, but I couldn't find any that do.

Edited March 6, 2023 by RainAllNight

[Stuie]

GEFS with good disruption of the lows on Wednesday. Much flatter profile.

[chapmanslade]

27 minutes ago, Alexis said:

Just a demonstration showing how poorly Harmonie is doing...

Looks pretty good to me, especially when you look at the visible sat as well.