Model Output Discussion 29th December - Into mid-Winter.

[Timmytour]

Amid my mounting excitement there remains within me the voice of past disappointments and ingrained pessimism which tells me, in the voice of unlucky Alf from the fast show, that just as everything appears to be going right, and just as everything looks like it's falling into place, the type of SSW event we so often crave will crop up, but this time ruin everything!

[Nick F]

Although 06z GFS doesn't make much of Thursday's wave low scooting along the south coast, can see why MetO have their concerns re: heavy snow/rain looking at their own 00z UKMET-G model which develops some heavy rain on the rear side of the wave low - thanks to a diffluent upper trough behind the cold front which induces heavy precipitation near and along cold front - plus a wedge of cold air (sub -6C T850s) with this trough and 2m temps not much to drop to freezing, especially through evaporative cooling in heavy ppn.

SLP and ppn + 500 hPa vorticity

T850s and 2m temps

Could do with dew point and wet bulb temp forecast charts too ... but will really come down to nowcasting at the end of the day and not certainty over exact track at t+48-60 hrs out.

ECMWF had similar track and also turns precip heavy on back end of wave as upper trough arrives and engages Tm airmass wrapping up into low

Other than this feature, of course there will be plenty of snow showers Thursday for EIRE, N. Ireland, SW England, Wales, NW England, northern and western Scotland, NWly flow could bring a Cheshire Gap streamer through the Midlands toward the SE too?

Friday similar, but with winds veering more northerly toward the east, could see snow showers down eastern counties too

So plenty of fun and games to look forward to, before some uncertainty over a low dropping SE on 06z GFS over the weekend, which could bring less cold air and rain preceded by some snow. 00z had it further west I think. Then of course the will it or will it not Scandi high and easterly.

Edited January 10, 2017 by Nick F

[winterof79]

The METO update clearly has issues with the erratic movement of leading edge snow on Sunday as it is referred to more than once.

They do not know for certain its progress Eastward but if it stalls somewhere may get dumped upon

You can understand why

Past experience is telling me that it will hit the buffers

 

[Dominic Carey]

I know were still firming up on details but how long could the cold last?

[Aaki Khan]

ECM 00z Ens Really Good. Overall Very Good Start To The Morning It Has Been. I Am Expecting The GFS Ens To Follow The Op Next Run Or So. 12z's Today With Popcorn. 

PS: Sydney Knows 

[winterof79]

Nice GEFS at192z

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=192

 

Here come the showers on a cold feed

And how far can that front move in to the colder air for our Southern posters?

Edited January 10, 2017 by winterof79

[jvenge]

Not sure if it was mentioned, but the 00z Parallel was very close to the Operational out to 8 days or so. Of course, the 6z operational was then totally different, but one wonders if another Parallel run will come today (doesn't seem fixed) and if it was also close to the 6z or not.

 

[bluearmy]

8 minutes ago, jvenge said:

Not sure if it was mentioned, but the 00z Parallel was very close to the Operational out to 8 days or so. Of course, the 6z operational was then totally different, but one wonders if another Parallel run will come today (doesn't seem fixed) and if it was also close to the 6z or not.

 

Yesterday's 12z para managed to get the ridge to s scandi so the new 00z run is a disappointment

you could look at the gfs 06z op and say that at some point the gfs op was bound to churn out a run like that, given that there were several gefs members present in each suite. On that basis, prepare to be let down by the 12z. The UKMO day 6 has hardly covered itself in glory recently so again, it may be further south in 90 minutes with the ridge

and yet, in he background the ec op had been ticking down like clockwork on the amplification.

all in all, quite important runs upcoming for continuity reasons- I generally don't like the 'this run is crucial ' comment but on this occasion, it has some resonsance.

 

[Just Below Zero]

47 minutes ago, winterof79 said:

Nice GEFS at192z

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=192

 

Here come the showers on a cold feed

 

And how far can that front move in to the colder air for our Southern posters?

 

This model seems to complete a watering down of winter in the southern coastal area known as snowdomia since the turn of the century 

[snowblizzard]

Surely this is why the Met Office are not going for an Easterly!

That damn Azores High is unable to extend NW towards Greenland

Atlantic fronts come over the top introducing less cold airstream.

No signs of height rises towards Scandinavia

Unfortunately, I think they will be on the money!

Edited January 10, 2017 by snowblizzard

[terrier]

Well not long to go now until the next saga of the model output. Will we see the gfs 12z upgrade the easterly potential. Will we see the ukmo get people at Exeter scratching there heads. Then the big dog ecm goes crazy with easterly winds and drifting snow. Only one way to find out buckle in get your popcorn here it comes.......

[Bazray]

When are the new charts available? Few hours?

 

[Summer Sun]

1 minute ago, Bazray said:

When are the new charts available? Few hours?

 

 

GFS starts around 15:30, ECM from 18:00 UKMO starts just before 16:00

[Skyraker]

2 minutes ago, Bazray said:

When are the new charts available? Few hours?

 

About 30 minutes from now for the GFS.

[Catacol]

5 minutes ago, snowblizzard said:

Surely this is why the Met Office are not going for an Easterly!

That damn Azores High is unable to extend NW towards Greenland

Atlantic fronts come over the top introducing less cold airstream.

No signs of height rises towards Scandinavia

Unfortunately, I think they will be on the money!

That's for Saturday. Scandy high, if it comes, is later....Classic battleground stuff by midweek - but all a long way off at the moment.

[Bazray]

1 minute ago, Skyraker said:

About 30 minutes from now for the GFS.

Oh good, Thank You 

[Met4Cast]

6 minutes ago, snowblizzard said:

Surely this is why the Met Office are not going for an Easterly!

That damn Azores High is unable to extend NW towards Greenland

Atlantic fronts come over the top introducing less cold airstream.

No signs of height rises towards Scandinavia

Unfortunately, I think they will be on the money!

Heights don't start extending towards Scandi until Sunday/Monday so a chart for Saturday isn't going to show that. The FAX chart there looks pretty similar to the ECM op in terms of the highs positioning and how amplified it is.

The Easterly route is still considered a lower risk than say, high pressure being too far South and over the UK, that's probably the most likely outcome if you were to take a blend of the models and ensembles. 30% ECM op Easterly, 50% high pressure over the UK, 20% return to milder Atlantic weather early next week. 

12z models coming out, expecting the UKMO and ECMO to hold their ground and I expect we'll see a further shift towards the euros by the GFS op and now it's ensemble suite. 

[Summer Sun]

Irish Met Office

Early to middle of next week: Milder at least for a time with a little rain but also a lot of dry weather. Risk of cold Siberian air encroaching from the East later.

Edited January 10, 2017 by Summer Sun

[Snowman.]

ARPEGE

 

This moves in at night too. 

[bluearmy]

I keep reading stuff about Exeter not believing in an easterly and then I read their 6/15 day forecast and it tells me that they do believe in it but not the whole hog just yet - within twelve hours the Atlantic has gone from Liverpool to nw Scotland on their public thinking 

patience people 

 

[chris55]

Easterly option certainly gaining momentum, with GFS op at least coming on board.

The thing is although the easterly element looks a good bet, where the block sets up will be crucial for the UK, 500 miles north or south will make ALL the difference for our patch, though in the grand scheme it's a similar pattern, and at 168 hours out, its asking a lot for the models to get it spot on.

And it makes all the difference, if the high is centred a bit further south then we could well get a milder feed coming over the top, further north and we get a cold easterly and potential undercut.

So for me it is far far far from nailed that we will get a cold easterly. We just need a bit of good luck for once and hope the High ends up in a favourable location. Many more runs needed.

Looking forward to the 12zs  

Edited January 10, 2017 by chris55

[Ali1977]

14 minutes ago, Summer Sun said:

 

A nice post to see from a MET Office weatherman, I hope it does come and i'm holding my breath for the 12z.  Can we scrape another upgrade or are we going to be dissapointed, I wouldn'y like to guess.  This place will be buzzing tonight if the upgrade happens, another one of those and we good be in a proper "big freeze". 

Well here comes some very important runs, the good thing is we are finally looking in the reliable timeframe instead of scraping around in FI.  Personally i'll be hoping an upgrade in the channel lows position on Thurs and the 850s, hopefully that gives something good down south.

Edited January 10, 2017 by Ali1977

[MR EXTREMES]

http://www.itv.com/news/meridian/update/2017-01-10/severe-weather-warning-for-south-of-england/

Clearly uncertainty.

so to right off things before they happen maybe is not a good idea of coarse they are saying a small risk.

Which would suggest they don't rule out the ecm and there raw output.

 it feels me with little more confidence in the ecm and ukmo over gfs.

Got to be a gfs back track on 12z or 18z 

[tight isobar]

Before the gfs 12z..

Confidence growing strongly for an easterly flow...

'However' its the format of flow we need to be looking for in form of current/upgrades. 

Need to be gaining momentum in a more northerly settlement of heights at Scandinavia. ..thus deeper set flow=colder incursion =hhigher possibilities snow/prolongement! !!!

Heads down. ;-)

[karlos1983]

19 minutes ago, Summer Sun said:

Irish Met Office

Early to middle of next week: Milder at least for a time with a little rain but also a lot of dry weather. Risk of cold Siberian air encroaching from the East later.

I would actually say especially in the south if* it sets up as illustrated!

Edited January 10, 2017 by karlos1983