Model output discussion - cold spell approaching?

[northwestsnow]

Nope.

None the wiser !!

Another big EC this evening.

Keep the faith EC ...

 

[Mike Poole]

10 minutes ago, ICE COLD said:

Gem is a bloody corker . Go on ECM I dare u to follow the gem  

The GEM looks fine from a pattern perspective but, very little cold air, at T240 anyway:

Obviously the pattern would be conducive to advecting the deep cold towards us to an extent unknown, but that would be longer term, for now it is too far west.

[phil nw.]

20 minutes ago, Kasim Awan said:

The forecast of "cold" is still very much a likelihood, it's the magnitude of cold during day 6 to day 8 which has been steadily downgrading recently.

Early days there though Kasim with the pattern still building and the trough to our ne still dropping.The landing point from my viewing of the eps for Warks are -5c uppers by day 8 which have been the steady message in those.

 

[Froze were the Days]

Just now, Cold Winter Night said:

The very cold upper air on the move over the relatively warm waters of the Norwegian sea generates lows.
I think @Singularity mentioned this too, earlier today, only about lows in the Atlantic.

So we're bug*ered by warm sst's off the Norwegian Coast and in the North Sea, this troughing I swear I've never noticed back in the day from an Easterly.

[bluearmy]

an illustration of gem snow charts here 

uppers above zero s midlands north but snow down to a coast
 

 

[That ECM]

Comparable mean. good perts. Inter run variables.

[Kentspur]

6 minutes ago, Tim Bland said:

️

I've not seen one GEM snow chart verify atleast for the south and SE so far this winter always over estimating the amounts/l and forecasting rain as snow etc i suppose its got to be close to verifying once though 

[NewEra21]

2 minutes ago, Mike Poole said:

The GEM looks fine from a pattern perspective but, very little cold air, at T240 anyway:

Obviously the pattern would be conducive to advecting the deep cold towards us to an extent unknown, but that would be longer term, for now it is too far west.

Yep, everything just needs to take a shift SE to allow the colder air over the UK.

[ICE COLD]

No one mention the para it’s dog . I’ll be happy if the ECM sticks to this morning run . @Mike Poole isn’t the gem poor at predicting 850s ?? I know it used to be . 

[Froze were the Days]

Strikes me as a pattern that in our location that just won't sink far south enough below 50 degree latitude, not seeing much at all in terms of real cold and as said the further north you are the more in the game in terms of snow and cold.

IMBY would much prefer a Scandi high pressure now the continent is showing 'real' cold.

[Cold Winter Night]

1 minute ago, Froze were the Days said:

So we're bug*ered by warm sst's off the Norwegian Coast and in the North Sea, this troughing I swear I've never noticed back in the day from an Easterly.

We're not looking at a true Easterly though. Not often an air mass this cold moves from the Barents Sea along the Norwegian coast towards the UK. Norwegian Sea and North Sea will always be relatively warm, due to the Warm Gulf Stream. Only after a longer cold period will the North Sea truly cool down, the Norwegian Sea will barely respond to seasonal influences at all.

A classic Easterly takes air over the Ural, Baltic Area, Poland or Scandinavia (mostly over land) towards the UK. It might move over the Baltic Sea, which is cooler anyway, and it has a shorter trip across the North Sea.

[SLEETY]

Don't like this gfs run , not cold enough, want to see more of an easterly  too much sea_track in this run  and it moderates the air further South, great for northern hills etc.

Edited January 12, 2021 by Paul

[Roger J Smith]

The numerical output for that GEM chart in question should predict a rain-snow mix over most of southern England, differentiated by elevation, trending to all snow at about the latitude of central Wales to Lincs. Not sure why it would depict more snow than those parameters would suggest, they must have it programmed as though the thicknesses and uppers were over central North America with no maritime interaction. Then a low with those characteristics would give mostly snow, albeit heavy wet snow, and to get parameters like that in that region you'd be talking very early or very late in the winter season, any interaction between a deep low and arctic air in that region would draw in -10 or lower 850s and produce a much sharper thickness ribbon. 

That being said, I find the map a bit overamplified anyway. The GFS depictions of a storm track running through southern England remind me a bit of a scenario in Feb 2008 which looked like this ten days out but ended up being much further north with most of the UK into milder air fairly quickly once some initial shallow cold was moved away. 

 

I would prefer to see output like the 06z GFS where deeper cold pushes in and stays around with the Atlantic held at bay. In this day and age, a raging Atlantic is not very likely to co-operate by running its business through France, although that of course is the route to heavy snowfalls in southern England. 

[Mike Poole]

3 minutes ago, ICE COLD said:

No one mention the para it’s dog . I’ll be happy if the ECM sticks to this morning run . @Mike Poole isn’t the gem poor at predicting 850s ?? I know it used to be . 

I’m not sure since the upgrade, it seems to verify quite well now as 3rd best model most of the time, but that is on heights not 850 temperatures. 

[I remember Atlantic 252]

1 minute ago, SLEETY said:

Don't like this gfs run , not cold enough, want to see more of an easterly  too much sea_track in this run  and it moderates the air further South, great for northern hills etc.

Can see why certain posters are absent, its crud actually for the South and SE 

all FI but I like the southerly tracking lows! no real cold but certainly potentially snowy, GEM too with the snowy lows

[northwestsnow]

While I understand the focus on how cold it might get  I rather think we should be concentrating on getting that ridge north at 120- 144 ...

Because we still don't have clarity in this crucial timeframe ...

[That ECM]

What’s gfs saying at T240. What was gfs showing 10 days ago for now and what is it? 

[Anthony Burden]

Plenty of uncertainty for the remainder of this week,with Atlantic v continental air.

snow possible in a few unsuspected places.Today’s charts GFS poor GEM Excellent,l

all about how how quick vigorous Icelandic low crosses over to our east and drags

that very cold air in during next week.Should be some exciting Synoptics next week

watch this space.

[Weathizard]

The GEFS mean has been getting better and better looking whilst the cold/rather cold 850’s keep getting pushed back to day 8/9, Groundhog Day for most winters in the U.K

I’m still positive though, I think the cold will come at some point it’s just frustrating the delays.

[Methuselah]

Not bad T+384 charts... Nothing to do with day-to-day detail of course... But I'm liking the southerly-tracking jet stream. Likelihood of verification? Ooh, about 0%!

    

[northwestsnow]

Just now, Weathizard said:

The GEFS mean has been getting better and better looking whilst the cold/rather cold 850’s keep getting pushed back to day 8/9, Groundhog Day for most winters in the U.K

I’m still positive though, I think the cold will come at some point it’s just frustrating the delays.

I'm totally with you.

At least you don't offer rubbish commentary on a run from 2 days ago like this silly old fool.

The mean is good, Exeters update is an upgrade.

I'm trusting ukmo model is struggling with this pattern.

 

[Battleground Snow]

Still looks good to me on the mean graph.

A few warmer extreme options pulling it up also.

And remember we don't need super low 850mb temps to get snow if other parameters are met, which has been discussed in depth already 

[Mucka]

Just a quick word on potential W based neg NAO (more phasing dramas)

First of all let's get past the first phasing hurdle (nearly there)

As for the trough dropping too far W and phasing with the shortwave trough undercutting the Atlantic ridge later, two things.

1. It would almost certainly still give us a cold spell unless it dropped further W still and allowed the SW trough to develop to our SW  instead of phasing cleanly. The ensuing cold would not be the depth of cold we could get by ant means with a boundary between the frigid air mass to our NE and warmer air to our SW possibly somewhere over the UK. Historically these set up somewhere over S England/midlands but can be further S or further N, These set ups give massive dumpings of snows at the boundary lines (unless it is too far s) as Atlantic lows disrupt against the cold air mass.

2. The low is likely to drop further E than some of W based runs have shown. It won't be a massively dissimilar situation to what we have just seen where the low was originally modelled to drop S much further W (except by UKMO that has it too far E)

Jan 9th V Jan 17th

So UKMO could be best guidance tomorrow on where it will actually be placed with ECM which I believe will be corrected E not W even though that goes against the norm of us getting another busted cold spell

Edited January 12, 2021 by Mucka

[NewEra21]

5 minutes ago, Battleground Snow said:

Still looks good to me on the mean graph.

A few warmer extreme options pulling it up also.

And remember we don't need super low 850mb temps to get snow if other parameters are met, which has been discussed in depth already 

It's very good to still see that cold clustering between the 20th - 22nd. A few milder runs and the op not quite as cold as the coldest cluster. But overall I'm more than happy with that!

Edited January 12, 2021 by NewEra21

[East_England_Stormchaser91]

Very interesting runs. A great example of high risk, but some very high reward returns in the form of drifts of snow. Absolute knife edge stuff for England. 100-200 miles could mean the difference between an absolute whiteout or a standard rain affair. Always a good sign seeing the jet stream so far south!