Model output discussion 02/02/20

[Beanz]

1 minute ago, ICE COLD said:

Gfs still pushing for snowy Thursday. 

And the BBC has got snow over my location to now .

Wow you must be my neighbour!  

MetO have upgraded their forecast from yesterday too.  Annoyingly I’m not at home tomorrow and have to travel south! 

[nick sussex]

Shame the ECM and GFS have bailed out just as the UKMO decided to pull out one of those better solutions helped by a wedge of heights to the ne.

They all disagree as early as day 5 but so far this winter if the ECM picks the worst solution it normally verifies whilst anything colder implodes .

Edited February 26, 2020 by nick sussex

[chris55]

Euro 4 highlighting the risk of some snow tonight. 
It’ll all be down to ppn intensity and organisation if we see any settling. Obviously hills much more prone to accumulations. 
 

[Gowon]

8 minutes ago, nick sussex said:

Shame the ECM and GFS have bailed out just as the UKMO decided to pull out one of those better solutions helped by a wedge of heights to the ne.

They all disagree as early as day 5 but so far this winter if the ECM picks the worst solution it normally verifies whilst anything colder implodes .

I'm not sure how well it's rated, but the Icon is similar to the UKMO? 

[jamesgold]

6 minutes ago, chris55 said:

Euro 4 highlighting the risk of some snow tonight. 
It’ll all be down to ppn intensity and organisation if we see any settling. Obviously hills much more prone to accumulations. 
 

That really goes for it doesn’t it?! Am I right in thinking there’s a tendency for these systems to be corrected southwards a day before an event? Sorry if this has been brought up already I haven’t read it all

[IDO]

4 minutes ago, nick sussex said:

Shame the ECM and GFS have bailed out just as the UKMO decided to pull out one of those better solutions helped by a wedge of heights to the ne.

They all disagree as early as day 5 but so far this winter if the ECM picks the worst solution it normally verifies whilst anything colder implodes .

Yes, ECM has impressed with it's consistent fail at D10 when height rises are involved. Yesterday I ignored it as I think there had been 20+ previous fails and statistically the probability of yesterday's D10 verifying was very low:

yesterday>Today>

We have also seen false dawns in FI from the GFS as it picks up a signal, then it crashes back to the ongoing pattern. The D16 mean offers little hope of a change pre-mid-March:

The tPV is moving around to our north so little sign that a ridge could sustain but maybe a brief respite from the zonal flow is possible. Any wedge help would be welcome but they are only worth a cursory look till they reach D5.

A mundane end to a rotten winter, 2.6c above average for Jan CET and currently 3.1c above for Feb! That is as far away from a cold winter the worst nightmare could come up with!

[Tim Bland]

ECM has snow falling from M4 up to Manchester and across to Norwich. Areas further south such as High Wycombe across to Essex could also see some. Children’s and downs look like the sweet spot with a whopping 5cm So almost enough for a snowman ️ This is probably the highlight of the winter

[SMU]

How many UKMO fails at day 6 have their been for height rises ^^^ Zero so far

So a good test coming up

[SMU]

@Tim Bland

I check ECM Snowline level for 04-0700 its 500 Feet ( 150M ) For reference. 

Cut off point for snow around Tonbridge across to crawley ( All rain further south )

S

[SMU]

GFS trends south towards ECM > 0c isotherm now only reaches as far North as about 20 miles inland

[Alexis]

6 minutes ago, Tim Bland said:

ECM has snow falling from M4 up to Manchester and across to Norwich. Areas further south such as High Wycombe across to Essex could also see some. Children’s and downs look like the sweet spot with a whopping 5cm So almost enough for a snowman ️ This is probably the highlight of the winter

That shows heavy snow over my house under 850s of -5C and a dew point of 0-1C. I won't even see a flake.

[Polar Maritime]

UKV's snow take on the early hours tomorrow.

[weirpig]

1 minute ago, Polar Maritime said:

UKV's snow take on the early hours tomorrow.

That model  like most others as chopped and changed    only yesterday it was showing  close to nil precipitation  through the middle swath    what looks likely according to that  is anyone wishing to build a snowman in southern england  may be out of luck 

[Mike Poole]

HIRLAM 0z has the following for Thursday morning, classic M4 scenario:

Cumulative snow to end of the run:

Going down to the wire this one...

[Banbury]

GFS 6z still on track for tomorrow IMBY 

Apologies I was on the wrong day 

 

 

Edited February 26, 2020 by Banbury

[tcc]

19 minutes ago, Steve Murr said:

@Tim Bland

I check ECM Snowline level for 04-0700 its 500 Feet ( 150M ) For reference. 

Cut off point for snow around Tonbridge across to crawley ( All rain further south )

S

I'll let you know if your right Steve, as I live in Crawley! 

[weirpig]

6 minutes ago, Mike Poole said:

HIRLAM 0z has the following for Thursday morning, classic M4 scenario:

Cumulative snow to end of the run:

Going down to the wire this one...

The 6z  though brings it much further South   sleety mix  for most   Cotswolds  best position 

Edited February 26, 2020 by weirpig

[Mapantz]

12 minutes ago, weirpig said:

That model  like most others as chopped and changed    only yesterday it was showing  close to nil precipitation  through the middle swath    what looks likely according to that  is anyone wishing to build a snowman in southern england  may be out of luck 

You couldn't be more wrong. I have been watching it for the past few days and it has been extremely consistent - hardly changed at all.

Edited February 26, 2020 by Mapantz

[Polar Maritime]

12 minutes ago, weirpig said:

That model  like most others as chopped and changed    only yesterday it was showing  close to nil precipitation  through the middle swath    what looks likely according to that  is anyone wishing to build a snowman in southern england  may be out of luck 

18z yesterday and latests.. Can't see much difference.

Edited February 26, 2020 by Polar Maritime

[weirpig]

1 minute ago, Polar Maritime said:

18z yesterday.. Can't see much difference.

Apologises   i was thinking of the UK4   i think 

[Frosty.]

Those of us looking for a possible end in sight to the very unsettled pattern could be cheered by the longer term GEFS 0z mean which indicates higher pressure in the vicinity of the U.K. towards mid March.

[weirpig]

13 minutes ago, Polar Maritime said:

18z yesterday and latests.. Can't see much difference.

Or maybe this   yesterday

Edited February 26, 2020 by weirpig

[nick sussex]

The wedge drama continues .

The GFS develops a wedge of heights to the ne . Every run though changes the evolution of low pressure over the UK .

This wants to split  low pressure over the UK taking one cell nw whilst the second tracks east .

If any wedge gets further sw then a better chance of some snow as the upstream low moves in later and hits the colder air .

Equally if the ECM trend is correct then zip chance of that .

 

[feb1991blizzard]

34 minutes ago, nick sussex said:

The wedge drama continues .

The GFS develops a wedge of heights to the ne . Every run though changes the evolution of low pressure over the UK .

This wants to split  low pressure over the UK taking one cell nw whilst the second tracks east .

If any wedge gets further sw then a better chance of some snow as the upstream low moves in later and hits the colder air .

Equally if the ECM trend is correct then zip chance of that .

 

I am increasingly becoming interested in what is happening at the end of these runs.

[SMU]

GFS mean & operational moving South -

So remember the gridpoint for this model is along the M4 out East through london in a straight line

This is why the snowline is pixelated in a fead straight line when of course it will be a transitional zone across about 10-20 miles. 

With that in mind even though every jog south doesnt change the overall pixel yet for SE Eng - it does actually make a difference to where the transition zone sits > NB UKMO raws have snow in NW kent etc around 8am - This is because the  transition zone ( Where the 0c > -2c isotherm sits is straddling mid kent to south London ) 

* Thats why I highlighted the cut off points early.

As we can see from the 500MB plot Mean V Mean 00z to 06z & the same with the 850s the 06z has nudged the transition zone back south of the water towards the Euros.

06z First

Edited February 26, 2020 by Steve Murr