Model Output Discussion - the cold has arrived

[TanHillWeather]

Christmas Day, frozen north with the cold air flooding south soon after.

[Mark wheeler]

Another terrible GFS run , Not

 

oh and Boxing day snow in the south after the north gets pummled before hand .

Edited December 18, 2022 by Mark wheeler

[Battleground Snow]

Just now, TSNWK said:

What you seeing.. I’m seeing it being a toppling high from 27th after a short granted pretty cold blast.

It's heading for scandi again, it was a near miss on the 12z, we will see if it has more success this run

[MJB]

The southern extent of the cold air is a kin to the Beeb forecast I saw earlier 

[tight isobar]

3 minutes ago, TSNWK said:

What you seeing.. I’m seeing it being a toppling high from 27th after a short granted pretty cold blast.

The jet with the Iberian ridge collapsing.. and enough nw height placement for rolling cold- we’ll see ..or indeed a road trip headed to Scandinavia points !!

Edited December 18, 2022 by tight isobar

[Don]

Just now, frosty ground said:

still dropping south.

but we all know this is impossible due to heights over Europe or so the legend goes 

I think if it wasn't for the Euro heights, we would certainly be in business?!

[Hotspur62]

Really is a fascinating set up with GFS consistent on pushing cold down from 23rd December,how far the cold air pushes south is another matter but there are small corrections southwards so it is possible Midlands northwards could see a white Xmas.Of course the other side of the coin ECM and UKMO just not having it.The clock is ticking but I would say this time tomorrow night the GFS will back down or the other Big 2 May swing to the GFS.Know what way I would like it to go but it’s a heart ruling head one I think.

[Ali1977]

For those that don’t know, look at ECWeather about 10 mins after a T240 GFS local details on the latest run. I’ll post Alston in cumbria soon to show what this latest run was showing. All for fun at the min but I imagine we are talking 40-50 cm 

The 12z showed a fair bit for Alston - it’ll be eclipsed some what

Edited December 18, 2022 by Ali1977

[tight isobar]

Locking in ere !!!

[Allseasons-Si]

1 minute ago, Tim Bland said:

Yep north York moors look good.. could be snow for many areas by Boxing Day though … 

Get yourself into the Tarn inn for a lock in

30th Nov 2021

seriously though,...anywhere could have a white xmas,just depends on where the battle line is come the big day,..if at all.

 

[The Enforcer]

7 minutes ago, Ali1977 said:

Merry Xmas from the GFS - trending further south. I’m sure someone is in for a pasting Xmas day - but will it be Scotland or the south coast - interesting times 

I realise this is low resolution and at range, but given the temperature profile, why does the model think that the northernmost section of the area of precipitation moving down from the north would be rain?

Edited December 18, 2022 by The Enforcer

[Ali1977]

2 minutes ago, The Enforcer said:

I realise this is low resolution and at range, but why does the model think that the northernmost section of the area of precipitation moving down from the north would be rain?

Just a glitch I reckon, especially with sub -7c uppers - 528 and Dew points are fine 

Edited December 18, 2022 by Ali1977

[Johnp]

This would be so much more exciting if any of the other models were on board. Fingers crossed for the morning. 

[tight isobar]

1 minute ago, The Enforcer said:

I realise this is low resolution and at range, but given the temperature profile, why does the model think that the northernmost section of the area of precipitation moving down from the north would be rain?

Simple answer= don’t use the gfs precipitation quotas after 96 hrs..

[feb1991blizzard]

-8c 850mb with a 1040mb high under snow cover.

[tight isobar]

What a run - 18z a locked in cold pattern that could yet further improve/impact!! As for snow potential.. well I think we all know the potential

[Snowman.]

Could be a juicy FI here.

 

[tight isobar]

I’m bailing out @240 hrs anything after good/bad is atm pointless from here on this run .. it’s probably 1 of the best/ if not thee best run of the season thus far.. and if I’m going to be honest- I think the pattern will look even better through the 850 hpa window as we go through the week ...

[Battleground Snow]

Control and mean generally agree with the OP out to 126.

You would think we are approaching the time when one of the models has to have a big climbdown.

For what it's worth, gem mean was nearer to GFS at 120

[Ali1977]

And there you go - about 70 cm for Alston.  

[northwestsnow]

GFS 18Z = VICTORY..

Chance of it being right ?

I'd say ,hand on heart 20%..

[frosty ground]

2 minutes ago, Ali1977 said:

And there you go - about 70 cm for Alston.  

When it shows 30 tomorrow it’ll be the biggest downgrade in history

[Mucka]

Example perturbation GFS 18z suit

The intensity of the cold air to the N is ripping those lows to shreds as they come in.

There is nothing like the same level of disruption on ECM or UKMO

Which is why the cold air gets cut off on those but still comes S on GFS.

Look out for that disruption on UKMO/ECM tomorrow morning 96h through 120h and hope it continues n GFS.

 

[Snowmadsam]

Control on the GEFS takes the cold air down quicker.

Question is, which model will be having to swallow a bitter pill.....

Or will we get a compromise? 

 

[Ali1977]

2 minutes ago, Snowmadsam said:

Control on the GEFS takes the cold air down quicker.

Question is, which model will be having to swallow a bitter pill.....

Or will we get a compromise? 

 

I imagine it’ll pull back, the op looks in the more extreme end of the ENS at 144 - especially for that snow event.