Model output discussion - Closing in on Christmas

[Zak M]

Good lord, P8 is something else - 'stonker' is an understatement. It almost has the -12/-13c isotherm over the whole country at one point..

         

Here's a friendly GIF:

   

And here's all of the ensembles combined into one graph - notice how most of the 850s hover around -5c as we head into the end of December and into the start of January:

Plenty of positives going forward.

Edited December 18, 2020 by Zak M

[Cheshire Freeze]

Excellent ICON this morning-

[northwestsnow]

Yep...

Icon 00z 144 poised to deliver an Arctic Northerly for Santa

I can safely say if UKMO looks anything like that at 144 I will be ecstatic.

It almost certainly won't be as nice as ICON.

[northwestsnow]

And here is what is at stake if the dice fall kindly...

[Cheshire Freeze]

3 minutes ago, northwestsnow said:

Yep...

Icon 00z 144 poised to deliver an Arctic Northerly for Santa

I can safely say if UKMO looks anything like that at 144 I will be ecstatic.

It almost certainly won't be as nice as ICON.

Snow maker for Christmas Day for parts of the NW of England

Synoptically similar to the '09 spell with a slack onshore flow and constant shower training

 

Edited December 18, 2020 by CreweCold

[Kasim Awan]

This is a "binary logic"

Either the shortwave tags onto the main low or fails to connect. ICON connects it which helps amplify the low and therefore the northerly. Fail to connect and loose all vigor.

This binary problem is why often see such large differences in output. It either works or doesn't. Very difficult to make the call.

[BlueHedgehog074]

Agree with the above, when the other cold weather fans wake up, they’ll be in for a lovely treat with the ICON ️

Pretty much keeps the North-Westerly to Northerly flow going from the 23rd right to the end of the run (Christmas Day) for the UK.

The 850 hPa temperatures do become supportive of wintry weather down to lower levels on the big day itself. 

One other thing worth noting, is that although that Low to the South-West of the UK doesn’t get trapped underneath the Atlantic ridge this time (merges with Low Pressure over the UK)...

...it still manages to sufficiently clear away to the East of us pulling down a cold Arctic flow. (Edit: Just noticed Kasim’s post above and see that we’ve both been at the black crayons ). Both that and the events further West upstream helps achieve some decent amplification of High Pressure in the Atlantic. The big, stormy, Low, coming out of Eastern Northern America/Canada, which digs quite far South to the West of the Atlantic ridge does something interesting. It swerves up Northwards going up the Western side of Greenland drawing the Atlantic ridging Northwards. This is instead of the Low quickly trying to head East and flatten out the ridge that risks cutting off our cold weather supply. Part of that Low does spilt with the Southern tip of it wanting to slide underneath the wedge of Greenland heights that formed to the North of it. So some slider possibilities their, and likely keep the cold going over the UK

 

Edited December 18, 2020 by DiagonalRedLine

[Daniel]

Happy boxing day! This chart would be a great Christmas present. 

[Cheshire Freeze]

GFS stunner alert

[Mucka]

Interesting GFS 00z even though it is not nice winter weather for Xmas day.

Normally with this 144 chart it would be tears and tiaras with the flatness of the pattern and the "spoiler" low developing SW tip of Greenland which so often ruins a blocking pattern for us.

But in this case it acts as a trigger low with a highly amplified pattern behind

GFS is quite good at picking up these lows SW tip of Greenland before the Euros so if it sticks with it a couple of runs more then it may well be onto something though how well it helps after hindrance as with this run remains to be seen

Edited December 18, 2020 by Mucka

[feb1991blizzard]

Big upgrade on GFS 0z, ridge gaining more latitude.

[Cheshire Freeze]

 

What a stunner

[Kasim Awan]

Every cloud has a silver lining - The lack of amplification to Greenland around 23rd/24th seen on the ukmo, gfs would make room for the secondary low to stir around GL, before attack. So even in the event of a muted initial northerly as per icon/gfs, we're in for a decent chance of a festive Northerly.. 

One of those instances where both favored possible outcomes could deliver..

As long as we can keep healthy tilting of the high on the Newfoundland side, as hinted on ecm #12z

Edited December 18, 2020 by Kasim Awan

[Ali1977]

A big GFS upgrade for day 10, look at that for a Greenland high!! If this has supper from the ENS and the ECM follows this forum will be buzzing this morning!

[swfc]

Morning. Well the oz gfs this morning will send the pulses racing possibly pre ten day the best run of the year I suspect. Enjoy

[Scott Ingham]

Right on cue New Year week now this has a level of credence and has done for a long time that the previous few weeks never really did. Big EAMT event at christmas time spoken about has a lot to do with this. AAM is being revised up closer to the time on a daily now. Upgrades are now coming after the models lost the plot with this new signall

Edited December 18, 2020 by Scott Ingham

[Ali1977]

Well, I think this is a BOOOOOOM

 

Id be surprised if this is supported, but you never know !! 

Edited December 18, 2020 by Ali1977

[northwestsnow]

So,UKMO GFS and ICON trap the low.

Over to EC...

[That ECM]

JFF that is some chart.

[Cheshire Freeze]

Warming up top intensifies further on this run

[Ali1977]

2 minutes ago, CreweCold said:

Warming up top intensifies further on this run

If this run and that warming verified we could be in for a considerable big freeze - I’m not holding my breath though!! 

[Cheshire Freeze]

Really REALLY hard to look at these charts and not get carried away. However, that GFS run is a stunner.

[Ali1977]

Reload from the North inbound - it’s a gift from God this one!!

[Kasim Awan]

The GEM is an absolute GEM at 240h with this strength of trough, a gfs 00z synoptic would likely follow

 

[Cheshire Freeze]

 Looks like the whole of the TPV is about to descend on us...jeez