Model output discussion - Winter has arrived and the hunt for cold is on

[Mucka]

ICON is quite improved this morning but it also looks a little unlikely with its handling of the trough, or at least unlikely to be repeated, so I will curb my enthusiasm until GFS and UKMO

 

The issue is the way it handles the energy coming off the Atlantic and the phasing with the main trough between Scandi and Greenland to our NE.

I'm not saying it is wrong, there is nothing to suggest that, but it requires near perfect timing and interaction of a shortwave at the base of the trough, speed and cycologenesis of the Atlantic low and then the phasing with the main trough.

With a Southerly jet and some trough disruption the UK could conceivably stay on the cold side of the jet from there as with some of the older output that gave us a good cold spell.

 

Edited December 5, 2019 by Mucka

[Mucka]

UKMO rolling out and sticking to playing party pooper, not much like ICON at 120 as expected. GFS though isn't miles away, just missing the runner shortwave at the base of the Atlantic trough that helps accentuate the Northerly. Could be an improvement on recent runs.

UKMO/ICON/GFS 120

UKMO 144 is not good, it is due to be wrong

Edited December 5, 2019 by Mucka

[booferking]

Here come the cold again gfs.

[Ali1977]

Day 8 is quite diff from the last run, over the U.K. and over the USA. The PV isn’t where it was, and the WAA holding in through Canada. Will that help with a better FI I wonder!! 

Edited December 5, 2019 by Ali1977

[Jordan S]

Morning.

What's more noticeable with this gfs update is the handling of the secondary area of low pressure which is modelled to sweep southeast across the UK through Sunday night into Monday behind Saturday nights frontal system. Its Shown deeper in this update with a tighter pressure gradient ie lines closer together with a period of gales across much of the UK.

Zoomed out view of wind gusts. Red is 50+mph.

The Gfs showed this a couple of days ago but as a single fairly straightforward area of low pressure crossing the UK but now modelled to be two low pressure systems rotating in a broader flow around each other which often adds more uncertainty to how strong the two of these will be and whether one is likely to be absorbed by the more dominant low the above scenario is a plausible outcome but a weaker system becoming mostly absorbed is possible too but less likely with a strong jet stream overriding it. 

Wind gust forecast Sunday night / Monday.

Uncertainty with regards to the precise wind strengths but Worth watching. 

The Gem similar for sunday's system.

Also this morning's update from the Gem for tuesday seems to move towards what the Gfs showed a couple of days ago with a frontal system moving through the UK with a period of snow for parts of northern England and Scotland so a little uncertainty here still as to be expected 5 days out. 

 

The jet stream becomes more aligned straight across the Atlantic as next week progresses and continuing strong too with the potential for further deep areas of low pressure later in the week but too far out for any more detail regarding that.. But not particularly mild as the jet would be over or just to the south of us. 

Tuesday..

Saturday 14th..

Synoptic pattern shows this well for next week too..

Edited December 5, 2019 by jordan smith

[West is Best]

Interesting runs this morning, especially the ECMWF evolution post T120. I like the look of that with the dreaded high to the south getting disrupted. It may not look like Armageddon but it's introducing cold zonality. The run up to the Election Day still looks lively with gales from Sunday onwards and snow especially in the north and on hills.

[ItNeverSnowsInWindsor]

Looking odds on for a decent snowy spell in Scotland next week!

[Tim Bland]

ECM day 10 looks cold enough for snow to me with uppers -4c - -6c In a PM flow

Edited December 5, 2019 by Tim Bland

[mb018538]

Best batten down the hatches for a while:



The only plus point i can see is that between day 8-10 the very low heights start to break away from Canada:



Much less of a baroclinic zone:

[shaky]

3 hours ago, Ali1977 said:

Day 8 is quite diff from the last run, over the U.K. and over the USA. The PV isn’t where it was, and the WAA holding in through Canada. Will that help with a better FI I wonder!! 

Yeh and not.in a good way!!dire runs this morning!!!purples have expanded big time over the pole!!!even flatter across our side aswell!!

[shaky]

7 minutes ago, mb018538 said:

Best batten down the hatches for a while:



The only plus point i can see is that between day 8-10 the very low heights start to break away from Canada:



Much less of a baroclinic zone:

Problem is it was showing that for next weeek and look what has happened!!its clearly an issue and something that needs work on on the models!!i mentioned a few days ago that come.closer.to the time it will be flat as a pancake and i was spot on again!!!!one of the posters asked me why and i sed cos it happens everytime!!its a massive weakness within the models!!!

[SLEETY]

Looking good for snow up in the mountains though,from midweek onwards according to the models.

Time to wax the sledges and skis and head up to the Grampians for a long weekend!

[mountain shadow]

3 minutes ago, SLEETY said:

Looking good for snow up in the mountains though,from midweek onwards according to the models.

Time to wax the sledges and skis and head up to the Grampians for a long weekend!

Given the strength of the winds forecast,  I would think the ski resorts will be too dangerous to ski on.

[West is Best]

6 minutes ago, shaky said:

 it will be flat as a pancake and i was spot on again!!!!

If you mean straight west to east then I invite you to back away from your moment of Johnson-esque self congratulation. You're not spot on. It isn't 'flat as a pancake'. The cold zonal meridionality from Sunday onwards has a lot of waves in it with intense north-westerly incursions bringing snow over the north and probably into the Midlands. Both GFS and ECM clearly show this.

[Beanz]

Cold zonality from the models for day 7-10 next week - I would forget any idea of meaningful snow away from higher parts of Scotland.  Certainly cold mid next week, but not that cold.  

Unfortunately this morning’s runs have not flipped back which I was hoping they might.  
 

[northwestsnow]

8 minutes ago, Beanz said:

Cold zonality from the models for day 7-10 next week - I would forget any idea of meaningful snow away from higher parts of Scotland.  Certainly cold mid next week, but not that cold.  

Unfortunately this morning’s runs have not flipped back which I was hoping they might.  
 

The higher routes round me are 400m+ so will be snow up there next week IMO..

WRT the models- you are long in the tooth to know once they converge on a raging Canadian vortex they very rarely revert back to anything approaching what we would like to see.

Its looking unsettled,for quite a while..

Edited December 5, 2019 by northwestsnow

[mb018538]

20 minutes ago, shaky said:

Problem is it was showing that for next weeek and look what has happened!!its clearly an issue and something that needs work on on the models!!i mentioned a few days ago that come.closer.to the time it will be flat as a pancake and i was spot on again!!!!one of the posters asked me why and i sed cos it happens everytime!!its a massive weakness within the models!!!

It wasn't really - the Canadian lobe was always there (as I've mentioned relentlessly), some runs just modelled the Atlantic ridge to have more influence. As that has now been steamrollered, we're just left with typical UK weather - windy, rain at times, some wintriness over high ground. Nothing out of the ordinary for December at all.  

[northwestsnow]

1 minute ago, mb018538 said:

It wasn't really - the Canadian lobe was always there (as I've mentioned relentlessly), some runs just modelled the Atlantic ridge to have more influence. As that has now been steamrollered, we're just left with typical UK weather - windy, rain at times, some wintriness over high ground. Nothing out of the ordinary for December at all.  

I don't disagree, the concern is without any blocking to the north (i can't see hardly any at all ) then pressure will inevitably rise across Europe and the PM airflow could become TM airflow.

All ifs and buts but i don't want to be scratching around at charts at 300hrs looking for hope.Been there got the T shirt ,quite a few times over the last 15  years or so actually..

Not sure what the latest from the strat is, its gone very quiet so i assume there is little positive going on.

[mb018538]

Terrible example as it was so exceptional, but Dec 2010 really was the holy grail. Zero vortex anywhere to our N/NW. Greenland high. No steep thermal gradients.


The problem we end up with the majority of the time here is perfectly shown on today's day 7 ECM. N Pacific high dominant across the western USA with a ridge/warmer air up the west coast. Deep trough pulled down the eastern USA with very cold air intertwined. 850 temps from +10c to -25c over just a few hundred miles. Powerful jetstream forms and crosses North Atlantic killing everything for the UK. Rinse and repeat.

[Mr Frost]

Morning all

Complex outlook this morning regarding potential snow events across the UK and Ireland (as always) - Scotland and Northern England look primed for some knife edge marginal snowfall events (significant over higher hills/mountains I would imagine) - beginning middle/end of next week.  (Other parts of the UK and Ireland in the mix also)

GFS

ECM

 

Upper 850’s of -4 to -8 across many parts of the UK and Ireland through most of the runs and with plenty of precipitation about.

Certainly the risk is there from all the above charts/information for a spell of wintry conditions - whether that be on low ground or above 300 meters...who knows until the time arrives? 

My glass remains half full as always. 

Have a great day everyone! 

Edited December 5, 2019 by Paul
Removed met office forecast part - please post that into the relevant thread.

[Anthony Burden]

Both ECM and GFS still chopping and changing positions of low pressure,will be crucial in regards to temperature 

and snow in places.Most likely weekend before knowing.

[Weather-history]

Hmm

Start of March 1995 and ECM 0z mean chart at 240 hrs

 

Then from January 1984 

 

 

[Weathizard]

Shows just how much the models got it wrong in the key areas, Iberian heights and low pressure much stronger around Greenland. ECM much the same, yes it was 8 days out but a poor effort from the main models IMO

 

[StretfordEnd1996]

Still a lot to play for next week Thurs-Sat or so. I mean it's STILL 7 days away (seems like we've been chasing it forever) and when there's this sort of spread in the GEFS ensembles 

It indicates there is fine margins in uppers cold enough for snowfall and those that are not. 

Few posts highlighting that it's now a 'certainty' that snow will be limited to high ground in Scotland - I personally don't share this opinion and think there is still potential and opportunity for snowfall much further South (though not perhaps the proper South). 

It'd be rather unusual for precipitation to fall as rain for the majority of us with those uppers.

The op then wants to shove much more milder air straight in as early as Friday but this is one of the mildest runs at that timeframe (with most members keen to keep the cold until after Friday).

Nothing about the current output highlights to me that next week will be a 'non-event' for much of the country - there's plenty to get excited about especially the further North you go (but yes I understand that its not going to be anything close to a snowfest). Thus is the case with these types of setup

Edited December 5, 2019 by StretfordEnd1996

[Faronstream]

3 minutes ago, Weathizard said:

Shows just how much the models got it wrong in the key areas, Iberian heights and low pressure much stronger around Greenland. ECM much the same, yes it was 8 days out but a poor effort from the main models IMO

 

Don't you see  the azores height that is a lot more to the east on today's run and that is the problem.It's always the azores height that is underestimated