Model output discussion - into the start of Winter

[Griff]

7 hours ago, blizzard81 said:

I would advise some on here to look back at the general synoptics of the past 9 Decembers. Then compare those with what the current models are serving up for us this December. It will really help get everything into perspective. We are are in a really good place with regards to cold prospects over the next few weeks. 

Ha, I was genuinely expecting the punchline to be "We see this promise every year, and it never delivers"! 

Glad to be wrong (so far)! 

 

It's already been and interesting 3 or so weeks of model watching. 

[Griff]

GFS like a dog with a bone regrading the Greenland / Icelandic block (in FI) , also anecdotally the 17th of December has been mentioned for many and various reasons regarding the strat, and the PV etc. Might be worth checking what the Mayans and Nostradamus had to say about that?

In the more reliable (maybe)... 

Edited November 29, 2020 by Griff

[Met4Cast]

Another beautiful run by the GFS, the ECM is okay but makes a bigger deal out of the low over the UK and as a result it's slower to disrupt, how the low disrupts seems to be a sticking point at the moment, not worth looking beyond that.

[That ECM]

T240. High pressure trying to go north on a lot of output. East and west.  Some cold rain and possible wintry weather for some prior to this. Going into December looking at this is encouraging for a coldie like me.  Now I like my snow to come up from France and there is much to fall right for that to happen but at least I can view with interest unlike many starts to winter.

[DavidS]

Model watching continues to be of great interest. The detail varies, but the theme continues. Higher heights to our north and lower heights being shown over Europe. All very positive for those that favour cold.  And in the extended GFS, is that an Arctic Hare I spy?

[Mr Frost]

On 28/11/2020 at 07:17, Mr Frost said:

Morning all!

Getting slightly excited now! 

Latest UKV chart snapshots below for Thursday at 0:00 

OC Isotherm (m)

 

Dewpoint Temperature (c)

 

850HPA Temp

528 dam line digging South - much lower for NW/N Scotland.

 

Precipitation Type:

 

That is what I call a proper start to Winter - showers get going late Wednesday afternoon.

Snowfall down to very low levels in parts of Scotland, risk of wintry (maybe even snow) showers for other areas such as NW/N England, Northern Ireland, Ireland and Wales (hopefully all the other areas would get something later on) - could see plenty of snowfall over higher hills/mountains throughout the UK and Ireland.
Bit of instability as well with this flow - thunder/lightning/graupel risk.  

Morning all!

Twenty four hours on...barely a change on the latest UKV run for Thursday at 0:00.

 

Showers really get going Wednesday afternoon/evening onwards! Thursday is not too shabby either! Wintry showers risk on fairly low ground in those areas previously mentioned - especially through Thursday. 

Big change on my regional Met Office outlook this morning. 

 

Wee mention for this - rainfall to snowfall over high ground (sleet low ground - maybe even wet snow) down South early Friday AM:

Very marginal for low ground but one to watch. 

Friday snapshots for 03:00

 

As ever these charts are subject to change at this range - not a bad start to Winter model viewing...radar watching begins later Wednesday for some of us. 

Have a good Sunday!
 

[SMU]

Morning-

Very happy with the overnight runs -

ECM cold ( not super cold ) for here - & the mean + operational showing stronger atlantic amplification day 9/10.

Becoming cold & frosty late on.

 

ECM for biggin Hill

 

Refenece to 2010 - the models looked remarkably similar to where we are - then in comparison the models over a 24 hour period showed exactly what we are seeing now -

But very quickly became more amplified-

Lets see what today brings however at this stage whats being shown > the angle up towards greenland isnt as acute > it needs to be more vertical!

Edited November 29, 2020 by Steve Murr

[sheikhy]

Still gfs sticks that trough slightly further at 96 hours on gfs!!good news is ukmo and ecm still have it slightly further east!!finally some interesting weather to talk bout compared to the dull boring stuff we have had over the last week or so!!

[weathergeek]

1 hour ago, Griff said:

GFS like a dog with a bone regrading the Greenland / Icelandic block (in FI) , also anecdotally the 17th of December has been mentioned for many and various reasons regarding the strat, and the PV etc. Might be worth checking what the Mayans and Nostradamus had to say about that?

In the more reliable (maybe)... 

I think that's known as "cross model agreement"??!!

[bluearmy]

9 hours ago, kold weather said:

I think this spell coming up in and of itself is going to lead to little in the way of snow chances apart from maybe on higher ground. Its a classic "if only it happened a few weeks later/earlier" type pattern and insanely marginal. Most may get rainy sleety mess and perhaps a few flakes at the back end of any heavy showers/cold fronts.

However rather than viewing this as the whole dinner, perhaps it would be wiser to view this as the starter course, the thing that helps to cool down Europe/SSTs from being very much above average towards something we can benefit from if we get a reload a few weeks down the line from what is being seen on the models at the moment.

I'd be very surprised if we don't get at least one more bite of the cherry between the 15-30th December based on how persistent  that diving LP set-up is becoming on the models. Also each day that passes and we stay under a below average set-up across Europe helps to sway us towards less marignal situations IF we can get any future slidders/divers. Often cold winters have these sorts of cold primers at some point either in November or early December.

So whilst it may feel like we are wasting this set-up, I'd be somewhat positive that this won't be our only attempt at cold. I know some people are still carrying battle scars from the last 2 winters and are desperate for a set-up to come off, but those of us who have been around a long time know sometimes you have to do the ground work first.

Some of the less experienced on here take heed of this ..... very insightful.....

 

[Methuselah]

So the overall blocked pattern continues well into FI, according to the 00Z... Ergo, the developing North European cold pool should grow and grow and grow... Nailded!

    

[sheikhy]

Low further east at 96 hours on latest icon!!so it joins the ukmo+!!

[SMU]

1 minute ago, sheikhy said:

Low further east at 96 hours on latest icon!!so it joins the ukmo+!!

I knew yours woukd be the last post-

The net difference is the -4c line gets to the SE

117 could be interesting > bringing a bit of snow to Norfolk.

by 120 the whole of the SE has avoided the WAA

 

 

[sheikhy]

Icon even further east than than ukmo and ecm!!!can gfs 06z follow...

[Anthony Burden]

Still some changes to happen with these low pressure’s heading south,some parts of the

UK Will in my opinion see some snow for sure.But it is after this incursion of unsettled 

weather that interest me key to cold being high pressure to the north of U.K. then winter

will really begin.

 

[Tim Bland]

4 minutes ago, Steve Murr said:

I knew yours woukd be the last post-

The net difference is the -4c line gets to the SE

117 could be interesting > bringing a bit of snow to Norfolk.

by 120 the whole of the SE has avoided the WAA

 

 

Quite a large chunk of the south east could get in in the action ..... chilterns perhaps could see something?

[Scandinavian High.]

3 minutes ago, Anthony Burden said:

Still some changes to happen with these low pressure’s heading south,some parts of the

UK Will in my opinion see some snow for sure.But it is after this incursion of unsettled 

weather that interest me key to cold being high pressure to the north of U.K. then winter

will really begin.

 

It be magical to be hit snow cold spell over Christmas period.

[I remember Atlantic 252]

5 minutes ago, Anthony Burden said:

Still some changes to happen with these low pressure’s heading south,some parts of the

UK Will in my opinion see some snow for sure.But it is after this incursion of unsettled 

weather that interest me key to cold being high pressure to the north of U.K. then winter

will really begin.

 

hopefully not like the one in Jan 2013, no snow off it here at all, actually thawed the snow I had from day before

[SMU]

4 minutes ago, Tim Bland said:

Quite a large chunk of the south east could get in in the action ..... chilterns perhaps could see something?

Yes possibly although often the chasing cold air is delayed & the undercut doesnt make it in time- but this is 2020- anything can happen

[johnholmes]

Nothing of any real consequence has changed in the past 2 days with the 500 mb anomaly charts so the idea of surface weather should stay the same:- so

The contour heights predicted over the uk are ‘about’ average for this time of year and there is no indication of deep cold air being advected over the country, from any other area, be that NW-N-NE-E so temperature wise around, perhaps a touch below, at times countrywide. No likelihood of any low ground snow from any ppn. Higher northern ground if anything falls. The far NW of the UK most unsettled/changeable and possible gales if any surface lows deepen close to that part of the country with temporary snow in the colder air behind the systems. But nothing unusual for late November/early December in the 6-14 day outlook in my view. With such a slack flow over southern areas then fog and frost could develop on suitable clear sky nights.

Just to add that the longer this pattern persists then the more likely the upper air is going to cool slightly and also the surface air. Thus,  there is some probabilty that the risk of snow is increased in any ppn, even for some lower ground, this most likely for more northern areas

[sheikhy]

Nope gfs still takes it west!!thatd gfs against ukmo ecm and icon!!!whose gona be right?

[markw2680]

9 minutes ago, sheikhy said:

Nope gfs still takes it west!!thatd gfs against ukmo ecm and icon!!!whose gona be right?

Probably non of them as there will be changes in all model runs for a while yet, hopefully all will settle with them taking it more east but we will see.

with the way of the world we may actually fall the right side for a change...

[IDO]

Sadly, GFS has the northerly cold flow too far west and we miss on that top-up of cold for the cold pool as we move into the next stage. As previous runs suggest no further injection of cold any time soon, so we really need that to correct for at least some interest, as we lie in that cut-off low as it warms out:

Still time for an eastward revisions though ECM similar in westward placement of the core low:

The 0z GEFS were a bit scattered post-d10, so hopefully will see some direction over the next few runs towards the op, with respect to a more blocked pattern?

[SMU]

2010 if you are interested > The GH was created but the force & movement of the Scandi high & atlantic ridge kicking the jet North

Lets see how close if at all the 06z gets

[swfc]

6z gfs not so keen on Atlantic ridging ie 180 hrs. Hopefully not a collapse of heights and flattening