Model output discussion - Winter approaches

[Day 10]

This is better, look were the Jet is headed.

[Eskimo]

Could this really be our year for a cold December? 

[nick sussex]

The models have had a hard time getting to grips with the blocking to the east .

The UKMO in particular has been woeful with that , originally it had the blocking aligned more north south .

Models seem to be finally agreeing , let’s hope converging on the correct solution .

Overall it looks like a quiet spell of weather coming up for a few days , depending on cloud cover could be some frost and fog .

The continent under the right conditions cools rapidly at this time of year , noticeable that any med sourced air is cut off by low pressure over Southern Europe .

Any easterly flow should become increasingly colder with time close to the surface even though the 850 values look higher .

The GFS by day 8 is now disrupting the troughing to the nw . I think a bit more energy needs to head se rather than south . That could then help to pull colder upper air into the UK .

Edited November 24, 2020 by nick sussex

[Ali1977]

The 12z does look much better with regards block to our East, and WAA up the East of Canada. Not sure it’ll come to much but if you think about what we’ve had the last 2 years we are in a pretty good place !!! 

[Tim Bland]

3 minutes ago, PerfectStorm said:

Could this really be our year for a cold December? 

Could do with it being a bit further East..could result in a stronger easterly if that low slips under

Edited November 24, 2020 by Tim Bland

[Cheshire Freeze]

GFS day 9...you beauty

[Day 10]

Looking pretty good to me.

[Tim Bland]

2 minutes ago, CreweCold said:

GFS day 9...you beauty

Looks good synoptically but there isn’t much cold to tap Into.  Lots of potential from there though..

[Ali1977]

If only we were in Early Jan , looks good but not sure much of the white stuff would come as the Easterly feed hasn’t got much bite coming from the Ukraine at this time of year, rather than Northern Russia.

[Day 10]

1 minute ago, Tim Bland said:

Looks good synoptically but there isn’t much cold to tap Into.  Lots of potential from there though..

Yeah pity about the uppers at this stage, but like you suggest not a bad position to be in.

[nick sussex]

Ironically the upstream flow becomes too amplified at the key timeframe !

This forces the energy south . It needs to head se to develop lower pressure in the northern Med not Iberia .

[feb1991blizzard]

1 minute ago, nick sussex said:

Ironically the upstream flow becomes too amplified at the key timeframe !

This forces the energy south . It needs to head se to develop lower pressure in the northern Med not Iberia .

Either way though, an E'ly won't deliver anything as there is no cold uppers, could be a stonking N'ly by the end of the run though.

[Tim Bland]

We would be very unlucky not to end up with a northerly a few days on from this point ...

[Cheshire Freeze]

4 minutes ago, feb1991blizzard said:

Either way though, an E'ly won't deliver anything as there is no cold uppers, could be a stonking N'ly by the end of the run though.

Yep it's going to have another go at building the N Atlantic HP in FI. saying this, the charts in the reliable aren't a bad situation to be in going forward.

[sheikhy]

If theres changes happening in regards to this easterly at only 72 or 96 hours then am not gona get too hung up what happens afterwards!!!god knows how many times ukmo has changed over the last few days!!one run a saggy high and then the next run is more amplified with cold air coming round the back in europe!!!

[kold weather]

8 minutes ago, feb1991blizzard said:

Either way though, an E'ly won't deliver anything as there is no cold uppers, could be a stonking N'ly by the end of the run though.

Could run the risk of having the cold air skew off SW too much, though of course it is just one run. Still far better than some of the guff last year if that's the worst case in that scenario.

Not a bad gfs, would be reasonably cool at the surface though upper temps are probably going to be on the milder side of the ensemble

Edited November 24, 2020 by kold weather

[Ols500]

Any ideas what allows a deep cold pool to develop to our east we can tap into? 

[bluearmy]

10 minutes ago, nick sussex said:

Ironically the upstream flow becomes too amplified at the key timeframe !

This forces the energy south . It needs to head se to develop lower pressure in the northern Med not Iberia .

Ens guidance has favoured Iberia for some time now nick - could do with getting uppers the right side of zero to our south if the continental flow does come in ahead of precip 

fwiw, the gfs op days 8/11 seems a decent stab within ens envelope 

 

[TSNWK]

6 minutes ago, nick sussex said:

Ironically the upstream flow becomes too amplified at the key timeframe !

This forces the energy south . It needs to head se to develop lower pressure in the northern Med not Iberia .

Nice to see you about nick.. to your point which nicely suggests how many ducks we need to line up for a decent snow and cold spell.. I guess if it was easy the feelings and the chase just would not be the same..

regardless of uppers we have air from a large landmass with little solar radation with its warm air supply cut off, my punt is that anything like that synoptic lands we are looking at daytime low single fingers and increasing harsh frost.. slip in bit of moisture then it’s  freezing fog persisting throughout the day.. hoar frost landscapes are not bad

[Ali1977]

Would this chart produce the first severe frost of the year, looks like it could with the forecast light winds and trapped colder air mass!! 

 

Maximums of 2-3c too, possibly. Definitely feeling like winter anyway!! 

Edited November 24, 2020 by Ali1977

[feb1991blizzard]

2 minutes ago, Ols500 said:

Any ideas what allows a deep cold pool to develop to our east we can tap into? 

A snap off of the siberian vortex that's potent  - usually much further into winter these days, or an East based -NAO first and a Greeny high with the high then toppling to scandi to draw it towards us, the high needs to gain good lattitude and be strong and stable though which again is unusual these days.

[kold weather]

At least in terms of synoptics upto 240hrs the GEM 12z actually looks pretty similar to the 12z GFS with how the low pressure evolves to our west.

Any major frost on the easterly flow would probably be cloud depending, but at least you'd get surpressed daytime temps, and if cloud isn't much of an issue, then frost would be likely.

Edited November 24, 2020 by kold weather

[Zak M]

12z GFS is showing a bitterly cold northerly at around the T300 hrs mark..

   

Edited November 24, 2020 by Zak M

[Tim Bland]

Here’s the northerly with some flurries around

 

Edited November 24, 2020 by Tim Bland

[IDO]

Much better upstream amplification on this run after d10:

That should cut off the stream of higher pressure leaking Pacific>Azores and allow a more static Atlantic. If this is now a clear signal then we can expect some sort of colder flow depending on how the dice falls. There was a small cluster within the 06z GEFS highlighting this scenario. Finer detail a long way off unfortunately!