Model output discussion - Closing in on Christmas

[Ali1977]

Well that is just bloody outrageous, hello big freeze 2021 !! 

Edited December 16, 2020 by Ali1977

[Zak M]

Well, would you look at that! The PV is completely shattered.

Cold upper-air temps too, which would be conducive for snow:

   

Certainly wouldn't be a bad start to 2021! 

[Howie]

3 minutes ago, Ali1977 said:

Well that is just bloody outrageous, hello big freeze 2021 !! 

This should come with an x rated warning 

[Mike Poole]

5 minutes ago, Trom said:

Presumably these are verification stats for the entire northern hemisphere.  I always assume (possibly incorrectly) that they would be much lower for the UK in isolation, given we are sat at the edge of an ocean with a continent to the east.   

Yes, they are, and one can surmise that for the UK in particular, UKMO might be a bit better, and GFS a bit worse, given the types of weather each are trying to model best.  But it is all we have got, Steve M did say that years ago there used to be some more local statistics but, if there were, there don’t seem to be now.  

[markw2680]

You get the feeling something quite special could be brewing between Xmas and new year with most models in some way bringing cold weather in, how cold and snowy nobody knows yet and it could all go the way of the pear but I’m quite optimistic atm.

tbh after the year we have all had I’m sure we would be quite happy with a cold Christmas with the chance of snow about even if it goes pear shaped afterwards 

[Djdazzle]

6 minutes ago, Howie said:

This should come with an x rated warning 

Yes it should - a warning that it has zero chance of happening.

I logged on to find people salivating over cold charts - then I checked the timescale.

[Anthony Burden]

I think for sanity sake we need ECM to stamp some authority on this and follow the yellow brick road.

If GFS is correct Siberian gloves and hats will need to be ordered,at least to the 18z pub run.

[Jason M]

3 minutes ago, Zak M said:

Well, would you look at that! The PV is completely shattered.

Cold upper-air temps too, which would be conducive for snow:

   

Certainly wouldn't be a bad start to 2021! 

850s are only one parameter though. Very borderline scenario as evidenced by the cold rain (and some snow) showing on the chart here. Clearly, trying to predict rain / snow on a chart 15 days away is a non starter but these charts do illustrate why people should temper any excitement as from start to finish its always marginal through this run (and virtually every other run I've seen today). Looking at the scenario it reminds me of the Feb 2005 easterly that resulted in so much cold rain for many away from high ground. The airmass is continental but its from a long way south, hence it never gets very cold.

Would only take a small change to drop the 850s a bit, but for any lurkers just be careful about some of the charts being shown as they are not as cold as they appear at face value. 

 

[TSNWK]

3 minutes ago, Djdazzle said:

Yes it should - a warning that it has zero chance of happening.

I logged on to find people salivating over cold charts - then I checked the timescale.

Oh come on! You  know the rules if GFS is gonna serve it up it's fair game to be gobbled up, used and abused on here I say..

[Mike Poole]

18 minutes ago, Ali1977 said:

Well that is just bloody outrageous, hello big freeze 2021 !! 

Yes, we would stop craving a SSW if that happened!  Who’d reshuffle the deck if we had a winning hand already.  

Way in FI though.  But they keep coming....over to the ECM.

[Djdazzle]

3 minutes ago, TSNWK said:

Oh come on! You  know the rules if GFS is gonna serve it up it's fair game to be gobbled up, used and abused on here I say..

It’ll all end in tears!

Id take that GFS run though.

[Allseasons-Si]

I go out to do a bit of shopping,...comes back in and the gfs is the best model because of what it is showing in fl,tut! tut!

THAT IS PURE FILTH!!!

[Chesil View]

13 minutes ago, Djdazzle said:

Yes it should - a warning that it has zero chance of happening.

I logged on to find people salivating over cold charts - then I checked the timescale.

I wouldn’t be so sure Djd. The ensembles lend it considerable support.

[Djdazzle]

1 minute ago, Broadmayne blizzard said:

I wouldn’t be so sure Djd. The ensembles lend it considerable support.

I have seen the GFS to be wrong at T96 with total ensemble support on several occasions. So I’m not holding out much hope at T360!

[Froze were the Days]

Well the GFS 12z (garbage forecasting system) has watered down the Xmas period not that it was looking that dramatic, I certainly wouldn't hang my hat on what it shows later on in the run, it struggles at +144z.

[MATTWOLVES 3]

Can't see why so many moan about GFS... Im loving some of the ens out to day 10...plenty of options in the table..Just imagine a great NH pattern setting up now,then a major SSW comes along and brings an Heatwave..   Heaven forbid folks, when Midnight Mass comes next week,I will prey that doesn't happen.

[Cheshire Freeze]

13 minutes ago, Mike Poole said:

Yes, we would stop craving a SSW if that happened!  Who’d reshuffle the deck if we had a winning hand already.  

Way in FI though.  But they keep coming....over to the ECM.

If we don't get a SSW we go zonal through January and February...it's as simple as that. At some point we'll see the trop and strat connect without one. That's why we need a SSW to maintain the cold chances deeper into winter.

@Uncertainy mentioned last night that we'd see westerlys flushed down if the SSW fails.

Edited December 16, 2020 by CreweCold

[Djdazzle]

Would be just our luck for a SSW to cause a warm up - but this is the UK!

[Chesil View]

4 minutes ago, Djdazzle said:

I have seen the GFS to be wrong at T96 with total ensemble support on several occasions. So I’m not holding out much hope at T360!

Totally agree Djd So have I. But there is more than one model suggesting this route to cold.

[Mike Poole]

1 minute ago, Djdazzle said:

Would be just our luck for a SSW to cause a warm up - but this is the UK!

That has happened before on a number of occasions.  

[swfc]

3 minutes ago, Djdazzle said:

I have seen the GFS to be wrong at T96 with total ensemble support on several occasions. So I’m not holding out much hope at T360!

Evening. Yes altho the gfs are churning out great fi charts and have been for a good few weeks. Problem is they never seem to land do they. Yes I remember a famous easterly being on the way and it was scuppered by a shortwave off Scandinavia. Still things look OK on the ukmo and ec so who knows

[Djdazzle]

1 minute ago, swfc said:

Evening. Yes altho the gfs are churning out great fi charts and have been for a good few weeks. Problem is they never seem to land do they. Yes I remember a famous easterly being on the way and it was scuppered by a shortwave off Scandinavia. Still things look OK on the ukmo and ec so who knows

Ah yes, the failed easterly at T72 which had cross model support! There was carnage on here!

Don’t get me wrong - I’ve no issue with people looking at FI charts. I just don’t want people getting suckered in, thinking that they have even a small chance of materialising!

[Beanz]

35 minutes ago, Djdazzle said:

Yes it should - a warning that it has zero chance of happening.

I logged on to find people salivating over cold charts - then I checked the timescale.

I thought exactly the same, a bunch of +366h charts!

[Tim Bland]

16 minutes ago, Froze were the Days said:

Well the GFS 12z (garbage forecasting system) has watered down the Xmas period not that it was looking that dramatic, I certainly wouldn't hang my hat on what it shows later on in the run, it struggles at +144z.

Op was a mild outlier for Xmas (see list for London) a very cold set of ensembles long term!

[Froze were the Days]

hhhmmmm...a huge flabby low over the UK post Xmas, looks a bit sceptical to me. Probably underplaying the Atlantic, some WAA there at first and then some undercutting to get to the solution in FI, what could possibly go wrong?