Model output discussion - Closing in on Christmas

[Matt H]

3 minutes ago, terrier said:

I’m sorry but yes we are seeing some nice output  this evening but those uppers are garbage. We are looking at cold rain for most of the U.K. unless you are up on high ground in the north these aren’t great cold rain and sleet really don’t float my boat thanks. 

We get it mate, you aren’t impressed by the model output and that’s a perfectly credible position to take. But is it really necessary to come on here after every model run to moan about the same thing over and over?

[Guest]

Just now, NewEra21 said:

Yep, it's why we need that trough over us to get a bit further E/SE. So we can then actually then get the colder air in, currently the coldest air is going into the Atlantic, we just need a slight shift Eastwards!

Good chance the low moves S & E nearer the time, certainly could evolve that way according to history.

[SLEETY]

N  Dec81 we had uppers of minus 3 and in that time we had   9inches of level snow outside in 5 hours and people trapped in snow-drifts 10ft deep !

 

Spoiler

 

 

[Anthony Burden]

GEM pick of the bunch so far this evening with the low further to the east,we will wait to see

how ECM models this low pressure from the north.Still up to changes at this range so plenty

to be exited about for snow lovers.In the mean time Christmas Eve and Day cold with frost

very festive.

[Weathizard]

You only need to look at the cold uppers for Christmas Eve and Xmas day to see how unreliable the models can be with 850 temperatures, they’ve improved from -4/5 to the point where there is now a fairly large area of -8/9 uppers.

 

Worry about getting a GH first up, 850’s are down the list of worries at this point.

[Scott Ingham]

19 minutes ago, MKN said:

Wont matter under deep low pressure and reduced day light hours - 3/4 would likely be ok. 

And low heights. Were looking at fronts of snow instead of showers. Its risky and marginal but this set up could be an absolute snow maker!

[sundog]

3 minutes ago, terrier said:

I’m sorry but yes we are seeing some nice output  this evening but those uppers are garbage. We are looking at cold rain for most of the U.K. unless you are up on high ground in the north these aren’t great cold rain and sleet really don’t float my boat thanks. 

At least cold rain would be seasonal rain,better then mild southwesterly rain.  

What the models are showing atm we are in a hell of a better place then many recent yrs which in itself is something to rejoice. It wont be a mild xmas period thankfully which makes a change to many recent xmas periods. Lets see how things unfold over the next while...........

[Steady Easterly]

8 minutes ago, Scott Ingham said:

Put these to the back of your mind the models wont have an idea properly until T'72. If we dont get snow from this set up ill skip through Rotherham Town Centre naked and record it!

Im sure there will be at least an inch.

[Methuselah]

Some pretty nifty charts, I must say... But don't mention the uppers, they don't like the uppers! I think I did it earlier, but I think I got away with it?

    

[Cold Winter]

The mean at T180 does appear to be a little further east than the op and control. Not much in it but it could help/be a sign that things might move east a little. Also the mean 850s for this stage are approx -4c, so 50% of ensemble members are going to be lower than that.

Edited December 20, 2020 by Cold Winter

[Guest]

Think people need to chill out on the uppers, I really can’t imagine that tongue of cold uppers ending up that far west. Experience suggests they might end up a little further east 

Edited December 20, 2020 by Guest

[SLEETY]

Anyway here come the COLD UPPERS lol

just a matter of time..

[Duane S.]

Irrespective of Arctic warming, climate change, things were better back in the 1700s blah blah blah, there are very simple synoptic reasons why the uppers are what they are. Nothing weird or sinister or strange  or ‘typical’ , the current Northern Hemispheric set up is why.  

Patience. Very cold uppers rarely arrive at the start of an emerging cold spell. The potential is there IF you want to see it.

And whilst I can barely be bothered to say it again, 850s are, as you know, only a part of the will it snow equation anyway...

[Ben Sainsbury]

9 minutes ago, Frosty Winter said:

We get it mate, you aren’t impressed by the model output and that’s a perfectly credible position to take. But is it really necessary to come on here after every model run to moan about the same thing over and over?

Those throwing their towel into the pram are the same that just take the 850hpa temperatures into consideration regarding snowfall.

The pressure/thicknesses are also crucial, the following chart below shows thicknesses of <512dam, pressure ~ 985-990hpa. This is the equivalent of having an extra 200-300m in elevation. Also with the knowledge that 850hpa are generally too warm way in advance, we would expect this to correct a little colder closer to the time so there's not too much to worry about from my POV. Synoptic setups like these are relatively uncommon in our part of the world and I can very rarely remember a setup like this that hasn't produced the goods.

 

Edited December 20, 2020 by Ben Sainsbury

[bumpydogz]

2 minutes ago, Scott Ingham said:

And low heights. Were looking at fronts of snow instead of showers. Its risky and marginal but this set up could be an absolute snow maker!

Still confused. Why does low heights make any difference to the 850s threshold at which we would expect snow?

[Sweatyman]

2 minutes ago, Cold Winter said:

The mean at T180 does appear to be a little further east. Not much in it though but could help/be a sign that things might move east a little.

Thats a Lovely Mean

[Allseasons-Si]

People stop worrying about the bloody uppers,they will change considerably the closer we get to the time,the synoptic pattern is evolving and i am as much on the bandwagon as anyone else that is wanting the white stuff to fall from the sky

anyway,good consistency from both the gfs and control @174

BTW,...who is ZONA LITY...

 

 

[Alexis]

GFS still sticking to its guns.

GEM follows ECMWF, which I expect not to change that much this evening.

UKMO at 144h leans towards GFS, not GEM.

So could well be UKMO and GFS vs ECM and GEM.

Edited December 20, 2020 by Alexis

[Methuselah]

2 minutes ago, Allseasons-si said:

People stop worrying about the bloody uppers,they will change considerably the closer we get to the time,the synoptic pattern is evolving and i am as much on the bandwagon as anyone else that is wanting the white stuff to fall from the sky

anyway,good consistency from both the gfs and control @174

BTW,...who is ZONA LITY...

 

 

Someone who's on his uppers?

[Vikos]

32 minutes ago, tight isobar said:

I Can we open a pessimist thread?? Twinned with magic fm playing in the background really depressing sounds!! And also link a reminder quotation that... 850hpa.. lean then drop under such Synoptics at a rapid pace.... It’s infuriating at times !!!.. some are clearly stuck in the woods with flow- and dynamics

Beeing realistic doesn't mean that one is pessemistic.  An -4 in 850hpa isn't nothing speacial in high winter time (starts 21.12.2020) and can come down even in may or june. For this setup, a -4 is ridiculous (my opinion).

[Sweatyman]

3 minutes ago, Alexis said:

GFS still sticking to its guns.

GEM follows ECMWF, which I expect not to change that much this evening.

UKMO at 144h leans towards GFS, not the ECM.

So could well be UKMO and GFS vs ECM and GEM.

GEM much better and towards GFS surely ??

[BLAST FROM THE PAST]

UKMO in range now, that LP will plunge almost N/S.....very cold Xmas Week.  Snow will be a factor Xmas week.

 

BFTP

[ITSY]

17 minutes ago, Ali1977 said:

busy In here tonight, don’t know why look at those uppers heading in from the north

But the uppers! 

Meanwhile, good news for Jan (much more reliable FI for strat than trop) 
 

[Drifter]

7 minutes ago, bumpydogz said:

Still confused. Why does low heights make any difference to the 850s threshold at which we would expect snow?

There’s a formula out there somewhere that explains this, but I can’t find it right now. 
Anyway, 500mb heights are one of the components and essentially the lower the heights, the lower the dam (lower dam = greater snow risk)

[Cold Winter]

1 minute ago, General Cluster said:

Someone who's on his uppers?

I was looking back at old threads earlier on from previous cold spells and there is often talk of dodgy uppers out at Day 7-10 with improvements by T0. Equally there are sometimes warm sectors that are only modelled nearer the time too, and believe me I’ve been the victim of these more than once!!