Model output discussion - Winter has arrived

[Iceaxecrampon]

8 hours ago, blizzard81 said:

Do you really believe it though? Firstly it is the gfs 18z pub run. Secondly we all know how the models can underestimate the upper temps in these situations until much closer to the time. Thirdly........ Well, as already said, it is the gfs pub run so it won't be anything like what it is showing anyway lol. 

Is that tomorrows disappointment? Oh no. It’s a full 12 Days away. 

[sheikhy]

6 minutes ago, Steve Murr said:

Morning

Lovely cold seasonal ECM all the way & beyond past day 10 today > hints of a continental flow at the end

Oh &.... ECM High Res T54

 

Lovely chart!!!anything for the midlands steve?

[BLAST FROM THE PAST]

7 minutes ago, Steve Murr said:

Morning

Lovely cold seasonal ECM all the way & beyond past day 10 today > hints of a continental flow at the end

Oh &.... ECM High Res T54

 

Steve

personally I’d like to see the lower heights to NW further deflected at day 10.  Not what I was expecting or wanting.....but at least it’s the last frame  

 BFTP

[SMU]

2 minutes ago, BLAST FROM THE PAST said:

Steve

personally I’d like to see the lower heights to NW further deflected at day 10.  Not what I was expecting or wanting.....but at least it’s the last frame  

 BFTP

Yes > but at least more amplification behind that small low!

@sheikhy

Yes Some

[sheikhy]

4 minutes ago, Steve Murr said:

Yes > but at least more amplification behind that small low!

@sheikhy

Yes Some

Bullseye and the amplification is a bonus❄

[SMU]

This is where using the GFS ENs data can come in handy.

Select ENS

Select ENS > par scenario > iso H

Is the height of the 0c isotherm in M ( basically the freezing level )

The focus time is T54 into T57 ( 6am-9am)

So there are 4 ENS that would give settling snow over 150M & those 4 would also see snow to sea level. ( the 90m one is PTB 14 that was highlighted by for 29cm )

After that you have about 7 ENS under 400M which would br rain or sleet as sea level & snow at about 200M with minimal cover apart from the very highest hills.

I imagine the met use a similar profiled chart for MOGREPS ENS when reviewing the snow potential...

 

[sheikhy]

Just looked at the charts past 144 hours and a worrying trend starting to emerge!!seems to be flatter since the 18z yesterday!!lets hope 12zs take us back!!

[Day 10]

Ordered this on Amazon, arrives the 18th.

I've been told the heavy snow package will be here by Christmas

[Man With Beard]

56 minutes ago, Weather-history said:

29cms of snow for London on this GFS ensemble Friday morning

These two only give a mere 19cms of snow for London

And this just gives a tiny dusting of snow......... 15cms with this ensemble

Fun to watch but important (for sanity's sake) to bear in mind that this "snow event" is pretty high up on the "unforecastable" scale. Quite a few things need to be just the right side of marginal, and that's before even pinning down where the precipitation will be!

It'll be chaos on the weather apps these next few days, it'll be "oh yes it is!" and 3 hours later "oh no it isn't"

[Tim Bland]

Still big differences with the details for Friday. ECM and Icon are still miles apart with the precip. High res models such as Euro4 . Hirlam  & Aperge will give us an indication soon. See below for Euro 4 which. Low goes as far as Early hours of Fri...

[snowsummer]

19 minutes ago, Day 10 said:

Ordered this on Amazon, arrives the 18th.

I've been told the heavy snow package will be here by Christmas

Great.  everyones ordering  now and caused the site to crash. Bet by the time i get to order mine they've  ran out and I'll  have to wait til january! 

[nick sussex]

Still huge differences upstream between the big 3 which start as early as day 4 with the handling of that low in the eastern USA . 

The ECM after that wants to take most of the shortwave energy ahead of that over sw Greenland se by day 5 .

The GFS and UKMO hold that back and then we see the same phasing calamity from the former and an attempt by the latter to try and slide the low by day 6 .

Given the lack of agreement hard to say which has the correct solution but US forecasters aren’t overly impressed by the ECM . It’s clearly out on its own upstream .

If it’s correct then the GFS would have to start moving that way by its 06hrs run given we’d now be within T96 hrs.

In terms of the medium term the lack of consistency between runs across the outputs isn’t inspiring much confidence so probably best to concentrate on the shorter term will it snow drama ! 

[Sky Full]

23 minutes ago, nick sussex said:

,,........

In terms of the medium term the lack of consistency between runs across the outputs isn’t inspiring much confidence so probably best to concentrate on the shorter term will it snow drama ! 

I agree, Nick.  How about these for Thursday and Friday....

   

Encouraging to see snow in the charts in early December even if it doesn’t happen quite yet.   At least there’s some good cause to be optimistic for later in the month.

[Turnedoutniceagain]

48hrs out and we might as well consult the chicken bones.

 

[BlueHedgehog074]

Just for a comparison this morning, the 00Z ECMWF for Saturday 5th December from 25th November was showing this:

Low Pressure to the South-West of the UK with positive 850 hPa temperatures getting drawn Northwards towards Southern Scotland. 

When compared with today, this morning’s 00Z ECMWF is showing this for Saturday:

Low Pressure directly over the UK (mostly towards the Southern part), With 850 hPa temperatures, while not impressive, staying below 0*C for all. Things could still change a little for that day, but it broadly shows how much further East and North-East the Low Pressure has shifted. 

Admittedly, the charts from 25th November did show stronger blocking over Scandinavia with some high heights stretching towards the East of Iceland over the top of that Low Pressure. And High Pressure more amplified to our West towards Greenland. 

Even though it’s a bit disappointing in that regard to see things in the Atlantic sector looking less amplified for the weekend now, the pattern is far from flat. The operational models this morning still show a Southerly tracking Jet overall. None of them really bringing a full on Atlantic onslaught (the Atlantic Lows do sorta make a bit more of a presence for a time during mid-week next week on the 00Z GFS and also towards the end of the run), otherwise things looking pretty blocked at times. No deep cold or anything, and the 850 hPa temperatures continue to look quite underwhelming, especially on the GFS which does wrap around some positive 850 hPa temperatures into the Southerly tracking Lows later next week through the UK at times. I admit of which does feel like a waste, though am sure will likely change again on the next run. But still feel things could be (much) worse. Plus, in spite of the marginal situation, a chance for sleety and snowy surprises for some, particularly on Friday and especially over high ground, over the next few days. Sometimes marginal wintry setups like this can bring the most surprising snowfalls, particularly if you’re just about on the right side of it.

41 minutes ago, Tim Bland said:

Still big differences with the details for Friday. ECM and Icon are still miles apart with the precip. High res models such as Euro4 . Hirlam  & Aperge will give us an indication soon. See below for Euro 4 which. Low goes as far as Early hours of Fri...

Literally looks like that misses my area by a few meters to the North lol. Will I’m sure change again on the next run, but a little shift further South-East would be great

Good luck to those who get some white stuff though. An fascinating few days to come, filled with what I imagine will also be a lot of suspense, tension and thrills

[Catacol]

2 hours ago, Penrith Snow said:

Hmmm, not sure whether its climate change to account for the poor uppers and lack of cold, it is only early December and I remember many like cool rather than cold easterlies in the past, Feb 1972 was an easterly month but apart from the first few days was wet rather than white. In the early days on Internet weather a early December easterly in 2002 brought much excitement on TWO but turned into a damp quib due to poor uppers.

February 2005 was similar although the colder time of year meant transient snow for many but it was disappointing.

The problem is the origins of this coming easterlyhad southerlies over Europe, had their been a northerly last week things would be different.

Andy

Agreed. It is very early December. Proper cold air sources until the second half of the month are rare. On a positive note though there are a few factors coming together now to suggest that a cold spell towards the third quarter of the month is possible. The exact impacts of the pacific jet blast on the back of the +EAMT is going to be very important, but modelling is suggesting a big wave break over Scandinavia and as momentum drops and the jet surge retracts (everything that goes up must come down) it is not beyond the bounds of possibility that we get cold air pulled westwards towards us. Much to watch and wait for...but there is a chance........

[Methuselah]

Not a bad 00Z t+384 chart, if I do say so myself... It's literally screaming POTENTIAL!

    

Or is that the fairies at the bottom of my garden, I'm hearing!

Edited December 2, 2020 by General Cluster

[johnholmes]

1 minute ago, General Cluster said:

Not a bad 06Z t+384 chart, if I do say so myself... It's literally screaming POTENTIAL!

    

Or is that the fairies at the bottom of my garden, I'm hearing!

Its the 00z chart output?

[sheikhy]

Hi could anyone post the latest ecm high resolution snow depth charts please for friday and saturday if possible?!!

[nick sussex]

Interestingly the ICON has moved towards the ECM by day 5 . What will the GFS do now ? 

[SMU]

The models that bring the snow for the SE & home counties develop a secondary low overnight Thurs which moves through into the colder air which makes the difference-

One to watch...

[carinthian]

5 minutes ago, sheikhy said:

Hi could anyone post the latest ecm high resolution snow depth charts please for friday and saturday if possible?!!

 

[sheikhy]

Just now, carinthian said:

 

Thanks mate!!!thats 5-10cms widely down the spine of the country!!i take that!!although im sure it will be wrong

[Kentspur]

1 minute ago, carinthian said:

 

I really cant see low ground along the thames here having 5cms+ I cant even imagine anything settling but I really hope this is right! Although BBC.has.Dartford with rain showers now all sleet symbols removed- Is it.just ECM and Icon that show snow for London and the Thames Estuary?

[Eagle Eye]

Snow for most of the UK, We must have moved to Siberia