Model output discussion - here comes the beast!

[skatefan]

Well, the first week cold will be there, whether or not delayed by a day or so! 

Then we go to FI-watching: will the Greenland high hold itself and tilt clockwise due to the energie on the Asian side or will there be a new pressure-rise from the south? Both scenarios open the door for a new invasion of cold.

Obviously there are numerous other scenarios but i like to look at it from the cold side......

[Johnp]

2 minutes ago, Mucka said:

There is no way this 18z FI will verify for several reasons which I just can't be bothered to get into, but basically if we get the sort of retrogession seen out to 168 there is no way it will sink back S/SE in FI as with this run.

18z FI is a bit of a joke actually but worth noting there is no actual breakdown.

In actuality the Atlantic would disrupt SE far more readily, the polar trough drop much more sharply, the high be further West through FI and the Atlantic undercut more effectively.

 

 

 

But apart from that, it’s bang on, right?

[WalsallWeather123]

Inter run variations were always inenvitable. Yes the GFS 18z is messier, yes there is a shortwave which may delay the cold slightly but when the cold comes it will be bitter, sub zero countrywide. And messier may not mean as cold but is certainly can equal more snow which I'm sure is what most people want. No-one wants the forbidden 'Dry Easterly'.

[kold weather]

1 minute ago, chionomaniac said:

Another variation but the trend is there. Blocking right until the end. The finer details yet to be decided....

Has to be said the 18z GFS does seem overly fast to erode the northern blocking deeper into the run, somewhat as expected given the low resolution. 

As others have said, the surface cold remains embedded because of just how severe the cold is in the days before. Surface cold can be real stubborn even when you get much less in the way of cold than what is forecasted.

[lorenzo]

That;s what you call a direct hit! Bewildering.

[Man With Beard]

Well it would appear the ECM op was the furthest south on the cold pool at T168 out of the 4 clusters!

[Mucka]

1 minute ago, Johnp said:

But apart from that, it’s bang on, right?

I don't know, I could take issue with the Atlantic forcing at 300h+ as well 

[Snow Queen one]

I don' post much here but have been on here for quite a few years now.

Gifs ALWAYStries to bring warmer air in quicker.  Cold air is heavier than warm air.  If you have ever tried to light a fire in the cold weather you would know the smoke comes out of the fire place instead of up because it can' push the cold air out of the way.

It would take some serious warmth to move cold air over snow fields.  And that in itself may mean any rain coming from the south could turn to snow.

Anyway as others have said it is too far out to even think about.   We might be glad to have less cold air after what may be over us next week.

[ITSY]

For anyone wondering, the extended jma brings the mother of all blizzards to the south eastern third of the Uk at about the same time as the GFS flirts with some snowy (and balmy) -1uppers from the south. Just let the cold in first and worry about the rest after. Worrying about breakdowns before the cold has arrived is crackers,  not least when the worst any supposed breakdown is set to bring is more dreaded snow. 

[bluearmy]

Really no strong guidance on how we go from the easterly to the cyclonic broad sceuro trough  nor’easter 

slightly larger eps cluster day 8/9 has the upper ridge close to our wnw which cuts off the continental flow by day 9 but I doubt the models have got this tied down as yet. 

[Scandinavian High.]

6 minutes ago, Snow Grain said:

I have a feeling that future runs will show the high further south which will water down the easterlies.  My gut feeling is that the coldest weather will head further south into France and Spain.

So marking a prediction on you gut..

[Wilxy]

I'm happy with that nothing to moan about here happy that the north has joined in then we can all be happy right?

[pandit-scholar]

Although the GFS shows a breakdown at T + 216, it way too far in future to start throwing the toys out of the pram, as some coldies have done.

The BBC forecast on TV just now has to started to hint that change is a foot, but wont go into to much detail yet, for obvious reasons. Just that Siberian winds are coming, and the core of the cold may reach the UK, or go south of the UK, as I can remember I think. If it does come, he said may last way into March (they are privy to more data than is available to us).

All we can say that some form of cold spell is coming, based on what we are all seeing on the model. I am  sure the MetO and other professionals are going to wait and see how deep the cold gets, and the snow potential before coming totally on board, as it understandable from their perspective. 

Edited February 20, 2018 by pandit-scholar

[kold weather]

2 minutes ago, bluearmy said:

Really no strong guidance on how we go from the easterly to the cyclonic broad sceuro trough  nor’easter 

slightly larger eps cluster day 8/9 has the upper ridge close to our wnw which cuts off the continental flow by day 9 but I doubt the models have got this tied down as yet. 

Yeah, we seem to have lost 'cluster 2' that had more of a northerly push of cold air by 192hrs, mainly due to the shortwave/LP that shoots SW from Norway (many runs look like the op ECM run, though location is very different...)

[craigore]

4 minutes ago, Man With Beard said:

Well it would appear the ECM op was the furthest south on the cold pool at T168 out of the 4 clusters!

Still think a half way house between GFS & ECM Would be best ( For the North & the South.

[Sam Mithell]

Looks like eastern scotland is best place for the several feet of snow ??? Shovels out 

[Stormyking]

The different scenarios that keep showing shows we definitely need more runs to be get a more accurate reading, but overall it still looks very very good and cold! 

Staying positive!  

[Ice Day]

The mean at 180 is looking really good, another solid set of ensembles coming up based on this.

 

[Man With Beard]

11 minutes ago, bluearmy said:

Really no strong guidance on how we go from the easterly to the cyclonic broad sceuro trough  nor’easter 

slightly larger eps cluster day 8/9 has the upper ridge close to our wnw which cuts off the continental flow by day 9 but I doubt the models have got this tied down as yet. 

We have what I call the "dreaded" one cluster after D11 - which I always translate as "we don't have a clue!"

[Frosty.]

Gorgeous GEFS 18z mean...nationwide freeze!

[Ice Day]

Most of the country under mean -10 uppers out at 226.  

[Mucka]

Op V control

168

240

The control is a far more realistic IMO 168 through 240

Edited February 20, 2018 by Mucka

[Banbury]

Very Good Ens

[Froze were the Days]

Control on the GFS 18z more in line with ECM op run at 240

[kold weather]

Still a wide range of synoptics on the 18z GFS ensembles, some have no easterly at all as HP never moves away and instead builds in the atlantic giving more of a northerly, most still have an easterly but quite a few are slacker than we saw from the 12z GFS suite of ensembles at least until 168hrs when most tighten back up.

Pretty much every run is cold from whatever angle the cold comes from, and there are really some insane runs in there that are every bit as good as the runs from yesterday evening.

Great ensembles, with the small caveat that the flow is slacker which may be an issue if it means pressure is rising nearby.

Edited February 20, 2018 by kold weather