Model Output - General Discussion

[Upgrade]

The 18z is a phenominal run for the whole country for bitter snowy weather - reminding me very much of 1981! Not good if you want to travel before Christmas! Can this country cope with such an event?!

i may buy some snowchains for the car this week. Interesting to see that the latest GFS shows a reload sitution post christmas.

[londonsnow]

just had a gander at the pub run. brings christmas back to whiteish for the east coast, but a ton of chopping and changing to get through. as i'm having to travel i personally could do without a white christmas. this week is fine though!

Edited December 13, 2009 by londonsnow

[cyclonic happiness]

Chrismas day blizzard back from the parallel

It was there a few days ago...let's hope it dissapears again!

Edited December 13, 2009 by cyclonic happiness

[Geordiesnow]

Because of the downgrades to the easterly, i'm not going to get carried away with the Northerly and i expect quite a few different scenarios being played out. I guess the good news is that we got more room for error with this Northerly than we would with a normal Northerly as 1) it's closer to the realible timeframe and 2) we got a much stronger block so it should not topple and miss us. However we could end up with something like the ECM and that the Northerly might not make all that far South so twists and turns to come yet.

[John Snow]

If I had a pound for every time somebody said this after seeing one run I would be a very rich person...

That is what would happen if this comes off though, the whole of Northern Britain and Scotland would get 3 or 4 feet of snow and we have seen 4 inches before cause mayhem, this country is just not equipped to deal with the level of snow that is going to cause a national emergency north of about Leiester

[Tim Bland]

i may buy some snowchains for the car this week. Interesting to see that the latest GFS shows a reload sitution post christmas.

i think some people are getting a bit carried away! I would save your money on the snow chains lol. even if this run verified exactly as shown you wouldnt need snow chains for major routes in SE London!! I have been looking through the snow depth charts etc and the Max it shows for London area is 5cm! That is classed as a dusting in most European countries!

[SMU]

Massive massive upgrades for the north, 3-4ft of snow across huge swathes of the north, north east and scotland if the 18z comes off

Less good down here for snow but confident of a little bit

I would go on record & say that obviously the easterly flow is Nailed,( all be it small changes here & there) then I think the Northerly FLOW is nailed- In terms of the Depth of how cold it gets from that Northerly is how much squeeze & wedge of air coming south-

Incidentally People concerned about marginal situaions for the S & SW in Northerlies- this is because the usually have VERY cold upper air modified by a warm suface ( or boundry layer)- that is by the sea & by the ground-

In this evolution the surface layer has a 'wedge' of even colder air stagnent ( originally very dry contiental air)- & with this combined with probably snowcover then you have PERFECT conditions for ice days & PPN ALL snow...

This is why its essential we get those easterly winds over the bulk of the UK- they may not bring tonnes of snow initially but it ensure the dewpoints are circa -5C

Nothing but win win out to 180 tonight- I would say the divergence is around 162 in terms of actual pattern- where we begin to focus our attentions of the profile of the jet coming off th eastern seaboard-

S

[Snowaddict]

What can I say? Lost for words really, the entire run from start to finish is amazing..

This cold spell has the potential for epic low temperatures and snowfalls on various occasions..

In addition, I would note the evolution in the Atlantic...

Just take a look at the Parallel Run:

Blizzards, crippling snowfall on Christmas Day, as the lows become elongated and take a southerly track, held back by entrenched colder air..

The British Isles would be shut down if these outputs verified, plus there would be a White Christmas for everyone..

These are classic outputs, treasure them for it's not often you see these types of runs..

[03jtrickey]

Parallel continues the theme with monumental amounts of snow sweeping down from the North

http://91.121.94.83/modeles/gfsp/run/gfs-2-132.png?18

after a snowy Thurs/Friday especially for the SE http://91.121.94.83/modeles/gfsp/run/gfs-2-108.png?18

[Bristawl Si]

The charts for next weekend are similar to some of the last few years, but with one exception - it looks like the UK is going to be the beneficiary of a 'direct hit' rather than the severe cold plunge diving thru' Scandinavia and eventually into s.e. europe, as we've seen in the past.

The one big 'if' is that they are still more than 5 days away and we've seen a number of changes in the detail in the last few days' model runs.

A note of caution to all: subtle changes will happen over the next few runs.

[Glacier Point]

Just a note or two of caution about those ensembles showing an upward tendency in the extended range:

1) check the scale ! ECM mean day 11-15 struggling much above 3/4C, in line with GFS and GEM means.

2) the range at which they move upwards looks based on empirical wave propagation in the Indian Ocean, basically models going for a convective signal to come into the west Indian Ocean forcing a downstream response over the Atantic and troughing in the Atlantic to gain some amplitude. This looks rushed.

However, this takes no account of where the global wind oscillation will be (probably orbiting phases 0 and 4) signalling a southward displaced jet extending well into Europe (no ridge). It also looks to me as if convection still wants to take place around the Dateline which considerably muddies the NWP waters.

Don't be suprised to see this cold become quite embedded. Although there will be a logical attack from the SW around Christmas, there is no strong signal right now for this to be overwhelmingly mild and leaves open the door for marginal error with the jet to the south of the UK.

Edited December 13, 2009 by Glacier Point

[bluearmy]

120hr UK Fax OK, but nothing spectacular. General Easterly flow, with an occlusion lying from the welsh borders to about Brighton.

last nights worzel - bit late this evening exeter.

[phil nw.]

Yet another stunning run, this time the whole lot is an upgrade...

The easterly is not really a big issue BUT instead we have a pretty interesting trough set-up over the SE which promotes quite a decent amount of precip, then we see a stunningly cold day on Saturday as the cold air comes down and cloud comes down from the north and keeps maxes surpressed, followed by snow. Then the whole lot eventually reloads...quite a mental run!

Yes the northerly after the easterly is being modelled regularly now Kold.Will certainly keep bitter cold close to Christmas.

Amazing stuff look how far south the jet goes.

http://www.wetterzentrale.de/pics/Rtavn1441.png

and all that cold air coming to us from the pole.

[Reading FC]

If I had a pound for every time somebody said this after seeing one run I would be a very rich person...

Yes Exactly - it will NOT happen anything like that. Classic 18z scenario that has about 10% chance of actually happening.

[Snowyowl9]

A bitterly NW-ly

http://91.121.93.17/pics/Rtavn1681.png

http://91.121.93.17/pics/Rtavn16817.png

[Bristawl Si]

Just a note or two of caution about those ensembles showing an upward tendency in the extended range:

1) check the scale ! ECM mean day 11-15 struggling much above 3/4C, in line with GFS and GEM means.

2) the range at which they move upwards looks based on empirical wave propagation in the Indian Ocean, basically models going for a convective signal to come into the west Indian Ocean forcing a downstream response over the Atantic and troughing in the Atlantic to gain some amplitude. This looks rushed.

However, this takes no account of where the global wind oscillation will be (probably orbiting phases 0 and 4) signalling a southward displaced jet extending well into Europe (no ridge). It also looks to me as if convection still wants to take place around the Dateline which considerably muddies the NWP waters.

Don't be suprised to see this cold become quite embedded. Although there will be a logical attack from the SW around Christmas, there is no strong signal right now for this to be overwhelmingly mild and leaves open the door for marginal error with the jet to the south of the UK.

Can i assume from your last sentence GP, that a possible 'battleground' LP approaching from the south west is a distinct possiblity on Xmas Day?

[PB22]

I like the way the Parallel builds pressure to our northeast again in F.I. This is IMO a plausible evolution further down the line given the intense cold that will be established over that part of the world by then:

http://91.121.94.83/modeles/gfsp/run/gfs-0-252.png?18

All in all, superb output again, and it will be interesting to see if the ensembles change at all.

[bluearmy]

In a way I hope this downgrades a little as those charts are truly terrifying in a way with what is coming to the North on xmas day on top of the 3-4ft of snow they will be under, by boxing day half of Britain could have 7 or 8ft of lying snow and 40ft drifts and that would not exactly be sledging weather with snow up to the necks of everyone who is not a pro basketball player, that is huge loss of life weather

john - you seem to get a bit carried away with your numbers. although it looks promising, its more likely to be inches than feet away from high ground.

[guitarnutter]

I think most people would be happy if this was night mins:

It's actually 3PM max temps!

[on the coast]

In a way I hope this downgrades a little as those charts are truly terrifying in a way with what is coming to the North on xmas day on top of the 3-4ft of snow they will be under, by boxing day half of Britain could have 7 or 8ft of lying snow and 40ft drifts and that would not exactly be sledging weather with snow up to the necks of everyone who is not a pro basketball player, that is huge loss of life weather

The 18z is good but not that good? nice to see the outlook keeps the cold into the festive period.

[PB22]

FAX charts:

T+96: http://www.meteociel.fr/ukmo/fax/fax96s.gif

T+120: http://www.meteociel.fr/ukmo/fax/fax120s.gif

Worth the wait I'd say!

[cooling climate]

The t72 and t120 fax charts look very very good.

Ah I see the t96 chart is out now as well.

Edited December 13, 2009 by cooling climate

[Snow Queen one]

In a way I hope this downgrades a little as those charts are truly terrifying in a way with what is coming to the North on xmas day on top of the 3-4ft of snow they will be under, by boxing day half of Britain could have 7 or 8ft of lying snow and 40ft drifts and that would not exactly be sledging weather with snow up to the necks of everyone who is not a pro basketball player, that is huge loss of life weather

But John these charts will never come off. We just do not get cold enough to see it. We are also surronded by a body of relativly warm water which will help keep temps higher. Don't worry you will not have to buy a dog sledge team to get to work. lol I know it is not model related but if you had ever seen 7ft of lying snow before you would not be saying it could happen here. I have actually seen snow like that in USA It won't happen.

[fear sneachta]

Chrismas day blizzard back from the parallel

It was there a few days ago...let's hope it dissapears again!

Oh no, I would LOVE this to happen. It would be my dream of the century. A snowstorm it would be!

[Polar Side]

The model outputs are outstanding !

Just goes to show what Strong High pressure over Greenland can bring !