Model Output Discussion - 12th December Onward

[Cheshire Freeze]

A good, solid run from the 12z GFS, I think a cold surface feed from the continent is a good bet- not conducive to snow yet but certainly that synoptic wouldn't be heading in the wrong direction. The 12z highlights what we need to see- the block staying close for if/when PV disintegration occurs.

Edited December 14, 2011 by jethro
Is there really any need?

[Radiating Dendrite]

short term todays model ouputs put a good possibility of snow and cold potential for the weekend for a cold lovers. but the long term puts a bleak picture on things with a dreaded bartlett high for the start of the christmas week. ian browns comments on this sanrio does look likely unfortunately for the cold lovers

Bartlett? Where?

I think you are getting confused. The high is ridging up towards Scandi, not supressed over Iberia.

Christmas would be cool going of the GFS, with temps just above freezing after a cold start.

Funnily enough, I stated that I thought we would see high pressure over xmas in my LRF (posted in the middle of October).

I have been successful upto now (in the main)

Edited December 14, 2011 by Radiating Dendrite

[MR EXTREMES]

short term todays model ouputs put a good possibility of snow and cold potential for the weekend for a cold lovers. but the long term puts a bleak picture on things with a dreaded bartlett high for the start of the christmas week. ian browns comments on this sanrio does look likely unfortunately for the cold lovers

cant see this outcome perhaps halfway house if im to be correct.

[jpwild]

The model thread is unreadable when Ian posts. I like to read what's being said, but I am just skimming though that thread now as it's very tedious unfortunately.

Watching Top Gear now on Dave - Clarkson on Skis in snow

[feb1991blizzard]

Yes Matty, it's a positive- a much better evolution to the 12z over the 6z GFS. The evolution shown would bring a cold, seasonal Christmas day which most people would have as their second choice over snow IMO.

Its what it could bring if it trends further North on future runs that excites me (although highly unlikely), is this a close shave and we will get progressively nearer as we go on culminating in GP's winter forecast verifying for late Jan feb as the strat becomes more favourable, i dont see it getting any further North if we had a T398 and T422, the jet looks like it will sink the heights to be honest but all good signs, the building blocks look to be slowly falling into place.

[MR EXTREMES]

i think gfs cold surface is whats being projected and although not a winter wonderland would most certainly bring down decembers cet.

so record warm december warmth is not going to happen.

i think we could well see the models shifting the heights a little futher north.

[shedhead]

Whilst the 12 GFS looks far more palatable, I'd caution against taking it as read. Clearly heights build far enough north to introduce a continental feed, but are the background signal there to support this evolution, or is it just another phantom easterly wobble that will vanish without trace in 6hrs time?

[Summer Sun]

Christmas day is now showing to be a cold and Frosty one

http://www.wetterzen...s/Rtavn2642.png

You would struggle to see any snow with that amount of high pressure around

[snowbob]

I would bank that now far better than mild and wet

[SP1986]

Tedious is a model run filled with ramping (either cold or mild), and a leaning towards selecting charts that fit someones own preference.

If we look at the charts as they are then the GFS represents a much different outcomes than the runs preceding it bringing an easterly in, although it doesn't looks an exceptionally cold easterly (like last year for example).

As it is only one run and the easterly is in FI it's not worth talking about, until there is some agreement from the other main models - even GFS ensembles aren't good enough I'm afraid - there is inter-model agreement that is needed in any scenario before you can blow the trumpet so to speak.

As it stands I wouldn't put too much faith in the 12z especially when look at the long range signals. However the short range is fairly as you where, not much different to the 6z, so i think until 96 hours is probably a fairly likely outcome as it stands.

[Ian Suffolk]

Fridays storm is certainly proving a headache. Looks like the GFS have moved the system slightly further south again. The Metoffice have issued a warning for the south coast, but surely the tail end of the depression at 12z T+42 is going to cause some quite wild conditions for East Anglia?

[Matty M]

Fridays storm is certainly proving a headache. Looks like the GFS have moved the system slightly further south again. The Metoffice have issued a warning for the south coast, but surely the tail end of the depression at 12z T+42 is going to cause some quite wild conditions for East Anglia?

see my post in the Atlantic Storm thread about how one GFS EPS member sees it.

[Osbourne One-Nil]

We could go through and delete so many posts that the trash bin would be overflowing more than my hatemail in tray; particularly on the previous page.

We don't like removing posts, particularly from newer members, but we need everyone to self-moderate. If it's not model related, this isn't the right thread for it. There are plenty of other threads you can post in, so just find the right one.

[Cheshire Freeze]

Watch out Netweather Gestapo about,

Lurking in the shaddows,

Ready to give your post a clout.

Trimming posts of those who rarely aprehend

Giving lectures to stay on topic

Whilst ignoring those who frequetly offend

All in all though there's no forum I'd rather be,

than right here on Netweather.TV

P.s in accordance with Netweather policy this post will self delete in 5 minutes

[summer blizzard]

Pretty good run in the medium to longer term from the GFS12z.

The cold hangs on until Wednesday and the UK then picks up a continental flow in time for Christmas which would likely produce a lot of fog and frost.

Ensembles are very spit from the 19th so this solution can certainly not be ruled out.

Add this to signs of a moderate warming of the stratosphere and things are shaping up well.

I bid you farewell (until my next post) with this...

[Summer Sun]

Pretty good run in the medium to longer term from the GFS12z.

The cold hangs on until Wednesday and the UK then picks up a continental flow in time for Christmas which would likely produce a lot of fog and frost.

Ensembles are very spit from the 19th so this solution can certainly not be ruled out.

Add this to signs of a moderate warming of the stratosphere and things are shaping up well.

I bid you farewell (until my next post) with this...

It's been a slow start this winter but hopefully things are starting to get in place for something more seasonal as the month comes to an end maybe Jan and Feb will deliver some decent snow if December can't though there is still time yet.

Edited December 14, 2011 by Gavin D

[phil nw.]

Tedious is a model run filled with ramping (either cold or mild), and a leaning towards selecting charts that fit someones own preference.

If we look at the charts as they are then the GFS represents a much different outcomes than the runs preceding it bringing an easterly in, although it doesn't looks an exceptionally cold easterly (like last year for example).

As it is only one run and the easterly is in FI it's not worth talking about, until there is some agreement from the other main models - even GFS ensembles aren't good enough I'm afraid - there is inter-model agreement that is needed in any scenario before you can blow the trumpet so to speak.

As it stands I wouldn't put too much faith in the 12z especially when look at the long range signals. However the short range is fairly as you where, not much different to the 6z, so i think until 96 hours is probably a fairly likely outcome as it stands.

Yes i agree Kold.I said yesterday that around T96 was the sort of time when uncertainty began.

On this run the modelling of the Vortex keeps the main energy back towards Canada long enough for the Azores High to really build much further north after the weekend,compared to the 00z run.

http://www.meteociel...ech=168&mode=0

The Euro trough then becomes disected and the Russian high joins hands with AH.

Meanwhile there looks like a very real snow threat overnight Thurs. into Friday around this neck of the woods,ie Wales, Midlands and maybe parts further south-looking at the latest plot of the Low for Fri.

http://www.wetterzen...cs/Rtavn422.png

http://www.meteociel...h=42&carte=1021

I would think anywhere with elevation stand a good chance of a covering as the cold air tucks in behind the Low.

It`s all a bit marginal and it`s the usual forecasters nightmare trying to pinpoint the detail.

[shedhead]

For me the one really disappointing aspect of tomorrows weather is that given the right set up to the north, this low looks on a perfect track to have delivered some serious blizzards for the S and SW, a la March *1891. Last winter when we had cold in place the models toyed with Channel runners on a few occasions, but they failed to materialise, this time we have the perfect system/track but not the required cold set up....

* http://forum.netweat...izzard-of-1891/

Edited December 14, 2011 by shedhead

[nick sussex]

I know a few people might think the GFS looks a leap of faith but its quite plausible even with a strong PV.

What helps at least initially is that slightly more amplified pattern which allows the high to get further north, the UKMO is flatter at 144hrs.

We'll have to see what the ECM makes of this.

[feb1991blizzard]

It's been a slow start this winter but hopefully things are starting to get in place for something more seasonal as the month comes to an end maybe Jan and Feb will deliver some decent snow if December can't though there is still time yet.

Are you feeling ok Gavin?, we will be seeing Ian Brown saying he wants winter weather next!

[summer blizzard]

GFS12z is a very plausible outcome, from the 21st to the 29th the operational run tracks the ensemble mean almost perfectly as opposed to almost being a warm outlier like the last few days.

[ITSY]

in terms of its progression and the possibilities that it brings from our East and North, there is no question that the 12Z was a sensational run - given from where its come from and what has been progged before. Has to make you think its an outlier, but more runs are now progging a longer (dry) cold spell.

having seen the above chart - this is a great time for model watching. by boxing day its a throwup whether we have a warm SW, cool zonality or a raging northerly/easterly.

[SMU]

Afternoon all

A mixed bag today- although the GFS still toying with the cold- certainly a better ensemble suite than earlier....

Remember the ensemble mean is usless here- only one solution will be correct & that will either be cold side of the block in cold continental flow or on the warmer side in a SW flow.....

A stalemate sort of day so far...- I think the scandi high is still being underplayed....

Possibly some snow here on friday monring! if were lucky- as expected the trend south continues on the UKMO & GFS today

S

Chart of the day from the GEM 12 z

http://176.31.229.228/modeles/gem/run/gemnh-0-144.png?12

http://www.meteociel.fr/modeles/ecmwf/run/ECH0-48.GIF?14-0

ECM has a nice patch of -6 over the SE at 48... thats a very good sign into the PPN..

S

Edited December 14, 2011 by Steve Murr

[Robbie Garrett]

I've always said all along, that our main cold weather will be in the new year! Come on models play nicely!

[karyo]

I see some people posting about the possibility for snow but to be honest that sounds rather optimistic to me!

Tomorrow night's event seems reserved for the midlands and further south, with our region mainly dry.

On Friday we have that occluded front (see fax chart) but the models project less cold uppers at that stage so likely to be rain away from the Pennines.

Over the weekend we look like having colder uppers. On Saturday, the flow looks too northerly to allow the showers to reach inland areas. Maybe better chance on Sunday when the wind turns more northwesterly but with pressure rising the showers will be fewer and lighter.

Karyo