Winter Model Discussion - The Hunt For Cold - 12th Dec

[shotski]

Hi Guys.

I have little knowledge of the models but this is my take on why I think our next cold spell could be about 10 days away.

On the last few ECM runs 00z and 12z the Siberian high has been nudged a little bit further west and a little bit further

north where as it almost touches scandinavia (Murmansk) This can be seen at T-144 & T-168. The other thing of

note is pressure seems to rise over Greenland, but this appears to only be surface pressure (at the moment) .

The last thing is the deep low that will be sat over us by the end of this week and the way it sucks up the warm air

over southern Europe on its back edge and projects it towards Greenland, the Siberian ridge appears to do the same

on its leading edge. I would be looking for a possible link up from the siberian ridge into Greenland ? all that warm

air going north can't be doing any harm ?

Shotski

[bluearmy]

Stormy and wet- especially in Scotland and Northern Ireland- with temps close to the seasonal average, and the chance of wintriness in sub-516 air in the highland peaks for Saturday evening.

need to be high peaks IS as the thickness is 538dam and the flow looks 'brisk'

[karlos1983]

Reading a few posts I'm not sure where some of the optimism is coming from, I just don't see any cold opportunities in certainly the reliable, or really in FI. The models are all pretty much in agreement that we are about to enter a very dull period ruled by the Atlantic.

I am always on the side of optimistic, but I just can't see it, even if the 18z give us hope, well 1 run won't be enough to get me interested. I however don't agree with anyone stating winter is over, I'm just commenting on what is being modelled, and its far from a cold snowy outbreak, quite the oppisite. Sorry.

[The PIT]

i dont get this place evryone was saying how we need a greenland high for extended cold and now the gfs is showing height rises around greenland and with further upgrades a link to scandi and now nobody wants know

The problem is that a proper Greenie high isn't been shown rather a low level feature created by the cold air on Greenland.

[Isolated Frost]

need to be high peaks IS as the thickness is 538dam and the flow looks 'brisk'

Indeed- especially with upper air temps of -1c or thereabouts-

I was referring to slp to 500hPa, not 500-1000 thicknesses

[Frosty.]

I fail to see how we will have to look west or south west for our weather for the next few weeks when only last week T72 was being described as FI.

The reason is simply that the models are much better at modelling weather from the west or southwest rather than predicting where siberian highs will end up, that is why a milder looking outlook is more likely.

[shotski]

Relating to my above post, below are 2 charts from 2010 I have just dug up from the archives.

17th November 2010: low pressure to the west of the uk and High pressure over europe.

20th November 2010: Link up from the euro high into Greenland (the rest was history)

Edit : maybe scandi High not euro

Edited December 12, 2012 by shotski

[cj114]

The reason is simply that the models are much better at modelling weather from the west or southwest rather than predicting where siberian highs will end up, that is why a milder looking outlook is more likely.

Exactly. The input into the Computers corralates with what you get out! The same with any other programme. Only Mother Nature herself can know exactly what is going to happen, and she is NOT telling.

[Snowly does it]

Optimism s one thing, but looking at he charts at say 120, not too far out and borderline reliable, high pressure is in all the wrong places for us to get cold - Hudson Bay, too Far East in Siberia and te Azores throws a ridge towards us. It's extremely difficult to navigate a cold spell against that set up, it relies on a bullseye undercut or, as has been said, we need amplification upstream.

Not looking good out to Xmas week.

Edited December 12, 2012 by snowmaiden

[Rocheydub]

i dont get this place evryone was saying how we need a greenland high for extended cold and now the gfs is showing height rises around greenland and with further upgrades a link to scandi and now nobody wants know

It's a surface high pressure on Greenie, not a proper HP. For a brief guide, look at the colours on the 500 charts, you need yellows touching Greenie as a rough guide.

I understand your grasping at cold straws at the moment, I love cold too, but it's presently not showing any possibility in any recent op outputs.

However, do not give up just yet. Plenty of time left in winter, as we are only on day 12... Keep the faith.

[karyo]

Ecm at 144 hours: http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=0&archive=0

As the first low fizzles out, another takes over from the west.

Karyo

[Chess01]

What is it with this forum when cold is shown fi is really early time frame yet when it shows mild at 200 plus hours everyone takes it as its a dead cert . People need to remember that gfs can forecast the zonal pattern easy so thats why it shows up at fi as default pattern but has a tough time of dealing with cold spells . I think that the gfs will be proven wrong because i just cant see how it will work out the way its shown when things were looking so good for a cold spell just a week ago . My call would be its finding it hard to cope with the current pattern and that in a weeks time when this mild spell has past we might have something different to view

[Matty M]

We could really do we losing that High pressure east of Hudson as it is preventing low pressure system providing some WAA up the west of Greenland to promote some well positioned blocking.

Low after low exiting eastern USA on this ECM OP run.

[Summer Sun]

After a brief warm up for some over the weekend colder air once again filters back over the UK during next week, just as we lose one low another begins to head our way at t144

With the colder air any precipitation over high ground in the North could well fall as snow

That area of high pressure along the east coast of America isn't doing us any favours at the moment

Edited December 12, 2012 by Gavin.

[Snowly does it]

Ecm at 144 hours: http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=0&archive=0

As the first low fizzles out, another takes over from the west.

Karyo

And by T168 another is tracking in behind to take over from that one.

Highs over Hudson and Siberia are locking us in with nowhere for the LPs to go

Edit - the only real consolation is the split in ensembles for around 144 hours. Everything downstream would look very different if te runs started following a more undercutting scenario as some of the ensembles do.

Edited December 12, 2012 by snowmaiden

[Kentish Snowman in Yorks]

Interesting little feature in the Azores region at 192 on the ECM.

Will it help to lower heights in that region or just ride over the top?

[chris55]

Energy coming out of eastern america is a lot slower on the ecm 12, will this end up supporting the Greeny ridge??

[Snowly does it]

Interesting little feature in the Azores region at 192 on the ECM.

Will it help to lower heights in that region or just ride over the top?

It will ride up drawing warm air with it I'd say

[karyo]

Horrible!

http://www.meteociel.fr/modeles/ecmwf.php?ech=216&mode=1&map=0&archive=0

Karyo

[chris55]

At 192 not a bad angle of WAA, everything slower and a little bit of energy heading into the Azores!

(edit or is that more a westerly WAA from the Low exiting the US? looking at the Metio version it looks more easterly. wetterzentrale' plotting is potentially confusing things in my head)

But the low cuts under and disrupts on this run, just what we don't want to see.

Edited December 12, 2012 by chris55

[Weathizard]

Well at least at 240 that Low looks to have landed a blow to the Azores high, dreadful in reality though but marginally better I suppose at least it under cuts to a point. Some interesting model watching coming up I feel.

Edited December 12, 2012 by Weathizard

[TEITS]

Awful ECM at +240.

The pattern over recent days for +240 and beyond really has been woeful with a positive AO/NAO, PV moving into Greenland.

[PubliusEnigma]

Hardly 'zonal' is it really, the low pressures barely reach our shores

I'd say thats as bout as zonal as it gets. Temps possibly up to 13oC in some sheltered eastern areas, if there

are some sunny spells. Which is remarkable considering it would be mid winter.

The GFS 12z says goodbye for any hope of winter coming back until next year. These few days may well be the

coldest days of December. We have to hope the Winter Spanish High, doesn't migrate into the Bartlett position. At

least the persistent Christmas Rainfall under these sypnoptic set up should favour more Northern areas, sparing

the sodden South West.

[nick sussex]

Well the ECM makes less of the Azores high and has some interest with some trough disruption in the North Sea, a little westwards correction and that could bring some interest.

Thereafter the PV looks to be on the move. The jet is still tracking quite far south and especially for the north and ne it wouldn't take much change to bring in some colder conditions.

Overall now the PV looks to be on the move we're sure to find different solutions thrown up, the Russian high waves goodbye after flattering to deceive once again.

[Isolated Frost]

I can't see an active atlantic, I can't see persistant low heights to the north and a cooling stratosphere, I can't see strong heights to the south-east, I can't see very mild (2-3c above average) temps anywhere around the UK but I can see complete grim on the forums!

I think some have had their levels set too high over the last 3 winters... temperatures are expected to be near average for a week or so and we are only 2 weeks into winter, chill! We ain't going to get persistent cold

This isn't your typical 'zonal' spell, nor 'mild'. It will be warmer than recent and chances of snowfall are much lower-

Weather enthusiasts, not just snow.. we'll get lots of different weather types and we should appreciate them instead of bemoaning some change