Winter Model Discussion - The Hunt For Cold - 10th Dec

[Snowmad79]

The predicted strat forcast charts have now changed this morning. Where as before

they solidly showed the PV relocating to siberia now they show it slap bang over the

pole. Bad news for us coldies. The warming that we are seeing at the 10hpa level

could very well be responsible for this change.

If that is the case the Strat followers also got trolled by the models! The output the models are throwing at us is just as bad as when the PV is located over Greenland, never mind the pole with unrelenting waves of LP T-boning this sodden little Island.

It's looking like Santa will be coming on a life raft this year

http://www.clactonandfrintongazette.co.uk/news/localnews/10090091.Santa_set_to_visit_Clacton_by_lifeboat/

Edited December 12, 2012 by Snowmad79

[IDO]

The latest GFS Op is as bad as it gets. During FI the Russian High is shoved to Siberia and more. The PV continues to shift around and by the end of the run is back in Canada. All heights to our north collapse. This allows the Azores/Euro high to build further north and at T384 the H500 looks like the latest UK seasonal:

http://cdn.nwstatic....384/npsh500.png

The GEFS: http://modeles.meteo...ndres&runpara=0

A bit more promising with about 15% of members going for and maintaining cold uppers from around D9-10 whereas the rest showing a zonal sine-wave pattern.

The mean surface temps: http://wxmaps.org/pix/temp4.png

They show most of the UK during week 2 now closer to average temps with the SW with above average. The precipitation charts suggest the next 7 days over 50% more rain expected: http://wxmaps.org/pix/prec4.png

The GEFS mean:http://modeles.meteo...-21-1-240.png?0

at T240 shows the relentless push of the heights east, with no strong GH. By T384: http://modeles.meteo...-21-1-384.png?0.

A westerly cyclonic flow with poor blocking and the PV poor for cold over the UK.

The ECM at T240: http://www.meteociel...1-240.GIF?12-12

This is as flat as it has shown for a while with low after low coming off the Eastern Seaboard with UK written all over them. The PV also poor for a cold synoptic.

Rain and cool and possible Azore’s High interaction over the south of the UK. Possible topplers for the north but no snow at sea level in England on the GFS op.

Reset please.

Edited December 12, 2012 by i'm dreaming of...

[Great Plum]

Optomistic lot you all are huh? I write this when it's -7.5c in Charlwood at the moment...

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

Ensembles are showing a dip before and around Christmas and some members go very cold...

http://www.wetterzentrale.de/pics/Recm2401.gif

Undercut?

[Jezzer]

Optomistic lot you all are huh? I write this when it's -7.5c in Charlwood at the moment...

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

Ensembles are showing a dip before and around Christmas and some members go very cold...

http://www.wetterzentrale.de/pics/Recm2401.gif

Undercut?

Yep, totally agree. I know this thread concentrates on weather to come but anyone would think we were currently experiencing mild S westerlies as opposed to the freezing conditions you mention. I'm loving this cold spell, could obviously do with some snow though.

Will be interesting to see how the models develop as we head into the Christmas period.

[Ian Brown]

This might cheer you up

The OP was as you might expect in the longer range very much on the mild side, with the appearance of the dreaded PV in the later timeframes.

Nothing to suggest that we are going to get out of the rut that we are about to enter. A large upper trough to the West with the jet at mid-latitude, pressure fairly high over Hudson and the large block out to the East. Unless there is some sort of upstream or teleconnective change then on we go, but the set-up could be far worse - like what the GFS shows at the end of its run.

[Timmytour]

The only comfort I can raw from todays models is the hope that they are as wrong as they were when, a week ago to the day, we had a thread entitled

Model Output Discussion 5/12/2012 18Z onwards - the one after THAT ECM

[Cecil Hogmanay Melchett]

Looks like patience is going to be the watchword.Little or no cheer in the reliable timeframe on any of the 0z runs with the Atlantic in control.There is some sings of something interesting at 240h on the ecm but we had much better charts than that at 168h last week so i'll not be holding my breath on that last ecm chart.

Ah well,never mind,theres more to life than hunting cold,time for a few days off and hopefully something decent will show its hand then...

[Nick F]

Optomistic lot you all are huh? I write this when it's -7.5c in Charlwood at the moment...

http://www.netweathe...;type=ens;sess=

Ensembles are showing a dip before and around Christmas and some members go very cold...

http://www.wetterzen...cs/Recm2401.gif

Undercut?

Fair enough, we all knew it will be cold this week, but after Friday realistically it is possible we may not see such cold conditions as we have now for at least 7 days, possibly even this side of Xmas.

Pinning hopes over the start of an undercut at t+240 is being very optimistic!

[TEITS]

The only crumb of comfort this morning is the GEFS ensembles.

http://cdn.nwstatic.co.uk/ensimages/ens.20121212/00/t850Cambridgeshire.png

Mean dropping to -4C in the run up to xmas with some runs much colder. I haven't looked at each member but I assume they are showing the kind of synopics I have been describing over the last few days.

My negative comments this morning are focused mainly on around +300 plus because the pattern the GFS Ops have been suggesting is simply shocking. A PV moving W and becoming centred over Greenland, jet running SW-NE, LPs moving across Iceland, is more like a horror film. Lets hope the models back away from this disturbing trend.

So in summary you cannot rule out snow potential in the run up to xmas due to the ensembles I have posted. However the period between Xmas and New Year looks potentially very unsettled and mild.

[russell k]

The OP was as you might expect in the longer range very much on the mild side, with the appearance of the dreaded PV in the later timeframes.

Nothing to suggest that we are going to get out of the rut that we are about to enter. A large upper trough to the West with the jet at mid-latitude, pressure fairly high over Hudson and the large block out to the East. Unless there is some sort of upstream or teleconnective change then on we go, but the set-up could be far worse - like what the GFS shows at the end of its run.

Thanks Ian

When the "Beast from the East" was almost banked some of ensembles started to go "south" we dont HAVE TO HAVE the right teleconnective synoptics to create a cold snap, just not the 2009/10 & 2010 winters which is unlikely. The potential towards the end of the month still exists

[Timmytour]

While the future looks bleak, what we wouldn't give for a model showing what we have right now. There's a very festive look to the trees, somthing I really only remember seeing in 2010 in recent times

[Frosty.]

The GEFS 00z mean shows colder weather towards T+240 hours, not sure how long it would last but at least it's getting close to christmas, the azores high looks well out of the picture and there is a general lack of high pressure at all, it's low presssure all the way apart from brief ridging, so, a chance of snow for some after next week. Big changes arriving this friday with milder, wet and windy weather sweeping north and east and a milder unsettled weekend, next week very unsettled, wet and windy at times with temps around average but sometimes milder in the south at least but then a chance of something colder beyond that.

[Great Plum]

Fair enough, we all knew it will be cold this week, but after Friday realistically it is possible we may not see such cold conditions as we have now for at least 7 days, possibly even this side of Xmas.

Pinning hopes over the start of an undercut at t+240 is being very optimistic!

It's as cold here as it has been for 2 years! I'm searching on the models for crumbs of comfort and that's what I've found...]

[MisfitDog3]

Hmmmm...counting the number of Low Pressure systems forecast to be crashing in over the UK from now until Xmas on GFS is rather alarming. Flooding will be a major talking point if that even remotely comes off. Saying that, I still reckon most models like a good zonal outlook as a holding point, so just transfix on that until any signs crop up in the medium term to change the signals. Running home to mama...

Nothing is set in stone for Xmas at this stage. In fact I rather suspect we'll get something cold and settled after a stormy 10 days or so.

[chris55]

A few positives this morning, and overall i get the feeling something could be in the making towards Christmas.

[phil nw.]

Looking behind the less than inspiring operational outputs the ens.graph shows pretty tight bunching around 0c for the next week indicating confidence in the forthcoming pattern.

The operational GFS is a mild run later though so looking at the means on both runs at T240hrs

show the UK on the colder side.The vortex is shown to be relocating towards Siberia and it wouldn`t take much amplification of the flow to bring further cold south.

The NAEF`S mean heights are trending this way here at T240hrs.

I think this is where we have to hope that this will ease our trough further east as those Siberian hts decline in week 2 of the outputs-maybe with some ridging further west in the Atlantic.This adjustment to the pattern would at least bring a north or north westerly incursion and the lower temperatures in Christmas week shown by the mean dipping on those ens.graphs.

[Tom Montalbano]

Can only agree with the comments above, the overnight runs are not great from a coldies perspective. Some runs offer a hint of something colder a few days before Xmas, most due to some temporary ridging in mid-Atlantic.

As TEITS states, rather more worrying is the GFS trend for a large chunk of the PV descending on Greenland/N.E.Canada again, over the Xmas period.

Regards,

Tom.

[Severe Siberian icy blast]

The only crumb of comfort this morning is the GEFS ensembles.

http://cdn.nwstatic.co.uk/ensimages/ens.20121212/00/t850Cambridgeshire.png

Mean dropping to -4C in the run up to xmas with some runs much colder. I haven't looked at each member but I assume they are showing the kind of synopics I have been describing over the last few days.

My negative comments this morning are focused mainly on around +300 plus because the pattern the GFS Ops have been suggesting is simply shocking. A PV moving W and becoming centred over Greenland, jet running SW-NE, LPs moving across Iceland, is more like a horror film. Lets hope the models back away from this disturbing trend.

So in summary you cannot rule out snow potential in the run up to xmas due to the ensembles I have posted. However the period between Xmas and New Year looks potentially very unsettled and mild.

Yea but TEITS why are you getting down about something that's 300hrs away? There is a SSW in line for the beginning of jan so any regrouping of the vortex will be very short lived I should imagine , granted it looks bleak this morning but we no how quickly things change, why don't we all take a wk off from the models? I no it's getting me down all this , but in reality we have an amazing cold spell on us at the min with some fantastic winter scenes and an amazing couple of wks coming up where we all get to see our families that none of us see much of due to work etc so I feel when looking at depressing charts it dampens our mood in otherwise a fantastic period.

[Dampdorset82]

Yea but TEITS why are you getting down about something that's 300hrs away? There is a SSW in line for the beginning of jan so any regrouping of the vortex will be very short lived I should imagine , granted it looks bleak this morning but we no how quickly things change, why don't we all take a wk off from the models? I no it's getting me down all this , but in reality we have an amazing cold spell on us at the min with some fantastic winter scenes and an amazing couple of wks coming up where we all get to see our families that none of us see much of due to work etc so I feel when looking at depressing charts it dampens our mood in otherwise a fantastic period.

Just to confirm the SSW is a prediction not a definite.

[Polar Maritime]

Just to confirm the SSW is a prediction not a definite.

All models are a prediction, as with the strat model, but at least it's something to cling onto at this morning for cold weather fans.

[Gibby]

Good morning folks. Here is the morning look at the 00zs of GFS, UKMO, GEM and ECM from my perspective for today Wednesday December 12th 2012.

All models show a slow increase in a SE airflow over the coming 24-36 hours as High pressure slips away SE into Europe. The weather will be cold and dry for many with areas of freezing fog slowly reducing in response to the breeze. Frost will remain widespread though for the next 35 hours or so. By Friday an active set of fronts in association with a very deep Low pressure area steaming across the Atlantic towards Western Britain will bring strong winds and rain across all areas through the day. The weekend then shows deep Low pressure up to the NW of Britain with relatively mild SW winds and spells of rain and showers for all areas though more especially for the South and West with an imminent flooding risk once more.

GFS then moves on to show a continuation of unsettled and relatively mild conditions with further spells of rain and wind with just a few brighter and drier interludes as brief ridges pass by. The block over Europe is pushed well away East over Russia by the end of the run with most of Europe in milder and wetter conditions similar to the conditions of the UK.

The GFS Ensembles show very unsettled weather for the UK over the coming two weeks with plenty of rain about. 850's show average temperatures given under and Atlantic flow with a few colder options shown in distant FI. The operational was one of the milder options at times with a noticeable dip in the run up towards Christmas though Christmas itself looks like being relatively mild with little chance of snow.

The Jet Stream shows a flow exiting Newfoundland crossing the Atlantic towards France over the coming days and then being maintained through the reliable time frame. It is shown to ridge slightly North near the UK with the flow directly over Britain in a week or so.

UKMO for midnight on Tuesday shows Low pressure just to the West of Scotland with another one approaching from the West for the following days maintaining the cyclonic breezy flow with spells of rain or showers for all in normal temperatures.

GEM shows Low pressure out to the NW or over the UK with bands of rain followed by showers the order of weather events through the periods. Some brief drier interludes are shown especially in the South and East later as Low pressure axis further away to the NW with slightly higher pressure to the SW.

ECM shows Low pressure filling near the UK with a weak ridge crossing East ahead of further deep Low pressure anchoring to the West of the UK later. This means further rain or showers in strong winds at times with the West bearing the brunt of this. Temperatures would remain close to normal though there are signs that it may begin to turn rather colder in the North and East later.

In Summary the weather looks like staying unsettled, windy and relatively mild in the run up to Christmas. With Low pressure close to or over the UK rainfall amounts could be rather large at times, especially in the areas of the SW that least need it. There is little sign of any return to cold weather for the UK anytime soon with the Atlantic in such volatile mood with Christmas looking to be distinctly green and probably wet not white.

[Methuselah]

Shouldn't all the models go blank on the 21st?

[Summer Sun]

There are still plenty of members from the GFS ensembles trending colder this morning with quite a tight bunch around the 19th with 0c uppers making there way back

Christmas week see's them drop quite a lot

Aberdeen has fairly good agreement of things turning colder

[latitude]

Just to confirm the SSW is a prediction not a definite.

And if there is a SSW how long will it take to show effects..quite a while as far as I know. All the signals were there a few weeks ago, ie blocking and the NW winter forecast. Currently that has all gone out the window.

[chris55]

Flicking through the GEFS ensemble options, concentrating on the "dip" period around the 22/23/24/25 there is certainly some opportunity for a colder and potentially snowier period.

Although we don't have any really strong signal for a big Greenland high or a split jet or a spectacular channel Low jet etc etc.....there is a trend for the pattern to move far enough south for us to be on the cold side, energy moving S.E into mainland europe is what we need.

We have seen this week how all the "recognisable" good signals can result in not to much for us, so what's to say a sneaky shift in the pattern without the bells and whistles of a huge Scandi high for example, couldn't actually deliver through the back door so to speak!.

ECM also hinting at this on day 10.