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

[SMU]

Well the 12s seem to be on the same sort of curve like last week- although last week it was a gradual downward curve to oblivian-

There isnt any deep projected blocking to develop- but as said many times before- find a wedge or sausage of +ve pressure across iceland to norway then it can distort the jet enough so we get on the Northern side of the PF-

If we are going to make a run at a decent cold festive period - then today is the day for it to start emerging in the models-

S

Edited December 13, 2012 by Steve Murr

[latitude]

Is this slightly different from last time, the models have picked something up at 120 a lot earlier?

[cooling climate]

Great run from the ECM this evening to lift the mood although I would have

thought no one is going to be taken in just yet especially with the let

down we had with the failed easterly still very fresh in our minds.

Lol it would not be the first time the models have let us down and then led

us up the garden path again. Its great that there is something of interest

again to talk about but after seeing how those shortwaves can throw a pattern

out at such short range there will be no ramping from me unless we are inside

t96.

Ens probably will not help much if they are at a lower resolution. At least

can look forward to the next model run now even if it is the 18z. It goes to

show though that even 06z should never be discounted completely.

Edited December 13, 2012 by cooling climate

[Ian Brown]

Europe has been cold for a while and snowcover can inhibit the Eastward progression of the jet. If I think back to anytime when the blocking out East came back to hold off the Atlantic, it was never picked up until it was in this sort of range.

This looks a little different than a vertical alignment and I would have some doubts about the jet taking an SE dive but let's see what subsequent runs bring. If the jet remains flat, then it should see off any attempts at HP to our North pretty readily.

[chris55]

Well the 12s seem to on the same sort of curve like last week- although last week it was a gradual downward curve to oblivian-

There is any deep projected blocking to develop- but as said many times before- find a wedge or sausage of +ve pressure across iceland to norway then it can distort the jet enough so we get on the Northern sife of the PF-

If we are going to make a run at a decent cold festive period - then today is teh day for it to start emerging in the models-

S

I think this is an important little nugget of info Steve, although "northern blocking" in the simplest sense, may need the yellows in the charts to raise some members eyebrows, it is not always the case that we need a huge Scandi or Greenland high to just nudge the pattern enough to bring us cold and snow.

The other day I did say northern blocking was evident, and I meant there was high pressure to the north, and was hopeful this may align in a more favourable position. But at the time this wasn't seen as to important. Just goes to show how slight adjustments can see a much more favourable outcome.

[shotski]

Great run from the ECM this evening to lift the mood although I would have

thought no one is going to be taken in just yet especially with the let

down we had in failed easterly still very fresh in our minds.

Lol it would not be the first time the models have let us down and then led

us up the garden path again. Its great that there is something of interest

again to talk about but after seeing how those shortwaves can throw a pattern

out at such short range there will be no ramping from me unless we are inside

t96.

Ens probably will not help much if they are at a lower resolution. At least

can look forward to the next model run now even if it is the 18z. It goes to

show though that even 06z should never be discounted completely.

Hi CC

Is the operational run all in high resolution to t-240 and are the ens members all in low resolution ?

And if so why ? is it to do with costs ?

Shotski

[Craigers]

what i love about the gfs 12z is how the low pressure fragments and splits into two systems with the lower system under cutting the block. looking good for my surf trip on the northern coast of scotland

[Pixel]

Interesting developments 'out there' for Christmas time...

would really like to see the jet take even more of a southerly route but hey we're not in charge of the weather - Santa is !

- and why not get excited... it Christmas time

[Matty M]

Only now are we truly seeing the Atlantic- Russian Block battle being waged

So in the next few days the models will have a better understanding of the actual flows of energy and will be better able to determine

what will happen subsequent Atlantic incursions.

So it is not surprising now that some operational output is starting to toy with different outcomes, uncertainty will likely increase

from now for a few days.

Edited December 13, 2012 by Matty M

[cooling climate]

Hi CC

Is the operational run all in high resolution to t-240 and are the ens members all in low resolution ?

And if so why ? is it to do with costs ?

Shotski

Yes the operational run is run at a higher resolution. As to why I am not sure money could

well be one reason. There are other posters on here that are more familar with workings of

the model runs and perhaps they can offer an insight.

[weather eater]

All very welcome as a mood enhancer, but I would be very wary of anything at this range, personally I don’t want to see great charts especially easterlies at 168hrs plus, they never come off, or at best are watered down, as we have recently seen. Even 2010 was not as good as some of the model projections preceding the event. I guess if nothing else we see again with model watching, that nothing is set in stone, those predicting no chance of anything wintery before New Year may need to think again, well at least for now.

[Tom Montalbano]

Watching the drama of that ECM run unfold at work. A long way off and although the easterly flow is soon cut off and a cold surface high develops over us at t240, wouldnt take much of a leap of faith to see that small high transfer NE and settle over, what now would be a very cold Scandinavia and develop into a much stronger feature. Anyway lets get to t120/t144 first!

[bobbydog]

Ok sorry, but the easterly if it does happen, was first spotted on the GFS on Sunday.

yeah but, so was 'hurricane higgins' 'the summer of 69' and the loch ness monster!

[swfc]

Struggling to see any pressure building at 240 hours on ECM but a move in the right direction .looks odd to me tho if honest !!

Edited December 13, 2012 by swfc

[Panayiotis]

yeah but, so was 'hurricane higgins' 'the summer of 69' and the loch ness monster!

Well Im sure the loch ness monster is under frozen ice by now

[Methuselah]

Well the 12s seem to be on the same sort of curve like last week- although last week it was a gradual downward curve to oblivian-

There isnt any deep projected blocking to develop- but as said many times before- find a wedge or sausage of +ve pressure across iceland to norway then it can distort the jet enough so we get on the Northern side of the PF-

If we are going to make a run at a decent cold festive period - then today is the day for it to start emerging in the models-

S

An HP sausage? Or a Walls?

[mcweather]

Just to keep the bubbling under cold vibe going after tonights ECM

Great oaks from little acorns grow.

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

http://www.wetterzentrale.de/pics/archive/slp/1947/Rslp19470120.gif

[mcweather]

Well Paul Hudson virtually ruled out a white Christmas for Yorkshire this evening on Look North...I bet he is sweating just a little after that ECM 12z run!

Yes Kirsty Macabe did the same thing tonight on BBC South today. I thought it was rash at the time and even more so after tonights ECM.

Lets face the it the Meto haven't covered themselves in glory over the beast from the east episode either last week their 6-30 forecast was going for possible milder incursions into the southwest. It was certainly not suggesting what is now happening.

Edited December 13, 2012 by mcweather

[Gavin Hannah]

IMO, the models have really struggled to model anything past day 3 this past week. This incoming LP has been very poorly handled. Never mind the LR stuff.

Edited December 13, 2012 by IBringTheHammer

[Gibby]

Good evening folks. here is the report on the 12z output from GFS, UKMO and ECM for this evening Thursday december 13th 2012.

All models show the breakdown already taking shape out to the west of the UK with pressure already quite low and falling further over the next 24 hours as an active system of fronts cross NE over the UK with deep Low pressure closing in on the West of the UK. A strengthening wind from the South will blow the remains of the frostiness still being experienced by many away overnight with cloud and rain following in from the SW to reach SW England and much of Wales by morning. After several hours of rain amounting to between 10-20mm for many brighter skies will follow in behind with temperatures rising abrubtly as winds decrease and veer SW later tomorrow. Any remaining rain and hill snow in the North will clear tomorrow night leaving a showery SW flow with some heavy and prolonged showers likely at times in the South and West. The output moves into next week showing the Low responsible for the coming rain filling up as it drists East across the UK on Monday with further rain at times for all then. By Tuesday a brief interlude of drier weather is shown by all models as a weak ridge crosses East through the day.

GFS then shows a slightly backed West position of the next Low pressure midweek meaning that the fronts become complex and with a strong wind shear across them meaning heavy and squally rain followed by a return to sunshine and showers soon after midweek. By Friday this Low has become absorbed by a new Low in the SW approaches and this one threatens an awful lot of rain and resultant flooding risk to the SW in strong to gale SE winds. All through this period temperatures will hold close to normal for much of the time though with the High pressure block orientated somewhat different tonight there is the potential for a colder feed from Europe to migrate across NE areas of the UK with time. In FI tonight a brief incursion of Continental air makes it to all areas for a time before the Atlantic moves up a gear again and pushes Low pressure back into the British Isles with a wet and windy Christmas the likely result from this run. The end of the run sees the potentially stormy and wet weather continue with rain and squally showers everywhere.

The GFS Ensembles show a fairly flat, average pattern close to the seasonal average for the foreseeable future. The colder blip from the operational is not well supported with most members preferring to maintain the average and wet Atlantic based pattern throughout. There are a handful of colder options on offer late in FI to balance the story for those looking for cold but there is no definitive trend indicated.

The Jet Stream shows a strong arm rattling across the Atlantic towards Western Europe making landfall at around 50 deg N and maintaining that position over the English Channel give or take a hundred miles or so until the end of the reliable time frame.

UKMO for midday on Wednesday shows Low pressure to the West of Ireland with a cold front having crossed East in the previous 12 hours or so. In its wake will be windy and relatively mild conditions with heavy showers, more especially but not exclusively in the South and West.

ECM tonight shows a complete about turn tonight which will please the cold camp considerably. With the pattern backed West at 144 hours as per GFS an undercut takes place in the trough associated with a mid Atlantic deep depression which having brought yet another spell of heavy rain across Southern Britain stalls over the Midlands and sheered away East. A new depression on a more Southerly track out to the SW is similar to GFS's evolution and on this run is a trigger to flood cold air from Europe back over the UK next Friday turning rain to sleet and snow quite widely, especially over the hills in the South. The East wind would become strong and biting temporarily with wintry showers near Eastern coasts. At the end of the run pressure has recovered with a frosty day on day 10 putting us back into a similar position to where we have been in the last few days with the Atlantic knocking on the door of the UK under a collapsing High.

In Summary tonight there is a little more hope for 'coldies' again as a backing West of the pattern has opened the door ajar to a chance for cold weather from Europe to put it's toe into UK air space in a week or so. As far as GFS is concerned it is not well supported from it's ensembles and we'll have to wait a couple of hours to see where the ECM operational lies within it's pack. In the mean time the weather looks extremely volatile and simply 'dire' at times with spells of unwelcome rain in a strong wind and temperatures close to normal. IMO the output tonight goes to prove how a couple of hundred miles in the position of Low pressures can have far reaching implications down the line and just goes to show that the weather in the UK is never straightforward and quick to make fools of us all. The biggest problem of all though is getting it to be shown in the closer time range and to get it to verify at all.

[damianslaw]

A word on the ECM output at the 168hr range this evening which is showing the type of evolution I have suggested is a very plausible outcome as we head towards Christmas i.e. the trough being forced SE thanks to the southerly alignment of the jet with heights building over the mid atlantic and over the top of the high aided by what is increasingly looking like a very strong block of cold high pressure over west russia. However, as others have said until such synoptics are shown within the 96hr range we should be very wary whether the synoptics are likely to verify. Very much will depend on the tracking and positioning of the second low pressure system due to move across the atlantic early next week, if this splits with energy being displaced to the south of us, then this will bode well for height rises to our NE to influence things.

The christmas period is notoriously a difficult time of year to predict, it is a very very topsy turvy time of year and often quite pivotal as the northern hemisphere settles down into its mid winter state. I've known many a pre-christmas period be dominated by the atlantic and mild or relatively mild weather only for a sudden change to arctic northerlies and generally much colder weather at christmas and in the days before New Year. 2008, 2004 (albeit a shortlived colder spell 24-26th), 2000 were good examples of such a change in conditions.

Keep an eye on the movement of the projected second atlantic low feature early next week, and also the movement of the russian high - a right royal battle could take place next week. A well established cold pool is developing over west russia/east scandi at present - very difficult to shift.. and the atlantic in my view is still in a relatively weak state against what is overall a very cold northern hemisphere background state.

[SMU]

The ECM at 240 is a UK dream with widespread sub -5c minimas-

Lets hope we get nearer-

S

[IDO]

EssexWeather

@kevski74 Looking through the 51 ensemble members, it has the support of less than 5%. A new trend which may increase over the coming days.

13/12/2012 19:36

[Gavin Hannah]

After the ECM, Lets have a pub run that's really on one tonight.!!

[Great Plum]

EssexWeather

@kevski74 Looking through the 51 ensemble members, it has the support of less than 5%. A new trend which may increase over the coming days.

13/12/2012 19:36

One thing I would say that often if the op and control follow each other in the ECM, then often the ensembles will follow in later runs...