Model Output Discussion - 18z - 25th Nov onward

[BristolBaggie]

MattHugo81

The UKMO model while consistent has little or no support from the ECMWF ensembles. The Atlantic is likely to 'sneak in' next wkend(or so)...

26/11/2012 19:18

It looks like a matter of time before the UKMO backtracks if the GFS and ECMWF ensembles are worth their salt:

http://cdn.nwstatic..../t850London.png

But GFS/ECMWF models appear to keep a cool/cold outlook form T168. But sustained cold not now looking the synoptic pattern for December. We shall see...

MattHugo81

The UKMO model while consistent has little or no support from the ECMWF ensembles. The Atlantic is likely to 'sneak in' next wkend(or so)...

26/11/2012 19:18

It looks like a matter of time before the UKMO backtracks if the GFS and ECMWF ensembles are worth their salt:

http://cdn.nwstatic..../t850London.png

But GFS/ECMWF models appear to keep a cool/cold outlook form T168. But sustained cold not now looking the synoptic pattern for

December. We shall see...

Realistic assessment. I think we have all been chasing shadows the last .few days. Damn those models.

[Snowmad79]

Just been speaking to matt Hugo via my twitter (@markydub)

Says ukmo is on its on and unlikely to verify

He also states you cannot rule it out with its consistency so please post all comments and not half the story. Many thanks. Would love to know of other occasions where the UKMO went head to head with GFS and ECM and came out the winner ?

Edited November 26, 2012 by Snowmad79

[Harsh Climate]

Funny how the ECM and GFS aren't great but the UKMO is actually quite good with the block likely to win. In past potential cold spell's it's usually getting the UKMO on board which has often been the final stumbling block.

I think it's finally balanced and even if the atlantic does win I think it will be short lived before blocking quickly comes back into play.

Tommorow morning as others have said we should know one way or another.

[UV-RAY]

Funny how the ECM and GFS aren't great but the UKMO is actually quite good with the block likely to win. In past potential cold spell's it's usually getting the UKMO on board which has often been the final stumbling block.

I think it's finally balanced and even if the atlantic does win I think it will be short lived before blocking quickly comes back into play.

Tommorow morning as others have said we should know one way or another.

I'm not so sure we will HC, this is going to the wire IMO.

[georgiedre]

All looking really messy. But no post from gp re all this. Any chance on him poping in?

[Dave Kightley]

MattHugo81

The UKMO model while consistent has little or no support from the ECMWF ensembles. The Atlantic is likely to 'sneak in' next wkend(or so)...

26/11/2012 19:18

It looks like a matter of time before the UKMO backtracks if the GFS and ECMWF ensembles are worth their salt:

http://cdn.nwstatic..../t850London.png

But GFS/ECMWF models appear to keep a cool/cold outlook form T168. But sustained cold not now looking the synoptic pattern for December. We shall see...

They look ok to me upto the 5th of December. Slight warm up if that up to that point. -5 never far away

[Mark Bayley]

All looking really messy. But no post from gp re all this. Any chance on him poping in?

[Harsh Climate]

I'm not so sure we will HC, this is going to the wire IMO.

Yes might even be longer. One thing is for sure though, the UKMO sooner or later is going to come out with a lot of credit or a lot of stick.

[chris55]

UKMO supported by JMA this evening

I'm gunning for the underdog, I know we have many signals coming in that the UKMO is missing this Atlantic push, and it may well be, although the consistency is notable, and having another credible model on boards helps!

JMA evolves into Snowmagedon for a good chunk of the UK,

It's the positioning of the Euro trough that looks to be dictating things tonight, the Canadian Low up to 120 looks pretty consistent between ECM and UKMO but the positioning of the Euro trough/ridging Arctic high is what is holding the Atlantic energy back on the UKMO and JMA.

UKMO, trough southerly based, Arctic high further south.

ECM, trough much further north, Arctic high much further north. This allows the Atlantic to push underneath resulting in a milder period. But looking beyond this on the ECM the cold returns.

[Jaffusmaximus]

I'm not giving up on a cold snap until after t96 and if the blocking breaks down after that point. Fact is its still holding its own at the moment, plus there are differing views from various models regarding the viability of the block, so I guess its an unbiased 50/50 at this stage. If come Thursday the Atlantic breaks through then I will modify my personal expectations for.

[Snowmad79]

Sorry but ensembles meant only as a guide and are erratic. Yesterday and the day before they were trending colder. Today the mean is slightly warmer and that means the UKMO is going to backtrack ?...... Laughable to be honest.

We will have to see heh.

[Isolated Frost]

UKMO prolongs the spell as it extends the arctic ridge south- and declines the shortwave activity w of Norway- if the fax at 96 and 120 agrees with the UKMO (considering the major talk going on apparently at Exeter)- then we are in business- the atlantic should come in around this wknd- but as Matt says, it is 'likely' 'or so' around the wknd area-so being slightly prolonged is possible- the major issue is the lack of nwp support it holds-

important h5 cpc update coming soon

[NickR]

He also states you cannot rule it out with its consistency so please post all comments and not half the story. Many thanks. Would love to know of other occasions where the UKMO went head to head with GFS and ECM and came out the winner ?

Yes, he says it can't be ignored it completely, but his take is accurately summed up by the tweets posted. To say half the story has been missed out is misleading... and seems to come from a desire inaccurately to push for anything that supports cold if I'm being honest.

[london-snow]

I appreciate Matt Hugo's & Ian F thoughts however these both do not have crystal balls do they however they do have access to other charts & data but how many times has this data been tested against the situation that is developing? I think going back at least into the 80s when data was sparse & limited. However cast your mind back to this morning when one of them said the UKMO will back down this evening and we all knew what happened there. In delicate situations as these nothing is a forgone conclusion until that low heads east towards us and stays east. Even if the Atlantic does break through it is very likely to be temporary at best. Until then i am just enjoying the ride and chat.

Edited November 26, 2012 by london-snow

[Frosty.]

UKMO prolongs the spell as it extends the arctic ridge south- and declines the shortwave activity w of Norway- if the fax at 96 and 120 agrees with the UKMO (considering the major talk going on apparently at Exeter)- then we are in business- the atlantic should come in around this wknd- but as Matt says, it is 'likely' 'or so' around the wknd area-so being slightly prolonged is possible- the major issue is the lack of nwp support it holds-

important h5 cpc update coming soon

Yes there could be some frontal snow at the weekend as the uk will be under a cold pool by then, could get very interesting for some as fronts hit the cold air and maybe grind to a halt.

[Backtrack]

He also states you cannot rule it out with its consistency so please post all comments and not half the story. Many thanks. Would love to know of other occasions where the UKMO went head to head with GFS and ECM and came out the winner ?

Also worth noting that with so much confusion with both us and the models right now, he was brave to make that call.

Remember guys, he's only a forecaster, not a god. He's been wrong before and he will be wrong again. Have all the computer power in the world and you'll still fail to forecast the weather more than a week out with any deal of accuracy.

With such consistency you'd be an absolute fool to rule out the UKMO (not aimed at anyone)

[Jupiters Winter]

I do not remember the exact year but within two years ago there was a similar situation where GFS/ECM showed mild South westerlies and UKMO showed Easterlies and it was I think similar timeframe as of now when the UKMO said You were right GFS/ECM....

He also states you cannot rule it out with its consistency so please post all comments and not half the story. Many thanks. Would love to know of other occasions where the UKMO went head to head with GFS and ECM and came out the winner ?

[Dave Kightley]

The -5 is never far away and nor will snow! All i care about is it snow and the big freeze can wait! For snow it looks good

[chionomaniac]

Another nail biting day, although there does seem to have been a general move towards the UKMO, containing the best output for those wanting a more sustained and potentially snowy spell (short to medium term).

Whatever happens, and despite what the models show, i feel any milder spell would be rather brief, as echoed by many of the resident experts. There is no support for a strong polar vortex, and a +AO, especially when viewing the latest stratospheric output. The recent geopotential height charts show a rather weak and fragmented PV, and unless i'm interpreting it wrong, there is a trend to send a fragment into Europe. This would support height rises around Greenland, which is supported by the latest MJO output, and NAEFS ensemble mean.

NAEFS ensemble mean, shows strong support higher pressure in the mid atlantic and Greenland area

The general trend is to send the MJO into phase one, as shown by GFS, UKMO and ECM.

This would give us the following composite. Note Greenland heights, and the trough over us. Although maybe not ideal for the south, it should be noted that these composites are of use as a guide.

Into and through December i see support for continued blocking, with some support for blocking around Greenland. The outlook to me, over the next few weeks, is a positive one if your seeking cold!

I would say that there is a hint of MJO phase 2 in those forecasts as well, Mark.

Perhaps a blend of both is the right mix.

Yesterdays ECM 12Z 100 hPA forecasts drift the Canadian daughter vortex towards Greenland at the critical timeframe (T+144) and I am sure that it is this that influences the energy ready to be thrown across the Atlantic.

http://wekuw.met.fu-...ast=all&lng=eng

Small variations in the position and timing of rejoining the Eurasion vortex of this Canadian daughter vortex will be critical in how much energy is available to be phased across the Atlantic.

No wonder this last week of model watching has been so intriguing and addictive!!

Edited November 26, 2012 by chionomaniac

[Backtrack]

I do not remember the exact year but within two years ago there was a similar situation where GFS/ECM showed mild South westerlies and UKMO showed Easterlies and it was I think similar timeframe as of now when the UKMO said You were right GFS/ECM....

And how many times has the reversed happened? All fine and dandy having a mild bias but at least post the second side of the story too.

[Harsh Climate]

I'm not giving up on a cold snap until after t96 and if the blocking breaks down after that point. Fact is its still holding its own at the moment, plus there are differing views from various models regarding the viability of the block, so I guess its an unbiased 50/50 at this stage. If come Thursday the Atlantic breaks through then I will modify my personal expectations for.

Remember in november/december 2010, there was sooo many times the atlantic looked like charging in but never quite did. Until we have cross model agreement It's certainly not a formailty, but I do understand why people go for that option as over the last 20/30 years up until recently that has been our default weather pattern.

[UV-RAY]

Yes there could be some frontal snow at the weekend as the uk will be under a cold pool by then, could get very interesting for some as fronts hit the cold air and maybe grind to a halt.

February 96 hopefully Frosty, ok a tad optimistic maybe but we can't rule out some significant snowfall in places by the end of Monday. Edited November 26, 2012 by Seven of Nine

[Isolated Frost]

MattHugo on twitter highlighting that he expects the 96 and 120 to be modified from the UKMO after discussion- probably negatively

[kold weather]

What the models are already hinting at is there is going to be a continued NW-SE dive occuring near our shores even if the atlantic were to break through, plus we WILL keep higher heights to our north (throw out ANY ensemble member that says otherwise, they are garbage) and this keeps the door firmly ajar for more cold intrusions.

Ensemble members are broadly milder...but then again they are also broadly redeveloping a PV, some actually get quite strong...which given the current conditions aloft, is pretty close to BS, so to speak! Not quite there, but close!

[Matty M]

The JMA is how i think things will play out.

UKM will be proved correct.

It has been rock solid and the ECM and GFS have trended towards it this evening.

It has the momentum.

People using Ensembles to forecast such a delicate synoptic will always fail.

You need every km of resolution to resolve such fine detail which have such massive ramifications.

And we are in a situation where we need this refined detail over southern Greenland and the Arctic.

Edited November 26, 2012 by Matty M