Model Output Discussion

[andymusic]

I agree re the seeming belief that now that FI is mild it is going to happen. There is Paul B and others telling us that we will have double digit temps next weekend - if we were saying it would be v cold would we be saying this - I doubt it. We have people talking about record max temps for Feb - have they gone mad! It would be nice to have some balanced posting on here (both sides)

Looking at the ECM ensembles it is clear that the op was very much at the top - especially in FI where people are ramping up the mild. This explains why the Meto are suggesting the possibility of a return to cold after or over next weekend.

I suspect that as was suggested earlier it only needs a small amount of undercutting to get blocking to the NE and return of a continental flow. It is clear to see on both the UKMO 144 and the ECM 192 that small changes could induce this.

Presumably this is what happens on the large number of ECM cold ensembles

The GFS has started overblowing the Atlantic LPs so is less likley to happen

GFS has always had a tendency to do this in the past - I see no reason why this might also be happening now

should be an interesting pub run anyway!

Edited January 31, 2010 by andymusic

[MP-R]

can anyone here,,hand on heart,,actually remember feb 2004,,,,i can barely remember feb 2010,,,and it hasnt even happened yet......

That's probably why you can't remember it then . I'm just saying that there was a very abrupt change around from northerly cold on the 28th/29th Jan and by the 01st/02nd Feb it was unseasonably mild with temps of 14-15C. For that reason I remember it.

[swilliam]

welcome, I guess youve been enjoying the snow your way?

The easterly was being shown for a while and was for much of time supported by the signals. One model however the UKMO suggested the easterly would not occur, so actually although all the models have agreed recently, the UKMO model has had this latest idea for a while.

I think a lot of people are hoping it'll switch back again, personally I'm sceptical it will but I don't think anyone would be wise to write off an easterly in the future, it may happen in 2 weeks?

Can I just clarify that the UKMO never showed the Easterly because it only runs out to +144, the real easterly was never shown by any model at this range (at mostly on 8th Feb which the UKMO has still not yet reached). It was assumed that what was shown by the UKMO at +144 could not develop into any Easterly even several days later. Also if people recall the UKMO cahrts were showing Atlantic LP extending right out to Denmark having passed over us. This also does not now look likley at +120 or later with the LP stuck west of Scotland

So it was not particulalry good either

The UKMO is always going to seem more reliable because it only runs out to this timescale

[nick sussex]

Good to see from the De Bilt Dutch ensembles that a prologned mild spell is not supported. A majority of members go for cold in the long term

Unfortunately those ensembles are yesterdays, the new update is alot more average looking.

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

As an example of a way out of the likely milder interlude take a look at tonights JMA, just as an example as its generally cannon fodder! I think people have to accept that unless the trough in the Atlantic is shunted much further west or disrupts very quickly then there is likely to be a milder spell. Every output backs this trough and its an easier synoptic for them to model and because of this is likely to verify.

I really don't want to pour cold water over a return to cold but sometimes a pattern has to play itself out in that you can't get from A to D without going through B and C, there is a plausible way out of the expected milder interlude but it might take a little time.

Edited January 31, 2010 by nick sussex

[SP1986]

The easterly was shown before 144, at one point on the GFS though and the building blocks at one stage where as close as 96 hours.

[Southender]

Watch the pub run throw another curve ball now and bring back the cold scenario...

[swilliam]

Hi Kent:

Nope.

Nothing other than I've already posted earlier on this very thread in terms of the UKMO standpoint. Will it prove correct? Who knows. But that's for the future.

I would add that the GM (the raw basis for our medium-range BBC graphics) often sees modifications made each day on the basis of Arpege, GFS, etc., so it's hardly a myopic standpoint being adopted at Exeter's Ops Centre. I'm sure the other national models are often being adapted based on UKMO output, too. Good science, I'd suggest.

After all, the essential business at Exeter is (peer reviewed: please note this key point) science and - unlike religion - science of any discipline should always be open and willing to accept tweaks or even massive U-turns representing new collective thinking / conclusions.

We do not see much of the above from the UKMO re climate change!

[Lewis]

Watch the pub run throw another curve ball now and bring back the cold scenario...

Afraid that won't be happening mate.

I admire your courage.

[damianslaw]

The longer term trend as we head towards the middle of February is still saying cold to me. With this in mind any breakthrough of the atlantic will be a temporary affair, energy will quickly tansfer into the southern arm of the jet during early part of second week of Feb I feel and it will take just one bout of undercutting to occur to help usher in the blocking to the NE to make headway in our direction helped by heights building over Greenland.

Many seem dispondent with the prospects of a south westerly, believing once it sets in it will stay in situ, however, I say look at the upstream signals, the atlantic is still very weak, the longer term signals favour extensive blocking and as is traditional with February, the atlantic will wane.

Going back to the short term, Scotland and N England will stay fairly cold all week especially Scotland, and there is a chance of widespread snow later in Wednesday in these areas. The atlantic low if it does steamroller through as being progged I doubt will bring maxes of much above 10 degrees, and in northern parts it will probably obly be just above average.

So in summary - a fairly cold week for the north, average but becoming mild in the south later, end of the week mild and wet for all with south westerlies, next week, south westerlies replaced by southerlies and then south easterlies - undercutting situ and as we head towards middle of the month, cold for all heights advecting from the NE.

Edited January 31, 2010 by damianslaw

[swilliam]

The easterly was shown before 144, at one point on the GFS though and the building blocks at one stage where as close as 96 hours.

The early easterlies were just at the edge of the block and were generally just a continental drift - also it swapped between have this early start and not. The real easterly with v. cold air involved the major block moving from Siberia to Greenland. As for the building blocks (large HPto the NEast, -ve AO, Southerly tracking jet etc.) they were also shown by the UKMO and I discussed the difference between the models re this aspect yesterday). These blocks are in fact still present but the Atlantic trough has much more unfavourable alignment. Having building blocks does not guarantee anything

Unfortunately those ensembles are yesterdays, the new update is alot more average looking.

http://www.knmi.nl/e...M_06260_NWT.png

As an example of a way out of the likely milder interlude take a look at tonights JMA, just as an example as its generally cannon fodder! I think people have to accept that unless the trough in the Atlantic is shunted much further west or disrupts very quickly then there is likely to be a milder spell. Every output backs this trough and its an easier synoptic for them to model and because of this is likely to verify.

I really don't want to pour cold water over a return to cold but sometimes a pattern has to play itself out in that you can't get from A to D without going through B and C, there is a plausible way out of the expected milder interlude but it might take a little time.

Yes - pity about the ensembles - a definite shift upwards for the mean - could change the meto guidance for the medium term.

[Yeti]

As far as I can see the main problem is the new trend for a ridge to develop over Europe; GP hinted at this a while back but unfortunately, rather than low heights over Europe sucking in undercutting LPs we end up with the ridge deflecting them N at the worst moment. Of course the west based NAO actually helps to lock in the mild for a time as lows struggle to make much eastward progress but then on the other hand, as others have said, it only takes relatively small changes to move the pattern eastwards into a more favourable position for the UK.

Certainly though nobody can honestly deny that there is a trend for milder weather now on all of the major models, and the ECM ensembles have taken a dramatic turn for the worse. So this has to be the most favoured outcome IMO, however annoying that is!

Edited January 31, 2010 by Yeti

[bluearmy]

having proved futile yet again, i fear the news that the NAEFS fi showing a rex block to our northwest is going to put us through the mill for a third time. at this stage, the mean uppers below -5c take until aroud the 12th of the month to reach us from the northeast. the last two failed model cold incursions both had some delays as time ticked away so i would assume nearer the middle of feb wil be closer to the mark. expect the gfs ops to begin to show consistent decent fi's beyond the 10th feb and the ensembles will continue to trend cold in the longer term. wheher this will prove to be another fruitless roller coaster ride remains to be seen but at least we should have somehting to look at.

one thing i will be interested to see is whether low res gfs copes with this colder trend or just takes its cue from the type of pattern as at T180 and just runs with it. the 12z did go colder towards the dates in question so thats a decent sign.

ecm spots the trend

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

fasten those safety belts - again

Edited January 31, 2010 by bluearmy

[Ben_Cambs]

having proved futile yet again, i fear the news that the NAEFS fi showing a rex block to our northwest is going to put us through the mill for a third time. at this stage, the mean uppers below -5c take until aroud the 10th of the month to reach us from the northeast. the last two failed model cold incursions both had some delays as time ticked away so i would assume nearer the middle of feb wil be closer to the mark. expect the gfs ops to begin to show consistent decent fi's beyond the 10th feb and the ensembles will continue to trend cold in the longer term. wheher this will prove to be another fruitless roller coaster ride remains to be seen but at least we should have somehting to look at.

one thing i will be interested to see is whether low res gfs copes with this colder trend or just takes its cue from the type of pattern as at T180 and just runs with it. the 12z did go colder towards the dates in question so thats a decent sign.

ecm spots the trend

http://www.knmi.nl/e...agse/index.html

fasten those safety belts - again

Great post. Ive certainly started to notice it now. Hopefully GFS starts a new trend. Something to watch for IMO

[Lewis]

Everything further east on this run

Thats bad lol!

[West Sussex Kate]

Thats bad lol!

Oh well, we will just have to wait, im sure something exciting will come along sooner or later!!

Science is science but theres always a bit of magic/luck as well

Edited January 31, 2010 by Westsussex1

[Optimus Prime]

Ignore that it's not further east.

[Jason T]

well there it is folks 12z at 72 and the 18z at 72

[swfc]

Great post. Ive certainly started to notice it now. Hopefully GFS starts a new trend. Something to watch for IMO

Hmmm like the one which ran out of gas last night.?????

[Ben_Cambs]

The band of rain preceded by snow on Wednesday/Wednesday night a weaker affair than 12z

Edit: The most energy from the band in the north west as regards to the previous run when more energy was in the south west

Edited January 31, 2010 by Snowman0697

[The Eagle]

GFS 18z is not that far from an Easterly at 96hrs.

[MAF]

Everything further east on this run

meaning????

Thats bad lol!

meaning?????

i hate trying to read the model thread when it's like this. one-liners do nothing for the novice trying to grasp the complexities of the models. its no wonder you often see the odd post with the phrase "i don't post here often for fear of been dismissed"

all it takes is a little expanding to the one-line post and then perhaps a few more people would understand what is meant, and possibly join in the "model discussion"

after all, that is what this thread is about ... isn't it?????

Edited January 31, 2010 by MAF

[Matty M]

18z shows better heights than the 12z.

Better angle of low etc etc.

Perhaps start of trend.

Not looking beyond 96hrs myself.

Lots of uncertainties prior to that.

Tomorrow morning could surprise quite a few people IMO.

[cooling climate]

A lot more energy undercutting the block to the east on this run giving the high to

the east a lot more support and better orientation.

[LomondSnowstorm]

http://91.121.94.83/modeles/gfs/run/gfs-0-102.png?18

Undercutting? Could well be blown away later in the run by the energy from the atlantic like in the ECM but this shows that perhaps the blowtorch comments are a bit too impetuous.

[Higher Ground]

Watching that 108h chart come out just now was tantalising!

Back to lurking.......