Winter Model Discussion - The Hunt For Cold -18z 17/12/12

[Jonathan Lang]

OK one chart is from an analysis for 19th november 2010 and the other is from the current ECM at 48 hours.

Interesting amount of similarity between the two charts including the Russian high and we all know what that led to!!!

If this is the case then January may have a surprise in store!

[BLAST FROM THE PAST]

I cannot agree with the GFS, for me its off on one and is too far removed from the rest. Let's see what happens over next couple of days. Lovely surprise if right.

BFTP

[Snowman31]

One of the reasons that I said watch and wait on the strat thread is because I didn't expect to see an evolution like this so soon.

And I still find it too soon, because of the wavering of the strat warming forecasts - one would have reasonably expected to see a SSW at the end of FI in the strat. But we haven't yet (haven't looked at the GFS 12Z though). So I set a date of a possible SSW of around 10th Jan - but this date is a moveable feast or possibly none existant at all. So strat warming, yes, SSW perhaps.

Oh and to TEITS I thought that you meant a cold spell before Christmas over the whole UK but realise that you are talking more before Boxing day. I think before New Year is a possibility but wouldn't go anywhere as high as 50% before Boxing day ( even after the 12Z GFS run)

I will guess that two of the GFS ensembles will follow the 12Z GFS operational. Any more than five and I may just prick my ears up!

With an SSW around the 10th Jan, would we not have to wait till about Feb for it to affect the troposphere?

[Tim Bland]

Re the precip type charts, these are never very accurate. However with very cold surface temps sleet or freezing rain is possible with uppers around 0c. Fingers crossed the ECM comes onboard

[NorthNorfolkWeather]

View the differences between the T96 and the T120 Fax charts here. Currently they both point to the same time as the T120 isn't updated until later.

Huge differences in just 5 days

[mulzy]

There is some support (4-5 runs) for the 12z GFS operational amongst the GEFS. The saga continues...

My favourite ensemble (pert 14)

Pert 18 and 19 not too shabby either.

Edited December 18, 2012 by mulzy

[Panayiotis]

There is some support (4-5 runs) for the 12z GFS operational amongst the GEFS. The saga continues...

My favourite ensemble (pert 14)

It seems that this one likes cold runs, showed cold easterly yesterday for Christmas day!

[Panayiotis]

Great thing is, models don't show anything zonal, which is always good IMO! As long as they dont, it seems we will never be far away from cold!

[Isolated Frost]

GEFS goes with the Op flow for the most part-

-8c uppers into Scotland for Saturday, -6c uppers in for Friday morning.. it's very positive oop norf

[Buriedundersnow]

why is so many people on here today not wanting the GFS when in the past all we have heard is people going on about how its the GFS that picks up on trends before any of the other models

[SMU]

Afternoon All-

An interesting run by the GFS-- the maxima for the UK on xmas day is 1c with a strong SE flow- Not quite good enough for a snow event prior to that but you never know - we need a faster inflow of colder air from the east-

Is it anything to do with the stratosphere- not a chance- much the way the shortwave scuppered our chance of the easterly had nowt to do with the stratosphere then nor does a sub 552 height high pressure wedged to the NE either- its not a broad scale enough pattern-- especially in its tiny size at 60 N -

S

Edited December 18, 2012 by Steve Murr

[Buriedundersnow]

heres what can easily happen if the high pressure moves back west its hoping i know but lets see it keep coming west

[Ian Brown]

why is so many people on here today not wanting the GFS when in the past all we have heard is people going on about how its the GFS that picks up on trends before any of the other models

We need what subsequent runs bring but I would point out that after much uncertainty in the run-up to Xmas 2005, it was the GFS 12z run that nailed the easterly for December 27 at T120 before the event.

[picog]

With an SSW around the 10th Jan, would we not have to wait till about Feb for it to affect the troposphere?

Maybe its the effect of the warming we had early December at the 30-hPa level?

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html

[Ian Brown]

One of the reasons that I said watch and wait on the strat thread is because I didn't expect to see an evolution like this so soon.

And I still find it too soon, because of the wavering of the strat warming forecasts - one would have reasonably expected to see a SSW at the end of FI in the strat. But we haven't yet (haven't looked at the GFS 12Z though). So I set a date of a possible SSW of around 10th Jan - but this date is a moveable feast or possibly none existant at all. So strat warming, yes, SSW perhaps.

Oh and to TEITS I thought that you meant a cold spell before Christmas over the whole UK but realise that you are talking more before Boxing day. I think before New Year is a possibility but wouldn't go anywhere as high as 50% before Boxing day ( even after the 12Z GFS run)

I will guess that two of the GFS ensembles will follow the 12Z GFS operational. Any more than five and I may just prick my ears up!

Surely this sort of development can having nothing to do with the Strat ? It's a relatively minor shift in pressure patterns at mid-latitude ?

[Tim Bland]

GEFS goes with the Op flow for the most part-

-8c uppers into Scotland for Saturday, -6c uppers in for Friday morning.. it's very positive oop norf

Not so good after though http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=0&mode=0&carte=0

[SMU]

There is no link with the stratosphere you cannot micro manage a high pressure covering such a small locale & link it to the strat- especially when there is no polar blocking.

S

[Matty M]

There is no link with the stratosphere you cannot micro manage a high pressure covering such a small locale & link it to the strat- especially when there is no polar blocking.

S

You absolutely can't, the most concrete relationship you can probably derive from Stratospheric influence is +/- 5hPa surface anomalies or slight Geopotential Height anomalies in large regions.

Finer details are impossible to associate.

[nick sussex]

Not much support from the other models for the GFS mystery tour.

The real problem is that upstream phasing and brief amplification which forces the Azores high ne towards the UK, at the same time you're trying to get energy going se'wards.

This is really hard going and the GFS is really an outlier solution especially as the UKMO doesn't want to know, we wait to see the ECM, even if that by some miracle backs the GFS then I still wouldn't be celebrating until the UKMO comes on board.

Even if you take the GFS at face value it still needs to take the pattern further south and west to deliver something for the majority of the UK.

[snowking]

Surely this sort of development can having nothing to do with the Strat ? It's a relatively minor shift in pressure patterns at mid-latitude ?

Ian (and Steve too

It's related to the pressure patterns suggested by Cohen in one of his papers that is a precursor to a displacement stratospheric warming following a high SAI in October, resulting in a large Siberian HP....if you take a look through the analogues, easiest thing to do would be to take a look at GPs winter forecast, they would suggest stratospheric warming around mid January....you can then run this backwards to around 28 days prior using the patterns suggested by Cohen (can be found in recent strat discussions)

Does this mean the strat is responsible? Possibly not, but we can use the strat as part of the puzzle and run potential scenarios either side of such an event

SK

[Mark Bayley]

SK beat me to it, but to back up his post here is the diagrams from Cohen showing height anomalies before PV displacements and disruption (posted by WM)

[Ian Brown]

Not much support from the other models for the GFS mystery tour.

The real problem is that upstream phasing and brief amplification which forces the Azores high ne towards the UK, at the same time you're trying to get energy going se'wards.

This is really hard going and the GFS is really an outlier solution especially as the UKMO doesn't want to know, we wait to see the ECM, even if that by some miracle backs the GFS then I still wouldn't be celebrating until the UKMO comes on board.

Even if you take the GFS at face value it still needs to take the pattern further south and west to deliver something for the majority of the UK.

Yes, I think its an outsider at present and I wouldn't expect the ECM to back it tonight even if there is some Westward correction, very interesting model watching nonetheless and the 0z runs will tell us more.

[LomondSnowstorm]

Ian (and Steve too

It's related to the pressure patterns suggested by Cohen in one of his papers that is a precursor to a displacement stratospheric warming following a high SAI in October, resulting in a large Siberian HP....if you take a look through the analogues, easiest thing to do would be to take a look at GPs winter forecast, they would suggest stratospheric warming around mid January....you can then run this backwards to around 28 days prior using the patterns suggested by Cohen (can be found in recent strat discussions)

Does this mean the strat is responsible? Possibly not, but we can use the strat as part of the puzzle and run potential scenarios either side of such an event

SK

Yes, I think a lot of posters on here are confusing the linkage between the SSW and the synoptic patterns with the notion that the strat caused the pressure patterns. If anything I'd suggest that the forcing is arguably the other way round ie the pressure patterns hint at a later SSW.

[TEITS]

Oh and to TEITS I thought that you meant a cold spell before Christmas over the whole UK but realise that you are talking more before Boxing day. I think before New Year is a possibility but wouldn't go anywhere as high as 50% before Boxing day ( even after the 12Z GFS run)

After viewing the 12Z GFS im going to give up making predictions mate and just see what unfolds.

Crazy run to be honest and I certainly wasn't expecting to see that from the GFS. Im blaming the approach of Niburu and the aliens that live on this planet.

[Matty M]

Well @48hrs ECM compared to yesterdays output is much better, but still the GFS seems more favourable at T48hrs, but definitely ECM closer to the GFS.

After viewing the 12Z GFS im going to give up making predictions mate and just see what unfolds.

Crazy run to be honest and I certainly wasn't expecting to see that from the GFS. Im blaming the approach of Niburu and the aliens that live on this planet.

Shurre we only got 3 days left lad