Model Output Discussion 17th Dec.2013-12z onwards.

[Gaz1985]

Yep, anything below the average in January should give us hope.

 

Yes that is true take Winter 08-09 which seen temps slightly below average and widespread snows.

[shaky]

Nothing of note on the 12zs yet folks??

[bradymk]

Nothing of note on the 12zs yet folks??

bit early yet for the timeframe people are concentrating on although GFS 12z shows better heights to our N at 144 between Iceland and greenland and a stronger arctic high.  Just catching up on GEFS, ECM ENS, somewhere around our latitude could get a very decent cold spell going into mid jan but whether that includes our little island, who knows. Some stunning GEFS 6z members and EC Ens consistent with the trough over Euro

Edited December 26, 2013 by bradythemole

[SMU]

Indeed there does seem to be a disconnect on here between cold and "cold"... 

 

I suppose it's because a lot of people looking at the models here are looking for snow and/or extreme cold.  Thus, the netweather definition of cold tends to be "cold enough to snow"...If it isn't cold enough to snow but surface conditions are around 2C, well, it's cold but not "cold"! 

 

Afternoon All-

 

There seems a lot of confident posts today around the continuation of mild weather out to mid Jan, all this based seemingly on Susan Powells comments & one or 2 other notions-

 

At this stage- Boxing day, that's an awful lot of faith to put on a forecast which is essentially the ensemble mean of the ECM DET32. Interestingly though whilst its not really been mentioned the ECM has been trending colder in the mid term (10-15 days) but not necessarily indicating a long cold spell ( of note is the ECM control which has seemingly been the leader of cold for the past 2 days & again today)

 

Consider the debilt T2M temps from the 00z

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=00

 

note 4 ice days 11-15.

 

Is anything really concrete at this stage past day 10? No, not a chance & that goes for a cold signal or indeed a continuation of mild- 

 

From the met office perspective though they will always play the odds & go with what info is being shown at that point in time where they have to issue a forecast. Then if that changes you will note subtle changes evolving within the updates ( particularly the 2 weekly ones)

 

So whats is actually happening-

 

We are finally getting some modest heights being predicted to get into Northern Scandi across to Eastern Greenland. - They are modest heights-

You can see them on todays 12z GFS 156

http://modeles.meteociel.fr/modeles/gfs/runs/2013122612/gfsnh-0-156.png?12

 

As can be seen, heights circa 532 DAM -  not exactly BIG anomalies- 

 

However this is the big positive, NOT a negative- because these anomalies are of a modest representation the signal will most certainly get muted out by the longer range runs- especially if they struggle to pick them up at day 6/7 in the first place.

 

Fortunately where this small anomaly sits is about as good as it could be for potenatially effecting the UK at day 10. WHY?

 

This small rise in pressure over East Greenland will steer the jet along a more southerly trajectory, but more importantly hold strong resistance up again any Canadian lows / vortex that are pushing into it.

 

As a result if the blocking is strong enough you get trough disruption & the jet becomes backed up & amplifies west & east of Greenland- surging NE up the west side, then recurving SE towards France-

 

This is the reason we are seeing low pressures slide across the UK & the atlantic ridge building NE -  The ridge is important because it can then link into the positive height anomaly over Greenland to reinforce it.

 

As it stands I think its 50/50 for cold for the UK past day 9, no bias either way. It all boils down to the ridge & having enough vertical component to reach the heights over Greenland.

 

 

 

 

As for the comment above about cold- I agree its funny, I bet in nearly ALL coldies minds if its NOT snow cold then its not cold- no matter how cold at the surface may be at the time.

I have changed my attitude towards this 'faux' cold these days- I like it, especially if it serves to prepare the upper soil temps for possible future snow events.

 

Eyes down for the 12 zeds- expecting the trend for cold weather to accelerate over the next 24 hours.

 

S

 

[shaky]

bit early yet for the timeframe people are concentrating on although GFS 12z shows better heights to our N at 144 between Iceland and greenland and a stronger arctic high.  Just checking GEFS, ECM ENS, somewhere around our latitude could get a very decent cold spell going into mid jan whether that includes our little island, who knows. Some stunning GEFS 6z members.

yup just took a look and the 22z is better low low pressure going further south and pressure stronger and higher across greenland!!

[stratty]

 

Eyes down for the 12 zeds- expecting the trend for cold weather to accelerate over the next 24 hours.

 

S 

...............sooner or later you gotta be right this winter Steve,,,,,,,,,,,,,let's hope it is sooner!  

ps

Temp not risen above 4C........perfect for a lovely walk this afternoon! So to me, that is cold already!

[SMU]

 

 

Eyes down for the 12 zeds- expecting the trend for cold weather to accelerate over the next 24 hours.

 

S

 

...............sooner or later you gotta be right this winter Steve,,,,,,,,,,,,,let's hope it is sooner!

ps

Temp not risen above 4C........perfect for a lovely walk this afternoon! So to me, that is cold already!

 

 

How can 50/50 be wrong .....

Also sooner or later- Winter is only 3 weeks old -

Edited December 26, 2013 by Steve Murr

[Mucka]

Poor GFS op in FI if that sort of thing worries you but an interesting UKMO in the more reliable.

 

[shedhead]

w

[A.J]

w

the most constructive post you've made all winter SH! 

 

just kidding, Merry Xmas! 

[shedhead]

Few would probably argue it was one of my most constructive AJ....  Well here we are post Xmas and entering the last knockings of Dec and there is still no sign of a colder pattern emerging, with max temps remaining near or a little above average for the bulk of the UK well into January. Given the generally unsettled pattern widespread overnight frosts will also remain conspicuous by their absence, ensuring mean temps probably end up on the mild side if anything, with any 'promising' charts like this remaining deep in FI....pretty much where they have been since Dec 1st.

 

Edited December 26, 2013 by shedhead

[IDO]

Forget the GFS op, poor for wintriness. Though it does maintain the Arctic High, and thats a positive. The Control is what BA, Mucka & others have been suggesting:

 

 

Good support at the same time from the ensembles:

 

  

 

   

 

 

 

So after a wobble from the GFS, a surface and upper trough back ahead of the pack for FI.

Edited December 26, 2013 by i'm dreaming of...

[bluearmy]

there is still no sign of a colder pattern emerging, with max temps remaining near or a little above average for the bulk of the UK well into January.  

 

 

 

charts please shed ?  both your statements are incorrect.

[shaky]

GGod ecmwf at t120!!heights building to our east north east!!

[SMU]

http://www.meteociel.fr/modeles/ecmwf/runs/2013122612/ECH1-168.GIF?26-0

 

1040 Scandi Block with a core @ 556 Heights.-

 

 

Wheres everything going at 192!!! jet aligned SE

 

S

[TSNWK]

ECM 168 not sure if cold at the surface I think so with the scandi high and us in a south Easterly drift, vortex looks poised to flattern things out though.

[shotski]

GGod ecmwf at t120!!heights building to our east north east!!

Well looking at the t168 chart all I can say is all hale Corinthian.

I'm not sure what models he's using in Austria but he seems to be onto

something  

[TSNWK]

How can you view the jet on the ECM please

http://www.meteociel.fr/modeles/ecmwf/runs/2013122612/ECH1-168.GIF?26-0

 

1040 Scandi Block with a core @ 556 Heights.-

 

 

Wheres everything going at 192!!! jet aligned SE

 

How can you view the jet on ECM please

[shaky]

Well looking at the t168 chart all I can say is all hale Corinthian.

I'm not sure what models he's using in Austria but he seems to be onto

something  

I did say at it looked very good at t120 hours and it looks to have gotten better from there!

[shaky]

Brilliant ecm tonight it really is!!hopefully we can build on it on tomorrows 00z!!

[nick sussex]

So close on the ECM to a big pattern change, we need the pattern further west though. This type of output is exactly why the UKMO were on shaky ground with their outlook. With trough disruption it's always difficult for the models to get this right at the later timeframes.

 

We might be unlucky with the PV refusing to relent for enough time to allow the ridge further west but overall this looks like turning into a nerve shredder for coldies!

[Tim Bland]

Nice to see a big scandi / Russian high, don't we need lower heights over Spain or the med to benefit from it though? Could just be a stalemate before the PV returns to its default position. Either way it's very different to the 00z so can't have much faith at the moment

[Grimsby Snow Lover]

Not the worse chart I have seen from the ECM. We are not far from an easterly here with quite a strong Scandi high that could prove difficult to shift.

http://www.wetterzentrale.de/pics/Recm2161.gif

[nick sussex]

Nice to see a big scandi / Russian high, don't we need lower heights over Spain or the med to benefit from it though? Could just be a stalemate before the PV returns to its default position. Either way it's very different to the 00z so can't have much faith at the moment

For the last few days the 12hrs of both the ECM and UKMO have been more amplified than their 00hrs runs. Let's think positively the 12hrs on Boxing Day would have more airplane data than Xmas Day!

 

Even with some sort of stalemate there could be some snow along the boundary, I think we need to hope for some westwards corrections and stronger ridging into eastern Greenland earlier.

 

Even putting aside the recent ECM FI bias both it and the UKMO have potential at T144hrs.

Edited December 26, 2013 by nick sussex

[cooling climate]

ECM and UKMO virtually identical at t144 with the ECM trying to get

into the festive spirit in its extended output and practically

succeeding. Definitely think the northeast is the direction to look

for cold. A little more amplifcation and westward movement and we

could very well be looking at some noteworthy cold and wintry weather.

Will future runs move the pattern more in our favour or not is the

question. Fingers crossed.