Model Output Discussion 1200 hrs 15/11/14

[swfc]

And there it is, just as mogreps suggests. Easterly incoming at day 12 and GFS P looking like heading that way too.

GFS doesn't hold on to the high in FI, that means nothing though.

Indeed it does but the 850s are slightly milder than what we have now tho?still synoptics better granted

Edited November 19, 2014 by swfc

[nick sussex]

Certainly a few signs that things might improve for coldies. still a long way into the future though but with a trough set up running nw/se you can get some WAA running nw ahead of the trough to build pressure rises to the ne.

 

Some luck is needed though upstream to stop the PV from constantly feeding energy into the trough.

[Cheshire Freeze]

So....we've taken a potential step forward tonight with perhaps the MOGREPS trailing the start of the anticipated potential December cold spell. I think perhaps the signal may be slightly too progressive. The landing zone perhaps between 7th-10th of December? Previous posts of mine (and others e.g Tamara) have explained why this was likely so won't go into it again! However, we'll have to see if this can manifest as a trend.

[knocker]

The Anomalies although not in complete agreement are all on the same page with the trough far enough west so the UK still under the influece of Atlantic transport.

 

[Jason M]

When charts like this appear at day 6 and 7 amongst the ensembles there is always going to be some interest.

For balance, plenty of other options on the table but this saga has a way to run....

http://www.meteociel.fr/modeles/gefs_cartes.php?code=1&ech=144&mode=0&carte=0

Jason

Edit - out to 180 and very little agreement in the 18z suite tbh.

Edited November 19, 2014 by Jason M

[ItNeverSnowsInWindsor]

Until we stop seeing low heights eroding the west Greenland coast, we'll keep getting the jet stream destroying things for us in the UK. Sorry but that's the way I see things right now.

Edited November 19, 2014 by prolongedSnowLover

[fergieweather]

So....we've taken a potential step forward tonight with perhaps the MOGREPS trailing the start of the anticipated potential December cold spell. I think perhaps the signal may be slightly too progressive. The landing zone perhaps between 7th-10th of December? Previous posts of mine (and others e.g Tamara) have explained why this was likely so won't go into it again! However, we'll have to see if this can manifest as a trend.

Caution re this interpretation being banded-around re MOGREPS, which has caused some bemusement having now discussed with UKMO colleagues: there's no such *definitive* cold signal as being described. Yes, a longwave upper pattern evident into December on latest MOGREPS-15 but crucially, Exeter point-out this may lead equally to something colder (via a fairly seasonable pattern but nought unusual for early December) or (and this needs emphasis) could leave door open for the Atlantic. So, some misinterpretation perhaps creeping-in but I've heard nothing this evening to warrant MOGREPS being described as offering a de facto, unusually cold signal. Hope this clarifies.

Edited November 19, 2014 by fergieweather

[Jason M]

Thanks Ian

Makes sense really as although we don't have access to everything, if there was a 'strong signal' logically we could expect some sort of hint to show across GEM, GFS, ECM suites (even if we assume they are inferior to MOGREPS). Looking at the GFS ensemble suite rolling out now its a complete mess by day 7.

[A.J]

Caution re this interpretation being banded-around re MOGREPS, which has caused some bemusement having now discussed with UKMO colleagues: there's no such *definitive* cold signal as being described. Yes, a longwave pattern evident into December on latest MOGREPS-15 but crucially, Exeter point-out this may lead equally to something colder (via a fairly seasonable pattern but nought unusual for early December) or (and this needs emphasis) could leave door open for the Atlantic. So, some misinterpretation perhaps creeping-in but I've heard nothing this evening to warrant MOGREPS being described as offering a de facto, unusually cold signal. Hope this clarifies.

Thanks for being the voice of sanity amongst the cold-seeking insanity that prevails the thread (nothing wrong with being cold-seeking mind you!)

Chinese Whisper syndrome has certainly been rife in here tonight with regards to the MOGREPS output, and a touch of realism is sometimes badly needed here 

[TEITS]

I hate to say it but I see very little to suggest a cold spell is anywhere near close to arriving in the UK. The stalemate between the High pressure and the Atlantic looks as though will be won by the Atlantic towards the end of the month into the beginning of Dec. We might see LP taking a SE track but we need to see the low heights to our NW back W before any blocking to our NE can become influencial.

 

Iceland SLP mean sums this up.

 

https://max.nwstatic.co.uk/ensimages/ens.20141119/12/prmslReyjavic.png

 

So the outlook towards end of November into first week of Dec could potentially be stormy for S areas in particular and any snowfall is only likely on the higher ground of Scotland. Looking at the overall pattern im more concerned with potential severe gales in the SW of England rather than any cold spell! In the potential pattern coming up you often find LP systems deepen very quickly and significantly at the base of the trough.

[knocker]

Nifty chart from the P that tends to go along with the anomalies.

 

[Cheshire Freeze]

Thanks for being the voice of sanity amongst the cold-seeking insanity that prevails the thread (nothing wrong with being cold-seeking mind you!)

Chinese Whisper syndrome has certainly been rife in here tonight with regards to the MOGREPS output, and a touch of realism is sometimes badly needed here 

Oh absolutely and I doubt I'd have even raised an eyebrow if it didn't fit in with expectations as we enter December. However, given the excellent analysis over the past week by some seasoned pros on here, suggestive of wave 1 led tropospheric feedback- I think today's MOGREPS signal (however stunted at present) should be noted.

[fergieweather]

Thanks IanMakes sense really as although we don't have access to everything, if there was a 'strong signal' logically we could expect some sort of hint to show across GEM, GFS, ECM suites (even if we assume they are inferior to MOGREPS). Looking at the GFS ensemble suite rolling out now its a complete mess by day 7.

Yup, ditto EC-30 looking standard seasonal fare but frankly anything beyond D5-7 isn't worth pondering too hard over for us folk concerned with operational/public forecast, unless there's a major identified driver looming into the M-R view like that SSW before cold spring of 2013.

[A.J]

Oh absolutely and I doubt I'd have even raised an eyebrow if it didn't fit in with expectations as we enter December. However, given the excellent analysis over the past week by some seasoned pros on here, suggestive of wave 1 led tropospheric feedback- I think today's MOGREPS signal (however stunted at present) should be noted.

oh definitely agree there CC, any potential signal should be noted, and the fact that there's a large spread on the GEFS members infers no straight foward forecasting trend

[Nouska]

The CFS four weekly Z500 outlook - they are also seeing the trend to a Scadinavian high pressure as the follow-on from the digging trough.

 

 

[essexweather]

That 'company' are to be taken with a pinch of salt, as they've been in trouble in the past.

 

As a director of 'that company' I would be interested in some actual evidence that we have been 'in trouble' of some kind as I have no knowledge of this - perhaps you could message me of this, thank you :-)

 

Back on topic, the snippet that was posted here from our twitter account stated we *may* end up with cold digging in. There was no mention of anything unusually cold or severe. Yesterdays run only took us to the 3rd of December. What happens beyond that point is of interest as there are hints of a strong North-Westerly or North-Easterly starting to develop which would bring in air cold enough for wintry showers across the Northern half of the UK.

 

I know last winter was a bitter pill to swallow for many, but we are in a hell of a better position then we were at this point last November and it's starting to become clear that a pattern change will play out in early December.

 

I think this sums up things pretty well:

 

Edited November 20, 2014 by essexweather

[Cheshire Freeze]

And just like that, GFS and GFS P showing sinking trough scenario in FI with the high trying to push west

 

 

This looks quite Jan 2013ish

 

Edited November 20, 2014 by CreweCold

[shaky]

Well the scandi high continues to gather momentum!! Ecm backs that scandi high much further west compared to yesterdayd 00z run!! Ukmo does not look to bad aswell!!

[Captain Shortwave]

Well the Euros really want to keep the Euro/Scandi block in place

Not too bad, the high to our east/north east is holding its own and again  developing its own cold pool. Still nothing for the UK mind you with winds generally from a southerly quadrant. 

Edited November 20, 2014 by Captain shortwave

[Duane S.]

No new direction carved out on the 00z suite, subtle hints more than baby steps at the moment. Decent amplification upstream and suddenly we could be looking at very different looking charts.

It all has a winter 12/13 (I think it was that year) about it, slow build up, backing west, waiting for that final trigger low/slider to dart down to our sw and drop heights over Europe with a favourable shot of WAA setting up a more robust block somewhere to our north.

It does mean we may all get pretty wet in the lead up, should that occur!

Edit; Just seen Crewe has already posted the same above ref winter 12/13 :-)

Edited November 20, 2014 by s4lancia

[Polar Maritime]

The GFSP this morning continues to show a very unsettled/stormy period coming up for the end of the Month, As the Low drops S/E on a Pm flow and anchors itself over the UK, In turn getting cut-off drawing a slack Easterly as i mused the other day. Further into the run shows a return of Pm air, As another Low pulls in from the N/W.

 

The ECMWF shows very similar to this, Only with the block holding on much stronger to our East, Dropping the Low from the N/W much sooner than the GFSP.  

 

Edited November 20, 2014 by Polar Maritime

[knocker]

Indeed PM.

 

[bluearmy]

starting to think that the polar profile entering December may not so different to that for beg November. (With a few seasonal adjustments).

'slowly, slowly catchy monkey ' - surely only a matter of time until something breaks from the east/northeast

Edited November 20, 2014 by bluearmy

[TEITS]

I agree a shift this morning towards the HP to our NE this morning rather than the Atlantic winning the battle. However the low heights to our NW over Greenland/Iceland are a concern if you're seeking a cold, wintry spell. This is because this could prevent the blocking HP to extend further. Also if the blocking could back W then we would then see much colder air before advected S on the right flank of the HP which may then advect W across Europe.

 

The UK can experience a bitterly cold E,ly when the PV is towards Greenland but we always need this to be just W of Greenland. Otherwise the E,ly train stops further E and does not arrive in the UK.

[Blessed Weather]

There's a big difference between the GFS P and ECM at Day10. GFS P has a sub-975mb low sat in France, the Azores ridge cutting off further feeds from a weak PV lobe on the Canadian side and the main PV clearly on the Siberian side. Indeed the Azores ridge and Scandi high looking like having a possible handshake.

Meanwhile the ECM fills the euro low and has a much stronger looking Canadian PV lobe continuing to feed the UK trough.

 

Very very different at Day10 and either or neither could happen with continued chops & changes the only certainty!

 

GFS P 30th Nov ECM 30th Nov