Winter Model Discussion 12Z 22/1/13 onwards.

[mulzy]

Depends if you're only watching the ops in low res?

naefs looks good to me and the ecm day 10 mean anomolys show the atlantic may have a tough time just riding through in week 2.

And just for good measure

http://www.meteo24.f...html?eps=london

Not wall to wall countrywide snowcover (yet) but not a bad mean at two weeks out !

Decent ensembles - can't argue with that. I just want to caution members that we're still pretty far away from a "big freeze" scenario akin to what we had earlier this month. Members suggesting that it might take 2/3/4 attempts to get the Atlantic ridging in the correct place is all well and good but since we're well into the second half of winter, time is a luxury we don't have especially for lowland southern Britain.

[chris55]

Regardless of potential snowfall, this feature showing up for the end of the week could turn out to be a potent little winter storm. Moving down from the north west then winding up as it moves into the channel, with some cold air wrapping round from the east.

[Jason M]

now this is a ridge (from the ensembles)

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=240&code=20&mode=0&carte=0

Jason

Edited January 27, 2013 by Jason M

[Jason M]

In fairness, the ensembles are very good indeed by day 10.

Lets see if we can get anything decent the right side of 192 hours on an opp run though.

For the first time probably all winter there is a def signal for a GH this time.

Jason

[Mucka]

Certainly some nice looking FI charts among the ensembls including a Greenland high here.

[davehsug]

I'm not entirely sure how people envisage a high latitude block setting up other than through the northward ridging of a mid latitude high. The problem for me is entirely not with the Azores high, but rather the low heights to the northwest which is stopping it from retrogressing towards Greenland. The northward ridging of the Azores high fits nicely with the currently MJO state and also to an extent fits with the stratospheric vortex placement and both of these would suggest that there is a decent shot that at some point we'll get the amplification upstream needed to establish a proper high latitude block. In the meantime, a few Pm shots from the northwest is an entirely welcome development compared to some of the milder runs we were seeing just a few days ago.

Except LS that ridges northward are always bounded by the jet. They can force it northwards but can't exactly cross it & build further north. If the jet suddenly breaks or splits, they might make the jump across, but other than that it's a rare bird indeed.

[london-snow]

Some great looking ensembles this evening and more inline with how i expect the pattern to play out post day 10 so 6th feb onwards. I expect a trend onto the op runs in the next 2~3 days for a GH post a northerly shot around day 8.

All in all over the past few days there is a lot to be happy about. For starters the mild spell is not locked in and looks to be a blip before a return to average or below average temps with a return for frosty weather. Post this there is a real chance for the uk to be put back in the freezer.

[Panayiotis]

Ensembles as a WHOLE are great,starting from 228hrs we have the Azores ridging north and more important IMO are the lack of heights over Spain, as long as we keep this feature, cold will not be far away and certainly mild weather will be far far away! V.Interesting times ahead!

From 228hrs - 384hrs:

Edited January 28, 2013 by Panayiotis

[summer blizzard]

Good to see good run to run consistency between the 18z and 0z in the high resolution time-frame.

Looks like Feb 2nd could be a good snow opportunity for England.

[Great Plum]

It looks like the low pressure progged for the 2nd Feb is causing the models some headaches...

The GFS has it dumping a lot of rain to the south:

http://www.wetterzentrale.de/pics/Rtavn1201.png

ECM has it much further east:

http://www.wetterzentrale.de/pics/Recm1201.gif

whereas the UKMO doesn't have it at all!

http://www.wetterzentrale.de/pics/Rukm1201.gif

If we look at the gfs ensembles for London, note the temperature spike on the 2nd Feb - the op only has a couple of members for support and it is certainly a precipitation outlier!

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

[SMU]

Morning All-

Nowt much exciting in the runs today - a few transient features here & there with some wintryness but a far cry from anything sustained-

ECM at 240 still trying to get there but even that pattern doesnt look great in isolation.

Im giving it to the 1st & a couple of days later to see anything move forward in terms of cold - then calling time.

Fat lady & her dance team warming up backstage.

S

Edited January 28, 2013 by Steve Murr

[Long haul to mild]

If we look at the gfs ensembles for London, note the temperature spike on the 2nd Feb - the op only has a couple of members for support and it is certainly a precipitation outlier!

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

Very good agreement from the ensembles this morning. They agree on next weekend being cold, followed by a brief return to normal, then a definite cool down in 10 days time. Could this be the start of something more longer term in the way of cold?

[stratty]

Morning All-

Nowt much exciting in the runs today - a few transient features here & there with some wintryness but a far cry from anything sustained-

ECM at 240 still trying to get there but even that pattern doesnt look great in isolation.

Im giving it to the 1st & a couple of days later to see anything move forward in terms of cold - then calling time.

Fat lady & her dance team warming up backstage.

S

.....reverse psychology Steve again?!? Ensembles continue to improve on cold trend. To give a date and then say + a couple of days to call it time at the start of February is twaddle!

[That ECM]

Morning All-

Nowt much exciting in the runs today - a few transient features here & there with some wintryness but a far cry from anything sustained-

ECM at 240 still trying to get there but even that pattern doesnt look great in isolation.

Im giving it to the 1st & a couple of days later to see anything move forward in terms of cold - then calling time.

Fat lady & her dance team warming up backstage.

S

Morning. Latest ens for London have mean 850's at -5 around the 8th a 45% chance of snow a few days later upto 50%. Why do you find this of little interest. Not being funny, just trying to learn. I think it looks encouraging but you must be seeing it differently.

Thanks.

[mountain shadow]

Morning All-

Nowt much exciting in the runs today - a few transient features here & there with some wintryness but a far cry from anything sustained-

ECM at 240 still trying to get there but even that pattern doesnt look great in isolation.

Im giving it to the 1st & a couple of days later to see anything move forward in terms of cold - then calling time.

Fat lady & her dance team warming up backstage.

S

My thoughts exactly.

Energy continues to be modelled around Greenland and without a proper Greenland high we can forget any hope of widespread cold spell.

Still, with a few northerly topplers some may see snow, at least for an hour or two.

Edited January 28, 2013 by mountain shadow

[stratty]

My thoughts exactly.

Energy continues to be modelled around Greenland and without a proper Greenland high we can forget any hope of widespread cold spell.

Still, with a few northerly topplers some may see snow, at least for an hour or two.

....what have we just had for the last 2 weeks then?!?

[UV-RAY]

You can tell when the models are grim for cold when you see post showing cherry picked ensembles, nothings changed in the last few days the pattern is flat and low heights over Greenland. Same old, same old, for most of this winter.

[Long haul to mild]

I sometimes think this thread is a little TOO obsessed with Greenland Highs. Sure they are great for cold when they happen but we have just had a two week cold spell with loads of snow for lots of people without any meaningful heights there!!

Edited January 28, 2013 by Chalk Serpent

[BLAST FROM THE PAST]

Personally I think things are moving along nicely and there is promise within the charts. The ECM 00z T240 may not look quite as good as the 12z yesterday inasmuch a tad slower, but compare the 00z to yesterday's 00z as per JH suggestion then we have a massive improvement and a real step forward. Some downbeat posts this morning. Funny, there was lots of this in beginning of Jan too and that soon changed, it came as no surprise to me and a potent Feb cold spell won't either.

I think yet again too much is wanted/expected here too soon also too much emphasis on the GHP not building in the near timeframe and because of this the rest of winter is written off. We don't need and probably won't start with a GHP this time round either.

Re Steve M giving until Feb 1st re the models, I tend to agree inasmuch I would certainly expect some decent supportive model output by then eg more good for decent cold than not so as a very decent finale is anticipated.

BFTP

Edited January 28, 2013 by BLAST FROM THE PAST

[Guest bjaykent]

Striking difference in the prog of that low in the channel at 120/126 between GFS and UKMO, rather hoping GFS have overcooked it for the sake of the south of the country otherwise could be very stormy here!.

[Jason M]

Very surprised at SMs post this morning. ECM is better this morning but the GFS ensembles are even better than last nights in my view. Ignore the low res opp run unless supported by ensembles. Last nights 18z opp was in line with many of the 12z ensembles which was why I wasn't that keen last night as the 18z ran out. Massive improvement this morning though with some rogue sights of the GH.

Jason

[bluearmy]

Steve's 'wedgie' still looking the most favoured way of delivering sustained cold as the low heights west and north of greenland show little sign of giving way in the reliable. Tbh, the mean sceuro trough edging slowly across us as each shortwave passes nw/se probably solves all the problems anyway. Would pobably require only a small wedgie to our north!

[Weather-history]

You can tell when the models are grim for cold when you see post showing cherry picked ensembles, nothings changed in the last few days the pattern is flat and low heights over Greenland. Same old, same old, for most of this winter.

Or you can tell who the pessimists are.... The pattern is not exactly flat, there is some amplification by the Azores high, that is pretty evident. It's better than nowt.

[Methuselah]

I sometimes think this thread is a little TOO obsessed with Greenland Highs. Sure they are great for cold when they happen but we have just had a two week cold spell with loads of snow for lots of people without any meaningful heights there!!

Exactly CS!

[Jason M]

I really recommend people look through the ensembles this morning at days 7-10. This is one of those times where they are useful. It also helps to put ECM into context.

I think that if its coming its via a Scandinavia high, others think via GH.there are a good few runs in the ensembles that would keep both parties happy at the same time ;-)