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

[Mucka]

Ensembles

 

NW England

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=238&y=37

 

SE England

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=293&y=125

http://www.meteociel.fr/cartes_obs/gens_display.php?x=293&y=125&run=18&runpara=0&type=3&ext=1

[fergieweather]

They have already mentioned a possible late winter SSW in the contingency planners forecast - I'm presuming this would be from the high-top Glosea - maybe now indicated to happen sooner than expected?

That's the enigma I'm trying to get an answer for; i.e., has it (a) offered such a signal and (b) if so, offered indication of a rather rapid downwelling. But clearly I can't speculate either way. The model performed well with the SSW last winter, however. Edited December 29, 2013 by fergieweather

[Duane S.]

This would spice things up a bit. GEFS member 14's interpretation...

 

We are in there somewhere...

 

Assuming the UK is still there after that little system moves through, we would have this to follow...

 

Cherry picking at it's finest but there are some good un's in there this evening so why not.

 

 

 

[cooling climate]

Following on from my last post regarding the stratosphere the 18z has picked up where the

12z left off. As long as this is not a red herring you could not ask for warming in a better

place than to the north of the UK.

I would imagine the met offices strat model has already picked this up hence their 30 day

outlook earlier. Depending on the strength of the warming this could really turn out to be a

winter of two halves and winter weather lovers could still have a lot to look forward to in the

last third of January and on into February. Not counting brief cold snaps before then that

could bring a surprise or two.

The warming already showing up at the 20mb level by the end of the run.

[weather eater]

Nothing has changed my thoughts from this morning, zonal, wet breezy with some colder interludes and confidence in a change to a substantive colder spell is low, hopefully that will change tomorrow or at least sometime soon. So the Ens have produced some colder alternatives they usually do but it’s the nature of NW that if the operational’s are naff then roll out the better Ens, if the operational’s are good then forget the Ens even if all the members are naff, it’s nobody’s fault, not even the Romans most of us are coldies so we naturally try to find some. 

[SMU]

One for Tom SE20

 

Classic Kumchatka ridge = bitter for the UK 5-10 days later

 

http://www.meteociel.fr/modeles/archives/archives.php?day=17&month=12&hour=0&year=1984&map=4&mode=2

 

http://www.meteociel.fr/modeles/archives/archives.php?day=1&month=1&hour=0&year=1985&map=4&mode=2

 

note the atlantic ridge is required- but perhaps its the natural teleconnector as its symmetrical across the globe...

 

Possibly  the best -AO induced KC ridge ever

http://www.meteociel.fr/modeles/archives/archives.php?day=1&month=1&hour=0&year=1940&map=4&mode=2

 

S

Edited December 29, 2013 by Steve Murr

[Panayiotis]

I dont know if its been posted earlier in the thread but the mean from the ECM is great showing support for an Atlantic ridge @D10

And even more interesting is the PV which IS NOT over Greenland!

Edited December 29, 2013 by Panayiotis

[Frosty.]

A stormy Gfs 00z op run but with rather more snow and ice potential than we have seen so far this winter,  temperatures really struggling at times as arctic air occasionally makes inroads south and east, and a number of knife-edge rain / wet snow events are possible with the set up shown by the 00z as there is an increasing amount of trough disruption and the jet digs well south at times. It's a wild run, little in the way of respite from the vigorous depressions, severe gales / storm force winds and heavy rain with further flooding which have battered the uk for weeks and weeks now, the jet stream remains unusually powerful with no slow down in sight. but like I said, there is a new dimension to the stormy outlook with sharper cold incursions from the north west / north as time goes on, especially further north.

Edited December 29, 2013 by Frosty.

[TSNWK]

All 3 of the big runs this morning appear to have ramped up the lobes of vortex being sent towards us. Plenty of cold rain about and i can see nothing to suggest we are about to break out of this wet pattern for a while yet. Maybe some cooler phases during the low res on the GFS which might support some transitory wet snow in the north is the best I can offer this morning folks.

ECM is consistent with its run from last night at 168 by sending energy south into Europe, subsequent frames are a long way from cold but do appear to be better than last night with the aZores high playing less of a role and the troughing further south. 240 looks lightly interesting in that in might send another load of energy to the south east out to our west.

Edited December 29, 2013 by TSNWK

[bluearmy]

Having mused on yesterday's 12z extended ens and raised a possible march west of the Russian block, what does the next op ECM go and do? it's the back end of an op run so we shouldn't take too much notice but the fact that the ens anomolys were playing with it does mean it isn't without foundation.

If we are to see this trend growing, then the modelling could be about to get more flip floppier than its been recently - you didn't think that was possible but as I showed on Thursday evening, the ens anomolys were consistent and in decent agreement. If this blocking trend grows, then the ens could become a mess as well with two different themes present.

Had to laugh when I noticed on e gem NH day 10 chart that not only was it still showing a typhoon in the pacific, but it had found a TD in the west Atlantic - lets see that interact with the pv chunks floating around the Atlantic basin! (Won't happen)

[Frosty.]

The GEFS 00z mean shows the PFJ generally well to the south of the uk and therefore a run similar to P6 which shows a sharp wintry outbreak with reload potential is easily achievable from T+240 onwards.

[tinybill]

not good  news for the  UK  if this comes off Jan 6-7

[Frosty.]

The Ecm 00z would also eventually lead to a more pronounced wintry outbreak once the low pushes further east, lots of arctic air waiting in the wings. the upstream pattern looks wintry to me. In the meantime, short bursts of colder showery air mixed with average temps and occasional milder days but offset by the strength of the winds and the spells of heavy rain with hill snow in the north.

Edited December 29, 2013 by Frosty.

[bluearmy]

The Ecm 00z would also eventually lead to a more pronounced wintry outbreak once the low pushes further east, lots of arctic air waiting in the wings. the upstream pattern looks wintry to me. In the meantime, short bursts of colder showery air mixed with average temps and occasional milder days but offset by the strength of the winds and the spells of heavy rain with hill snow in the north.

the ' interior' track of the depression upstream the main cause of the larger ridge. At day 10 it's just another item to keep at the back of ones mind but no doubt our resident east coast system track man, nick s, will be on the case, should it become of greater interest in a few days time.

[NO LONGER POSTING]

not good  news for the  UK  if this comes off Jan 6-7

 

What a monster..

 

Hmmmmmm.. 

 

[Gibby]

Hi everyone. Here is today's look at the 12 midnight outputs from my perspective for today Sunday December 29th 2013.

 

All models show a ridge of High pressure crossing quickly East over the UK today followed by an active frontal system moving equally quickly East later today and tonight with rain and SW gales returning tonight. Tomorrow shows the front having cleared all but the far SE with a strong WSW flow and scattered showers but the rain may hang on for some while in the SE. On New Years Eve another set of troughs spill East off the Atlantic crossing the UK with further rain and strong winds for a time before New Years Day is ushered in on the back of a strong WSW wind and showers, some heavy and prolonged. Throughout this period all models suggest average temperatures offset by the wind.

 

GFS then takes us through the start of 2014 showing Low pressure after Low pressure crossing The Atlantic and the British Isles throughout the period bulldozed along by a very powerful Jet Stream over the Atlantic. This means incessant periods of wind and rain alternating with short drier and more showery weather when thing become a little colder at times. Winds are always very brisk and sometimes very strong with gales or severe gales at times. Even by the very last frames of the run the pattern remains the same with little evidence of any cessation to the prolonged, unsettled wet and windy spell.

 

UKMO closes it's output this morning at Day 6 with Low pressure well established up to the NW of the UK with a strong and unstable SW flow littered with troughs, each delivering their own version of wet and windy spells as they cross East in the flow. Temperatures look very close to average for all.

 

GEM today is much the same with little of any evidence to support any drier and colder weather lasting for any length of time before the next Low pressure returns wet and windy weather across all areas between the short drier and sometimes chillier interludes.

 

NAVGEM shows a strong Jet flow too propelling Low pressure after Low pressure across the North Atlantic with troughs swept quickly East and NE in the strong SW flow with rain and showers continuing for all areas out to the end of the run.

 

ECM also maintains a strong Jet stream rushing over the Atlantic spawning frequent development of Low pressures winding up to the North of the UK with strong winds and heavy rain carried East in the flow then followed by sunshine and showers with any ridge development flattened quickly by the strength of the overriding Jet flow. Temperatures will be largely close to average for early January.

 

The GFS Ensembles in general maintain their Atlantic driven status this morning throughout their run with spells of rain at times in average temperatures, Low pressure to the North and NW and strong winds at times.

 

The Jet Stream as already mentioned remains very strong and blowing due West to East across the Atlantic towards France and Southern England. It strengthens even further towards next weekend while maintaining a collision course with the UK. It then in the unreliable time limits show signs of weakening somewhat and drifting towards the North.

 

In Summary today the outlook remains one of frequent periods of wet and windy weather when local flooding events are likely to make News headlines as there seems little respite in this sustained period of Atlantic driven weather. Some of the rain will be heavy and prolonged with gale or severe gale force winds at times making for some very unpleasant conditions. Brief ridges are shown by all models to temporarily quieten the weather but none last much more than 24 hours before the next rain event driven by a very strong Jet Stream arrives. With regard to the way out of this period of wet and windy weather it is hard to find anything significant that could change the pattern from today's output but if there was a way it looks like it would most likely arise from a ridging North of the Azores High over the Atlantic hinted at by some of the output in their latter stages but for this to be accomplished we need to see a much weaker Jet Stream at the United States end to enable this process to take place and currently that looks unlikely within the next few weeks.

[weather eater]

I don’t think any amount of spinning is going to deflect away from the unfortunate fact that in reality we have little change this morning from yesterdays output and I have to say bluearmy I see little evidence of model flip-flopping, quite the opposite in fact, pretty consistent out to 144hrs and may be a little beyond, I think that’s as good as its gets the vast majority of the time and swings further out are pretty common place most of the time, although in this instance let’s hope it’s because a pattern change to a colder solution is coming.

[IDO]

The resurgence of the Azores High (MLB) has been clear on the GEFS in the last few days and this mornings GEFS has it as the main cluster, at 35% by the end of FI:

 

The Control for eg: 

 

Before that, the clusterings are pretty much 70:30 in favour of zonal, till around D12 when the pattern is pushed north and a pressure rise from the south becomes the alternative. There are brief interludes where a surface trough tries to establish but either the AH or another LP system kills that off.

 

From the GFS mean (FI) the main surface MLB is the Russian High; no real sign of a N.Pacific region ridge, and it figures more in the ens:

 

 

 

The mean Canadian PV is not a good sign, as it appears to have regrouped and edged towards Greenland, compared to T240: 

 

That could explain the zonal clusterings of the GEFS in FI. Only one run so not a trend yet. For instance the ECM D10 mean: 

 

A much stronger Canadian Vortex at D10. The GEM at D10 marries on a macro scale with the ECM mean: 

 

Maybe the best guide at the moment. As for a wintry spell, still well into FI, and more rain is the main theme for the next ten days. The next 8 days total rainfall:

 

 Up to 140mm on the western side.

 

[bluearmy]

Thinking back a while, gefs and gfs were keen to build a mid Atlantic ridge this coming week. ECM was never keen and only wanted something flatter and transient. result is we are unable to break out of the very mobile cycle of depressions coming sw/ne. We see this week the track becoming more w/e and the shove east at the end of the week of a chunk of Canadian vortex is almost crazy. By the 8th jan ECM really is keen on this mid Atlantic ridge, just se of Newfoundland. That will stop the depression train - for how long is unknown. Consequence will be us close to the downstream trough so no let up in the unsettled - infact, at least we currently get some respite between systems. If we get close to a cut off trough, might be even worse for a time!

[bluearmy]

I don’t think any amount of spinning is going to deflect away from the unfortunate fact that in reality we have little change this morning from yesterdays output and I have to say bluearmy I see little evidence of model flip-flopping, quite the opposite in fact, pretty consistent out to 144hrs and may be a little beyond, I think that’s as good as its gets the vast majority of the time and swings further out are pretty common place most of the time, although in this instance let’s hope it’s because a pattern change to a colder solution is coming.

ECM has been woeful post day 6/7 re consistency. That is not the norm for this model. Gfs low res - yes, it's not noted for its consistency, I'll grant you that.

I'm dreaming - that resurgence of the AH on the gefs has been coming for some runs. The general consequence to relax the progression of mean lower heights into s Europe but I'm not sure we can draw any conclusions yet. It maybe more to do with a wider picture of heights rising in and where this becomes centred will dictate the pattern that follows. It will be interesting to compare the gefs and ECM ens anomolys from a few days ago to now to see how much has changed.

[weather eater]

 If we get close to a cut off trough, might be even worse for a time!

What a cheerful thought, I wish I could say that sounds like negative spin but unfortunately I suspect it’s close to the mark. Re the ECM I would agree its more consistent than the GFS but swings are still pretty common post days 6/7 IMO.

Edited December 29, 2013 by weather eater

[kev238]

Nothing in my opinion has really changed since Xmas. Very wet , often windy weather within temperatures around average , leading to flooding.

Very little sign of a route out at the moment , the only crumb of comfort being the met office mentioning colder towards end of January .

The main news will surely be flooding, especially in larger slow responding rivers where cumulative rainfall will cause big problems . I don't think there will be anything as severe as last Monday but incessant passages of low pressure will cause increasing problems on rivers such as the Thames, Trent , Avon and Severn

[lassie23]

The jet continues to rule for now!

[ITSY]

Keep an eye on the strat temps over the next couple of days, will be interesting to see if GFS keeps the warming growing over the North Atlantic in low res. if it does then there's the chance of seeing some rather interesting surface Synoptics accompanying it

[Methuselah]

Heard Jo speaking on LBC earlier; the immediate outlook still looks mostly Atlantic-driven. But, just because neither computer models nor forecasters have pinpointed any major imminent pattern-change, doesn't mean that a change'll not happen anyway - four weeks is a long time?