Model Output Discussion: 12Z (02/12/12) And On...

[phil nw.]

Significantly the 00z mean outputs continue to show troughing around Scandinavia which holds off any link up of Atlantic and Russian heights.

It looks more likely that the Atlantic ridging will be the dominant block going into week 2 with those disturbances being ejected south east in the cold north westerly flow.

If the ridge sharpens then this could introduce bursts of much colder Arctic air from the north at times as those lows travel down the N.sea into Europe enhancing the possibility of snowfall.especially further north and east nearest to the coldest air..

The Warks ens graph show the 850hPa mean running again between -3 and -5C through the period.

which gives low single figure max`s most days and night frosts when the clearances occur.

Overall the weakness in the vortex is still very apparent but the latest models still show enough of it hanging around our side of the pole to hold back extensive blocking right across to our north.

Having said that we are already in a fairly cold block which could easily intensify in time.

[stainesbloke]

Ithink you will find that anything more than a week away on the models will come the time be almost deff not in line with the original forecast.You will here folk forecast severe weather based on the strat,nao,no,mjo ete ete.The truth is if you stick around the 120-144 hour mark it will be close but that said the fax charts are at the moment swinging and changing!!!.Living on an island at our latitude makes the weather interesting but very difficult to forecast lol

Definitely! Cold and snow are always really difficult to forecast in the UK. I've been enjoying the model output over the last few weeks, it's good to be getting a normal early winter rather than just raging south westerlies I reckon the next few weeks will be interesting for sure, I just hope the chances of proper cold are not continually shunted into FI.

[Isolated Frost]

• Olympic sailors
  
• International sailing competition support both for competitors and fans
  (Transat, Ostar, British Olympic Sailing teams, Gypsy Moth IV etc)
  
• F1 racing teams (Midland F1)
  
• World rally teams (BP-FORD World Rally Team)
  
• Electricity grids
  
• Wind farms
  
• Nuclear Power plants
  
• Offshore research facilities
  
• European Space Agency Midas project
  
• Building Industry
  
• Pilots
  
• Rescue and Lifeboat organisations
  
• Ferry companies
  
• Fishermen
  
• Paragliders
  
• Windsurfers
  

Found this new 'precision' model that caters for these above ^, so I guessed it wouldn't be that bad?

Fairly unstable N flow at 06z Wednesday, sub zero temps across much of northern england and scotland- plenty of snow shrs to be had, especially on eastern and northern coasts

[Gibby]

Hi Folks. Sorry for the lateness. It's my busiest time of year currently work wise and I have to fit this in during a quieter moment but as I mentioned before you can always see this report on my website from 8am and 7pm daily. Anyway OT here's today's effort.

Good morning. A new week and a look at the first set of 00zs from GFS, UKMO, GEM and ECM for Monday December 3rd 2012.

All models follow a similar route up to 120hrs. with a cold front clearing East currently with a milder west to NW flow over the UK today. This steadily becomes colder as winds turn more Northerly midweek as Low pressure moves SE down the North Sea. Showers would turn more wintry with time even on the hills of the South by Wednesday though they would become more confined to the East later. A ridge passing East on Wednesday is followed by another Low moving SE from Iceland over the UK and exiting Eastern England on Friday. A spell of rain and snow would move SE through Thursday and into Friday followed by cold Northerly winds once more and snow showers to end the working week. From then on the models beegin to diversify.

GFS shows yet another Low pressure following a similar route to its predecessor on Saturday and Sunday with further rain and snow followed by snow showers crossing SE though Saturday and Sunday before High presssure builds to the NW tilting winds NE over the Southeastern half of Britain by the start of the second week. Northwestern areas would become cold and dry with harsh overnight frosts while the SE would stay cold and breezy with the threat of snow showers. In FI this morning the trend is for High pressure centred to the NW of Britain to be the dominant player. It's location is a little close in to Britain on this run to deliver the harhest cold but nevertheless there would be plenty of cold and bright weather with the threat of wintry showers in the East and SE. Frosts would be widespread by night.

The GFS Ensembles show fairly consistent pattern for cold or rather cold conditions today. The operational was a cold outlier for a while in the South in Week 2 though there is plenty of support for below average uppers with just a handful of warmer options in the usual large spread by the end of the run. Further North the operational was conversely a milder option through Week 2 with more precipitation shown here than further South. The likelihood of some of the precipitation shown to be of snow though North or South is quite high.

The Jet Stream currently west to East over the UK tilts SE over the Uk and down to the Med in the coming days with just small variations day to day on this general trend for the next week or so though there is a strong ridging North of the flow over the Atlantic later.

UKMO for midnight on Sunday shows a High pressure area over the UK with light winds for all with frost and patchy overnight fog followed by a dry and bright if cold day next Sunday.

GEM for the same time point looks weakly similar moving forward to bring low pressure in from the West with rain and somewhat milder conditions early the following week ending with Low pressure to the West and strengthening High pressue to the East with a Southerly flow over the UK. The weather would become largely dry with temperatures close to normal in a cool breeze.

ECM for next Sunday shows a ridge having crossed on Saturday leading us into a SW flow on Sunday with rain reaching the NW with some hill snow in places their. This transfers SE by Monday with cold North winds returning with wintry showers to start the new week. A ridge of High pressure stretching down from Iceland late in the run ensures a very cold spell develops as winds turn towards the NE with the prospect of some wintry showers near the East coast and the chance of more general sleet and snow in the SW with time. Frosts would become sharp and widespread by the end of the run.

In Summary things still look like turning cold with time. To gain the ideal synoptics it looks like we are going to have to be patient with some rather changeable and often chilly conditions over the next week. By Week 2 there are some positive vibes from the models that with pressure High to the North an Easterly or NE flow seems likely with attendant cold and frosty conditions developing and thechance of at least a little snow for some seems very possible today.

[swfc]

Looking threw the current set up it does appear that troughing will not drop sse enough for the blocking to connect and bring a direct run of easterlys.Everything seems to be modified and mixed out at the moment.Maybe a bit of luck is needed to get the pressure pushed just that bit further north i guess but the pv seems to able to but another hoop to jump threw at every opp!!!!

[TEITS]

ECM ensembles remain very cold even into the long range.

http://www.knmi.nl/e...E_06260_NWT.png

Have to say if any coldies have anything negative to say about the output then to be honest you're living in the wrong country. Historically speaking what we are seeing from the model output is actually quiet unusual for Dec and normally reserved for later in Jan, especially Feb.

I shall also add the ECM mean at +192.

You really cannot ask for anything better than that.

Edited December 3, 2012 by THE EYE IN THE SKY

[East_England_Stormchaser91]

All we need to do is get rid of them pesky shortwaves around near norway. Then bang, there's the link up! If we get that, then we can really get ready to rumble!

[Weathizard]

Very consistent within a reliable timeframe again from the GFS, I criticised it a lot for its inconsistenty so I think its only right I be fair and say it seems to be doing very well at the moment, consistency wise.

Surely a genuine Scandi or Greenland high coming from this at 192(again) ridge being squeezed both sides

Edited December 3, 2012 by Weathizard

[Nick F]

Thursday/Friday's low needs keeping an eye on, it deepens as it passes NE Scotland and continues SE across the N Sea. 06z GFS showing 50-60 mph gusts across northern and central Britain and coupled with cold air wrapping into the circulation from the N and NE - could be some atrocious conditions over the hills of N and NE Britain.

Another deep low follows from the NW over the weekend and follows a similar track on Sunday bringing a risk of gales and blizzards over higher ground of the north.

Then behind the weekend's low, some differences over the amplification in the PFJ upstream over the Atlantic - 06z GFS has sufficient amplification still for a decent Atlantic ridge towards Iceland, the Euros, however, more progressive with that trough moving east from new Foundland - so we don't get the same height rise needed.

However, there is still the underlying signal for blocking to the N and NE, it's just what route do we take to get there. The easy route or the painful route?

Edited December 3, 2012 by Nick F

[TEITS]

Very consistent within a reliable timeframe again from the GFS, I criticised it a lot for its inconsistenty so I think its only right I be fair and say it seems to be doing very well at the moment, consistency wise.

Just about to say that. The difference between the 0Z/06Z is so tiny its incredible and infact you wouldn't get such consistency even in a more predictable zonal pattern.

My only critical comment is the HP at +180 which is located NW of Scotland, I would prefer this further NW to be centred over Iceland.

[Weathizard]

I know I shouldn't get pulled in... But look at the beast coming at 252 and the uppers

[SMU]

Excellent outputs today-

ECM great, UKMO great- would just need a 168 chart- now the GFS on the right track-

ECM ensembles showing some BIG cold reaching the west of europe day 8 onwards with some -15s in there- I think our outcome post day 8-9 is either very cold - 2-4 maxima or bitter cold if we get the right allignment of the winds to the East-

I keep watching that bowling ball of cold -28c air wishing it would roll this way!

S

[weather_it_will]

Next Moday still possible for a marginal snow event for the SE, which was also shown on last nights 18Z.

http://modeles.meteociel.fr/modeles/gfs/runs/2012120306/gfs-0-180.png?6

After then, anything could happen, or even before then, as nothing looks rock solid beyond 7-days in any of the models.

What we can be certain of is that the outlook is staying cold with odd milder blip as the patterns change.

[weather eater]

Just about to say that. The difference between the 0Z/06Z is so tiny its incredible and infact you wouldn't get such consistency even in a more predictable zonal pattern.

My only critical comment is the HP at +180 which is located NW of Scotland, I would prefer this further NW to be centred over Iceland.

Yes I’ve been saying it for the last two days that’s now eleven runs in a row, here’s the 00z and 06z charts for 150hrs and 192hrs.

[TEITS]

My favourite chart is this though.

Look at the BOM and its completely different to the GFS as like the UKMO it tracks the LP E rather than SE.

However now look at what happens.

We still get an E,ly.

[Iceni]

My favourite chart is this though.

http://modeles.meteo...om-0-144.png?00

Look at the BOM and its completely different to the GFS as like the UKMO it tracks the LP E rather than SE.

However now look at what happens.

http://modeles.meteo...om-0-186.png?00

http://modeles.meteo...om-0-240.png?00

We still get an E,ly.

Nearly time to crack open your 'beast from the east' graphic? I hope you haven't lost it… once seen never forgotten.

[Timmytour]

GFS shows temps in double figures getting into southern parts at the outer reaches of FI

I hope it takes as long for that to actually happen as it seems to be taking to get some of the deep cold it's had over the UK in runs since October!

[Robbie Garrett]

My most favorite easterly of them all...

Slowly getting there...

[Dave Kightley]

Looks like we will be saying goodbye to the mild weather until March on the output today. Next week looks rather chilly.... More like rather cold. I sure we wil see some Convective precipitation at a short notice so i'm not that bothered what the GFS chuck out

[Just Before Dawn]

Thursday/Friday's low needs keeping an eye on, it deepens as it passes NE Scotland and continues SE across the N Sea. 06z GFS showing 50-60 mph gusts across northern and central Britain and coupled with cold air wrapping into the circulation from the N and NE - could be some atrocious conditions over the hills of N and NE Britain.

Another deep low follows from the NW over the weekend and follows a similar track on Sunday bringing a risk of gales and blizzards over higher ground of the north.

Late Thursday into Friday looks very tricky especally for The Grampians and Northern Scottish mountains - genuine white-out conditions for a time if the 06z output verified. Less problematic to the south of the Central belt perhaps (except the North York Moors, who's geography is such that it can catch some bad weather even when the flow is slightly west of north) but definately one to watch.

[Adam lufc]

Everything in the models is constantly so far away. Never closer. Doesn't matter if the signals are in place because you need the snow n cold to make it worth while. The Scottish mountains as per 06z will do well in most situations regardless.

[Dexter29]

Everything in the models is constantly so far away. Never closer. Doesn't matter if the signals are in place because you need the snow n cold to make it worth while. The Scottish mountains as per 06z will do well in most situations regardless.

Yes this is my general feel this morning. Although I have to agree with previous posts - the GFS has been remarkably consistent.

The Scottish mountains yes look good for snow this week, but quite frankly - what's new! Nothing out the ordinary for white out conditions in the highlands this time of year.

[Buzz]

Those wishing to have a whine about the model output are of course entitled to do so .......... but not here. There's a thread just for you:

[Weather Boy]

Just about to say that. The difference between the 0Z/06Z is so tiny its incredible and infact you wouldn't get such consistency even in a more predictable zonal pattern.

My only critical comment is the HP at +180 which is located NW of Scotland, I would prefer this further NW to be centred over Iceland.

But (and this is not an entirely rhetorical question), if you recall about a week ago the UKMO was rock solid in its consistency in giving very cold and unsettled weather this weekend just gone, and of course in the end, as many predicted on here, it bowed to the GFS and ECM. So does it not follow that consistency is not necessarily a good trait?

Perhaps the appropriate reply is that in the current scenario, all the models are singing from the same hymn sheet - it is not a case of one defying the others with its consistency. However, this is all a very long way off, and if you remember, at longer range the GFS and ECM were (at times - not consitently) agreeing with the UKMO, hence all the excitement on here.

I still consider it a little too far off to be too excited, although it's better to see what we are seeing than a promise of zonal dross, which seems nowhere near the cards.

[Frosty.]

A much better 6z from the gfs relative to the 00z beyond T+240..there is still a dodgy period with the high just to the northwest of the uk but unlike the 00z, there is a pivotal moment and we have a stronger pulse of cold cyclonic energy from the east/northeast which pushes the high further west and then northwest towards iceland/greenland and we are into a very cold ENEly unstable flow with snow showers galore pushing in from the north sea with temps struggling to rise above freezing and persistent frosts. For this week, the pattern remains broadly the same as the 00z with lows diving southeast across the uk and with cold arctic air digging south in their wake with wintry showers of hail, sleet and snow together with widespread frosts but also some less cold intervals with rain rather than wintry ppn. Today however is the mildest day of this week and indeed probably the next few weeks with 9-11c in the south and southwest but colder again by tomorrow at 6 to 8c, colder air pushing south through tomorrow with wintry showers into the far north and spreading south, into wednesday, snow showers for the north and east, especially coastal areas, fine and frosty elsewhere, the frost probably not really lifting and a very frosty night on wed night, thursday slowly turning a bit less cold as another low pushes southeast with rain, sleet and hill snow, then friday looks a degree or so colder with a strong n'ly and rain clearing south followed by wintry showers, the weekend starts that bit less cold again with low pressure over the uk and with rain and showers, wintry on hills, turning colder through sunday as the low pushes further east allowing another surge of arctic air south with showers turning more to snow, next week very cold nely winds, perhaps more settled to the north and west but frosty with a few wintry showers to n/e coasts, more frequent wintry showers to eastern and southeast counties of england bordering the north sea, feeling bitter. There are signs of the atlantic trying to push in later in FI but that's a long way off and the block may ultimately keep milder air away.