Winter Model Discussion 12Z 15/02/13 onwards.

[Liam J]

Predominately dry for much of the UK this week with locations on the other side the Channel likely to see the most of any decent snowfalls which may clip the far south, more like flurries elsewhere. I just hope it isn't a very cloudy scenario or without a doubt this will be a very boring spell of weather indeed.

A record breaking cold start to March over parts of the continent looking quite possible as the PV and severe cold air drop south into Europe.

Edited February 17, 2013 by Liam J

[bluearmy]

Not much change on the 00z's.the spread of possible instability pretty well set for later next week. Adjustments north/south within that remain on the table. Blocking tending to remain the fi favoured solution although where its likely to be centred uncertain. Note the recent trend to ridge the azores north mid range and cut the undercutting energy whilst the euro trough lifts ne in se europe. Could generate some quite different solutions over the next feww runs for the uk post day 6/7.

[PB22]

A prolonged cold and dry spell is on the cards for many it would appear now. Main snow risk for the far southeast but the main core of the cold now looks set to hit mainland Europe along with most of the snow potential. Winter 2012/13 looks set to end with an anti-climax for many, but a few may get lucky. Once again we have failed to get heights over Greenland which sums up the story of the winter well.

[Duane S.]

No trend back N for the block this morning, still time yet though so lets no despair. Yesterday I posted to say the Ian's 'very low' probability of heavy snow come the weekend for some areas didn't tie in with the charts we could see which in my opinion gave a good 30% chance of that. However, this morning's charts certainly do tie in. Dry for most with most instability occuring far S and to the SE bringing wintery showers.

Same theme but some differing (when isn't there?) from the models for 6 days time in terms of where the trough is over France and the orientation + where the centre of our high resides...

GFS....

ECM...

UKMO...

NO Gaps...

GEM... (possibliy of most interest)

But as always this is just one set of operationals from one set of runs out at +144. Much could and likely will happen between now and then to paint a very different picture (maybe better, maybe worse).

And then the general FI theme is there for all to see as well as the cold feed is cut off and our high draws in warmer air. I suppose I'd be happy enough with that as long as we can get a good strong bitter Easterly beforehand!

Edited February 17, 2013 by s4lancia

[bluearmy]

Just to add that a front is off the east coast at T144 on ecm. (Stretching north to w norway). No doubt that would provide some impetus to instability, moreso, the further south but not exlusively.

[Mark Parsons]

And for about 90% of the country unfortunately, cold and dry sums it up. The far south and south east still look set for a snowier looking week. The place to be though is France, absolute snowfest there. If only the pattern could've setup further north so the uk could get a direct hit.

Again in FI the lack of Greenland high is apparent.

Why are you and others saying that there will be a snowfest in N.France??? With the feed straight down through central Europe will only be dry and bitterly cold, yes the coldest uppers may advect south of the BI but that does'nt necessarily mean snow for them............

[Weather-history]

I just hope it isn't a very cloudy scenario or without a doubt this will be a very boring spell of weather indeed.

I think that is the likely scenario, to be honest. A clean easterly flow for that length of time, seems highly unlikely to me. Could end up in the worst case scenario with this, a too weak easterly flow for appreciable snow amounts but just strong enough not to prevent cloud amounts spreading in assuming the high is not cloud ridden to begin with.

[shaky]

To my eyes ecm and ukmo are further north slightly

[Iceberg]

Just to add that a front is off the east coast at T144 on ecm. (Stretching north to w norway). No doubt that would provide some impetus to instability, moreso, the further south but not exlusively.

Yep Surprised there isn't more mention of this, Its on the GFS and GEM to varying degrees, temp differential is quite marked as is the pressure difference hence the iso kink.

This will definately get upgraded imho, firstly to a shortwave and maybe even to a closed low by T72 with a Sub -5 warm segement moving into france, keeping the uk in the cold but enhancing instablity to a great extent. Always something to watch out for in late feb in an easterly with enough sea track and most glad to see the models picking it up at the T144 range.

Forgot to add one of the rare occasions where a developing shortwave is welcome rather than watching one scupper an easterly when it forms in the baltic.

[stainesbloke]

Why are you and others saying that there will be a snowfest in N.France??? With the feed straight down through central Europe will only be dry and bitterly cold, yes the coldest uppers may advect south of the BI but that does'nt necessarily mean snow for them............

There is nothing to suggest a 'snow fest' in N France IMHO, looks like a mainly dry cold-ish spell to my eyes. Hopefully a SUNNY one! Very bored of cloud.

[shotski]

Could it be that the JMA is picking up on a signal that the other models have not latched into yet ?

Looks very interesting at t-192 and out of kilt with the other models.

[Iceberg]

Looking at the feature at T144 its predominently a shallow trough on the 00zs evident at the 925-950 layers, with some residual effect to 850 in the RH. A bit more diurnal warming at the lower levels along with the N.Sea SST +5 +6 being taken up with moisture and we end up with a 850 surface low...

06z will be interesting.

[IDO]

The GFS looks dry for 90%+ of the UK. Total rainfall (current) for the next eight days suggest only coastal regions will get a flurry or two:

(Usual caveats for snow potential apply)

About a 5 day cooling down, no ice days or big freeze, though wind chill will make it feel colder in eastern districts:

Then a return to average (+) temps according to GEFS.

The ECM appears to have more potential for moderate snow in the SE/south but the window of opportunity is only about 48 hours.

UKMO Fax for midday Wednesday has the 528 dam line 100 miles off the east coast:

So the working week looks cold and settled and we await the firming up of snow potential for next weekend on.

[nick sussex]

Morning all

Not much change this morning with still room for manouevre with the high. I'm sure this is causing a few headaches at the UKMO because with still margin for error at this timeframe.

I think the key timeframe is between 120 and 144hrs when the trough energy disrupts to the west heads se into Iberia then east into the Med, the models develop a low in the northern Med which pivots throwing a bit more instability nw towards the UK.

The GEFS still has a cluster taking lower heights much further north, the ECM postage stamps are really all over the place in terms of high placement at 144 and 168hrs.

I think realistically its not a great set up for areas away from the south and se unless theres a northwards correction in the outputs which still may happen depending on how that trough disrupts to the west so still alot of uncertainty which is really typical of easterlies.

In terms of 850's the ECM does develop a decent cold pool with even some -13s thrown into the mix in central Europe and so whereas there were worries about the depth of cold on previous ECM runs this isn't such a concern now, its just where the deepest cold will be directed.

Even a hundred mile northward correction could make a big difference to snow potential. So at this point in terms of the cold pool that probably won't be nailed until T72hrs so still a way to go.

[Gustywind]

Why are you and others saying that there will be a snowfest in N.France??? With the feed straight down through central Europe will only be dry and bitterly cold, yes the coldest uppers may advect south of the BI but that does'nt necessarily mean snow for them............

Sorry mark yes you're quite correct, on closer inspection of the precipitation charts France looks mainly dry also.

[phil nw.]

Something of a change to the pattern from around 48hrs ago is shown on the 00z runs.

The undercutting Atlantic trough modeled then has been weakened and split with any attack from the south west now off the menu.

http://modeles.meteo...gfs-0-120.png?0

Enough energy still going north is keeping the high closer to the UK than previously expected so the pattern now is just that bit further south.

http://nwstatic.co.u...fd9233294f9178;

Anyway we still have the cold air coming west but the core of the deepest cold and much of the instability linked to the pool of lower hts are headed for France.

Still some prospects for some light flurries of grains as the leading edge of the cold comes in and perhaps the far SE getting some enhanced snow from the nearby passing disturbance heading into the continent.

It does look mainly dry for most of us though this coming week -let`s hope the high is not too cloudy so we can at least get some bright days with the cold.

[No Balls Like Snow Balls]

A good set of model runs overnight. Very cold by day and some severe frosts by night where cloud clears. As for snow clearly no one at this stage can have a accurate answer to whether there will be widespread snow next week, not even the pros at Exeter, but at least we have 1 of the 2 important ingredients in place for snow and that is the cold, next stop precip LOL.

[Ian Brown]

Pretty good agreement between the big models about the High placement, and that placement is far too close to the UK to bring anything other than very light PPN to the far East and South. Certainly nothing to be 'booming' about.

On the positive side, a prolonged dry spell will be welcomed by many and it looks the driest spell of weather since the rainfest began last April. Beyond the reliable and nothing to suggest that we can get that elusive Greenland High.

[Froze were the Days]

mmm...not much change as mentioned from the 12's, very little precipitation about. Is the winter about to finish how it started with another anti-climax? - I wouldn't mind so much if it was sunny cold but I have a feeling we could see numerous cloudy cold days - yuck!

[TEITS]

Mixed feelings this morning.

Whilst the outlook I posted last night appears unchanged i.e snow showers light at first, increasing towards weekend, im aware of past disappointments and the general downgrade of convective potential over these past 24hrs. What I have noticed over these years is E,lys either completely disappear from the output or they downgrade. The usual downgrade is the depth of cold, strength of E,ly flow, amount of convection. So my fear is come Mon/Tues the general pattern has shifted further S so that even locations such as E Anglia/SE miss out.

On a more positive note we could yet see a shift N and like Nick S says only a shift of 100miles would make a difference, even better if it was around 300miles N. I would also like to correct an error made my a member saying no streamers are indicated. Let me tell you streamers are a localised feature and the models never pick up on these until 24hrs away at least. The Feb 2009 Thames streamer wasn't modelled until Sunday lunchtime and the streamer arrived 5hrs later. I believe the famous Dec 2010 streamer across Lincs, Yorks wasn't modelled until very near the event.

[Gibby]

Good morning. Here is the latest report on the 00z output of the big 4 namely GFS, UKMO, GEM and ECM for today Sunday february 17th 2013.

All models show a quiet spell of weather to take us through the following working week. A High pressure ridge lies just to the East of the UK with a freshening SSE wind over the UK today and tomorrow as a Low pressure trough slides SE well to the SW of Britain. Th weather will be dry for all in the coming few days with some bright sunny spells by day following some early fog in the East. A fresher breeze in the West will make it feel a little less mild than of late but temperatures will hold close to normal by day. Winds fall lighter again before midweek as a ridge from a developing Scandinavian High reaches down across the UK with quiet rather cloudy conditions for the UK in a slack East flow. Later in the week the flow strengthens in the South with colder air filtering West with a lot of cloud in the South with light snow grains or snow flurries in the SE in particular, The North will see the best of the brighter interludes where frosts at night will be at their sharpest.

GFS then shows the weekend with cold and rather cloudy ENE winds over the South as High pressure sits over the NW of the UK. All areas will be largely dry though a few snow showers are still possible towards more SE areas. Through FI the main belt of High pressure slides SE over the UK with calm and anticyclonic conditions which in February would mean frost at night but some reasonably bright and sunny weather through the days. High pressure then remains a dominant force shuffling around to the East of the UK and eventually back towards Scandinavia with a spell of rain reaching the SW and occasionally other far Western areas late in FI.

The GFS Ensembles show a similar pattern to yesterday with a cold snap this week before High pressure realigns to a less cold position for the UK and the increased likelihood of Atlantic influence increasing chance of rain later in the run. Temperatures at 850 levels recover more slowly as the NE drift of later this week hangs on rather longer from most members.

The Jet Stream shows as plit flow developing as we move through this week and next weekend with a weaker arm moving East way up across Northern Greenland and the far North off Scandinavia with the ain stronger arm maintained well South over the Atlantic and Southern Europe.

UKMO for next Friday and the start of the weekend as High pressure over Northern Scotland with a cold and raw NE flow over England and Wales. A lot of dry weather would be likely. If skies stay grey and cloudy a few snow grains are possible in places but in any brighter spells weak convective snow showers are possible too near the SE.

GEM today shows a stronger East flow at the end of the week and start to the weekend before it decreases away as pressure builds from the NE. Towards the end of the run pressure holds High to the East and NE with continuing largely dry conditions though with time it will feel less cold by day as the cold feed of previously would be cut off with a more moderate SE drift for most.

ECM finally shows a similar pattern of High pressure from Northern Scotland to Scandinavia with a cold and raw ENE flow over England and Wales. As per UKMO there may be a lot of cloud low in the atmosphere within the flow allowing some light snow grains to fall in places while if skies break then some weak convection could develop some light snow showers at times across Southern England and Wales with little change out to the end of the run.

In Summary today a cold and dry spell is on the way. Many areas may see no rain at all over the next two weeks with High pressure in total control of the UK weather. The High centre will mostly lie close to Northern Britain with a cold and raw Easterly flow over Southern Britain making it feel very cold at times. Heavy snowfall is unlikely but with a lot of low cloud likely trapped in the flow from the East some occasional snow grains are possible. Should cloud become more broken there could be some more organised convective activity late in the week with light snow showers in the SE. All areas would likely stay dry with frost at night but at least the chance of some sunshine by day, the best chances of which would be reserved for the extreme West and NW of Scotland.

[stratty]

I concur. Brave post on this forum, incidentally ;-)

.....as is your post in return! lol

[mushymanrob]

Looks dry for me.

viewing this mornings runs would certainly suggest no real precipitation (outside a flurry here and there).

. I just hope it isn't a very cloudy scenario or without a doubt this will be a very boring spell of weather indeed.

.

...and thats likely imho, as ive previously cited instances in other years where thats what we got. march 69 was a month of grey raw easterlies from very similar synpotics.

As for snow clearly no one at this stage can have a accurate answer to whether there will be widespread snow next week,

disagree. theres nothing on this mornings runs that would produce any appreciable amounts of snow.

[Harsh Climate]

Not liking the output this morning. South east just about stays in the game for some light snow flurries next week but apart from that looks mainly dry.

Biggest disappointment is though all the models have backed off any retrogression of our blocking high north west, instead signals of it gradually retreating south east look back on.

[CWT2012]

Still lots to play for

Things are disappointing compared with 2 days ago or even yesterday morning but there are 20 lots of model updates before the action is supposed to kick off (next weekend) so the 'winter is over' brigade need to relax, a lot can and will change in those 20 runs.