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

[BLAST FROM THE PAST]

Latest comment from BBC weatherman a few minutes ago. Quote,going into next week nothing dramatic on the horizon just yet. HEDGING THEIR BETS?

Their horizon and our horizon [less sensible I suppose] are at different points I suspect, let's see what is said come Tuesday

BFTP

[Severe Siberian icy blast]

I know this is unlikely but . . . . . If the models upgrade further , like they have this morning , and by upgrade I mean rather than -10 850's they bring in say -12,13 850's , along with the thickness values from the trough to the south a bit further north , say 300 miles , then that would look a very similar set up to this

The great midlands blizzard of 91

Look at this now for next week

Now this from the UKMO is potentially a very snowy period , that's not ramping , that's saying it how it is, with those thickness values.

91 and feb 13 are not a million miles apart synoptically

Edited February 16, 2013 by Severe Siberian icy blast

[nick sussex]

You need the whole setup miles further south for snow!!!!!!!!!!!

I don't expect much if any snow here just cold rain! I was talking about for you guys in the UK, all my posts are only in relation to the UK unless I clearly state otherwise.

You only get a very rare IMBY post from me!

[Tamara]

Taking an overview of the model output as a whole then you would be hard pushed to hope for better suggestions for delivering wintry potential for later in February than on offer this morning. The GFS has followed up its Friday evening extravaganza and the ECM looks rather mouthwatering for snow prospects. The UKMO is encouragingly looking better for snow potential too.

Looking at the EPS members, it has to be said that nearly all of them offer either convective potential from the North Sea or atlantic undercutting to provide western and south western areas plenty of interest. Or both!

Yesterdays ECM ensembles showed a cold cluster amidst the wide scatter - these do seem to be leading the way this morning. Any breakdown far far to much in the distance to think about with the coldest weather still some days off anyway- even if its eventual destination is (perhaps) some kind of lift out from a west based NAO. Having such good agreement for a cold spell several days out is a refreshing change - lets hope that we can reel this in right in front of our windows

Edited February 16, 2013 by Tamara Road

[Blizzardof82]

I don't expect much if any snow here just cold rain! I was talking about for you guys in the UK, all my posts are only in relation to the UK unless I clearly state otherwise.

You only get a very rare IMBY post from me!

That is why I look for and respect your postings as there is no imbyness about them, keep up the good work Fascinating model watching again this week and you could not ask for more this late in the winter for the south.

[Freezing-Point]

I know this is unlikely but . . . . . If the models upgrade further , like they have this morning , and by upgrade I mean rather than -10 850's they bring in say -12,13 850's , along with the thickness values from the trough to the south a bit further north , say 300 miles , then that would look a very similar set up to this

The great midlands blizzard of 91

Look at this now for next week

Now this from the UKMO is potentially a very snowy period , that's not ramping , that's saying it how it is, with those thickness values.

91 and feb 13 are not a million miles apart synoptically

However the size and deepness of the cold pool in 91 was immense, so I cannot see that this period could be anywhere near as severe.

[nick sussex]

That is why I look for and respect your postings as there is no imbyness about them, keep up the good work Fascinating model watching again this week and you could not ask for more this late in the winter for the south.

Thanks, yes the output for this late into the winter is very good but we need to see the convective potential come within the key T96hrs timeframe.

Certainly though as long as some energy gets diverted into wards the Med then its looking very likely. I expect lots of shredded nerves in here over the next few days!

[Cecil Hogmanay Melchett]

Id be interested to hear about the progged wind speeds of this easterly,we here in the spine need decent winds to push showers streamers inland,thoughts on the strength of the eastrly?

[Jason M]

Very good charts this morning. We're likely looking at a five to six day cold spell. It looks like it will pack a punch but at this stage looks

a fair way short of anything that could be described as severe.

Uppers are better so the chance of convection is better. ECM much better than yesterday in terms of upper temp profile.

The form horse is then a breakdown, but some ensembles hint at a northerly outbreak after the easterly with a scandi trough. That issue will remain wide open until day 10 as is this morning moves into the high res section of GFS so we can see how its handled at that point. If we could get a true arctic blast in the first week of march that would give some lively weather with a stronger sun.

In a perfect world, easterly, northerly then spring please :-)

This forum has been pretty good of late so let's all avoid rounding on anyone today who dares to go against the consensus. After all, they may be proved right :-)

Jason

[chris55]

Good runs this morning, obviously a lot of people posting are towards the east, and looking for that convective easterly with heavy snow showers.

For me it is difficult to judge how far inland any accumulating snow showers would actually get, it's a set up that I can't ever remember delivering for places further west. Although please correct me if anyone more experienced could tell me different. As SSIB has posted something akin to 1991 would do the trick, but as of today's runs we are not quite there for more western areas.

So my interest from a south western perspective is watching any potential incursions from the Atlantic. ECM once again brings this opportunity closer than GFS and UKMO but probably keeping any fronts out west at this stage.

So overall a cold period coming up, some great snow potential in the east, and if any fronts troughs are in the flow then more inland places might see something, then we also have the slim chance of an attack from the Atlantic as the low undercuts around Friday. And even if the Atlantic fronts don't make it in, the low will tighten the flow and may well increase snow risk inland anyway.

[Frosty.]

It looks pretty showery over most of the UK to me Mushy..? But at this range there's plenty of time for precipitation to change.

Yes PM, looks like most of the uk will have snow showers based on that, just the western isles, western ireland, west and south wales being dry, most sheltered from the bitter Easterly flow, really it looks like the coldest spell of the winter to me, much colder than that spell in January.

[Stu_London]

And this winters winner of the the RAMP of the season is.......

Next week could well be talked about in many years to come, I fully expect COBRA might meet if the GFS 18z verifies

[bradymk]

Id be interested to hear about the progged wind speeds of this easterly,we here in the spine need decent winds to push showers streamers inland,thoughts on the strength of the eastrly?

Fron ECM data, the max wind speeds get to around 20mph next Friday (not gusts) but on most days they are averaging at 15/16mph for your location. GFS shows max speed 20mph also on next friday and 17/18mph other days. GFS also shows 28mph gusts for next friday. Would feel bitter. Not sure how reliable these are though.

[Jason M]

In terms of penetration of snow showers from the east it may not prove so vital now. With an upper cold pool the sun is now strong enough to cause showers to form over land as long as we don't get lots of low cloud drifting in from the east over night. That's probably why GFS precip charts are showing hatching over most of the country.

Jason

[Ian Brown]

Id be interested to hear about the progged wind speeds of this easterly,we here in the spine need decent winds to push showers streamers inland,thoughts on the strength of the eastrly?

That's not a problem, the problem is if the block is too close to Scotland (the UKMO has it quite close) then pressure would be too high in Northern England and it would be dry.

[That ECM]

Differences on the 06 GFS with low to to the west moving further south, what effect will that have on this run? Encourage the block to move further north?

[Ian Brown]

dont agree... "heavy snow showers everywhere"? off that chart?... here in derby (a nice central position so not a remote enclave) charts like that produce cold, overcast, dry, bitterly raw weather.

or have i missed a point of irony or sarcasm?....

that is possibly the most disrespectful remark ive ever read on here in relation to a seasoned respected and accurate forecaster. shame on you.

well snowlovers this morning appear to have more to get excited about as this mornings runs show the easterlies to be more northeasterly, which will be more condusive for brighter days with snow showers, then the southeasterlies shown last night which are more likely to produce bitter, overcast, dry, days like they did in march 69, jan 76 and feb 83.

I think Steve'e chart would produce snow showers for Derby. Not everywhere though - certainly not the far NW of England, N Ireland or much of Scotland.

[LomondSnowstorm]

That's not a problem, the problem is if the block is too close to Scotland (the UKMO has it quite close) then pressure would be too high in Northern England and it would be dry.

From an IMBY perspective that's my concern too, though we still usually manage to do relatively well due to proximity to the east coast provided the uppers are cold enough even with relatively high pressure. Anyway no point worrying about it at this stage, I'm just quite pleased like the rest of us that we're seeing the convective potential and cold uppers (which actually are critical the further north you go) remaining and even increasing in the charts.

[TEITS]

Because EC EPS has a notably muted signal (but wIdespread trace sIgnal) for anything other than light snow showers generally (more localised convergence aside) & events into weekend remain low probability currently. So as previously stated, we're too far away to 'big up' anything other than the cold and (for many) largely dry story.

Well I feel your answer just illustrates the problem with the BBC/Met O forecasts.

I have learn't that the models are useless when it comes to predicting convection and this is especially true with E,lys. If the output today remains unchanged then you don't even need to look at the projected precip charts from the models to know more than light snow showers will occur. The term light snow showers is only correct for Wed/Thurs but that isn't the case for the end of the week into the weekend when heavier showers would develop especially across E Anglia/SE.

Again just illustrates my point of over reliance on computer models these days. Remember a recent snowfall when you stated the SW was at greatest risk and I disagreed. Well the reality was the SW actually experienced mild temps whilst others enjoyed snowfall.

Just add im not having a go at you but I get frustrated at times because forecasting instinct has disappeared due to this over dependance on forecast models.

[Penrith Snow]

This coming spell looks very much like February 2005 almost down to the day, that did give widespread snow showers before the easterly feed got cut off, are we looking at something the same or better than Feb 2005?

http://www.wetterzentrale.de/archive/2005/brack/bracka20050224.gif

Andy

[Jason M]

Cold front moves in from the east.

Rain turning to snow.... Nothing severe or heavy at this stage but last couple of runs GFS has shown a signal for a more defined front to form on the boundary as the shortwave drops into France.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=90&code=0&mode=2

Jason

[Summer Sun]

The GFS ensembles continue to show a warm up as we enter March they also precipitation increasing at the same time

The Aberdeen ensemble remains the coolest of the 3

A week or so of cooler weather seems certain from the 20th the around the 27th after which we start to see things warm up again as we enter spring

[bradymk]

Well I feel your answer just illustrates the problem with the BBC/Met O forecasts.

I have learn't that the models are useless when it comes to predicting convection and this is especially true with E,lys. If the output today remains unchanged then you don't even need to look at the projected precip charts from the models to know more than light snow showers will occur. The term light snow showers is only correct for Wed/Thurs but that isn't the case for the end of the week into the weekend when heavier showers would develop especially across E Anglia/SE.

Again just illustrates my point of over reliance on computer models these days. Remember a recent snowfall when you stated the SW was at greatest risk and I disagreed. Well the reality was the SW actually experienced mild temps whilst others enjoyed snowfall.

Just add im not having a go at you but I get frustrated at times because forecasting instinct has disappeared due to this over dependance on forecast models.

I am not sure about this, Ian will have to confirm but I think Ian's quote was using yesterdays 12z data as I am sure he said that he does not get issued 00z until 11am. That may explain the light snow showers as it has really only been on this mornings runs that we have seen a greater amount of convective activity and a better chance of some heavy showers so maybe the MetO guidance will change based on 00z and Ian may show this after 11am. Just a thought, and i would say the over use of models has only really affected nowcast situations, this occured a few times last winter.

[UV-RAY]

For large parts of the UK, the upcoming cold spell still looks likely to be dry and cold than anything else, with any precipitation reserved for the East, SE and some Central parts of England. I still think some members are setting themselves up for a fall again with talk of heavy snow everywhere, hopefully it shall be me with egg on my face when these predictions come true.

[Severe Siberian icy blast]

The GFS ensembles continue to show a warm up as we enter March they also precipitation increasing at the same time

The Aberdeen ensemble remains the coolest of the 3

A week or so of cooler weather seems certain from the 20th the around the 27th after which we start to see things warm up again as we enter spring

Gavin I have never heard some one ramp warmth and sun up as much as you lol

As you no anything can change when you'r looking deep into fi for warmth . Agree the gfs ens show a warming trend but we all know the gfs is famous for its wild and wonderful fi's .