Model Output Discussion - 21st - 28th November

[Gibby]

Good evening. Freshly back from holiday in the Canaries here's the return of the report on the 12zs today from GFS, UKMO and ECM designed especially for the less knowledgeable chart readers. While I catch up on work the morning reports might be a bit short for the next few days.

GFS shows quite a mobile pattern with deep Loww pressures running east North of Scotlan with a notably deep one on Saturday driving wind and rain east over all areas later on Saturday. severe gales could occur in parts of the North for a time. Then as time passes Low pressures continue to pass East with progressively deeper and colder conditions pushing South at times. Rain and wind would continue to cross Britain in bands with colder showery conditions following. As the air turns somewhat colder there could be some snow on higher elevations in the North with some frost possible as transient ridges pass by. Towards the end of the run the AzoresHigh ridges strongly in with drier weather returning to most areas later especially in the South.

The GFS Ensembles suggest the operational shows a typical mobile flow with alternating rising and falling uppers. The mean for the run shows 850's falling slightly below the long term mean with no real suggestion of advanced cold weather yet.

UKMO tonight shows High pressure never far away from the South while Low pressures track East north of Scotland. Winds will be mostly Westerly or Southwesterly with rain at times chiefly in the North with longer drier and milder conditions maintained further South with only weak bands of rain passsing by at times.

ECM also shows a similar pattern to UKMO with rain and strong winds at times in the North with longer drier spells further South closest to High pressure to the South. The model goes on to show Low pressure becoming slightly more dominant for all areas by the end of the run with strong winds and rain possible for all areas at times by then with temperatures close to normal.

In summary the weather looks in typical late Autumn fashion further North with gales and rain at times. Further South there will be some longish dry spells and lighter rain as cold fronts pass. Temperatures look close to normal with some colder air indicated from GFS later cold enough for some snow on Northern hills for a time. Prospects for deep cold remain hard to see at this time.

[nick sussex]

Yes please JMA.....not too much to ask?

It probably is but desperate times call for emergency strawclutching measures!

Joking aside I would be interested to hear what GP makes of tonights developments, the east Pacific ridge alone might not lead to cold salvation but its certainly a welcome development as long as we can get the trough far enough eastwards.

[Glacier Point]

Still some way off Nick, but the blocking mechanism - the longwave trough located over the UK - is starting to trigger height rise to our north-east and this all over the GFS Ensemble suite from t300 onwards. Tonight's NAEFS and CPC outputs should be quite interesting in this respect. So probably becoming cooler and unsettled and then becoming milder again but all eyes east.. for January onwards, but I must stress January when this becomes much more viable.

The most likely evolution here is that the trough becomes more or less stationary, wobbling east and west in its axis and successional troughs dropping into our trough, probably every ten days, each time reinforcing the block to the north-east

Edited November 22, 2011 by Glacier Point

[Grimsby Snow Lover]

I know this is from a 'lesser' model but I can see a fair bit of potential here. The hight rise over Greenland looks more promising as does the fact that the low has driven quite far south forcing the high to our south away from our shores. Perhaps a few days later we would see quite a potent Northerly. Something to look out for in future runs possibly.

[Frosty.]

looks pretty zonal with temps up and down a bit, just either side of average with no very mild weather for a change but nothing cold either unless you live on a mountain in northern scotland.

Still some way off Nick, but the blocking mechanism - the longwave trough located over the UK - is starting to trigger height rise to our north-east and this all over the GFS Ensemble suite from t300 onwards. Tonight's NAEFS and CPC outputs should be quite interesting in this respect. So probably becoming cooler and unsettled and then becoming milder again but all eyes east.. for January onwards, but I must stress January when this becomes much more viable. The most likely evolution here is that the trough becomes more or less stationary, wobbling east and west in its axis and successional troughs dropping into our trough, probably every ten days, each time reinforcing the block to the north-east

Beast from the East in the new year..luvly jubbly.

[Iceni]

looks pretty zonal with temps up and down a bit, just either side of average with no very mild weather for a change but nothing cold either unless you live on a mountain in northern scotland.

Beast from the East in the new year..luvly jubbly.

Can we persuade TEITS to reinstate his Beast avatar after Christmas?

[BLAST FROM THE PAST]

Hey fred, do you expect the ukmo to jump on board with the gfs 12z and bring cold weather further southeast later next week?

I do think after all said and done the GFS will have come out of this quite well. Mind you it does have 4 runs a day

BFTP

[ANYWEATHER]

To be honest folks we are looking at a "normal" regime of late Autumn weather rather than the static mush of recent weeks, even months! The Ecm tries to keep somesort of Euro High but fails to develop it in its later stages, the Gfs shows a very mobile and at times stormy period especially and as normal for the North. Looks as though we are going to get shots of rPM air and shots of rTM air at regular interludes during the Gfs run. Anyway, something a "little bit more normal" coming up and something weatherwise to talk about. The 500mb chart of both Ecm and Gfs look somewhat similar right out to t+240 obviously with slight differences at that range, but interestingly similar at that range.

[SLEETY]

Still some way off Nick, but the blocking mechanism - the longwave trough located over the UK - is starting to trigger height rise to our north-east and this all over the GFS Ensemble suite from t300 onwards. Tonight's NAEFS and CPC outputs should be quite interesting in this respect. So probably becoming cooler and unsettled and then becoming milder again but all eyes east.. for January onwards, but I must stress January when this becomes much more viable.

The most likely evolution here is that the trough becomes more or less stationary, wobbling east and west in its axis and successional troughs dropping into our trough, probably every ten days, each time reinforcing the block to the north-east

Sounds good to me ,A big freeze in the New Year

[Frosty.]

I do think after all said and done the GFS will have come out of this quite well. Mind you it does have 4 runs a day BFTP

Thanks Blast, I really hope we see the more amplified gfs version for next week, would be a shame if the pattern is flatter with more of a tropical maritime influence than polar maritime.

PS. I hope we do see the famous beast avatar again soon.

[SLEETY]

I don't think GP is forecasting at this stage - merely suggesting that it is going to be later rather than sooner that we get a shot at a pattern change.

I would be a surprised if there are height rises over Scandinavia, surprised if we develop a situation where depressions struggle to pass the Meridian given the strength of the Polar Westerlies and anomalous low heights at Northern latitudes.

Well a bitter spell in January would be most welcome.They have been so rare the last 20+ years.I do think it will be the 2nd half of winter before we see any serious cold ,as you say the current pattern doesn't support this.But we have many weeks of winter to go yet

Edited November 22, 2011 by SLEETY

[Cecil Hogmanay Melchett]

I cant for the life of me see anything in the way of cold in the near medium or long term in the models.

[nick sussex]

Still some way off Nick, but the blocking mechanism - the longwave trough located over the UK - is starting to trigger height rise to our north-east and this all over the GFS Ensemble suite from t300 onwards. Tonight's NAEFS and CPC outputs should be quite interesting in this respect. So probably becoming cooler and unsettled and then becoming milder again but all eyes east.. for January onwards, but I must stress January when this becomes much more viable.

The most likely evolution here is that the trough becomes more or less stationary, wobbling east and west in its axis and successional troughs dropping into our trough, probably every ten days, each time reinforcing the block to the north-east

Thanks for that GP.

Looking at the CPC charts they edge the trough slowly eastwards but it still remains stuck over the UK, this backed by the NAEFS, in recent days this has edged the pattern a little further east before replacing that troughing with more and your height rises are evident to the ne.

In these situations though its difficult to make a call regarding any PM air, a couple of hundred miles either way with trough location could make a big difference, can I throw a curve ball into proceedings, as much as theres growing confidence for the pattern near the UK just how much have you factored the effects of more amplification upstream could have on the pattern.

If for arguments sake we see a slightly more amplified upstream pattern and see this troughing elongating and digging further se couldn't we see a possibility of that trough disrupting as those growing positive anomalies to the ne start to gain a greater influence, earlier than expected.

Just a thought, perhaps I've gone crazy, I can't blame it on the wine as I've had nothing but espressos all day, maybe I'm suffering from a caffeine overdose!

Edited November 22, 2011 by nick sussex

[damianslaw]

At long last the promise of some proper autumnal weather is on the cards from Friday onwards.. next week at this range is looking distinctly seasonal, average temps for many, with some decent snowfall for our northern hills.. I am really happy at the coming prospects, yes no significant cold weather on the cards but compared to recent weeks which I have to say have been absolutely tedious and devoid of anything to talk about, the upcoming spell of weather from Friday onwards will be a refreshing change.

Upstream changes taking place in NE USA and SE/E Canada will determine events for early December - a northerly could very easily crop up if events play ball, or we could end up with pesky shortwaves spoling the party, but the long term 500MB flow is suggesting winds from a predominantly SW-W-veering NW quarter at times, as opposed to being firmly stuck in the SW-S sector as they have been for weeks and weeks, so the chances of anything particularly cold look quite slim.. but early december is probably the most least likely period in the whole year to deliver below average temps - westerlies are at their yearly maxim peak..

[stewfox]

Good evening. Freshly back from holiday in the Canaries

You have been missed.

[mountain shadow]

Still some way off Nick, but the blocking mechanism - the longwave trough located over the UK .

If the long wave trough was located over the uk, would we not see frequent polar maritime/arctic air being pulled in from the north west more frequently then? Surely a better a thing than having the trough situated 1000 miles out in the atlantic with the uk on the warm side of the trough?

[A Winter's Tale]

I think for the end of November and first half of December we'll have to rely on Polar Maritime incursions but even so it probably wouldn't deliver for Southern Areas.

Still, thank god it's Novemer and December is out of the reliable time frame. This leaves us with 3 months of winter to enjoy and I'm sure by 0000hrs on the 1st of March we would have had at least something to remember.

However what I see with the Models is a more flexible pattern and I believe that anything could happen in December.

[January Snowstorm]

The 18z gfs is far from mild next week.

Why do i keep thinking that bitter air up towards Iceland has our name on it..........

It would only take minor changes to drive that bitter air down over us

[A Winter's Tale]

For now I'll be keeping an eye on what potential a NWly Airflow can bring to this part of the UK. However throughout December and Winter I'll be keeping an eye on any signs for a Greenland High or even a Scandi Hi. Here's hoping we get it.

Anyway, how long has the Euro High dominated our weather this year.

[nick sussex]

If the long wave trough was located over the uk, would we not see frequent polar maritime/arctic air being pulled in from the north west more frequently then? Surely a better a thing than having the trough situated 1000 miles out in the atlantic with the uk on the warm side of the trough?

The problem if you have the trough stuck over the UK is its more difficult to tap into the PM flow, of course northern areas would stand a better chance but at this range shortwaves aren't well modelled.

You really need the troughing sat to the east of the UK, we're still not sure where this will set up until we enter the 144hrs timeframe.so if we're lucky we could see some movement east in the pattern.

[SuttonStorm]

That's better :-) The pub run has sent me to bed with dreams of snow covered Alpine peaks :-)

SS

[nick sussex]

That's better :-) The pub run has sent me to bed with dreams of snow covered Alpine peaks :-)

SS

Lol!

Yes the GFS 18hrs run is okay for the Alpine resorts but we still have the problem of the ECM and its determination to keep the Euro high sat to the south, until that switches then my skis will be gathering dust !

Everyone knows the ECM is my favourite model but it's beginning to really annoy me!

[feb1991blizzard]

The problem if you have the trough stuck over the UK is its more difficult to tap into the PM flow, of course northern areas would stand a better chance but at this range shortwaves aren't well modelled.

You really need the troughing sat to the east of the UK, we're still not sure where this will set up until we enter the 144hrs timeframe.so if we're lucky we could see some movement east in the pattern.

True but it looks more of a zonal pattern anyway so i just cant see it staying there for very long even if it does and also it really needs to be a tad further south than on the 18z. Sorry to be a defeatist but im really lacking in confidence for december at the mo, at least the first half of it anyway.

As MS says though even non snowy NWerlys are still better than southerlys.

Edited November 22, 2011 by feb1991blizzard

[nick sussex]

True but it looks more of a zonal pattern anyway so i just cant see it staying there for very long even if it does and also it really needs to be a tad further south than on the 18z. Sorry to be a defeatist but im really lacking in confidence for december at the mo, at least the first half of it anyway.

I can understand your lack of confidence, its probably a culmination of mediocre model fatigue and the current teleconnections which aren't great.

It's of course always easier to view the output when the background signals suggest a big change due, even though you view some underwhelming output you think well somethings going to pop up shortly.

We should remember though that even though teleconnections can give us clues to the general pattern they don't accurately forecast to within a few hundred miles where a trough will set up etc.

We could have a neg NAO and an amplified pattern and still be stuck on the warmer side of any troughing so in this instance everyone will be saying what happened, wheres my cold and snow?

Because we don't have any background signals for higher latitude blocking then we should accept that the best probably on offer is some shortish PM incursions if the trough moves far enough east.

At the moment if this happened I would be jumping for joy, its not what I'd really like but at least I can go skiing and more importantly I can play in the snow with my dog who loves the stuff!

Yes folks you can be over 40 and be a complete child when it comes to snow! I don't even care anymore if people think I'm nuts; you know you're getting old and bitter when the mere mention of snow in the forecast has you moaning about the transport disruption, or the cold or that you might slip and break a hip!

Rather than OMG this is so exciting I can't wait to go out and play in it! :smiliz19:

[A Winter's Tale]

I can understand your lack of confidence, its probably a culmination of mediocre model fatigue and the current teleconnections which aren't great.

It's of course always easier to view the output when the background signals suggest a big change due, even though you view some underwhelming output you think well somethings going to pop up shortly.

We should remember though that even though teleconnections can give us clues to the general pattern they don't accurately forecast to within a few hundred miles where a trough will set up etc.

We could have a neg NAO and an amplified pattern and still be stuck on the warmer side of any troughing so in this instance everyone will be saying what happened, wheres my cold and snow?

Because we don't have any background signals for higher latitude blocking then we should accept that the best probably on offer is some shortish PM incursions if the trough moves far enough east.

At the moment if this happened I would be jumping for joy, its not what I'd really like but at least I can go skiing and more importantly I can play in the snow with my dog who loves the stuff!

Yes folks you can be over 40 and be a complete child when it comes to snow! I don't even care anymore if people think I'm nuts; you know you're getting old and bitter when the mere mention of snow in the forecast has you moaning about the transport disruption, or the cold or that you might slip and break a hip!

Rather than OMG this is so exciting I can't wait to go out and play in it! :smiliz19:

Exactly!