Model Output Discussion - 21st - 28th November

[kold weather]

Pattern is quite good for Scotland to get a strong windstorm at some point in the next 7 days, maybe even a couple. Not much agreement yet but the models do agree on the set-up being condusive for lows to blow up.

[A Winter's Tale]

Pattern is quite good for Scotland to get a strong windstorm at some point in the next 7 days, maybe even a couple. Not much agreement yet but the models do agree on the set-up being condusive for lows to blow up.

I think that this bound to change but who knows!

[feb1991blizzard]

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:

I have to say that although what i know about weather you can write on a stamp compared to you and the other big hitters on here but one thing i have definately changed my opinion on since ive been on the NW forum is that teleconnections play a massive role in our weather, i thought LRFs were a load of you know what a few years back.

As for PM incursions though i will get excited if one shows some snowfall for my area!

Anyway Nick thanks for the updates and heres to a happy and snowy new year,

[A Winter's Tale]

I see that GP is lurking.......

Come on GP, give us the good news and make us filled with joy just like some magical prescription from the GP that deals with Severe Snow Deprivation.

On the other hand, please don't give us the dreaded news that we'll be suffering severe snowmonia and Beasterly Withdrawl symptoms for the while.

I've got to admit that the Models are particulary uninteresting at the moment. It kills me when I think about what we were looking forward to this time last year.

[A Winter's Tale]

It's awful quiet here!

[Liam J]

I see that GP is lurking.......

Come on GP, give us the good news and make us filled with joy just like some magical prescription from the GP that deals with Severe Snow Deprivation.

On the other hand, please don't give us the dreaded news that we'll be suffering severe snowmonia and Beasterly Withdrawl symptoms for the while.

I've got to admit that the Models are particulary uninteresting at the moment. It kills me when I think about what we were looking forward to this time last year.

The model outputs are the most interesting they have been for weeks if not months, finally some decent seasonal weather on offer with gales and rain on the cards for the medium term with unsettled conditions likely into December with the trough setting up home close to or over the UK.

Edited November 23, 2011 by Liam J

[k19]

NAO forecast to take a dive of some kind or another by the start of december, and the models are toying with the idea of a colder scenario around then, i suspect that the most negative member of the NAO is on the same wavelength as the colder model members.

[A Winter's Tale]

NAO forecast to take a dive of some kind or another by the start of december, and the models are toying with the idea of a colder scenario around then, i suspect that the most negative member of the NAO is on the same wavelength as the colder model members.

Sounds a bit more optimistic.

[ZONE 51]

GFS 18z - Outlook, potentially Stormy, wintry North.

At the moment we have high pressure in the south with light to calm winds and mostly dry conditions, low pressure brushing the north bringing windy and wet weather in from the atlantic with the rain hitting the far north now with gusts of 40-50mph here.

This week a potentially damaging storm winds up in the Atlantic and heading to our shores later this week, its something to keep a close watch on, with the wintry risk for Northern areas towards the end of the week.

by Thursday the dartboard low deepening moves into Northern areas with gales or severe gales for some areas especially the far North, while the South especially the Southeast wonders what all the fuss is about with rather calmer conditions continuing here on thursday.

Through friday afternoon/evening colder air gets all the way through to the south, with the coldest conditions setting in across the North, and this is where some wintry precipitation is likely, high ground/mountains in Scotland seeing a risk of snowfall through friday, i would say a risk of snow to lower levels down to around a few hundred meters maybe.

As we get into saturday another big deep storm pops up from the Atlantic! this one looks like more of a direct hit to our shores, the Atlantic has woken up after a quite shift! the milder air sweeps back in across the South, not getting to mild in the North though, this storm on saturday has the potential for damage with widespread effect across the North and possibly the West, gales could affect many areas, a change of track could bring the storm to hit a wider area.

As the storm moves off through sunday it brings back some cold and wintry weather for Scotland, the high ground is at the highest risk of snowfall, by early sunday the cold air has once again swept across from North to South through all areas, with the coldest in the far North again, the deep low pressure(storm) pulling down some really quite cold air here. and with further low pressures next week with

some potentially deep ones! the Atlantic is sweeping in and wintry is the word not used that often this season so far! but for the South i cant use that word just yet!..

So some very interesting model watching to come for the several days ahead.

Here are the charts to go with my post!

The Atlantic storm heading towards us for Thursday

The potential storm/gale moves into the North

The storm/deep low moves away from our shores to the Northeast

The next storm for the weekend

-saturday

-gusts saturday

upper temps at 850hpa for friday evening

and early sunday(last chart)

Anything not correct please let me know!

Edited November 23, 2011 by ElectricSnowStorm

[A Winter's Tale]

GFS 18z - Outlook, potentially Stormy, wintry North.

At the moment we have high pressure in the south with light to calm winds and mostly dry conditions, low pressure brushing the north bringing windy and wet weather in from the atlantic with the rain hitting the far north now with gusts of 40-50mph here.

This week a potentially damaging storm winds up in the Atlantic and heading to our shores later this week, its something to keep a close watch on, with the wintry risk for Northern areas towards the end of the week.

by Thursday the dartboard low deepening moves into Northern areas with gales or severe gales for some areas especially the far North, while the South especially the Southeast wonders what all the fuss is about with rather calmer conditions continuing here on thursday.

Through friday afternoon/evening colder air gets all the way through to the south, with the coldest conditions setting in across the North, and this is where some wintry precipitation is likely, high ground/mountains in Scotland seeing a risk of snowfall through friday, i would say a risk of snow to lower levels down to around a few hundred meters maybe.

As we get into saturday another big deep storm pops up from the Atlantic! this one looks like more of a direct hit to our shores, the Atlantic has woken up after a quite shift! the milder air sweeps back in across the South, not getting to mild in the North though, this storm on saturday has the potential for damage with widespread effect across the North and possibly the West, gales could affect many areas, a change of track could bring the storm to hit a wider area.

As the storm moves off through sunday it brings back some cold and wintry weather for Scotland, the high ground is at the highest risk of snowfall, by early sunday the cold air has once again swept across from North to South through all areas, with the coldest in the far North again, the deep low pressure(storm) pulling down some really quite cold air here. and with further low pressures next week with

some potentially deep ones! the Atlantic is sweeping in and wintry is the word not used that often this season so far! but for the South i cant use that word just yet!..

So some very interesting model watching to come for the several days ahead.

Here are the charts to go with my post!

The Atlantic storm heading towards us for Thursday

The potential storm/gale moves into the North

The storm/deep low moves away from our shores to the Northeast

The next storm for thev weekend

-saturday

-gusts saturday

upper temps at 850hpa for friday evening

and early sunday(last chart)

Anything not correct please let me know!

Best to get the best of the Atlantic now to leave the rest of the winter for more favourable set ups for cold and snow. 2009/2010 anyone!

[ZONE 51]

Has anyone seen this Snowmodel, it looks accurate, rather fun!

http://www.snow-fore...maps/dynamic/uk

Edited November 23, 2011 by ElectricSnowStorm

[A Winter's Tale]

Has anyone seen this Snowmodel, it looks accurate, rather fun!

http://www.snow-fore...maps/dynamic/uk

I've seen it once or twice. But it's pointless for my area because of all the hills.

[ZONE 51]

Ive just read back a few pages and im really looking foward to what is interesting weather ahead, mostly all the exciting stuff for the North, but it makes model watching interesting.

Here is the Jetstream interacting with the storm, this deepens quite a few mbs as it brushes the far North, i do have a concern of what could evolve in the next few days, with what is storm trains from the Atlantic, one is likely to be severe i would think.

Chart above is Thursday

below look at saturday, see the angle of the Jet, im thinking some very damaging gusts sweeping in, i expect saturday to be the widespread storm system going by GFS

Edited November 23, 2011 by ElectricSnowStorm

[shedhead]

Good to see the thread finally latching onto the interesting and potentially severe weather later this week, rather than simply obsessing about the prospects (or rather lack of) for cold, wintry conditions. Plenty of time for that when get to winter, for now tho it's Autumn storms that look set to provide the north at least with some hitherto elusive blows.

Edited November 23, 2011 by shedhead

[Heisenberg]

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.

I have to say AWT, its so nice to see some light in here after all of the "nothing on the cards for this winter so lets pack up and go home" attitude.

Surely winter is only just begining and so anything can happen. Models change, jets move and things do happen that we cant currently see.....As others have said, the key to this season will be patience.....

[Gibby]

In summary this morning the main three models show a mobile Atlantic pattern with Low pressure crossing East north of the Uk at times. In the shorter term High pressure stays close to the South so rainfall down here will be infrequent and light while further North some heavy rain and gales would occur periodically in temperatures near normal for late November. In the longer term GFS and ECM show Low pressure digging further South with time extending the spells of heavier rain SE to Southern areas while temperatures could fall to the lower side of normal at times allowing some snowfall on Northern hills and a touch of frost anywhere at night in the quieter spells. The GFS ensembles look fairly typical for a mobile Atlantic pattern with the overall mean not far from the long term average. I'l look at the models in more depth on the 12zs later.

[chionomaniac]

Good to see the thread finally latching onto the interesting and potentially severe weather later this week, rather than simply obsessing about the prospects (or rather lack of) for cold, wintry conditions. Plenty of time for that when get to winter, for now tho it's Autumn storms that look set to provide the north at least with some hitherto elusive blows.

This little depression has its origin from some warm moist air south of the jet stream. After it crosses the jet stream this warmth interacts very well with the colder air and sits nicely on the left exit of the jet streak which allows further rapid development. It appears that it misses the UK, though cookie is probably rubbing his hands together in anticipation.

[Frosty.]

No sign of anything cold on the gfs or ecm in the reliable timeframe, the gfs 00z shows a short cold spell towards the end of the first week of december but the pattern soon flattens out again with milder air moving in. Both models show a strong but mostly flat jet blasting across the uk with shortlived ridges inbetween bringing some fine interludes between the wet and windy spells, the T850's are too warm for anything wintry for practically the whole of the uk, maybe the very far north could be cold enough for wintry showers at times but amounting to nothing really, The Gem 00z shows the coldest pattern with a brief arctic blast by T+168 with a good chance of further cold incursions, especially to the north but by far the coldest weather on the charts is this morning, with an early frost before temps recover to 11c this afternoon..generally it's not looking good for wintry prospects in the next 7-10 days at least and the 552 dam line will be a regular feature for southern britain keeping it milder in the south for much of the time but nearer average temps further north although a reduced risk of hill snow on the main models this morning.

Pattern is quite good for Scotland to get a strong windstorm at some point in the next 7 days, maybe even a couple. Not much agreement yet but the models do agree on the set-up being condusive for lows to blow up.

whats good about a windstorm kold?

[nick sussex]

Not much change this morning, mobile pattern, Euro high a few glancing shots of colder air in the far north.

The ECM has ditched its previous FI output and all the models are in generaly good agreement with the outlook.

Yet more disappointment for the European ski resorts, some snow does appear in FI but its hard to trust the models at that range especially as over recent days any amplification at that point has been flattened as we enter the nearer term.

Because of this i'd be wary if they did manage to show a PM flow into the UK unless this manages to get within 144hrs.

The ECM ensembles look pretty solid behind a mobile pattern, the control run does bring in some colder zonality later, higher wind speed and dew points close to zero which negates against this being surface cold from the limpet Euro high.

http://www.weerplaza...?type=eps_pluim

The ECM ensemble maps upto 168hrs have a few colder options with a more w/nw flow but these are far outweighed by the rest which show a much flatter pattern.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

Edited November 23, 2011 by nick sussex

[shedhead]

Not much change this morning, mobile pattern, Euro high a few glancing shots of colder air in the far north.

The ECM has ditched its previous FI output and all the models are in generaly good agreement with the outlook.

Yet more disappointment for the European ski resorts, some snow does appear in FI but its hard to trust the models at that range especially as over recent days any amplification at that point has been flattened as we enter the nearer term.

Because of this i'd be wary if they did manage to show a PM flow into the UK unless this manages to get within 144hrs.

The ECM ensembles look pretty solid behind a mobile pattern, the control run does bring in some colder zonality later, higher wind speed and dew points close to zero which negates against this being surface cold from the limpet Euro high.

http://www.weerplaza...?type=eps_pluim

The ECM ensemble maps upto 168hrs have a few colder options with a more w/nw flow but these are far outweighed by the rest which show a much flatter pattern.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

Good assessment Nick - as I said yesterday, it's difficult to have any faith in the models bringing in colder PM air longer term, when the upstream pattern

suggests things will remain essentially flat. As far as FI eye candy is concerned, 120-144hrs represents the current line in the sand for me.

[chionomaniac]

Here are the ECM and GFS10 day forecast vortex charts at 100 hPa.

These give an idea of the overall NH flow and possible wave patterns. As one can see they both look pretty zonal across the Atlantic with very little amplification at all. The direction of the GFS hints at surface troughs over East Usa and a smaller one over the UK The best we will see is NWesterlies from these.

[nick sussex]

Good assessment Nick - as I said yesterday, it's difficult to have any faith in the models bringing in colder PM air longer term, when the upstream pattern

suggests things will remain essentially flat. As far as FI eye candy is concerned, 120-144hrs represents the current line in the sand for me.

Thanks yes I agree although the overall pattern looks set its always difficult to look past that timeframe regarding how much colder air could possibly get pulled se behind low pressure.

The models have a tendency to overdo any PM air past that point so although I think the general pattern looks solid for at least the next 10 days, in terms of temps a bit more uncertainty especially for northern areas.

Looking at this mornings NAEFS thats been resolute in its outlook with troughing near or over the UK, it does however bring lower heights se towards the Med with high to the west and high building to the ne, its really how this juggling act plays out that will determine whether the UK can occasionally see some colder PM air. If the trough gets held further west its likely to turn milder, sat over the UK more average, further east a little colder.

Edited November 23, 2011 by nick sussex

[Northern Sky]

whats good about a windstorm kold?

I can't answer for Kold but personaly I really like a good storm. It's all about preferences and at the moment the models look great to me. I'm happy to wait for some real cold and although it's a shame the models always seem to water down the PM air influence, at least we are not (at the moment) looking at endless SW's.

[Frosty.]

I would say the chances of polar maritime incursions have substantially reduced since some of the output yesterday, the jet looks flatter although wavy at times as ridges occasionally push east between atlantic depressions, the airmass looks more like returning tropical maritime for the southern half of the uk but maybe more of a returning polar maritime influence for northern uk but not cold, I would say cool zoneality is more appropriate but with milder spells affecting all areas at times and the 552dam line rippling across southern england for long periods.

[No Balls Like Snow Balls]

GFS 06z = Storm moving through on Saturday with the NW and Scotland worst affeceted, everywhere will see some rain though and gusty winds. Another storm for Tuesday is on the cards with the same areas worst affected again, not in the reliable just yet so still room for change. Another low being progged for Thursday next week, but this time further South, with the strongest winds and heaviest rain in the South and West, lots happening in the models at the moment, a very dynamic period of weather we are entering Hooorah