Model Output Discussion 26/10 2012 >

[camiscool]

whens the ecm out?

[Buzz]

whens the ecm out?

[Summer Sun]

whens the ecm out?

Between 19:00 and 20:00 BST

18:00 to 19:00 GMT

Edited October 26, 2012 by Summer Sun

[SMU]

http://www.meteociel...H1-168.GIF?26-0

Huge Pressure rise across the pole at 168 on the ECM especially East based ( towards Svalbard)

At some point that whole lot will be heading SW.....

S

Edited October 26, 2012 by Steve Murr

[AWD]

The GFS Op was pretty much a cold outlier in the second half of its output all the way through;

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=306&y=141&ville=Londres

[Gibby]

Good evening. Here is the latest review of the 12z output from GFS, UKMO and ECM taking a lok at the GFS Ensemble data and Jet Stream outlook on the way.

All models show a cold and showery Northerly flow over the UK. Inland the weather will become dry this evening and overnight with increasing amounts of clear skies and frost by dawn. In Eastern counties of Scotland and England some wintry showers will occur overnight with slight falls of snow possible over the hills for a time. The Northerly will back Westerly through tomorrow cutting off the cold feed as Low pressure develops to the North of Scotland. A series of fronts will move East and Southeast across the UK over Sunday with rain pushing across all areas through the day. Monday sees the rain clearing South with a chilly and bright day with just a few showers following. By Tuesday and Wednesday a deep and intense Low pressure develops near Northern Scotland with strong winds and heavy rain sweeping over the nation followed by rather chilly and blustery conditions with heavy showers midweek.

GFS then moves into the latter stages of the week with continued unsettled weather as North or Northwest winds bring cold and rainy weather with some snowfall on higher hills at times. Into FI and High pressure tries to build in from the West and eventually it succeeds. the unsettled weather of the week before lessens with time, being replaced by fine and frosty conditions with patchy fog too. In the SE a Northeast flow could keep the fog away but it would feel raw in the wind and probably be rather overcast. High pressure clings on late in FI before moving slowly SE at the end of the run dissolving the NE winds and occasional rain from the SE to be replaced by slowly rising temperatures and a SW flow to end the run.

The GFS Ensembles show the operational as a big cold outlier in the South but less so in the North. All areas see plenty of rainfall in uppers which average at a level a little bit below the long term average.

The Jet Stream forecast shows the Northern arm exiting Southern Greenland and moving SE ovr the UK over the coming days. The Southern arm gradually weakens in the coming days too. In a week or so the flow takes up residence blowing East near to Southern Britain.

UKMO at noon on Thursday shows Low pressure just off Northern Scotland with a rather cold and unstable cyclonic airflow over the UK. All areas would see plenty of heavy and thundery showers, falling as snow over the hills and mountains of Northern Britain merging into longer spells of precipitation at times.

ECM shows rather cold and unsettled conditions too at 144 hours in a synoptic setup similar to UKMO. It evolves forward keeping deep Low pressure just North of the British Isles with an unstable and showery (wintry over the hills of the North) Westerly wind over all areas with further troughing developing to the SW on day 7. With Northern blocking looking strong this evening the Low pressure to the North of Britain has nowhere to go so the UK remains in a very unsettled and rather cold mode with showers and some longer spells of rain with snow on Northern hills at times.

In Summary a very unsettled outlook is likely over the coming week or two. With Low pressure having origins well North of usual there will be rather cold conditions for the UK with some snow at times on Northern hills and mountains. Elsewhere either heavy showers or longer spells of rain will occur with some regularity in a blustery wind for most of the time. In FI tonight GFS does show an incursion of High pressure through FI but it was an outlier with a more changeable FI the more likely option from the ensembles. ECM shows strong Northern blocking still evident at the end of it's run with the prospect of further cold and unsettled persisting for some days after day 10.

[chionomaniac]

The GFS Op was pretty much a cold outlier in the second half of its output all the way through;

http://www.meteociel...1&ville=Londres

What that doesn't show AWD is that at no point does the mean ensemble get above average. A cool set of runs from the GFS.

[Geordiesnow]

http://www.meteociel...H1-168.GIF?26-0

Huge Pressure rise across the pole at 168 on the ECM especially East based ( towards Svalbard)

At some point that whole lot will be heading SW.....

S

Yep, the models are certainly hinting there will still be some areas of high pressure around at higher latitudes which of course always can lead to some sort of blocking down the line.

Interesting output at the moment, remaining on the cool side and as I said yesterday, with some very low thicknesses around, that is a good recipe for convective showers, the highlands could get quite a bit of snow if things remain cold enough.

[tcc]

What a beautiful chart...where's the PV again?

Isn't this what is termed a 4 wave pattern? Would this pattern also help chiono's Canadian Warming....maybe?

[SnowObsessor90]

Whatever happens from this point onwards I have to say it's been a very interesting week or so of model watching, what we would have given for similar looking charts last year when all they were showing was boring mild and settled rubbish.

[Continental Climate]

seems to be a hint of pressure rises to our north and also continuing pressure in the mid atlantic on all the main models at 144 which has got to be good news for cold lovers.

http://www.wetterzentrale.de/pics/Rtavn1441.png GFS

http://www.wetterzentrale.de/pics/Rukm1441.gif UKMO

http://www.wetterzentrale.de/pics/Recm1441.gif ECM

As SM said the northern hemisphere picture after 144 is also particularly encouraging with a split or non existant vortex.

http://www.wetterzentrale.de/pics/Recmnh1681.gif

http://www.wetterzentrale.de/pics/Recmnh1921.gif

Not sure where all this is coming from though as the strat forecasts arent that encouraging at the moment i think.

Maybe one of our resident experts could tell me why all this Northern blocking is forecast to take place as it all looks potentially very impressive.

[scottishandy]

Just a quick thought, and hopefully counted as model discussion, but I think Steve M was looking at a specific gfs chart just over a week ago. On my phone so not able to check accurately but to my amateur eye that chart looked pretty similar to what we now have! And we had a snow shower today :-) Anyone able to confirm or deny?

[NorthernRab]

Not sure where all this is coming from though as the strat forecasts arent that encouraging at the moment i think.

Maybe one of our resident experts could tell me why all this Northern blocking is forecast to take place as it all looks potentially very impressive.

I could be wrong, but only about half of all "big" coldspells are preceded by sudden stratospheric warming. It's perfectly possible to get a block without a SSW.

[chionomaniac]

I could be wrong, but only about half of all "big" coldspells are preceded by sudden stratospheric warming. It's perfectly possible to get a block without a SSW.

It's always worth pointing that out, but it is also worth mentioning that we have yet to see northern blocking following a vortex intensification (VI) event following a supercold strat.

Somewhere in the middle is fine.

[Cloud 10]

The 12z NAEFS at day 10 slowly migrates the main trough to our East,so looks like

cool/cold and unsettled for the forseeable future.

Today's CPC 500mb outlook showing a similar idea.

Climate Prediction Center - 8-14 Day 500mb Outlook

[Don]

The 12z NAEFS at day 10 slowly migrates the main trough to our East,so looks like

cool/cold and unsettled for the forseeable future.

Today's CPC 500mb outlook showing a similar idea.

Climate Prediction Center - 8-14 Day 500mb Outlook

That outlook looks the complete opposite to this time last year?

[Met4Cast]

The 12z NAEFS at day 10 slowly migrates the main trough to our East,so looks like

cool/cold and unsettled for the forseeable future.

Today's CPC 500mb outlook showing a similar idea.

Climate Prediction Center - 8-14 Day 500mb Outlook

A trend we can hopefully see continuing over the coming days. Ideally we want that trough to be to our East rather than over us, opens up a lot more potential for colder air being sucked down from the North.

[Cloud 10]

That outlook looks the complete opposite to this time last year?

Indeed,a totally different ball game to last year!

[Neilsouth]

Does having the main trough over the east give colder conditions for north/north eastern europe which is better in the long run?, where does the trough usually sit itself in a zonal pattern?

[liam300]

Not too impressed by this

[chionomaniac]

Not too impressed by this

Please explain why not, Liam. Thanks

[JP1972]

Oh dear Liam, the MOD's are still up

Snowing in Newcastle

[Tim Bland]

Not too impressed by this

But compare that to the above from

Last year and it's a much better position to be in moving towards winter. Less structured and powerfull PV and better heights to our north. Could be allot Worse IMO. Hopefully the predicted warming occurs and has an impact end of nov.

[Adam lufc]

Presuming the 18z gfs not very good as no comments.

[SnowObsessor90]

And yes FI is a bit boring to say the least.

Let's hope it hasn't started to pick up on a new trend. Now I know it's the 18z and deep FI thus shouldn't be taken too seriously but I've seen this kind of thing happen on numerous occasions before.