Model Output Discussion 23/11/2012 18Z onwards

[Snowmad79]

Without ramping... Some could see none stop snow for 24 hours or more Snowmageddon even. Don't think I need to view anymore of the GFS run after 168hr because it reaks of awesomeness.

Edited November 25, 2012 by Snowmad79

[Met4Cast]

WAA into Greenland, yes, but not perfect, however energy from the low is going Northwards to the West of Greenland so that's perfect!

This'll help support blocking across Greenland, the colder air is now flooding South-Westwards out of Scandinavia. Much, much cleaner evolution from the 00z and moves a step closer to the UKMO.

Don't take the rest of the run from T144 onwards too seriously.

[LomondSnowstorm]

WAA into Greenland, yes, but not perfect, however energy from the low is going Northwards to the West of Greenland so that's perfect!

This'll help support blocking across Greenland, the colder air is now flooding South-Westwards out of Scandinavia. Much, much cleaner evolution from the 00z and moves a step closer to the UKMO.

Don't take the rest of the run from T144 onwards too seriously.

Quite right, from here on in this is the fun run really:

This was the slight southward adjustment we were looking for. A bit more to lower the margin of error would be grand too but this looks a nice solution and we're at that stage I believe where, hopefully, we should be looking for how optimal the cold is rather than whether there will be a cold spell at all. Now for the UKMO

[Met4Cast]

Quite right, from here on in this is the fun run really:

This was the slight southward adjustment we were looking for. A bit more to lower the margin of error would be grand too but this looks a nice solution and we're at that stage I believe where, hopefully, we should be looking for how optimal the cold is rather than whether there will be a cold spell at all. Now for the UKMO

Agreed. I think we can say with certainty now that it WILL be turning colder next week, the questions are whether it can be sustained, how cold it'll get and where will the snow fall? Great to see the GFS ditch it's fetish with the short waves to the South of Greenland on this run. Lets hope the UKMO doesn't suddenly start wobbling!

[Panayiotis]

WAA into Greenland, yes, but not perfect, however energy from the low is going Northwards to the West of Greenland so that's perfect!

This'll help support blocking across Greenland, the colder air is now flooding South-Westwards out of Scandinavia. Much, much cleaner evolution from the 00z and moves a step closer to the UKMO.

Don't take the rest of the run from T144 onwards too seriously.

Yes hopefully it can continue with the 06z.. Edited November 25, 2012 by panayiotis

[Met4Cast]

BINGO

UKMO remains consistent, wow!

[LomondSnowstorm]

Looking good:

Better:

And it stuck the landing!:

Game on.

[LomondSnowstorm]

Just calculated the uppers coming into the east coast on that UKMO: widely sub -8C, sub 520dm air flooding over the UK with more to come. A direct hit.

[Met4Cast]

Just calculated the uppers coming into the east coast on that UKMO: widely sub -8C, sub 520dm air flooding over the UK with more to come. A direct hit.

The consistency from the UKMO in the last couple of days has been remarkable! The BOM has been pretty consistent too with it's modelling whilst the GFS has been all over the place, I don't think I can remember the last time the GFS was quite this inconsistent!

[Zenarcher]

UKMO and GFS great runs so far,

UKMO 144 looks great,

[Dave Kightley]

Great Charts this morning! Look's all go from next weekend but wouldn't be surprised on a late upgrade with the Northerly Wednesday either

[Panayiotis]

Time to go bed; in the short to medium time frame looking better for cold and possibly snow, weird end to the run with a greenland block and high pressure over Europe with low pressure stalling out in the atlantic to bring us warm southerly winds, but its FI so it doesnt matter!

Edited November 25, 2012 by panayiotis

[LomondSnowstorm]

The consistency from the UKMO in the last couple of days has been remarkable! The BOM has been pretty consistent too with it's modelling whilst the GFS has been all over the place, I don't think I can remember the last time the GFS was quite this inconsistent!

Probably the last big cold spell. I recall one cold spell where even at +48 there was divergence between the others and the GFS and we genuinely had to startlooking at the high resolution charts for larger scale synoptic guidance!

[Dave Kightley]

The consistency from the UKMO in the last couple of days has been remarkable! The BOM has been pretty consistent too with it's modelling whilst the GFS has been all over the place, I don't think I can remember the last time the GFS was quite this inconsistent!

I swear over the years it struggles with most things other than default

[LomondSnowstorm]

Time to go bed; in the short to medium time frame looking better for cold and possibly snow, weird end to the run with a greenland block and high pressure over Europe with low pressure stalling out in the atlantic to bring us warm southerly winds, but its FI so it doesnt matter!

A bit odd in FI, a much better one though than the 12Z certainly, with Scotland never really losing the cold pool until the end when a reload looks like coming in from the northeast. This:

would potentially be very snowy.

[Dave Kightley]

Lots of snow potential in FI is well.

Lows trying to break through is always a good thing for frontal snowfall across the south as long we stay on the right side of it of course.

[essexweather]

Nice UKMO run. 850s of -5c to -7c across England and Wales, a unstable North-Easterly flow wrapped up with thickness of around 527!

Vastly improved GFS run as well. Now we await what the ECM has in store :o

[Great Plum]

To my untrained eye, ECM looking good at 144hrs... - -5 air flooding over most of the country...

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

http://www.wetterzentrale.de/pics/Recm1442.gif

[Dave Kightley]

To my untrained eye, ECM looking good at 144hrs... - -5 air flooding over most of the country...

http://www.wetterzen...cs/Recm1441.gif

http://www.wetterzen...cs/Recm1442.gif

Not bad.. The think the heights over Greenland are best on the UKMO this morning and quicker getting the uppers here then the others too.

Not far off the GFS run i don't think? At 144h anyway

Edited November 25, 2012 by Dave Kightley

[chionomaniac]

To my untrained eye, ECM looking good at 144hrs... - -5 air flooding over most of the country...

http://www.wetterzen...cs/Recm1441.gif

http://www.wetterzen...cs/Recm1442.gif

It is the deep depression at the tip of Greenland that needs watching here.

The direction of travel is all important. In zonal years it races towards the UK, but this year it does not!

Yes - it heads north reinforcing the split section of Canadian vortex and keeps us in cold flow for the foreseeable....

To edit T+192 onwards shows what happens if energy escapes eastwards....still a cooler flow though.

Edited November 25, 2012 by chionomaniac

[Jupiters Winter]

ECM Wobbles' in terms of long term

[chionomaniac]

Even if the ECM correctly guesses the amount of energy crossing the Atlantic ( which I supect it hasn't), any run that ends with a Svalbard 1035mb high with increased heights is no bad run ( and is certainly not zonal and leaves the window still very much open).

And this should be remembered when the usual doom mongerers wake up and view the charts.....

Edited November 25, 2012 by chionomaniac

[Liam J]

Hmmmm.... What has happened to the ECM, it looks more the like the GFS with a heightened risk of an Atlantic attack. The depression doesn't actually make it much further east from from that position, but, it's still a bit close for comfort!

GEM looks quite horrific but thankfully all post T200 so really not worth getting overly concerned about.

UKMO looks stunning, I really hope this model will prove correct on this one.

Edited November 25, 2012 by Liam J

[bluearmy]

Ecm fi - i suspect the depression is overdone and if this is the correct solution in general terms, its direction of travel will be further se.

I would wait to see where it sits within its ens (berln, rome and warsaw etc important here). Looks like it takes the troughing too far north in its entirety early part of the run.

encouraging strat forecast aswell with warmng back above average now on the agenda. stewart made the point yesterday about what happens with the canadian part of the split vortex. That still seems crucial to what follows the initial cold next weekend. Currently, there seems to be too much energy left too close to greenland though developments following that with another aleutian ridge etc etc will probably take care of that eventually.

[Nick F]

Hmmmm.... What has happened to the ECM, it looks more the like the GFS with a heightened risk of an Atlantic attack. The depression doesn't actually make it much further east from from that position, but, it's still a bit close for comfort!

Yes, we need to keep a close eye on developments upstream over N America, as there are signs that the Canadian Vortex may elongate eastwards across the NW Atlantic/S'ern Greenland - which would strengthen the upper flow eastwards across the Atlantic towards NW Europe, with an attack from Atlantic depressions. All past t+168 atm, so wouldn't get too concerned for now until the models keeping showing this scenario.

Chances are though, the block towards Svalbard may have enough strength to suppress the PFJ enough to keep any mild attack from the Atlantic at bay.

Colder air characterised by T850s AOB -5C creeping south on Wednesday & Thursday, though the N'erly flow looks fairly dry to the end of the week, apart from the usual wishbone effect with showers around the coasts, which look to turn increasingly wintry through the week.

Edited November 25, 2012 by Nick F