Model Output Discussion 18/11/2012 12Z onwards

[Gowon]

Don't be silly RP...

Edited November 19, 2012 by Seselwa

[UV-RAY]

I don't want be the one to deflate things - but isn't the 06Z missing a lot of balloon data?

Only when it's showing a mild outcome.

[snowking]

I think you will find the last chart is nearer than the others to what actually happens

Very much hope so John

0z extended ECM control out at around +300 has the trough dropping down the north sea and strong greenland heights too, more of a NNE flow than the ENE suggested by the NAEFS and 6z GFS, but more and more support for Greenland ridge/Scandi-North Sea trough developing now

SK

[snowmadchrisuk]

I think the initial actual outcome will be close to what john thinks, but the far reaches of FI could very easy happen after. I am wondering if the constant Low pressures will be good or bad for the South, If Cold air gets embedded then it could mean Snow heaven and constant undercutting of the Northern Block. But it could also mean there is a constant threat of Milder air especially in the SW .... I think it is going to play out so it will deliver for everywhere eventually , but the South could have to wait a little longer for any fun and games until we get some Cold air embedded. M4 North though FI is Winter wonderland.

[nick sussex]

This from the NOAA aviation longer term discussion:

RETURN TO WARMER WEATHER HEADING INTO SUN AND MON...BUT DO NOT

THINK IT WILL LAST ALL THAT LONG THIS TIME. HIGH LAT BLOCKING IS

BEGINNING TO TAKE PLACE IN THE KARA SEA AREA AND IS LIKELY TO BRIDGE

WITH THE EASTERN PACIFIC RIDGE...ALLOWING FOR DEVELOPMENT OF MORE

CROSS POLAR FLOW AND COLDER TEMPS FOR MUCH OF CONUS.

[Zakos]

GFS giving full support for major northern blocking, and massive polar vortex disruption. Last three runs have been astonishing if you look at the polar setup.

ECM also showing a very blocked pattern, but the PV looks slightly to strong in order for there to be a potent and long lasting cold spell, it doesn't look as if the block gets far north enough. close but no cigar it seems.

Unfortunately, amazing charts like this are just out of the reliable timerframe on the GFS.

It will be a few days yet before we can start to really get our hopes up.

Some form of northern blocking is virtually certain IMO. I am confident the above chart depicts a perfectly plausible scenario, but we must have cross model support, and although things are looking very good, the time range is just too far to start greasing your sledge runners. There is still enough time for significant downgrades to occur.

This week is going to make for nail biting model watching

Edited November 19, 2012 by Zakos

[Joseph Watts]

Amazing GFS 06z in FI!

[Ice BIast]

I had to post this run from one of the GEFS ensemble members, its just insane!

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=13&mode=0&carte=1

[pyrotech]

I don't want be the one to deflate things - but isn't the 06Z missing a lot of balloon data?

As is the 18z but remember even without this data, 18z has often been the first to spot a trend and it was gfs 18z that first showed the winter 2010 cold.

The computers run a full processing with too much data, so may be less data actually helps GFS spot a trend in fi.

I am not quoting that as fact, i really do not know why. But this often crops up in GFS 18z and 06z runs that it finds the trend and is the only feasable reason i can come up with, an educated guess. So especially with the 18z do not fully discount it in fi just coz it has less data inputted.

[lightningst]

I had to post this run from one of the GEFS ensemble members, its just insane!

http://www.meteociel...&mode=0&carte=1

can i ask whats insane about it? as it dont look so its that cold over the uk in the chart you have posted.

[Joseph Watts]

I had to post this run from one of the GEFS ensemble members, its just insane!

http://www.meteociel...&mode=0&carte=1

Blimey! That would be spectacular if it happened!

[MR EXTREMES]

cross polar setup sounds good to me.

id love to see the experienced put a percentage on the likely outcome of cold whether it be cold and settled or cold and unsettled.

[MR EXTREMES]

can i ask whats insane about it? as it dont look so its that cold over the uk in the chart you have posted.

thats insaine due to the easterly flow coming round from siberia in a very strong flow would be bone chilling even with modification over the north sea,

but also possible some sharp snow showers.

but id rather a direct straight northeasterly then your talking arctic bone chilling with shed loads of snow.

Edited November 19, 2012 by badboy657

[Ice BIast]

can i ask whats insane about it? as it dont look so its that cold over the uk in the chart you have posted.

It's the blocking over greenland. Its not too often you see red on these charts in that area.

Edited November 19, 2012 by lce Blast

[Zakos]

can i ask whats insane about it? as it dont look so its that cold over the uk in the chart you have posted.

it certainly is

[Buriedundersnow]

just came on and checked the charts and is it just me or is the gfs maybe coming up with a solution as both the last 2 runs were very similar to each other

[Harve]

While the British Isles don't get a chilly blast until well into FI, heights begin rising and warm air is dragged up to western Greenland at around +150, which is encouragingly soon. Meanwhile, conditions look to settle down after Thursday, and temperatures meander between slightly below average to rather mild. Despite a rather blocked Atlantic/Arctic for most of the run, it takes until +324 for the real cold to arrive.

it certainly is

That's only one perturbation (presumably the coldest), and not the Operational run that everyone else is looking at.

edit: oops, I should've read what you were replying to - excuse me.

Edited November 19, 2012 by Harve

[BLAST FROM THE PAST]

If the MetO rate the JMA......then its run is worth looking at....its very pleasing to the eye. Sorry can't post the link as at work

BFTP

[AWD]

If the MetO rate the JMA......then its run is worth looking at....its very pleasing to the eye. Sorry can't post the link as at work

BFTP

Yes, the JMA as good amplification to the east & west of us as soon as T120, with colder air filtering down over the UK as early as T144;

http://www.meteociel.fr/modeles/jma.php?ech=120&mode=1&nh=1&archive=0

http://www.meteociel.fr/modeles/jma.php?ech=144&mode=0&nh=1&archive=0

With heights to the NE & NW of the UK by T192;

http://www.meteociel.fr/modeles/jma.php?ech=192&mode=1&nh=1&archive=0

Keeping the colder air over the UK;

http://www.meteociel.fr/modeles/jma.php?ech=192&mode=0&nh=1&archive=0

[AWD]

Not much as been said of the GEM this morning either but that's another model that has height rises to our NW by day 10, along with a trough to our SE;

http://www.meteociel.fr/modeles/geme_cartes.php?ech=240&code=0&carte=1&mode=0&archive=0

[MR EXTREMES]

Yes, the JMA as good amplification to the east & west of us as soon as T120, with colder air filtering down over the UK as early as T144;

http://www.meteociel...&nh=1&archive=0

http://www.meteociel...&nh=1&archive=0

With heights to the NE & NW of the UK by T192;

http://www.meteociel...&nh=1&archive=0

Keeping the colder air over the UK;

http://www.meteociel...&nh=1&archive=0

indeed the fax charts show the start of pressure rise botheast and west.

[lightningst]

it certainly is

thanks for all the answers I understand now.

[SMU]

Afternoon All-

Well the wheels feel firmly in motion today- I would say the overnight UKMO looks the best with a better angle of ridging towards greenland V the ECM, however they all get there in the end.

Its been a long time coming & the GFS has thrown so many doubts into the equation- & we need to remember the model bias for next time around-

now though- the atlantic ridge is in the semi reliable timeframe, so even runs like the 06z will throw up crackerjack runs because the heights are in the right place before you get to the lower resolution part.

lets hope what actually lands some 8 days from now is worthy of the build up!!!

S

[Ian Brown]

Indeed Steve, but it will take longer than 8 days to get any proper cold air here. Some potential great blocking available but we will need the pressure alignment to be spot on to tap into the eventual cold air from the N/NE/E. SEerlies are not going to be much fun at this stage.

[January Snowstorm]

Well Steve I have to say both yourself and GP were adament changes were afoot when the models were having none of it.

It's looking good now though and it's clear the Meto share the same view.

Edited November 19, 2012 by January Snowstorm