Model Output Discussion

[Snowyowl9]

The 12z is a spectacular one with significant snow for some parts of the West & wales, possibly even the west country & ireland- not to mention Eastern scotland through convection-

not quite so good for the South & SE- the key though is some consistency on the 'cone' of error- yesterday was all over the shop- lets see what the UKMO & ECM bring to the Party- as well as how far the models sustain the cold-

S

Merry christmas Steve.

http://91.121.93.17/pics/Rtavn1021.png

[phil nw.]

The 12z is a spectacular one with significant snow for some parts of the West & wales, possibly even the west country & ireland- not to mention Eastern scotland through convection-

not quite so good for the South & SE- the key though is some consistency on the 'cone' of error- yesterday was all over the shop- lets see what the UKMO & ECM bring to the Party- as well as how far the models sustain the cold-

S

Yes more pcpn for the snow risk area than 06z.

Close to this mornings T84hr. fax i think Steve,

http://www.meteociel.fr/modeles/ukmo2.php?ech=84&carte=2000

http://www.wetterzentrale.de/pics/Rtavn722.png

A sign that the modelling is starting to home in on the detail.

[nick sussex]

A good run so far from the gfs 12hrs but i suspect it's making a meal of these shortwaves and the 12hrs often prone to overdoing these,I suspect here it's a mild outlier for southern areas in the earlier timeframe.

[swilliam]

I think there may be a better chance of getting the Easterly shown on the GEM on this run . The Siberian high is better aligned and the LP near Norway is less deep - we shall see.

[SMU]

Detail is becoming a little more focussed- Although at t 96 theres still a margin for around 200 miles either way....

THe easterly isnt developing because of the jet over iceland going west & not south west & the large uper trough over Norway- it will take time to give way....

S

[I remember '63]

Wow... 42 hour blizzard showing on this run for valleys and mid Wales.

You spoke too soon, at least for my location - starts around 3.00pm Tuesday and just about finishes at midday on Friday. That phrase 'be careful what you wish for' comes to mind. Surely this is impossible!

[swfc]

that ridge pushing up from the south is really annoying.very close to a good easterley here

[swilliam]

12Z different again, but the strong height rises remain over Greenland. There seems to have been a lot of talk about if the Low gets as far as North as shown on this sort of run then it somehow scuppers the potential cold spell afterwards - no it does not - the only thing that would scupper it is if the Low ended up off Aberdeen.

What scuppers it is the low coming under the block and generating hts over Iberia/France - like this run has just done.

What is helping this time though is the block has extended from Greenland across to Scandi

Edited December 26, 2009 by swilliam

[Snowaddict]

The 12z is a spectacular one with significant snow for some parts of the West & wales, possibly even the west country & ireland- not to mention Eastern scotland through convection-

not quite so good for the South & SE- the key though is some consistency on the 'cone' of error- yesterday was all over the shop- lets see what the UKMO & ECM bring to the Party- as well as how far the models sustain the cold-

S

Indeed Steve,

Spectacular blocking to the North @ T+150 also.. Far, far better than the 06Z.

However, the ridge building over Iberia could be the one problem away from the Holy Grail, because @ T+150 we are pretty darn close to something Spectacular,

M

[nick sussex]

Detail is becoming a little more focussed- Although at t 96 theres still a margin for around 200 miles either way....

THe easterly isnt developing because of the jet over iceland going west & not south west & the large uper trough over Norway- it will take time to give way....

S

Hi Steve

I think the ecm and gem will have the low further south, the gfs seems to be taking an age here to sink the low. The ukmo looks like spoiling the party, a poor run unless we see a southwards correcton of about 300 miles!

Edited December 26, 2009 by nick sussex

[Barb]

You spoke too soon, at least for my location - starts around 3.00pm Tuesday and just about finishes at midday on Friday. That phrase 'be careful what you wish for' comes to mind. Surely this is impossible!

Well the only way from a run like this is down isn't it? Unlikely to come off. Interesting potential though.

[phil nw.]

There could be 2 days of snow for some if this run evolved like it`s shown.

http://www.wetterzen...s/Rtavn1442.png

The fronts seem to stall and wavers and it takes until Friday before the low is far enough east to allow the cold air to the south coast.

I wouldn`t be suprised if many further south got at least some snow before it moves away.

Edited December 26, 2009 by phil n.warks.

[Evening thunder]

It all depends on location. This run is a big downgrade for me and I by far prefer the 06z run. If it turns out like this then the SW will be seeing rain and milder temps while we watch the rest of the country get all the snow again. At least most places places further north got some out of this last cold spell! so it's slightly frustrating when most people want the SW to miss out again to get another snow event for them even though it more likely means that we may turn milder afterwards instead of getting a more prolonged cold spell. when will my turn come I wonder!? :cray:Ok the 12z run downgrades the following northerly as well I seriously hope its wrong!

[Optimus Prime]

Looks like we have a block extending through Asia, Russia, Siberia cutting through the arctic and over Greenland. Have never seen blocking like this since the cold and snowy winters of the past.

[SMU]

Well not really the set of 12z Id hoped for so far- however room still for change-

12z to far north for me- but plenty of snow for some & then a sinking high in FI because we cant get low pressure under the block-

METO totally pisch again, almost dream synoptics at 144,but actually a rain fest for England the entire run-

Bit disapointed- I really hope it doesnt pan out like that- with the best AO value since december 1976 & a tanking NAO & we end up on the wrong side of the low...

S

[Optimus Prime]

That really is text book stuff.

[nick sussex]

Well not really the set of 12z Id hoped for so far- however room still for change-

12z to far north for me- but plenty of snow for some & then a sinking high in FI because we cant get low pressure under the block-

METO totally pisch again, almost dream synoptics at 144,but actually a rain fest for England the entire run-

Bit disapointed- I really hope it doesnt pan out like that- with the best AO value since december 1976 & a tanking NAO & we end up on the wrong side of the low...

S

I agree the ukmo would have me reaching for a bottle of brandy and a huge supply of comfort food if i was in the UK! to have that pattern and not get cold and snow would be a real clutching defeat from the jaws of victory scenario!

[SMU]

That really is text book stuff.

Not really- with the upper trough over Southern Norway ( just where the spolier was the other year) Its textbook stuff + 1 hitch that is the spoiler for the UK--

S

[cold snap]

Well not really the set of 12z Id hoped for so far- however room still for change-

12z to far north for me- but plenty of snow for some & then a sinking high in FI because we cant get low pressure under the block-

METO totally pisch again, almost dream synoptics at 144,but actually a rain fest for England the entire run-

Bit disapointed- I really hope it doesnt pan out like that- with the best AO value since december 1976 & a tanking NAO & we end up on the wrong side of the low...

S

Steve are you reffering to your own location or U.K overall?

[Lewis]

If you keep looking at every model, and every chart that comes off, look at the DAM shifting all the time, and look how mild the dew points are, messy 12z with shortwaves and warm sectors all over the place, certainly one i would like to put into the bin.

Let's see what the ECM shows and UKMO later.

Lewis

[Optimus Prime]

Bit disapointed- I really hope it doesnt pan out like that- with the best AO value since december 1976 & a tanking NAO & we end up on the wrong side of the low...

S

Lol you should know better. Never take each run and never compare each set with the previous set...all room for change. It's going to be the best start to winter since 1981/1982, that's the main thing.

[kold weather]

Well not really the set of 12z Id hoped for so far- however room still for change-

12z to far north for me- but plenty of snow for some & then a sinking high in FI because we cant get low pressure under the block-

METO totally pisch again, almost dream synoptics at 144,but actually a rain fest for England the entire run-

Bit disapointed- I really hope it doesnt pan out like that- with the best AO value since december 1976 & a tanking NAO & we end up on the wrong side of the low...

S

Its just about the most odd evolution i've ever seen any model output ever IMO....not implausable or anything like that, but jsut mega rare I'd iamgine.

We have a powerful Greenland block transfering eastwards and then just as everything falls into place the PV powers up and drops towards Scandinavia...its just about the only time we DON'T want to see a PV drop towards there as it forces the high to come crashing southwards...

You could probably count on one hand how many times that has happened in the 20th century, must be one pof the rarest of all evolutions simply because of the type of powerful Greenland high thats involved.

I'd suspect thats our good friend lower resolution playing a hand in the FI...the truth would more likely be a sustained SE airflow.

[rich1]

irritating output for my part of the world to say the least

was kind of hoping for better for NYE and beyond

good in the north

lots of scope for change as details hard to pin down

[cold snap]

Im really confused .Why is this run not so good?

Please can someone explain.because it looks okay to me

[SMU]

Steve are you reffering to your own location or U.K overall?

In Summary there- the 12z GFS is good for the intial snowfall over wales, midlands NW, Ireland & Eastern scotland for potentially 2/3 day of snowy weather- where the threat of snow receeds back to the NE- then because the trough over Norway doesnt want to budge we end up on the southern side of the Polar front again because of it-

so 5-6 days of cold weather & snow for some-

UKMO is rain for all except Western Scotland- has all the cold air at 144 going westwards but North of the UK-

take your pick- but I doubt these runs are close on the reality yet-

S