General Model Output Discussion:

[Cecil Hogmanay Melchett]

is gfs looking more like the GEM at 96?

[kold weather]

GREAT models this morning with the exception of GEM.

There is a critical period for this upcoming cold spell and thats around 96hrs mark,most of the models have that lp to the SW digging south but GEM doesn't,and that spells trouble.

I dont want to knit pick but thats the only potential fly in the ointment this morning.

Lets hope the gem is having a wobble and the other models dont follow it!

ecm/ukmo/gfs look amazing tho'.

Even the GEM would normally be a stunner of a run, with a 9 day cold spell, shows just how impressive and sustained the cold spell really *could* be...

[Lewis]

is gfs looking more like the GEM at 96? :unsure:

Nothing like it

GFS another excellent run on the way!

[nick sussex]

people have been saying cold 850`s etc yes it will snow if these charts come off it will be great, for weeks!! yesterday definately snow !! guess what, wrong type of cold air no snow !! i think some are just hyping things up to keep interest on here, and others are talking bull so deep you can walk in it ! come on people leave it to the known members on here. they know who they are, lets have the old dependable net weather back not this boll--s

I take it you weren't happy with your Xmas presents then! :unsure: Regarding the disappointment by some members regarding yesterdays events as Dave pointed out, it was not precip running into very cold upper air like with a longstanding block and so was going to be marginal. In terms of hype it really depends which posters you listen to in here, the main point of the low was as a trigger to reload the pattern back to cold, it was never going to be a widespread snow event.

To be honest i'm just at a loss as to some of the posts in here, IMO the longer a cold spell can last the more chances there will be for snow, but we need the cold first.

[Tom D]

It's ironic that the GEM has dropped the ball having been the one model which was showing a prolonged wintry set-up but hopefully it will just be a blip.

Well the GFS looks very similar to the GEM at +108, with the low smashing into the cold air over the UK. Could be some significant snowfall in the SW of the UK. Let's see how this pans out.

[Roadrunner]

Well all i can say is wow! These charts are bringing back memories of the cold and snowy 80's for me. Can i just ask TEITS, Nick or Steve do you think we can almost assume this is now nailed at T144 or will there be small adjustments? Seems to my novice eye that the cold will win now but weve been here so many times only for it to go pear shaped at the 11th hour. Something tells me it's different this time now though with all not being in FI AND with the big 3 on board.

[leroys35]

just look at the gem blocking out to 15 days no sign of this mornings gem on there or check out nafes charts

[Lewis]

Only thing i'm worried about now, is that the GFS is trying to shunt the colder pool/feed quicker.

It picked it up on last nights 18z, and it looks like the trend is continuing, that LP need to be further South.

How weird ay, this LP was causing the headache for the past 5 days on here, and here it is doing the same again, but this time it hinges on something very cold and prosperous for all of us!

Lewis

[snowking]

6z looks to take the track of that LP a bit further north - its fairly similar to the ECMWF, maybe a tad further north, although it doesnt elongate quite as much as the 0z ECMWF, which could make things a bit more marginal right in the far S

A definite trend for another potential channel low now though - and with cold air embedded already, maybe a bit less dissapointment this time from people who may have expected too much from the current LP

SK

Edit: I was a bit hasty there! It does eventually elongate, it just takes a different angle with more of a SEly flow. Provided the cold is embedded across france this is pretty good!

Edited December 30, 2009 by snowking

[kold weather]

Aslightly less cold 06z run thus far as the LP is a bit more to the NE as the upper block over Greenland is placed a good bit more to the west then the last run.

However a big snow event for most in the SW, with proper cold air embedded into the country by then any front will have a fight for its life to try and get any further north...

[Solar Cycles]

I take it you weren't happy with your Xmas presents then! :unsure: Regarding the disappointment by some members regarding yesterdays events as Dave pointed out, it was not precip running into very cold upper air like with a longstanding block and so was going to be marginal. In terms of hype it really depends which posters you listen to in here, the main point of the low was as a trigger to reload the pattern back to cold, it was never going to be a widespread snow event.

To be honest i'm just at a loss as to some of the posts in here, IMO the longer a cold spell can last the more chances there will be for snow, but we need the cold first.

I'm sorry Nick, but past memories of Easterlies IMBY, don't bring back fond memories. Off course your right about getting the cold established first!

[Shunter]

Normal service resumed on 6z operational run.

Cold spell finished for the South by the 4th Jan....

http://www.wzkarten.de/pics/Rtavn1322.png

Just hope this is an outlier and not a new trend !

Deja vu ??

http://www.wzkarten.de/pics/Rtavn1503.png

Edited December 30, 2009 by Shunter

[Iceberg]

Yes the charts are very cold and are as good as can realistically be.

However lets not start bashing anyone that dare say anything negative or even realistic. !.

Ice days across England are out at T150+ So still pretty much beyond the reliable timeframe, also this far out trying to gets temps right is nigh on impossible.

Talk about the netherlands ensembles rarely geting a mean of 0, is also way off the mark, It frequently has a mean of 0 in winter. !. Also the netherland ensembles are a pretty poor indicator for the UK, lets wait a hr or so for the London ones.

Back to the models GFS brings the low in more (there was previously support for this from the other ensembles and the METO ensembles according to Ian.

If so parts of the SW could get alot of snow (also notice the raise in 850's).

[Cecil Hogmanay Melchett]

Not liking 06z at all.

:unsure:

Yes it shows a cold spell but its getting very marginal by tuesday for many!!

[Lewis]

This post is to the more "experienced members" regarding models, whats the chances of this LP just buggering off? and pushing south into France so we can get a full on NE/Easterly?

Like yesterdays 12z lol.

Lewis

[swfc]

hmmm,well there goes our record low temps.lol.See how this run pans out :unsure:

[kold weather]

Not quite so good in the mid term this run, though still not witohut interest but the LP is amazingly stubborn to get out of the way because the upper high is just that bit too far west on this run.

Still its not without interest, a decent snow event coming in though this run really isn't what you want for sustained cold, much further north and that low would become more of a problem then a help.

I'd imagine the 06z will be very much on the milder side of the ensembls as well...

[Yeti]

The 6z has the trough over the US weaker at 144 compared to the 00z and this demonstrates perfectly the effects this would have. Still a very good run (!) but as the trough is weaker over Baffin and slightly further SW, the block retrogresses W of Greenland with only weak ridging into Iceland:

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

As a result, the Atlantic low is pushed under the block at an earlier stage and then moves slightly more NE - and whilst this keeps the UK in an easterly flow, the rest of Europe warms (notice the southerly flow over the Alps). This then filters over the South of the UK as the source of the easterly is not as cold here:

http://www.wetterzentrale.de/pics/Rtavn1442.png

Not really too much to worry about at all at this stage but it shows how important it is for that trough to develop as deeply and as far NE as possible to hold the block further E.

However I do remember the NOAA discussion yesterday suggesting that the trough should be weaker than progged, though still further NE, so perhaps the 6z has some support in this respect.

Ideally we want the low to track as far S as possible, even over the Alps as in yesterday's 12z ECM although today's other models are still outstanding. :unsure:

Edited December 30, 2009 by Yeti

[nick sussex]

Normal service resumed on 6z operational run.

Cold spell finished for the South by the 4th Jan....

http://www.wzkarten.de/pics/Rtavn1322.png

Let me get this straight you believe the gfs 06hrs run over the ecm and the general model guidance!and anyway this would bring major snow and is totally different to this low currently as its running into cold air embedded at the surface, anyway i don't know why i'm even talking about this gfs run as it pulls the block too far west and so is rubbish and won't verify.

[Pennine Ten Foot Drifts]

Well, no doubting the potential across all the models. So, playing devils advocate and applying the old 'what can go wrong will go wrong' approach, what should we be watching out for in the models which might scupper this, because whilst everyone agrees that the current predictions are great, no-one has yet stuck their neck out and said that a remarkable cold spell is absolutely nailed for next week.

Edit: maybe the 06z has provided one answer !!!

Edited December 30, 2009 by Pennine Ten Foot Drifts

[Lewis]

28.7%

Thanks for an exact % :unsure:

This 06z is certainly not over, i think the LP is starting to fill and sink Southwards drawing in an E/ESE wind with colder upper again.

Lewis

[TEITS]

Not liking 06z at all.

:unsure:

Yes it shows a cold spell but its getting very marginal by tuesday for many!!

Not sure where your getting marginal from as this is a band of heavy snow across Wales, Midlands, E Anglia.

http://www.wetterzentrale.de/pics/Rtavn1624.png

However I would prefer the 0Z. At +144 the 06Z is very much at odds with the ECM/UKMO.

Edited December 30, 2009 by THE EYE IN THE SKY

[kold weather]

Not liking 06z at all.

Yes it shows a cold spell but its getting very marginal by tuesday for many!!

Nothing marginal for those away from the SW and the far south, for most places thats a big snow event on the 06z GFS.

Anyway the 06z is amazingly stubborn to shunt the upper low to our SW out of the way because the upper high just doesn't have the thrust and power to shunt it out of the way witohut help from the diving PV to our north.

Painfully slow evolution though has to be said, I'm fully expecting this to be one of the mildest runs of the ensembles in the south.

[Barb]

Hmmm I'm getting a feeling of Dejavu

Hopefully the result is much better this time.

[Guest North Sea Snow Convection]

I should have added to my earlier post, that one thing that never changes on model output discussions is following the hyperbole, there will always be a single GFS output to follow that sends some people panicking off in the other direction.

Not the ideal result we would want to see in terms of sustaining a very cold spell - but the 06z is pretty much out of kilter with the other models. The general guidance has been that the block will be further east for this period - the GFS here wants to shunt off too quickly westwards. This will be very much on the mild side of the bunch methinks