Model Output Discussion - 8th - 14th January

[Summer Sun]

I'm guessing the 12z was a good run then?

Yes it is a good run only right out at 384hrs does mild air show it's self again but other than that its better than it has been for cold lovers maybe not much snow though at times with high pressure keeping it cold but mostly dry.

384hrs

Edited January 9, 2012 by Gavin D

[danm]

Can't see what all the fuss is about. 12z isn't that good a run in my eyes:

Okay, we start with a better looking PV for cold over the UK, it's been weakened substantially, split in half almost, probably aided by the stratospheric warming we've been seeing lately.

With this hemispherical chart, we can take a look at the jet stream. Looking good I must say, it's a southerly tracking jet, a good indication that cold will be aloud to build:

Although, if we move forward towards the latter part of the run, disaster happens. We see the PV really shifting into gear yet again, and we are seeing mild westerlies:

With an absolutely raging northerly tracking jet:

Not good at all in the latter frames. A good upgrade in the medium term though. I think if FI verifies, we can probably write off February.

The point is, we are finally starting to see some decent cold weather being modelled in the reliable time frame. Yes, even the 12z shows the jet moving back across us and milder weather returning, but that is out in FI and hence nobody should be getting hung up on those kind of details at this stage.

There are a lot of background signals now giving us a POTENTIALLY cold 2nd half to winter.

[johnholmes]

Can you explain more about the Hadley Centre? Not heard this before? Are you refering to the Meto long range outlook of the ECM extended model?

My Concern re the 12Z is that it is V dry. I would rather take my chances with a low undercutting and marginal snow events. At least this way we can drive up a hill if necessary to see some snow! The 12Z would be dry and cold for the majority of the uk with the odd flurry in the east. Nit picking I know and its the overall synoptic we need to look at.

the Hadley centre have nothing to do with routine forecasting. ECMWF products are assessed by a team within the main forecast room at Exeter.

The Hadley Centre is a separate centre given to climatological research only.

not exactly a beasterly - the 12Z gives us a cold spell rather than prolonged period - but an easterly with widespread -10 uppers and potential opportunities for snowfall. wait for ECM and the ensembles, then worry about UKMO - the Hadley centre altered the 32dayer this morning and that says all you need to know about the uncertainties attached to the upcoming pattern change.

see my reply to another poster-Hadley have nothing whatever to do with forecasting they are the climatological centre

[Zakos]

Can't see what all the fuss is about. 12z isn't that good a run in my eyes:

Really? http://nwstatic.co.uk/gfsimages/gfs.20120109/12/240/h850t850eu.png This is without doubt the best chart I have seen since last winter. Huge upgrade on the 06z.

Of course I agree that we shouldn't get our hopes up because we need the ECM to back it up first at least.

But to use a chart at 384 hours out which shows mild while the rest of the run shows deep cold is just plain wrong.

[Summer Sun]

After the excitment UKMO has gone un-noticed is not perfect but its not bad either

Really? http://nwstatic.co.u.../h850t850eu.png This is without doubt the best chart I have seen since last winter. Huge upgrade on the 06z.

Of course I agree that we shouldn't get our hopes up because we need the ECM to back it up first at least.

But to use a chart at 384 hours out which shows mild while the rest of the run shows deep cold is just plain wrong.

Indeed and just look what your link above brings

Lets try and be positive for once changes are happening not every run may be perfect but that's life the past 3 or 4 days have saw huge changes towards somthing colder, now for ECM

[Backtrack]

Really? http://nwstatic.co.u.../h850t850eu.png This is without doubt the best chart I have seen since last winter. Huge upgrade on the 06z.

Of course I agree that we shouldn't get our hopes up because we need the ECM to back it up first at least.

But to use a chart at 384 hours out which shows mild while the rest of the run shows deep cold is just plain wrong.

The same could be said for you. That 'best looking' chart, is at +252hrs. Even if it was to verify, it's watered down to hell by the next frame, and disappears the frame after. Hardly spectacular?

[phil nw.]

Although UKMO still shows the Atlantic winning-just-at T144,it`s a closer run thing than the 00z version

The GFS continues the same trend as it`s 006z run and again shows signs of the Greenland Vortex losing some it`s influence at last and sending more energy SE.

The block is not classic by any means but it does enough to halt the Atlantic and this is a step towards a colder pattern.

Now let`s see if the ECM continues along this road.

[Earth Wind and Snow]

This morning the main 3 models were all showing a different outcome at T120-144

This evening UKMO and GFS have a diffeent outcome at 120 again

ECM will be interesting this evening to see if it backs up either of the above models or goes its own way again

FI was T96 this morning and will probaby still be T96 this evening so probably another day or so before the weekend / early next week is resolved

This type of uncertainty normally only occurs in the build up to a cold spell - all eyes down for ECM then

EWS

[Zakos]

The same could be said for you. That 'best looking' chart, is at +252hrs. Even if it was to verify, it's watered down to hell by the next frame, and disappears the frame after. Hardly spectacular?

No one said it was spectacular though did they .... and it is compared to anything we have seen this winter....

I genuinely fail to see how you think this is a poor run. Everyone else on this forum seems to think the opposite.

[LomondSnowstorm]

The control run too has a very interesting evolution with the jet managing to properly undercut into FI after a major battleground scenario for central and northern Britain

http://176.31.229.228/modeles/gens/run/gens-0-1-192.png?12 http://176.31.229.228/modeles/gens/run/gens-0-0-192.png?12

[Snowy Easterly]

Control run in FI is a stonker

[bluearmy]

Fair to say that the op is not without ens support. will be interesting to see the ecm postage stamps this evening.

[Backtrack]

No one said it was spectacular though did they .... and it is compared to anything we have seen this winter....

I genuinely fail to see how you think this is a poor run. Everyone else on this forum seems to think the opposite.

The way you posted it, you were implying that it was wonderful.

Tbh, I don't see how a dry, convection lacking 1 and a half day SE'erly is the best chart we've seen this Winter. The best charts were the start of December for us in the West. We had a few inches of snow from a NW'erly.

Although there is some agreement from the models for an Easterly, I don't see it coming off, and think any cold will likely be from the North.

Onto your second comment, I really don't care if everyone else thinks it's a pukka run, I can see the potential in the medium term, hence why my original post was non-bias, covering both mild and cold. Everyone interprets the models in a different way, and I have chosen to interpret it in the way I please. If you have a problem with my posts, please put me on ignore.

[saintssupporter]

what time is the ecm update?

[weatherguy]

Lovely OP run on the GFS 12z; I think we all know that it's what is shown in the short-medium term that is the important stuff - How many times did FI show the block breaking down into raging zonality last year? Main thing is that there are promising signs of an easterly of some kind (definitely a pattern change at least) creeping into the reliable time frame*...Unfortunately they are quite hard to achieve and may implode before our eyes as we approach it, but for now I'm optimistic

As to snowfall potential, would we not get a fair amount of convection coming off the North Sea?

*With the stratospheric warming continuing, and a weakening of the PV ongoing, its my personal view that if a block is established strongly (is not blown away by the jet shortly after being established), it may be around for a while. That's just my opinion though!

Edited January 9, 2012 by weatherguy

[Zakos]

what time is the ecm update?

It finishes around 7.00pm i belive, it starts to update around 6.00pm on here - http://www.meteociel.fr/modeles/ecmwf.php

[Stormyking]

The same could be said for you. That 'best looking' chart, is at +252hrs. Even if it was to verify, it's watered down to hell by the next frame, and disappears the frame after. Hardly spectacular?

Compared to what we have seen this winter, they are the best charts this winter at the moment by far!

No its not spectacular but its a very good run IMO, decent amount of cold, snow showing, better looking Jet and PV!

[Summer Sun]

what time is the ecm update?

18:00 to 19:00

[Zenarcher]

Looking at the ensembles for GFS it does have some support I believe better support than before.

GEM 12z run sticks to what it was saying for the first time yet and I think it looks better than 00z run. Shows a weaker PV and more high pressure to our North East.

Just have to wait for the ECM now.

[phil nw.]

Can't see what all the fuss is about. 12z isn't that good a run in my eyes:

Okay, we start with a better looking PV for cold over the UK, it's been weakened substantially, split in half almost, probably aided by the stratospheric warming we've been seeing lately.

With this hemispherical chart, we can take a look at the jet stream. Looking good I must say, it's a southerly tracking jet, a good indication that cold will be aloud to build:

Although, if we move forward towards the latter part of the run, disaster happens. We see the PV really shifting into gear yet again, and we are seeing mild westerlies:

With an absolutely raging northerly tracking jet:

Not good at all in the latter frames. A good upgrade in the medium term though. I think if FI verifies, we can probably write off February.

Really Backtrack you ought to try and be more objective when summarising.

Saying that Feb. is a write off based on 1 run and sypnotics that are 10-15days away is,to put it mildly, not very objective.

It`s also misleading to new members who perhaps do not realise that changes can happen before next week.

I think you know better which makes your flippant comments even less acceptable.

[Stormyking]

The way you posted it, you were implying that it was wonderful.

Tbh, I don't see how a dry, convection lacking 1 and a half day SE'erly is the best chart we've seen this Winter. The best charts were the start of December for us in the West. We had a few inches of snow from a NW'erly.

Although there is some agreement from the models for an Easterly, I don't see it coming off, and think any cold will likely be from the North.

Onto your second comment, I really don't care if everyone else thinks it's a pukka run, I can see the potential in the medium term, hence why my original post was non-bias, covering both mild and cold. Everyone interprets the models in a different way, and I have chosen to interpret it in the way I please. If you have a problem with my posts, please put me on ignore.

Yes December good for you lot in the North but the GFS 12z run is the best looking for the South and South East this winter :L

[danm]

As to snowfall potential, would we not get a fair amount of convection coming off the North Sea?

All depends how strong or slack the flow off the north sea is. A slack flow would probably result in very little precipitation, and vice versa.

The key to getting heavy snow showers off an easterly is a sufficiently strong airflow and cold enough uppers to create the required instability that will allow showers to form in the North Sea. So, the ideal is very cold uppers, -8 and below, and warm sea temperatures. The greater the disparity between sea surface temperatures and the uppers temps flooding in from the east, the greater the chance of heavy snow showers.. All of that though, needs to be driven westwards on a potent enough airflow. Too slack, and any showers will mainly affect coastal areas, before petering out as they move inland.

[Bristawl Si]

"Trends" is the key word.....as always IMO.

I'm sure these interesting weather pattern change developments will gradually build over the next few days.

As for looking at charts at +384, not really worth it at this stage......again.....as always.

[Backtrack]

Really Backtrack you ought to try and be more objective when summarising.

Saying that Feb. is a write off based on 1 run and sypnotics that are 10-15days away is,to put it mildly, not very objective.

It`s also misleading to new members who perhaps do not realise that changes can happen before next week.

I think you know better which makes your flippant comments even less acceptable.

Sorry Phil, I was basing my summary on the fact that I think if the PV and jet behave like they are modelled in FI (which isn't likely) we will probably see a repeat of what we have now.

I don't expect the charts in FI to verify, quite the opposite, I'm expecting a record breaking February in terms of cold.

Sorry for any confusion.

Edit: I've edited the original post to reflect my opinion.

Edited January 9, 2012 by Backtrack

[bluearmy]

as far as the 12z ensembles are concerned, not many runs that you wouldnt bank. some trend towards the ncep ens mean anomoly that joe B tweeted yesterday (though a tad early)