Model Output Discussion - 23rd Jan - 12z onwards

[Cloud 10]

06z NAVGEM ( ) has the High much further North as well.

 

[Polar Maritime]

 I'm really struggling to see what it is that is driving the changes in the various outputs.  

 

As has been seen many times before, Blocking Heights always seem to skitter the Models with big swings/shifts inevitable. I would expect more of the same over the coming days, Model watching at it's best.

[Fingers]

A couple of lows diving southwest out of Central Europe to prop up the high and send it to Scandinavia leads to a low coming up in to the southeast at day 9!

A long wait to the 12z to see if it's a trend or an outlier!

Everything crossed.

[DIS1970]

IF this type of setup is still there in 4 or 5 days time things COULD get interesting,

[polar vortex]

I think the 06z is much more believable than the chances of pressure rising north towards Greenland as S. Murr has suggested. The reason being that we know that the strat profile shows the vortex moving back towards the Greenland area in the mid term and if this is so then it would leave the door open for higher heights to our north, northeast perhaps. Of course I could be talking a load of cobblers agreed but it would make sense to me. 

I would take the 06z run with both hands as I am sure most on here would but we have been here before where a cold spell looks lost only for a run from one of the models to resurrect it only to find it was a complete outlier and red herring. Still because of the reasons mentioned above and the stage of winter we are now in I am in the GFS 06z camp and rooting for another 100 or so miles of amplification then we really would be in a deep,deep freeze.

Edited February 1, 2015 by Polar Maritime
Amended to make it easy on the eye's.

[Gustywind]

As has been seen many times before, Blocking Heights always seem to skitter the Models with big swings/shifts inevitable. I would expect more of the same over the coming days, Model watching at it's best.

Didn't Chiono yesterday post something about the pattern repeatedly amplifying more than modelled as we approach reliable timeframe?

[SMU]

Ok so theres 3 ways to go it would seem....

 

2 deliver cold sustained, 1 delivers the mild middle ground.

 

* Scenario 1- Sustained Easterlies-  likely 30%

 

Whilst I dont like the 06z taken at face value its a fantastic run.-  I posted ( I think yesterday with the red circle ) that when you get those deep italian lows modelled in Easterly scenarios often a second wave is throw west to the UK

 

The 06z GFS shows this particularly well & puts a wave exactly where the red circle was on my diagram

http://modeles.meteociel.fr/modeles/gfs/runs/2015020106/gfs-0-168.png?6

Coming through the low countries ejecting west.

 

This most certainly bings with it the potential of a decent snow event similar to Feb 09 for England - so worth keeping an eye on. Its not amplified at all, however doesnt need to be -

 

 

* Scenario 2 - the deep cold polar outbreak, A la 2010 ( but not as amplified)

 

The UKMO today @ 144

http://www.meteociel.fr/ukmo/runs/2015020100/UN144-21.GIF?01-06

 

& indeed the 06z NAVGEM

http://modeles.meteociel.fr/modeles/navgem/runs/2015020106/navgemnh-0-144.png?01-11

 

both these models are looking to take a scoop of polar air down across western Scandi that may well infuence the UK at day 7-8

The more amplified the pattern goes the further west the cold is backed.

Of Note is how the GEM control looks like the UKMo @ 144 & then moves on to a cold scenario

http://www.meteociel.fr/modeles/cmc_cartes.php

Current risk around 30% - of evolution bringing -8c line back into the Uk from the NE

 

 

 

* Scenario 3, - the halfway house... 40%

 

the high pressure sits neither to far north to allow the Bitter Easterlies in nor retrogrades far enough west to allow the cold to back up into the Uk, so we end up in the south cold & dry & the north becomes increasingly milder & windy from the west-

Something like this-

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

 

Ultimatly we are very finely balanced this morning between any of these 3 outcomes, with the GFS resurecting the sustained easterly flow from the ashes.

the non descript halfway house may end up the solution as usually thats our luck, but it is a very evenly shod 3 horse race...

 

Regards

S

[Cloud 10]

Well that was an entertaining 06z from the GFS,and a strong Scandi high to finish.

 

[winterof79]

Well looks like Blue's musings for the 6z have spoken.. Another shift 50m North of the High would be even better. It's not much to ask for is it !

 

 

 

 

Yes.....another 150 please I stated earlier that i was not confident of a high slap bang over us for a week.Lots to play for never mind the clocks ticking posts and the suns strength that does not cut any ice with me on the 1st Feb.Historically it is always an unpredictable outcome following entrenched cold,which is what we will have come mid-week.

Edited February 1, 2015 by winterof79

[Polar Maritime]

Yes..^ An interesting run from the GFS 6z with a Scandi High to finish.. This evenings run's are going to make for interesting viewing to see if these signals have any meat to them. 

 

Edited February 1, 2015 by Polar Maritime

[Severe Siberian icy blast]

Just goes to show how blocked a pattern can be . Wether we get a mid lat high over us or a Scandi high we still have blocked conditions . But once a Scandi high sets up shop they can very very hard to shift , even right out in la la land we still have a very similar set up.

I don't pretend to know what would happen in a weeks time but good to see this been modelled , it shows it's feeseble.

Remember the gefs are the old run so really need to look at the gfs and the gefs as 2 different models rather than taking them as one . They run off different resolutions so can't relate them .

[West is Best]

Yes.....another 150 please I stated earlier that i was not confident of a high slap bang over us for a week.Lots to play for never mind the clocks ticking posts and the suns strength that does not cut any ice with me on the 1st Feb.Historically it is always an unpredictable outcome following entrenched cold,which is what we will have come mid-week.

 

We don't have entrenched cold midweek. Yes the 6z operational is encouraging for cold, but it comes from a backdrop of ensemble scatter with many mild members of late. We need to see how the op sits in the grand picture, and then see how the ECM and UKMO shape up.

 

Looking into my crystal ball, I see the words "massive cold outlier" being used in this thread in the next hour or so!

Depends if it is. I doubt it. I suspect it will sit within the other members, just on the colder side. As opposed to an outlier which would mean it's out on its own. Certainly hope it isn't the latter.

Edited February 1, 2015 by Polar Maritime
To move discussion on.

[West is Best]

Ok so theres 3 ways to go it would seem....

 

2 deliver cold sustained, 1 delivers the mild middle ground.

 

* Scenario 1- Sustained Easterlies-  likely 30%

 

 

* Scenario 2 - the deep cold polar outbreak, A la 2010 ( but not as amplified)

 

 

* Scenario 3, - the halfway house... 40%

it is a very evenly shod 3 horse race...

 

 

Think there's a Scenario 4 Steve which is the high does belly flop down and then slowly slides away over the continent to park itself somewhere over north Germany or continental Europe. From the current setup I think it's the form horse, so I'd rate it around 9/2. By no means a cert, but still a plausible option that you'd flutter on.

 

I'm not going to let myself get too excited about this right now: too many near-misses so far this winter even if it is 1000x better than last.

Edited February 1, 2015 by West is Best

[captaincroc]

Ok so theres 3 ways to go it would seem....

 

Cheers Steve, a brilliant post that helps us learn from the current charts.

 

Thanks for posting.

Edited February 1, 2015 by Polar Maritime
To remove full quote.

[winterof79]

We don't have entrenched cold midweek. Yes the 6z operational is encouraging for cold, but it comes from a backdrop of ensemble scatter with many mild members of late. We need to see how the op sits in the grand picture, and then see how the ECM and UKMO shape up.

 

Depends if it is. I doubt it. I suspect it will sit within the other members, just on the colder side. As opposed to an outlier which would mean it's out on its own. Certainly hope it isn't the latter.

 

It is not cold ramping.I see things differently to you.

 

[bluearmy]

]

I don't pretend to know what would happen in a weeks time but good to see this been modelled , it shows it's feeseble.

Remember the gefs are the old run so really need to look at the gfs and the gefs as 2 different models rather than taking them as one . They run off different resolutions so can't relate them .

It's not really the different resolutions Shaun - the ens always run at a lower res than the ops. It's the way the atmosphere is resolved into little packets. the gfs does this differently to the gefs. So yes, different models is a good way of looking at them and as we don't have an operational to compare the gefs to, it makes them a tricky tool to use at the moment.

[polar vortex]

This is the strat profile at t 216 70mb from the ECM and you can see a week sausage shaped vortex which 

would  be conducive I think for height rises to the north, north east rather than over the Greenland plateau.

If this is a new trend from the 06z then perhaps we will see more amplified heights to the north, north east 

from t96 onwards.

[Paul Sherman]

Well the 06z Goofus has awoken the thread somewhat, Guessing as its a new month Paul or one of the other Reds will start a fresh Model Discussion thread from 12z (1st Feb) as it looks like this will be an ongoing debate!

[Rollo]

So many false dawns this winter,I would hold fire on hopes of a proper arctic outbreak for at least a couple of days,mind you just when I am off to Oman the promise returns and knowing my luck there might be raging blizzards while I am away.

[knocker]

If you have very cold 850s you are probably looking at an unstable airmass, not anticyclonic, and wouldn't get inversions under the 850s (this very much a generalisation).

 

Not too sure what you mean by the last sentence. Forget the toppler bit but an inversion of this nature associated with an anticyclone is a subsidence inversion as I mentioned in my earlier post. The inversion itself is not directly affected by surface conditions although snow cover would affect the minimum temperatures, particularly in calm conditions as there will be less turbulent mixing. In case you are going to ask why Sc forms and dissipates You will need to consult a higher authority as it's above my pay grade. Not that easy to forecast and of course it does affect the max and min temps.

 

One thing I should have added (not that it's of any interest at the moment ) is that the inversion can of course be above the 850mb level so you still could have cold (relative) 850 temps.

 

The evolution of the 06z ends here out of interest.

chart courtesy weatherbell

Edited February 1, 2015 by knocker

[winterof79]

 

 

Cold until the end of the week and then its all over the gaff.

[bluearmy]

I assume the 06z gfs op courtesy of Ian (TWS) !

It's not just popped up. That run has been on every ens suite from the gefs but this is the first time it's cropped up on the op. Perhaps that gives us an idea of the odds of it verifying??

London eps cold and dry out to mid month. Low wind speeds also. BLOCKED

Edited February 1, 2015 by bluearmy

[Timmytour]

Could the 6z be the beginning of a switch around comparable to what happened after THAT ECM?

In that instance we had all models singing from the same hymn sheet in out favour only to drop it. This time could they be about to do something similar but this time in our favour?

Let's hope so! i think it just goes to show that these set ups are often knife-edge. what's bad can flip inot something good....and we all know from experience that can happen the other way round

[weather eater]

Can't see why anyone should be surprised by the 06z the last two GFS runs have hinted  at the vortex getting far enough north to allow this kind of more favourable elongated MLB to form. The question now is can we keep a level of support for this and will the inevitable changes over the next few days in its evolution benefit us. We need it as far north as possible, if it sinks then we wind up on the wrong side. Overall though this is a relatively subtle change as a MLB over or close to the UK has been the theme of the operationals for days , there has been no real sign of a return to Atlantic mobility. The biggest shame so far, is that for many of us all we have seen so far is mostly cold rain or snow that fails to lay.

[Captain Shortwave]

The GFS favouring a high somewhere between the centre of the UK and Scandinavia, that seems to be the majority cluster here. Not many other solutions really by day 7, no sign the the potential strong retrogression signal on this suite.

Control run is well represented 

Starts off cold with the risk of snow showers but dries up later, question is do we see the clear skies filled in with cloud over time.