Winter Model Discussion - 11/01/13 00z Onwards

[kold weather]

I'd say t+96 is the start of FI, perhaps earlier if you are looking at the mesoscale.

I'd say so, though as I said before, hard to deny there has been an almost total 180 in terms of what heights we are seeing compared to what the models were showing on their 12z runs (IE from a weak/mod Greenie high, to the PV linking up again briefly at 120hrs on todays 06z GFS). The ECM ensembles far closer to this GFS run than its own operational run.

PS, this is reminding me so much of the December downgrades its untrue...

Edited January 11, 2013 by kold weather

[Dave Kightley]

I cant believe after so many days model watching we still dont have after Monday sorted yet. I blame such Shortwave action.

[bluearmy]

very uncertain if you are judging the current ops. the 00z naefs update smacks of yesterdays ecm ens with a pincer attack on nw europe from the atlantic on an undercutting trajectory and the ne around the weak 'wedge' of blocking as mentioned by steve and gp yesterday. i would be waiting to see where the 12z's head before having any strong thoughts on where this cold spell goes. pointless having strong opinions after each run (both ops and ens).

[Southender]

Finally!!

There she goes, up up and away.

22nd Jan folks...

PV split @ Day 10. Lobe heading SE. Ridge into Greenie. NE flow. That simple!

EDIT: PV Fires up into a monster and flattens the lot in hours!

Edited January 11, 2013 by Shrimper

[Timmytour]

GFS 6z not good.....the graceful Atlantic swan flying north west disappears and we get the return of the scrawny seagull flying straight towards us

Edited January 11, 2013 by Timmytour

[Robbie Garrett]

What have you guys done to the ECM overnight? Passed 122/144 hours it just goes for this, incredible...

[WhiteFox]

I'd say t+96 is the start of FI, perhaps earlier if you are looking at the mesoscale.

Yes, somehow the GFS has managed to conjure up a halfway house between the shortwave dropping south and moving east (the same one that gave so many problems over the past two days). The first shortwave drops some energy south and then hangs around giving the following shortwave enough time to move down and bringing in milder air.

The jet is really causing problems at the moment; the models can't decide on the strength or direction, so I think we have to assume FI remains at 96 hours. The 6z shows a strong, flat jet coming out of North America heading towards the north of Scotland whereas the 0z had it heading south. It seems that the ECM and GFS are starting to agree on a strengthening jet however.

I'm sure Nick S will keep us updated with the upstream developments!

[Methuselah]

This really is becoming fascinating to watch, it's an epic model battle, with more end to end drama than an FA Cup final. I can't even begin to fathom which model has the upper hand, because there simply no way of telling at the moment.

Obviously there is a signals for Atlantic energy from a few models now, which cannot simply be swept under the rug, but on the other hand the ECM is consistent in keeping the colder solution, it's really finely balanced at the moment

What is almost certain though is we have a period of weather ahead which includes hard frost, and some decent snowfall, so even in the event the Atlantic does March back in, it's still a decent (albeit typical) spell of winter weather.

It is indeed, Ste! We must remember, as well, that models have to arrive at a discrete solution; even if that solution is (as is usually the case) nothing remotely like reality...Part of me hopes that they never will be 100% accurate!

What would be the fun in that!

[mulzy]

Finally!!

There she goes, up up and away.

22nd Jan folks...

PV split @ Day 10. Lobe heading SE. Ridge into Greenie. NE flow. That simple!

EDIT: PV Fires up into a monster and flattens the lot in hours!

Interesting but later it gets flattened as PV reforms and powers up (all FI anyway) - oops seen your edit!

Edited January 11, 2013 by mulzy

[Yarmy]

FWIW, GFS

00z Yesterday for Mon 14 at 7am

06z Yesterday for Mon 14 at 7am

00z Today for Mon 14 at 7am

06z Today for Mon 14 at 7am

Differences, but not a million miles apart, then...

00z Yesterday for Wed 16 at 7am

06z Yesterday for Wed 16 at 7am

00z Today for Wed 16 at 7am

06z Today for Wed 16 at 7am

No point looking beyond T102 for me, even for trends. My strategy is to look up to then and stop, then read the meteorological arguments given here (even when they soar over my head) for future evolution.

[Snowmad79]

Well the gfs 6z is once again, another run, another outcome, really start to get tiring all these changes run to run, a poorer run due to lower heights to our north but dont worry im sure this will change by the 12z. No model is being consistent and its all getting a bit annoying, ECM ENS stay cold until at least the end of next week before there are a few milder members due to an atlantic attack however so far out im sure this will change to. An atlantic attack could see snow and the cold winning or snow to rain or just rain.

All Models have been consistent in the 0-120hr with one of the main factors . The almost total removal of any kind of Block to our North West with most only having a shabby blob of HP to our immediate North and East which gets sucked into Europe.

Steve Murr even said after that last failed easterly how there really wasn't any kind of real block and without it, the outlook would be crap.

The Model Output has been crazy, much as the world in "The Matrix" .......A nice quote for you:

GFS: Do not try and defend the block. That's impossible. Instead... only try to realize the truth.

ECM/UKMO: What truth?

GFS: There is no block.

ECM/UKMO: There is no block?

GFS: Then you'll see, that it is not the block that builds , it is only the Atlantic.

[stainesbloke]

Strength and direction of the jet stream will be the deciding factor here, hopefully it will move S and not NE as shown by the 6z.

[Frosty.]

Except T+144 is FI.

I think T+96 onwards is FI, the models are more complex than hampton court maze at the moment but at least it's turning colder and colder with an increasing risk of snow through the weekend and especially on mon/tues.

Edited January 11, 2013 by Frosty039

[Mac_SE]

So all to play for, but the uncertainty with the models, run to run, make all the pages of 'BOOM', snowmaggedon' comments that relentlessly appear on a tasty run for coldies so laughable. Especially when they're out to T144+.

[Southender]

Interesting but later it gets flattened as PV reforms and powers up (all FI anyway) - oops seen your edit!

Indeed.

I think that is something to watch over the next week though. To see if it trends...

Look for a PV split around 20-22nd Jan. PV lobe headed SE and a ridge building into the GIN corridor there after. Giving a NE flow.

[snowmadchrisuk]

Based purely on next week , I actually like the 6z , Amazing amounts of Snow on offer , with the West in on the action with Cold air right across the country ... I'm not really expecting Dec 2010 so 4-5 days of Heavy Snow that even includes the South West would make me very happy . Then who knows what after ?? Might get a reload .. Also note , even when the Atlantic wins on this run , it is very cold Zonal , (lots of Snow chances) with -5 -8 uppers before another pressure rise..

[Jason M]

Model divergence is now so great that frankly looking out beyond 4 days is an absolute waste of time. If anything things are worse today than at any stage during this whole saga. On the plus side, its going to be very cold, many will see snow but beyond Monday its impossible to tell. My best guess is that we will eventually end up with an easterly followed by Greenland High and PV into Scandi.

It seems that Monday is the problem day and until we know what happens after the shortwave things will be unclear (probably until tommorow morning).

Lets see what tonights runs bring. Personally I suspect we are all due to spend the evening with Shannon Entropy.

Jason

[Bristawl Si]

I'd say so, though as I said before, hard to deny there has been an almost total 180 in terms of what heights we are seeing compared to what the models were showing on their 12z runs (IE from a weak/mod Greenie high, to the PV linking up again briefly at 120hrs on todays 06z GFS). The ECM ensembles far closer to this GFS run than its own operational run.

PS, this is reminding me so much of the December downgrades its untrue...

If one believes there is some trust in the later stages of these model runs, then it begs the Q what effect is the Strat warming of a few days ago ACTUALLY going to have, esp if the PV is firing up again? It seems to go against what was meant to happen.

OR am i just being a bit stupid here?

[chionomaniac]

I think that I understand the evolving synoptic situation a little bit more now that I have sat back for a few days. To get a clear picture it is better to step back and look at the NH profile from today right out into FI. I think that we have been focussing a little bit close to home.

What is bvery much evident is that we are seeing a waxing and waning of Pacific and Atlantic ridges as the seperate vortices reorganise themselves following the SSW. Remember the stratospheric picture - we have split vortices that are both programmed to undergo further warmings that will alter their shape and position such as this:

As this occurs the tropospheric vortices reorganise correspondingly and like that wheel of fortune analogy, the negative reverse mean zonal wind anomalies are dropped off alternatively both in the Pacific region followed by the Atlantic leading to alternating blocking patterns. The GFS 06Z shows this well.

Atlantic T+42

Pacific T+186

AtlanticT+300

Pacific T+384

So whereas increased heights are always likely to our north (across the split region) the overall pattern will be cold followed by Atlantic push and so on and so forth until the SSW downwelling runs out of steam, or the vortex reforms.

So prolonged cold - probably no, but short relapses between cold spells highly likely.

Edited January 11, 2013 by chionomaniac

[Paul]

If one believes there is some trust in the later stages of these model runs, then it begs the Q what effect is the Strat warming of a few days ago ACTUALLY going to have, esp if the PV is firing up again? It seems to go against what was meant to happen.

OR am i just being a bit stupid here?

I think you have to keep going back to the fact that the models are going to have issues dealing with the strat changes currently - we're seeing this flux between runs and models so having any trust beyond a few days even in terms of the broad pattern is quite a big leap of faith, and probably too big to take at this point.

It's one of those situations where short term is not going to be nailed until nowcasting in terms of rain/snow mix and shower distrubution, and medium to long term is uncertain in terms of setup and broad pattern, so a watching brief is definitely the way forward!

[chionomaniac]

If one believes there is some trust in the later stages of these model runs, then it begs the Q what effect is the Strat warming of a few days ago ACTUALLY going to have, esp if the PV is firing up again? It seems to go against what was meant to happen.

OR am i just being a bit stupid here?

Hopefully just answered your question.

[SMU]

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=6&code=0&mode=0&carte=1

I Suspect the outlook will be something like a blend of the UKMO & Control 06z which are both excellent- split flow nw of ireland-

S

[SnowObsessor90]

Well some of the more cautious folk did warn yesterday that there was little margin for error and any unfavourable shift could easily lead to the pattern tracking further north as opposed to south, could this be what we're currently seeing?

[Weathizard]

So prolonged cold - probably no, but short relapses between cold spells highly likely.

Thanks for that post Chiono, very useful!

Rather disappointing though not to expect any prolonged cold, I thought with warmings like that that would support blocking In that region? Seems as though the Vortex is just powering up over W.Greenland/Canada throughout the 6z, is this just bad luck that this is where the vortex piece will be?

Cheers

Edited January 11, 2013 by Coast

[kold weather]

06z GFS ensembles look a right mixture, but I'd say more look like the ECM run at 120hrs than the GFS operational run with some sort of high pressure, however weak trying to form over the top of any dropping low.

Just a mess!