Model Output Discussion 12z 30/11/2012

[SMU]

Strong onshore wind steve. sypnotics may not be big outlier

If that was the case then the rest of the ensembles would reflect that- so yes an outlier-

S

[AWD]

06z has the trough to the east a little sharper than previous runs. Wouldn't be surprised to see some snowfall in places from these;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=96&code=0&mode=0&carte=1

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=96&code=code&mode=1&mode3h=0&runpara=0&carte=0&

[lorenzo]

GEFS Control and Ens @ Day 10

ECM Control and Ens @ Day 10

Blocking clearly on the table at this range, going to be much drama no doubt getting to this position as each operational run does different things with lows spawning from East Coast US. The re-analysis from GFS always suggesting that LP deepen in this area, but also bullish with greenland heights at 6 day period, so a difficult one to pick through when we have 4 runs per day. Gladly not 6 runs per day as Nick mentioned last night - too much drama !!

Was wondering if that tropical wave low is going to at some point sit in place and support a Greenland High, the models have toyed around with a Rex Block for some time now?

Correlation here drops below 0.8 at 168 hours suggesting the timeframe for FI, the above means and controls of course highlighting the trend of height rises and European temps falling.

It's all about the triggers, GP mentioned a starter pistol pacific low, and am sure the trigger slider is being hunted on every run now that it has confirmed itself as having the ability of Dynamo to vanish.. Going to be another fun 10 days or so. I think the ECM Mean is the run to watch, this seems to have been favoured in the CPC blends.

[Weathizard]

The low around Greenland now has two cental pressures at 126? Bad thing? And the second "tropical' low is less developed as you'd expect and infact the second low coming off the eastern seaboard is a lot weaker, tropical low was 985 now 1005, other was 995 now 1005

Edited December 1, 2012 by Weathizard

[Catacol]

I'm going to post once more this morning before heading off to raise my pulserate for a while.

This ECM ensemble image for 144 shows how finely balanced it is for the end of next week:

As Chio has pointed out a few times now we have energy transfer from Siberia to Canada, clearly visible here. What we are left with in our part of the world is the trough to our south which is deep enough for confidence on its maintenance, but then 2 high pressure cells growing from both NE and SW trying to fill the gap to our north. Staring at this chart for a while (assuming it has some ensemble accuracy at 144h) hasnt helped me work out which way it is likely to go. Frankly finely balanced is an understatement. This particular ensemble run has the mid atlantic ridge seize control, largely because it models the siberian high to push eastwards and suck some of the scandy potential out of its locker. However if you take the time to flick then to the GEFS ensembles you see a totally different modelling of the siberian ridge, with pressure maintained and more of a scandy influence. However that run also drops a segment of vortex down in between the mid atlantic ridge and the developing scandy high, giving us a near 2010 scenario!

This is wide open. The consistent driving force would indeed appear to be the energy transfer from Siberia to Canada, but what happens in the wake of that transfer looks frankly indecipherable at present. We could have stagnant high, easterly flow off scandy rises, vortex segment drop on our heads or I suppose a strong icelandic ridge (though that is not one obvious option that I can find this morning.)

I think the aussies would say - it's a beaut. More unpredicatable than an Andy Murray grand slam campaign... but with 2 consistent features: a vortex in awful disarray and consistently low heights to our south - and if you want cold that is ALWAYS a good thing!

Edited December 1, 2012 by Catacol_Highlander

[Weathizard]

Why will that low to our North at 150 not move? Its stationary for practically 60 hours? Won't budge still at 168

Had a sneaky looks at 240, what is going on with the Jet? Its practically gone? Very differently looking run but still end in a cold outcome, think we are beginning to lock in the cold now, how cold/snowy it is remains to be seen

Edited December 1, 2012 by Weathizard

[Tim Bland]

This run has a trough coming down on Weds, most could get a dusting from that. Next weekend te high is building west of Greenland with a low to the north of Scotland. Hopefully a northerly ten north easterly to follow of the low slips SE

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=90&mode=2&carte=1

[phil nw.]

Looking at all the mean outputs from the 00z`s they all point to the trough extending into Europe with occasional ridging from the Atlantic high out to T240hrs.

The NAEF`s ,ECM mean and the cpc mean thickness flow similar

http://176.31.229.228/modeles/gens/naefs/run/naefs-1-0-240.png?12

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

The one consistent is the continuing below average temps with uppers mainly between from-2 to -5C.

http://nwstatic.co.uk/viewimage.pbx?type=ens;date=20121201;time=00;file=t850Warwickshire;sess=8b699036de806e96d1291fcf352210e3

It looks like a rather cold north westerly pattern continues through at least to next week becoming drier with frosts as pressure looks like building nearby.

[AWD]

Pure conjecture of course, but that's some PV;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=336&code=0&mode=0&carte=1

Greenland heights and the Jet Stream heading down into Africa;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=336&code=0&mode=5&carte=1

Leaving Europe in the freezer;

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=336&mode=1&carte=1

Just for fun of course, no point in even thinking it will verify like that.

[Weathizard]

Well, another strange end by the GFS have a look at the z500 charts for 384, what on earth is going on there? Wont happen anyway, just another outcome to add to the list. Seem to be swinging from Cold/Cyclonic to Cold/Anti-Cyclonic. Will be interesting to see if the ensembles continue the trend we have been seeing

[kold weather]

Well I think its fair to say from a cold point of view, thats the best run of the winter, low heights, decent upper cold combined with a strong cold pool at the surface. That run would pretty much look in a below average December.

Probably on the cold side of the ensembles.

[Tim Bland]

Never seen a pettern like the final few frames before! Does anyone know if this has ever happened before? Would be mighty snowy for some!

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0&carte=1

[chris55]

GFS 384, Epic synoptics!

[bluearmy]

Never seen a pettern like the final few frames before! Does anyone know if this has ever happened before? Would be mighty snowy for some!

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0&carte=1

Not since '79 ??

[Polar Maritime]

Wow, looks like the PV has moved to the uk out in FI...

Blizzards galore if it verified.

Edited December 1, 2012 by Polar Maritime

[Frosty.]

Just zooming in on the interesting developments later on sunday shown on the gfs 06z as the low pushes fronts into the residual pool of cold air over the uk, a spell of snow is likely before it turns back to rain and temps rise, northern england northwards could have a longer period of heavy snow but then turning back to rain, but it's scotland and especially higher ground which could have a blizzard lasting quite a few hours with up to 8 inches of snow before that front clears to the northeast by monday morning.

Further into next week shows a cold blast sweeping south by midweek followed by a brief ridge then the winds become westerly and less cold of north atlantic origins for a short time by next friday before a deepening depression pushes southeast from greenland/iceland with wet and windy weather spreading south and east followed by another arctic blast with heights rising to the northwest around greenland, follows the gfs 00z in that respect which is nice to see.

Edited December 1, 2012 by Frosty039

[bobbydog]

on a positive note, although we know this won't happen-

something like it could happen....

[weatherguy]

FI is an absolute beauty, but it's important to not that it is, well, fantasy at this point...

Been saying for a long while now though (as have most others), with heights to our north and a weakened PV, the UK is in a good position for cold. Though we rely on very fine tuned synoptics for true cold to reach our tiny island, the overall northern hemispheric signals are about as good as it gets in terms of boosting our chances! December is looking good for a major cold spell, question is whether it will come from the north or from the east...

With the (depleted!) PV expected to move over towards Canada however, north/north-east seems more likely. Unless of course GFS FI occurs where the jet seems to like the idea of Africa...

[TEITS]

Quiet a big turnaround in the model output this morning and now we're possibly looking N intially rather than E.

The first headache is this LP around Iceland.

http://www.wetterzentrale.de/pics/Recm1681.gif

Now whether this tracks SSE, SE is still uncertain but what the models suggest is a rise in pressure behind this as the LP tracks E/SE.

http://www.wetterzentrale.de/pics/Rhavn1681.gif

Yesterday I said the chances of blocking over Greenland look very unlikely but today im not so sure. The difference is the shape of the PV compared to yesterday as it appears to become elongated

Alot to be resolved but overall im delighted with the model output. The general trend again is cold and the ECM ensembles are the coldest this winter and actually remind me of 2009, 2010!

[Liam J]

on a positive note, although we know this won't happen-

something like it could happen....

That is an awesome chart, much of the country would be crippled! Only in FI can we see such mega synoptics.

[Bobby]

Never seen a pettern like the final few frames before! Does anyone know if this has ever happened before? Would be mighty snowy for some!

http://www.meteociel...&mode=0&carte=1

1947?

I wish, hah.

[Bobby]

NAEFS spreads showing plenty of uncertainty with the handling of developments around Iceland way at day 6-7, until this is sorted then I guess we're in the dark with regards to anything beyond then.

[Frosty.]

At least we can safely say the next short cold blast is nailed between tues/thurs followed by frosty ridge and then brief flattening of pattern before the next deeper amplification, the gfs 00z and 06z ops are very bullish about this, beyond that the gfs shows epic cold in FI, the 6z even an upgrade with FI blizzards.

[snowking]

The extended ECM 0z control paints a pretty similar picture to the rest of the output, though its a little later to the party.

Broad synoptics in the later timeframes are NEly feed at 240 with HP to the NW of the UK slowly being sunk towards 300 by some energy going over the top - when it sinks, it gets temporarily pulled NEwards, following this the block (now over the UK extending into scandinavia) gets split in half by the energy which had gone over the top of the HP, dropping a trough down the north sea with the western half of the split HP heading up towards Greenland. Looks very December 2010 in its later evolution.

SK

[Gael_Force]

1947?

I wish, hah.

....and more recently, christmas '78.