Winter Model Discussion - Cold Hunting -12Z 30/12/12

[southbank]

Again no real signs of pressure dropping around the med at T186 , if we had some sort of low forming there then we could see CAA , The heights at NP look impressive , interesting run buts its the 06z afterall !!

[bluearmy]

the 06z op is one of the runs which drives the heights from the ridge on the other side of the NH and sends the AO sharply neg. lets see how close the vortex chunks to our ne can get to nw europe in low res.

[-uksnow-]

Also a much stronger secondary warming on the 06z!

[TEITS]

Haven't had a chance to look at the archives but the 06Z is reminding me of Jan 1985, or I could be wrong.

http://www.wetterzentrale.de/pics/Rtavn2401.png

[bluearmy]

low res no surprise - it wouldnt happen like that from where high res ends up. hopefully some of you will now dare to believe !!

[nick sussex]

Whilst the models continue to try and throw up roadblocks to cold eventully they'll wave the white flag and accept that it's time for winter to arrive.

The best thing about todays output is the westwards correction and the Arctic high making an appearance. It just goes to show how futile looking deep into FI can be with these SSW's.

The models show a clear signal now for a quick initial response to the SSW, if we can just get a bit more dig south of energy in the mid Atlantic then you'd think we'd see much colder solutions showing up in the operationals.

The ensembles have really been all over the place which I think is testament to a change in the NH pattern.

[mountain shadow]

A pretty stunning day 10 chart, very rare.

Trying to kurb my excitement now after the December debacle.

Edited January 3, 2013 by mountain shadow

[Rocheydub]

Wow.

Here we go again folks!

[TAFKAP]

Great to see excitement mounting once again, that 10 day chart mentioned by mountain shadow is looking very promising indeed. I anticipate that within the next day or so the doom mongers will be out in force again but I am convinced this time the cold is going to be the real deal.

[Weathizard]

What happens at 240? A superb chart and then in one frame it all seems to go wrong with the high attaching back to its mummy rather than flocking the next, the 2 lows south of Greenland look strange as well one just disappears! Classic GFS FI. Still much better signs from the OP today let's hope the ens continue the trend even colder!

One questions I'd ask is that if a little bit of HP breaks off like this is it likely to be a short cold spell (if it gets to the Greenland/Svalbaard area as it looks quite flimsy really? Or could it build?

Edit: just to add, that Artic high is a true thing of beauty to behold, a rare occurence that I don't think I've seen in 4 years of watching models.

Edited January 3, 2013 by Weathizard

[TEITS]

Here are my drawings to explain.

Over the past 12hrs the area I have highlighted (H) has seen an increase in pressure. At the same time the LP has seen a correction W compared to recent runs. Also the arrow pointing SE is where we are seeing the trough digging further SE compared to recently.

Moving onto +192 and im going to use the ECM chart to highlight where I think its wrong and how this might change.

Now based on recent trends I believe the HP will be where I have highlighted with H. At the same time the LP will be tracking further SE than the ECM shows. This will result in a NE,ly flow as I have highlighted with my dodgy arrow. Now before im accused of hopecasting my earlier post of expecting a cold spell sooner was actually made before the 06Z had fully come out and was only at +96 when I made my post.

Apologies for my shocking drawings but my hands constantly shake due to my medication.

[pipsta]

Remember, no mentioning to family or friends of the potential coming, you know what happens when we do that!

[Bobby]

Looking at the output this morn there are certainly signs something may be stirring, some epic winter charts starting to show in the ensembles. Its still concerning how LP from the NW wants to attack us, there still seems to be a fair bit of energy in the Atlantic, hopefully we will get a good block. Nothing concrete yet and we're a long way off but the trend is certainly good. The model watching will be interesting over the next few days either way!

[TEITS]

Wow.

Here we go again folks!

Yep and worth pointing out that after the failed E,ly fiasco in Dec we had the dreadful zonal pattern. Now without tempting fate if a cold spell fails to arrive say at +240 I doubt we will return to a mild, zonal pattern. Current indications thanks to the excellent Strat thread suggests other opportunities as the PV continues to take a hit from further warming episodes.

[snowking]

ECM, GFS and UKMO not a million miles away from each other out to 144:

ECMWF and GFS show two different routes from there, and so you would suggest that this is your FI point at this stage

SK

[nick sussex]

I think looking at the changes we've seen in recent runs it makes you wonder how adept NWP is at deciding the impact of the initial change to reverse zonal winds.

This really isn't a common thing they have to deal with, I think we should perhaps be a little cautious in that they may over react conversely they maybe slow to factor this in.

If its the latter then one wonders just how much impact that would mean on the medium term outputs.

I will be interested to see the UKMO update today because its hard to ignore the possibility of a change to colder conditions sooner than perhaps they have anticipated.

Looking at the ECM ensembles and current trends its plausible for colder weather to arrive around the 14th or perhaps sooner, perhaps we might see a caveat with more uncertainty earlier.

Edited January 3, 2013 by nick sussex

[pyrotech]

The Ensembles are quite interesting, alot of agreement till 11/01/2013 then they have not got a clue, looking at Cardiff for instance ( its the same accross the South UK)

We have the operational going for 2m temps of 9c lowering later to 6c (daytime max) The control has -2c lowering to -5c daytime max. The mean also drops consistantly throgh that same period. So the trend looks like getting colder looking at the mean, but uncertainty between the op and control is huge. 850mb temps are also 13c different around 17th between the control and operational.

[Rocheydub]

Yep and worth pointing out that after the failed E,ly fiasco in Dec we had the dreadful zonal pattern. Now without tempting fate if a cold spell fails to arrive say at +240 I doubt we will return to a mild, zonal pattern. Current indications thanks to the excellent Strat thread suggests other opportunities as the PV continues to take a hit from further warming episodes.

Indeed, polar pressures should keep us out of zonal trains for some time... I am quietly confident, probably more so than our December trip on the NWP Express! **covers scars**

[AWD]

Yesterday's EC ens;

Today's EC ens;

Clearly the signal for colder solutions from Mid Month is growing.

[TEITS]

GEFS control exactly like my drawing.

With the exception of a dodgy arrow.

[The PIT]

Aah I've seen 06 oz GFS has thrown in a deep FI tease. Well it was due too I suppose. Klingon pain sticks at the ready once more.

The only question is it a new trend shown in the next few runs or will it simply disappear on the 12 oz?

Next stage does still stay out at the same time period or move towards the reliable frame?

If it stays at the same time period with the odd lurch further forward and then further back again then it will be a prolonged tease.

If it moves forward with minor variations the chances then are greater and even more so if the ECM comes aboard.

If it survives to T120 you may even be able to hold your breath.

[bobbydog]

in case anyone missed it and due to some posts commenting on the longer range model output, some people obviously did-

Just to re-stress a key point, as some might have overlooked it, judging by certain frustrated posts! UKMO emphasizes again (in new 6-15d briefing) how potential cold/blocked outcome from incipient SSW remains v possible but crucially how this may not be manifested within their current 10-15d forecast period. So - as others have also tried to stress - NOTHING in any NWP output in further reaches of MR should be taken with even moderate confidence! We are entering a truly fascinating & potentially rewarding period for this thread.. but it'll take time! I'm hoping to hear tomorrow how the good folk at Hadley Centre are assessing fortunes from this SSW.

[bluearmy]

not many gefs members mimic the op closely in high res period re the arctic high position. fwiw, i would be following ptb's 17, 19 and 20 to see where they go post T192.

control may also be relevant.

Edited January 3, 2013 by bluearmy

[AWD]

UKMO keen to move the MJO through phases 4&5 into phase 6;

Other models not so keen moving it out of phases 4&5;

GEFS similiar to the UKMO though, heading into phase 6;

[TEITS]

Mouthwatering ensembles.

http://modeles.meteo...s-0-1-264.png?6

http://modeles.meteo...s-7-1-228.png?6

Probably some even better ones but I haven't looked at them all.

There is No 17 with bitter E,lys.

http://modeles.meteo...-17-0-276.png?6

Edited January 3, 2013 by THE EYE IN THE SKY