Winter Model Discussion - Cold Hunting -12Z 06/01/13

[bradymk]

Hemispherically, the GFS 12z is much better with plenty of potential towards FI once again. FI again though however im sure this run will change once again come the 18z and 00z. very unlikely the right solution on 12z shorterm term but possible. At the end, the PV in eastern canada moves eastwards when I am sure all the other signals point to this moving west?

Edited January 6, 2013 by bradythemole

[snowstorm445]

No 'reorganisation' of any vortex here...shredded into pieces...Synoptically beautiful...As chio said depends where wheel spins but beautiful to look at

T204

Hehe wild swings....

Jaysus that's a serious cold pool in the final chart, we only need the G High to become a bit stronger! Pity it's so far out.

[karyo]

UKMO brilliant at 144h!

The UKMO is not that good! There is residual low pressure to the northwest of us and the Iceland area. On top of that that deep Atlantic low needs to be further west and the Iberian high needs to be weaker.

Karyo

[Cheshire Freeze]

One positive for me from a more sustainable perspective is the fact the GFS seems to have retracted its willingness to power up the PV into FI on the last couple of runs

It was becoming quite a baffling trend yesterday, given the strat warming.

[nick sussex]

Can I just remind people that this is an operational model, we need to pay attention to the ensembles to see if this is the general outlook overall or simply a mild(er) outlier.

Forget the ensembles because if the higher resolution operational output can't agree within 144hrs and lay out a clearish route forward then they're likely to be just as all over the place.

The simple Azores high retrogression route forward seems far too simple for the models they've decided to take us on a mystery tour.

I await the ECM with a sense of trepidation!

[EML Network]

I'll await for the Ensembles to come out before getting too worried and tbh hoping for cold and snow before Mid Month wasn't even something we we're thinking possible given the output at the beginning of the month.

I've lost count the amount of times that this forum has gone from upbeat (in the morning) ...to dispondent (in the afternoon) ...back to upbeat again (in the evening) ...could today be one of those days ?

The cold looks very much like it's coming, how long it stays and whether or not it will bring snow with it, won't be something we can really know until it's within sniffing distance

[mcweather]

To be honest no matter how poor or good this run is, it means nothing until we have seen the esembles.

Even on stellar runs you usually get a few poor perpetrations, this run could very well be one of those..

Eyes for me firmly on the ukmo and ecm.

possibly the most sensible post of the afternoon.

[johnholmes]

For those who may be getting dizzy with the changes, apparent or real, that folk are posting about with GFS. Take a look at the longer term. No longer term model was suggesting cold before mid to late this coming week. Is that happening, when compared to current and recent conditions.

Do the longer term models continue to show a cold spell or not-take a look don't take my word for it.

The sooner some of you stop chasing rainbows every model run, calm down, post T+144 compare the 12 to day with the 12 yesterday for each model. Do they show marked changes, if so does that change fit with what it showed 24 hours previously.

It does work far better than being worried by what the current run shows compared to the last one at those time scales-believe me.

And no the longer range models consistently still predict cold from late on this week.

[SMU]

so far both 12s are poor compared with what the ECM depicted overnight,

more runs needed, however little to get excited about if your looking for snow....

S

[mountain shadow]

You will note that as we approach the reliable time frame the cold and snow is pushed back. Not a good sign.

When i said that yesterdays ECM was too fast i expected the change to a slower evolution today and i fully expect the 12z ECM to follow the GFS tonight.

I do think thr cold and snow will come just not as quick as some would like.

Edited January 6, 2013 by mountain shadow

[bradymk]

Forget the ensembles because if the higher resolution operational output can't agree within 144hrs and lay out a clearish route forward then they're likely to be just as all over the place.

According to meteociel Nick, the ensembles are the same resolution as the Op so disagree there regarding the ensembles if that is correct obviously.

Edited January 6, 2013 by bradythemole

[AWD]

Are heights low enough to our south yet?

:p

Another run, another variation. Not bitterly cold but definetly not mild either.

[karyo]

Greenland high with blocked Atlantic coming.......at 276hrs!

At 276 hours it can show arctic condditions if it wants to but what's important is what is happening in the first 144 hours!

Worryingly, the sun is waking up which may tip the balance against the cold spell : http://www.spaceweather.com/

We need to see the solar activity drop quickly. I remember GP saying that the last upstick in activity may have contributed to the early December failed cold spell.

Karyo

[Cheshire Freeze]

so far both 12s are poor compared with what the ECM depicted overnight,

more runs needed, however little to get excited about if your looking for snow....

S

Really Steve? I thought the opposite when looking at the GFS for next weekend/early next week with LP colliding with a cold advection of air from the east.....

Not quite -15 upper temps and streamers but, having not seen a fall of snow at all this winter, I'd quite happily take anything.

[Geordiesnow]

The UKMO is not that good! There is residual low pressure to the northwest of us and the Iceland area. On top of that that deep Atlantic low needs to be further west and the Iberian high needs to be weaker.

Karyo

I think the UKMO is better overall on the blocking but the details of the run is not the greatest, of course at that range they are subject to change.

You do have to say at this stage, the ECM's idea of a more stronger easterly flow and better Atlantic heights do look a bit of an outsider bet at the moment - just because the last 2 ECM runs shown this does not mean much really, but hopefully for the mood in this thread, it shows at least the initial easterly flow, whatever happens after that is as per usual speculative.

[bluearmy]

Gfs has much lower uppers and heights into n greenland in its back end high res. that helps drive the atlantic into week 2. Gem and ecm still to come but anyone hoping the 12z's would solve anything need to think again. Tomorrows 12's at the earliest re the weekend and gawd knows about what follows.

[snowstorm445]

These model outputs are certainly not poor as some are suggesting, in fact compared with what was seen around the New Year I am very pleased. All the building blocks are here and frankly as pretty as the models may look beyond 5 days I won't be taking them seriously until the cold is within 5 days.

[East Herts Snow]

I don't know whether to laugh or cry at the GFS 12z run. Upper temps are higher, with much more energy and precipitation throughout, but we could just be on the right side of marginal for snow and a lot of it.

[Zakos]

Regardless of small-scale changes which will continue to occur for days, the GFS actually shows an upgrade to the overall pattern

yes the cold is delayed on this run, but IMO it is delaying the inevitable. Nothing can stop the cold spell now. The only thing that remains to be seen is the severity of cold, and snow potential.

We have what I would call "Bartlett low" which is basically the exact opposite of Bartlett on this run. quite an epic run for snow potential. We have winds coming from Svalbard right down to the Azores, a truly substantial block.

In my view, the Scandi high is a temporary feature, which has the potential to deliver severe cold and widespread to the UK. I then feel shortly after we will see the High set up shop over Greenland, with ridging in the Atlantic.

The GFS displays a classic "default" at the end of the run. In my view we would have to be extremely unlucky to miss out on a significant cold spell this time.

Edited January 6, 2013 by Zakos

[bluearmy]

According to meteociel Nick, the ensembles are the same resolution as the Op so disagree there regarding the ensembles if that is correct obviously.

They dont. There is a thread on model resolution in the archive section.

[Froze were the Days]

Are heights low enough to our south yet?

Another run, another variation. Not bitterly cold but definetly not mild either.

Yes they are! but also low enough to our north - GFS desperately lost in the SSW signals I believe and searching for a solution towards mid-term outlook. UKMO slightly better with Heights to our north and a low cutting through us at this time next week but as ever it was always going to be fascinating model watching once the SSW event was in place whether we receive the 'goodies' is another thing!

Far more runs needed until we know roughly what direction we are heading in and it might well be the case FI might be within 3/4 days for some period to come.

[bradymk]

They dont. There is a thread on model resolution in the archive section.

Ok thanks BA

[Cheshire Freeze]

Some people need to transport themselves back to Christmas week when all we were offered up by the NWP was endless zonality and SWly winds- right through to the end of the runs.

Given what we saw during December, I'm quite happy to take a few days of anything which breaks up this incessant mild!

I also don't think people realise that new directions will be picked out in the NWP in the mid range so anything we see past 168 is highly likely to change.....especially given the SSW. For me, personally, there has been a positive shift in the 12z in early FI.

[TAFKAP]

What's ugly about it? A nice little Scandi High forming and an even better Arctic High forming above!

You're right there is nothing ugly about it. Just the same old nonsense that comes up every time cold is progged. A busy few days ahead for the mods methinks.

[Panayiotis]

GEM at 126hrs is interesting those isobars in the atlantic are nearly vertical compared the 12z which had them rounded, the GEM is far better as the heights/warm air can go straight up into Greenland instead of curling round the low in the 12z.

Also what that low does to the SE of us may become interesting too!

(GEM mind!)

Edited January 6, 2013 by Panayiotis