Winter Model Discussion - Cold Hunting -23/12/12

[-uksnow-]

Just looked through each other the 20 GEFS runs from 192-384... a large proportion of runs showing established cold or cold of sort (alot better than we've seen in a while)

Perturbation 2 floats my boat just a little bit.

[bobbydog]

Maybe next weeks high pressure is whats needed to change the pattern

that and a Sudden Stratospheric Warming!

[TEITS]

Assuming the gefs are following a trend, each gfs op run from now on could well throw up some v cold fi patterns.

That for me is exactly what im looking for. Im not expecting to see a sudden cold spell appear at +192 and for the moment content to see a trend of very cold runs in distant F.I I suppose the current pattern is so poor that we have to start somewhere.

Im going to keep a tally of how many -10C ensemble members appear over the next few days. The number of these on the 12Z is 3.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=12&ville=Londres&runpara=0

[mountain shadow]

Another improvement in the GEFS today. The FI 0z had 2 cold runs, the 6z had 3/4 and tonights 12z had 5/6.

Baby steps, but maybe the pub run will give a cold Ops.

[Tim Bland]

CFS starting to be co sister with a pattern change around 18th. Showing some interesting scenarios with chunks of the PV over the uk with very low pressure over Parts of europe and a ridge in the Atlantic. Of course it's way out in fantasy land and won't happe. Exactly as shown but hopefully the pattern we are will be similar ?

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=540&code=0&carte=1&mode=0&run=10

[Duane S.]

Aha! Here we go.

Just gone through the GEFS ensembles and there continues a trend of increasing number of cold members in amongst them. We will see a very cold op in the not too distant future, I'm convinced.

Also, a definate trend for the Azores high to pull back into the Atlantic, excellent precursor to WAA into Greenland thereafter. Got a lot of weather to get through before any of that (if it happens at all) comes to fruition. Looking good though.

[That ECM]

Assuming that chart is correct, a northerly is in the pipeline. It ties in with the MetO forecast.

UK Outlook for Sunday 13 Jan 2013 to Sunday 27 Jan 2013:

There is greater than average uncertainty through this forecast period, though it looks likely to start with fairly average climatological conditions, meaning the south and and east of the UK will see the driest and brightest weather, while the north and west will tend to be more unsettled. However, there could be some rain at times anywhere across the UK. Temperatures will tend to be close to average for the time of year. Later, some marked changes of weather-type are possible, and the risk of spells of colder than average conditions increases.

Issued at: 1600 on Sat 29 Dec 2012

What this tells you is that they do not see the NH as currently shown by the output. If they thought this was the case then they would not need to put caveats in regarding potential cold. Sure they are aware that a SSW will happen and like the rest of us, they do not know what impact this could have. Though they must believe this increases the chance of cold.

The last output from GFS is encouraging as the NH is starting to look very different. Large swings in output to come over the coming ten days. Going to be very interesting to observe.

Regards

That ECM

[ChartViewer]

ECM192 interesting compared to the 00z

216

Edited December 29, 2012 by ChartViewer

[Methuselah]

The signs from the GFS are looking quite promising...NAO to tank like Aston Villa's goal difference?

[snow1975]

What this tells you is that they do not see the NH as currently shown by the output. If they thought this was the case then they would not need to put caveats in regarding potential cold. Sure they are aware that a SSW will happen and like the rest of us, they do not know what impact this could have. Though they must believe this increases the chance of cold.

The last output from GFS is encouraging as the NH is starting to look very different. Large swings in output to come over the coming ten days. Going to be very interesting to observe.

Regards

That ECM

I agree! By the way, there's an interesting programme on More4 right now, relevant to what's coming later this month perhaps? Snowstorm: Britain's Big Freeze.

Edited December 29, 2012 by snow1975

[chris55]

That's the most interesting chart I have seen for a while, nothing to get up and shout about, but a break in the zonal domination and hints at pressure rises to the north east

Edited December 29, 2012 by chris55

[Panayiotis]

Would that undercut, bringing in those -16C uppers from Moscow, from that part of the PV?

Edited December 29, 2012 by Panayiotis

[cooling climate]

ECM192 interesting compared to the 00z

216

It would be nice to eek out a seasonal feel to the weather prior to the onset of the strat warming and

whatever that may have in store for us down the line. In fact the t240 chart is synoptically one of the

best I have seen over the UK for getting on three weeks I think.

[chris55]

Best ECM Det run for a while

[latitude]

GFS possibly smelling the strat coffee...we hope....

Interesting to see ensembles over the next few days....

What coffee do you mean? If the coffee is the SSW, well that hasent even happend yet....and is not 100% forecast to even happen, let alone propagate.

[Long haul to mild]

This thread can be so confusing at times for those of us with less expertise.

For example, earlier today, in the space of just three posts, the GFS 12z was described as :

1) promising for those seeking cold

2) a disaster for cold lovers

What chance have we got of learning anything given the above?

Sorry for the rant, but it can be so frustrating at times!

Edited December 29, 2012 by Chalk Serpent

[ChartViewer]

What coffee do you mean? If the coffee is the SSW, well that hasent even happend yet....and is not 100% forecast to even happen, let alone propagate.

Having been viewing the runs all of them for weeks then the GFS12 and the ECM12z are improvements on previous runs........Wether its the strat or not the dynamics are better....

Regards

[Panayiotis]

This thread can be so confusing at times for those of us with less expertise.

For example, earlier today, in the space of just three posts, the GFS 12z was described as :

1) promising for those seeking cold

2) a disaster for cold lovers

What chance have we got of learning anything given the above?

Sorry for the rant, but it can be so frustrating at times!

I can see your confusion, it depends on who is saying the comment because the less experienced/knowledge may see a chart/run and say its poor/bad for cold (if they give no explanation dont listen to them), just make sure you either listen to the pros or learn from people who give charts and explanations behind their reasoning, therefore you will get a better idea of whats happening.

Well that's what I did when I found this forum 2 years ago, and in those 2 years I have learnt a lot, but I made sure I listened to the right people.

Edited December 29, 2012 by Panayiotis

[bluearmy]

This thread can be so confusing at times for those of us with less expertise.

For example, earlier today, in the space of just three posts, the GFS 12z was described as :

1) promising for those seeking cold

2) a disaster for cold lovers

What chance have we got of learning anything given the above?

Sorry for the rant, but it can be so frustrating at times!

I'm afraid you need to spend sme time on here to learn how to interperate the posts, never mind the models! Ithink gavin was merely refering to the run itself re snowfall. Others were looking at the bigger picture and seeing more amplification in the near term, less jet energy as we head through the run and some retrogression of the pattern later on. I think we have a tough week ahead as quite a few members feel unable to take on board a drift to cold, having been through the letdown earlier this month.

[LomondSnowstorm]

What coffee do you mean? If the coffee is the SSW, well that hasent even happend yet....and is not 100% forecast to even happen, let alone propagate.

It looks highly likely to occur now, since we have cross model agreement and have had for a few days, along with the stratosphere being far easier to model than the troposphere. Whether it propagates or not is another matter, and with the EP flux starting to look more favorable I wouldn't be all that concerned about propagation issues yet. However, in this instance I believe the 'coffee' isn't directly the strat warming but the combination of increasing angular momentum coupled with a movement of the MJO towards phases 6,7 and 8, and there does appear to be a large degree of linkage between the MJO and the strat. Anyway, while that's for another time, the point is that the signs have been there for some time that a pattern change was likely to start showing up on the charts from around the second week of January onwards, whichever way you look at it, and we've seen this starting to show up on the charts. Let's see where we go from here.

[bluearmy]

What coffee do you mean? If the coffee is the SSW, well that hasent even happend yet....and is not 100% forecast to even happen, let alone propagate.

It is 100% forecast to happen but all forecasts are in the future so none are 100 % guaranteed. The propogation is an issue. Remember we sometimes see an immediate trop response to an SSW so as the same run is modelling the strat as well as the trop, its possible for a run to show this. fwiw, i havent noticed anything in an op run thus far that reflects a quick response.

[bradymk]

The signs from the GFS are looking quite promising...NAO to tank like Aston Villa's goal difference?

haha Yes looks like something is starting to cook tonight, especially within the GEFS ensembles. A trend i hope will continue. GFS 12z op also is a near perfect match for phase 6 MJO anomalies and the ECM is the best we have seen for a while going forward. Is this our next rollercoaster beginning? saying that, the rollercoaster hasnt stopped since Mid November, hopefully we will have a bit more luck this time.

Edited December 29, 2012 by bradythemole

[Froze were the Days]

Would that undercut, bringing in those -16C uppers from Moscow, from that part of the PV?

Most probably not, a developing system like we see all to often deepening and moving somewhat northwards - doesn't seem to be that NW/SE jet for the needed undercutting - but that's just 1 run showing that so not really bothered at the moment.

[mcweather]

JFF

http://www.wetterzentrale.de/pics/archive/ra/1947/Rrea00119470121.gif

http://www.wetterzentrale.de/pics/Recm2401.gif

Compare, contrast , discuss.

[bluearmy]

JFF

http://www.wetterzentrale.de/pics/archive/ra/1947/Rrea00119470121.gif

http://www.wetterzentrale.de/pics/Recm2401.gif

Compare, contrast , discuss.

Nothing to discuss - yet. Too muh contrast. We may see a run which looks smilar but not today.