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

[Cheshire Freeze]

Steve Murr has done the research regarding SSW events if you look in the strat thread. It seems that where the SSW has propogated a -NAO has resulted every time. That's as good news as one could expect at this early stage in proceedings. What we don't know is whether we'll get propogation or a east or west based -NAO or even how long any potential -NAO will last for.

In terms of the NWP tonight, there's nowt to say except that it looks dreadful at the minute if you're after cold in the near future. Briefly settling down from the south then a return to more tradiational zonal conditions with the vortex located over Greenland spawning more depressions.

Edited December 29, 2012 by CreweCold

[Ice Day]

Sorry im just so disappointed with todays overall output. I find the GEFS means especially depressing because when you compare +300 with previous runs its a case of spot the difference.

Im not even convinced a SSW will come to our rescue. When it comes to N blocking it isn't just what occurs in the Stratosphere that dictates the frequency of blocking because their are many other factors. For example if members revisit the 2009/2010 Strat thread we only had minor warmings and yet look at the exceptional blocking that developed over Greenland and the incredibly negative AO.

As I said a few days ago some other factor is causing this dreadful pattern and the resulting positive NAO which only the ECM seasonal picked up on. The question is can this SSW override this other unknown signal that is causing the positive NAO???

I share your disappointment. Ultimately, despite millions being pumped into better forecasting techniques and getting hung up on the next big thing (SST, SSW or whatever's coming next), the weather is chaotic and will do what it does. In general terms, we've been very lucky with recent winters so we are probably due a dud. Hopefully there's better things around the corner but let's just accept the weather will do as it will.

[ChartViewer]

I share your disappointment. Ultimately, despite millions being pumped into better forecasting techniques and getting hung up on the next big thing (SST, SSW or whatever's coming next), the weather is chaotic and will do what it does. In general terms, we've been very lucky with recent winters so we are probably due a dud. Hopefully there's better things around the corner but let's just accept the weather will do as it will.

We had that last year. I still maintain we are in for a Jan 87 or a Feb 91 event for UK...eg cold and snow.. ...............Cant be that unlucky to get an SSW and not get it to deliver to us................Wonder if 87 or 91 were due to sudden warming events?

Edited December 29, 2012 by ChartViewer

[Ice Day]

We had that last year. I still maintain we are in for a Jan 87 or a Feb 91 event for UK...eg cold and snow.. ...............Cant be that unlucky to get an SSW and not get it to deliver to us................Wonder if 87 or 91 were due to sudden warming events?

Compared to some winters in the late 80's/early 90's, last year was a corker!!!

[ChartViewer]

Compared to some winters in the late 80's/early 90's, last year was a corker!!!

Ha ha very true!...would say mid 90s to early naughties were our Bartlett period?

Edited December 29, 2012 by ChartViewer

[kumquat]

Compared to some winters in the late 80's/early 90's, last year was a corker!!!

This is where location has a massive bearing! (In all kinds of setups).

The way I see it tonight after the 18z we're at stalemate (stalemate is never a loss!). Dross charts past few days. SSW and subsequent effects on the cards (we all hope and pray). The gfs 18z shows almost a neutral standstill out in FI, although there's an inverted horse-shoe PV opposite from us in the NH. It's been pretty mashed.

We continue to bite our fingernails at every run!

Edited December 29, 2012 by kumquat

[joggs]

For peeps so dissapointed with the over all output well the crumbs of comfort we can offer is, remem 2009/10 n things can and will change in the blink of an eye but more often they dont. Also peeps put alot into the strat thread being a big indicator, but until this is scientifically proven then count me out. Im sticking with the big 3 n mo further outlook. With GP,S great enthusiasm n skill i still do not see the point of people relying on the strat thread because too many variables n players seemed to be linked in ways we do not understand. Thats not to say i dont appreciate his efforts.

[joggs]

Sorry for the bad grammar- red wine.

[Panayiotis]

I really hope a SSW happens, not because it *could* lead to cold but to learn from it but if leads to cold we will know what to look out for next year(s), if it doesnt give us cold but changes the overall pattern of the troposphere it will be interesting to see, in what way it does this.

In short it will help us understand more about how weather behaves.

Edited December 29, 2012 by Panayiotis

[Iceni]

I really hope a SSW happens, not because it *could* lead to cold but to learn from it but if leads to cold we will know what to look out for next year(s), if it doesnt give us cold but changes the overall pattern of the troposphere it will be interesting to see, in what way it does this.

In short it will help us understand more about how weather behaves.

That is a very intelligent post.

[Duane S.]

Overall another poor day in terms of sustained cold potential.My biggest concern was looking upstream for signs of amplification and not seeing much. NOAA concurring with that as well. I'm not sure if we can get a boost from an upsurge in mountain torque in a weeks time or so. Jet seems to be heading north so at least the south should get a bit of a respite from the flooding of late. Conclussion is, right now it's difficult to see where any prolonged cold is going to emerge from before mid Jan at the earliest. Thereafter, we have every chance IMO.

But having had more thunder in the past week than the through all of the summer, tornadic potential later today and probably again on NYE, can't complain really!

[swfc]

Not much interest to be seen on the oz!!!Bit more of a push north with the high from the south early on but soon gone and the bland outlook continues.Jet moving north so i guess it will be drier for a while,Iwas going to say"lets see what the ecm brings"but if its any different to gfs ill ride a camel naked threw sheff singing "ssw gangnam style"!!hmmm it is different its worse

Edited December 29, 2012 by swfc

[IDO]

No changes on the large scale from GFS 0z. The pattern remains zonal with the AH giving us some respite. The longevity of this ridging next week fluctuates but 4/5 days for the south looks close.

The GEFS mean at T120: http://modeles.meteo...-21-1-120.png?0

At T240: http://modeles.meteo...-21-1-240.png?0

From there its back to cyclonic westerlies: http://modeles.meteo...-21-1-300.png?0

With a cool zonal flow: http://modeles.meteo...-21-0-300.png?0

The 850s continuing the trend to cool seasonal temps: http://modeles.meteo...ndres&runpara=0

ECM is similar, synoptically.

All really academic, as the pending SSW will disrupt any current long term pattern, so we are really just biding our time, till this feeds into the models.

Edited December 29, 2012 by i'm dreaming of...

[Bobby]

Hmm, the runs just keep getting worse if anything. A shocking set of 00z runs for cold, good agreement across the models of the setup with high pressure gradually flattening under the infuence of the Atlantic freight-train with more wind and rain, especially further North initially but then for most.

The jet and Atlantic look very powered up.

[Gibby]

Good morning. Here is the report from the 00zs of GFS, UKMO, GEM and ECM for this morning Saturday December 29th 2012.

All models show no changes this morning to the general flow of things between now and the end of next week. The strong to gale SW flow currently blowing over the UK has a squally cold front currently lying North/ South down the western side of Britain moving East carrying a band of heavy rain with it, clearing the far East this evening. Following this mild and windy spell temperatures will fall back to normal levels with frequent showers and brighter intervals replacing the rain. Through the night the showers, heavy in the West will fall as hail to lower levels and sleet or snow on upland Northern areas later. Tomorrow will see a showery day, with the potency of the showers decrease with time as a new area of cloud and rain approaches the West and North later. On New Years Eve the new front carries another band of squally rain East over the UK through the day followed by a colder NW flow for New Years Day with sunshine and showers for the Day itself. On Wednesday the weather turns milder again as a warm front crosses East bringing rain and drizzle to all areas though more especially to Northern and Western areas before drier and rather cloudy weather but for the most part dry conditions affect most areas up to the weekend.

GFS then shows the High close to the South responsible for the drier weather slip away SE with SW winds freshening everywhere as Atlantic fronts bring the return of rain and strong winds to all areas before the new week. The rest of the run shows a period of zonal weather again with periods of rain mixed with spells of sunshine and showers with temperatures rallying overall close to the normal for mid January though this does not exempt the North from some wintry showers behind the cold fronts.

The GFS Ensembles show a few more days of zonal weather before a High pressure cell swamps the UK in warm uppers for 4-5 days when it becomes dry. Thereafter a return to normal values is shown with the increased frequency of rain once more as the Atlantic train rolls in again.

The Jet Stream shows a flow moving over the UK for a couple more days before a strong forcing of the flow North over the British Isles in response to the High to the South. Later next week and weekend a very powerful surge of energy is pulled across the Atlantic towards Europe and it's this that will eventually break the High down SE into SE Europe.

UKMO for midnight on Friday shows a strong Anticyclone circa 1040mbs near NW France with a ridge North over the UK. A slack westerly flow would deliver a rather cloudy and dry day with near normal temperatures for that time of year.

GEM shows the High in a similar location to UKMO at that time pulling it slowly away SE later as troughs wind their way slowly SE later bringing rainfall to the North and West by the end of its run.

ECM too is virtually identical to UKMO with its positioning of the High on day 6, it too carrying it slowly SE, albeit less dramatically so than GFS. Nevertheless, the infiltration of the Atlantic reaches all Northern and Western areas with occasional rain by Day 10.

In Summary today there is a period of dry and mild weather still on the way for the middle and end of next week. The problem is no model shows the High gaining total control, all models keeping it's centre South of the UK and making for rather cloudy and benign weather conditions with temperatures well up to normal or somewhat above in any brightness. Longer term all models show a breakdown of sorts, especially for the North and West where rain would return by the start of the second week. How far this moves South and East will be firmed up on over coming days. Temperatures look like remaining well up to the normal or above for January with little risk of significant frost and snow problems for Farmers and Growers to worry about in the period, and I'm sure they will be equally relieved that a window of drier weather is on the way.

[ANYWEATHER]

Just a quick one, the area of high pressure for next week never really gets a foothold over the uk, and it looks like the drier window of weather forecast from the models is becoming more and more shortlived, a worring trend Im afraid due to the state of the soggy conditions in the uk.......

[mountain shadow]

I notice a couple of very cold GFS ensembles at the very end of FI.

With Steve's possible target date for cold arriving around the 14th it will interesting to see if the colder members start to increase as we get nearer this date.

[bluearmy]

Signs of interest in the extended gefs this mornng. Hopefully we will have something to look at soon because the situation pre 12th jan looks decidedly tedious if you are seeking a cold scenario.

[Bobby]

The 00z NAEFS continues the theme of the pattern flattening with low pressure in control after that until the end of the run

+192

+240

End of run

Edited December 29, 2012 by Bobby

[bluearmy]

The 00z NAEFS continues the theme of the pattern flattening with low pressure in control after that until the end of the run

+192

+240

End of run

And the weak upper ridge developing to our northwest at day 10. Just a transient feature or something thats going to grow? Take care not to just look at the pressure patterns on mean charts - can be misleading although in this case, i think they wont be too far from the truth

[Ian Brown]

Hard to be positive this morning, the PV over Greenland is as large and as intense as anything seen for some of the mildest winters over the last 25 years, and the NAO/AO strongly positive, despite suggestions that the reverse should be happening.

It will take a seismic shift to see a change in fortunes.

Edited December 29, 2012 by Ian Brown

[Ian Brown]

No changes on the large scale from GFS 0z. The pattern remains zonal with the AH giving us some respite. The longevity of this ridging next week fluctuates but 4/5 days for the south looks close.

The GEFS mean at T120: http://modeles.meteo...-21-1-120.png?0

At T240: http://modeles.meteo...-21-1-240.png?0

From there its back to cyclonic westerlies: http://modeles.meteo...-21-1-300.png?0

With a cool zonal flow: http://modeles.meteo...-21-0-300.png?0

The 850s continuing the trend to cool seasonal temps: http://modeles.meteo...ndres&runpara=0

ECM is similar, synoptically.

All really academic, as the pending SSW will disrupt any current long term pattern, so we are really just biding our time, till this feeds into the models.

You can't assume that the 'pending SSW' will reverse the situation. It is not a guarantee that even if it develops as suggested that it will see cold air displaced to the mid-latitudes. The starting point will be from the worst possible position, with a deep PV over Greenland and established stagnant HP over Europe.

[IDO]

Just had a look at CFS to see whats happening late Jan/early Feb. The model showing signs of height rises near the pole that pushes the 500pHa Pv to Greenland/ N Atlantic. with the Russian High blocking it there. The real cold 850s uppers hit Canada and USA:

http://modeles.meteociel.fr/modeles/cfs/run1m/cfsnh-2-714.png

On this run (and I know its the CFS) very little cold potential for the UK. We miss out again, on some astonishing wintry weather.

I cannot help think that with the PV in W. Greenland we will not be in an ideal position for cold when the SSW happens.

[Snowman31]

One trend no one seems to have noticed is that the PV seems to start moving away from greenland at the end of the last few GFS runs. Surely that is a positive? I think we will need to wait till about mid Jan, so don't expect anything of note up to then and you won't be too disappointed.

[ghrud]

Downward trend of the 850hPa temperatures continues on the 18z ensembles, it has been showing this on all of today's runs, including some of yesterdays.

http://forum.netweather.tv/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=150293

What location is this graph for? Cardiff?

Edited December 29, 2012 by ghrud