Man With Beard
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Posts posted by Man With Beard
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UKMO goes same way as yesterday's T12 - massive undercut T96-T144, heavy snow for all most likely.
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As good as some of the models look for T120 onwards, they are still fairly knifeedge and at such a long way I wouldn't be overly confident that the mild air wont move in just enough to cut off the east feed. For example, this: http://www.meteociel.fr/modeles/ukmo2.php?nh=0&ech=120&carte=1021
is a snow feast, but 200 miles north and most of England will be on flood alert instead. Snow in these parts is rarely far from milder weather, which is why it often doesn't verify. Rather than 5-10 more says of cold, I think we're looking at 5-10 more days of knifeedge. Of course, it is these knifeedge situations that often lead to major snowfalls, so anyone seeking snow over just cold should be very pleased with the 12Z output.
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Well if nothing else, I for one am looking forward to this output at T96;
It should feel quite 'bracing' out and about on Wednesday if these charts come to pass.
It's funny that these charts seem to have been forgotten a little in the light of Monday's event and the long-term picture. These are a cold-lover's dream (in England anyway) and the kind of charts that spawn late developing disturbances. Wouldn't be surprised to see a late developing feature run across England from this, obviously the SE in the very best position. Goodness knows how much snow will be on the North Downs in Kent by Friday - surely over a foot somewhere.
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For SW England from Saturday to Thursday the PPN is rain with mild (as per the ECM) on Thursday. Turning into a non-event for Cornwall, Devon, Somerset, Dorset and Wiltshire. As per the GFS 18z.
All models showing cold backing west by Wednesday, you'd be unlucky not to get something out of that. Even on the precip charts there is snow over SW at times.
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Just looking at the latest fax chart for T72hrs, interestingly the UKMO have removed the warm sector with just an occlusion clearing se.
This probably also ties in with Ian F's comments on the BBC where he hinted at the snow risk perhaps extending further west.
It seems characteristic of the models (especially GFS) that undercutting shortwaves/lows end up further west than originally programmed. I can remember so many examples of this, indeed tomorrow's events are going a bit that way. If this happens again on Monday, the west may well end up with more snow than anyone.
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TBH in situations where two big models oppose each other, I have always found there is a bit of truth in both of them. I was thinking this yesterday, (ECM significant northern blocking, GFS no northern blocking) and this mornings ECM did exactly what I expected - a compromise, a little northern blocking - and now if you look at GFS 06Z you can see the tiniest upper high has snuck into Greenland at around T144. Probable result? Battleground UK from Tuesday onwards. High chance of stupendous amounts of snow in the north. The south could go either way, in fact there may be transitions between snow and rain through the week, but could be all rain (yet more flooding?). That's what I expect taking all models into account.
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GFS Mean at T126 ... 850s widely below -8C!!
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+ 10 850s over Scandinavia on the 00z ECM have been replaced with -10 850s on the 12z!!
If this chart came off it would be like a repeat of this week - low stuck off Ireland
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Whats going on here then? Thats one messy fax.
Is it normal for the 564 line to get so close to Spain at this time of year?
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Just to put the 18z in perspective, the wind direction is as follows:
1 day SW
2 day SW
3 day SW
4 day SW
5 day SW
6 day SW
7 day W
8 day SW
9 day SW
10 day NW
11 day SW
12 day W
13 day SW
14 day W
15 day SW
16 day SW
I was hoping for a XMAS miracle, but no.....
In terms of looking for cold, I see things a bit differently when there is a block to the east - I look for how close the east wind gets to Kent. Less than 500 miles out at T168 and I'm interested. Usually comes to nothing but sometimes moves in our favour (i think last Feb was a little like this, also Feb 2009?). On this basis, the current situation is still worth watching though not looking as promising as yesterday for sure.
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http://www.meteociel.fr/modeles/ecmwf/runs/2012121312/ECM1-168.GIF?13-0
flattening of Low, looking much better +168hrs. not bad not bad.
and here comes the secondary low too.
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patch of 552 dam heights just west of Norway due to WAA... Russian high backing west.
That's two runs in a row that bring the Russian high back and the third in a row to trend that way. Very, very interesting.
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Well yes, the 6z op run is looking isolated with it's return of the cold block, latest meto sounds like near average temps will prevail next week with a lot of rain across the uk, later in dec sounds colder in northern britain with a westerly of polar origin but no mention of the S word in the extended outlook, I have to say it's looking grim for frost and snow prospects after today, much as it pains me to say it being a major coldie.
Of course the 6z will probably come to nothing but what interested me was how the 00z came quite close to the same outcome ... GFS op runs have been rubbished more than once this winter already before turning out to be true ... if the 12z repeats the trend I'll be interested...
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The 6z is the perfect example of how all the posts writing off the rest of December are just silly. I'm not saying this is what will unfold just that the weather is not as straight forward as some GFS runs out to 384 might look!!
ECM ens also have a scatter of members dipping around this time, have not looked at the postage stamps but maybe they are along the same lines?
Yes absolutely, if you look through T120 to T180 the block to the east pushes back - and I'm looking at Mr Shortwave coming from the easterly flow, now if that comes a little further south as GFS 06Z shows and joins up with Mr Decaying Low then the cold can come that little bit further west and hey presto. Funny I was looking at the 00z charts thinking it wasnt a mile away and then the 06z goes and does it. It's actually very close to coming off and far away enough into the future to upgrade (or of course downgrade). Stay tuned!
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GFS 06z Ensembles also show a cooling trend after this weeks warm up;
http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png
If we could knock out some of those mild members in FI then the mean would probably go sub zero again in FI.
Anyway, off to the regionals I go now. Ice days being reported IMBY.
Virtually all the runs get to -5C (850's) towards the end. Suggesting that our Atlantic low will not get stuck in situ for weeks on end - winter gets another chance from mid next mid-week onwards perhaps. (Oh, and I see a few nowcasts creeping up at T24 / T48 ... latest indicators suggest it may well be more than just rain
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Absolutely no clouds here. Must be cold though, white frost still surviving on some pavements here in Portsmouth
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Well you were a late developer
but looks like you hold last nights record low localy Prospects for a little snow before we get steam rolled by atlantic seems a little better now
Ian Fergussonâ€@fergieweather
W COUNTRY Thurs tricky as potential for snow early AM, perhaps 1-2cm so hopefully not disruptive. Most likely areas Mendips/B&NES/ N'wards..
...and hello? Met Office website now showing a little snow on the South coast tomorrow morning too? If we have a dusting in Pompey that would count as a significant cold spell, cos it hardly ever happens!
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i just had a look back at the ecm runs from the middle of last week to see where they went wrong as i just dont buy the scandi shortwave for causing the complete failure. and surprise surprise, it didnt. its a combo of the scandi shortwave preventing the russian ridge from supporting our fledgling block plus there should have been a ridge coming off the eastern seaboard tomorrow/monday which would deflect the second shortwave on a more ne interior track and enable this east coast ridge to add support to our block from the west. the lack of this east coast ridge is a double whammy. firstly, it means there is absolutely no support for our ridge due to the shortwave drama to our northeast and secondly, (more importantly) the second shortwave now flows straight into the west atlantic depression and gives it the energy to rush straight across the atlantic. our ridge stands no chance and to make matters worse, the shortwave to our northeast is sufficiently far enough north as it tumbles the energy southwest to draw the low heights of atlantic attack at that lattitude towards it. take the scandi shortwave away and we would probably have the cold air far enough west to repel the initial atlantic attack to our south giving a dramatic battleground scenario. keep the east coast ridge and the atlantic isnt strong enough to smash through our ridge and the cold would tumble in from the northeast. i dont think the combination of these two things happening at less than day 6 could reasonably have been factored into any forecast. thats why the cold period upcoming will be so shortlived.
Fantastic post - I could add that the development of a mini-high over France/The Alps also keeps the northern blocking further north - what an amazing start to the winter season with two heavyweights battling out, northern blocking knocking the Atlantic to the floor, it looks like a knockout only for the Atlantic to get back up and lay out the block, reminds me of Eubank vs Watson 20 years ago!...
Seriously though, the fact that there is both unexpected strength in the Atlantic and a continued signal for northern blocking tell me this battle is not going to be conclusively won this week. Writing off Christmas to the Atlantic is far too premature; the Atlantic may stronger this week but any drop in intensity will let blocking push back, as indeed many FI charts already suggest could happen. Indeed, some tiny changes even in the next 48 hours could lead to big changes at T96 - when you have weather hitting each other from two opposing angles any margin for error will be multiplied - so personally I will be watching closely all the way until Thursday this week as I expect surprises even at T24.
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hold on ... is that some flakes on the windscreen I see?
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Rain in Portsmouth ... but then you'd expect that, wouldn't you!
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Sorry on mobile so can't post link - but looking at GFS snow cover charts for Europe after T144, the whole of central and eastern Europe looks certain to be under snow cover - meaning any feed from the east next week will even more potent for cold than 850s might suggest, I would have thought?
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http://www.wetterzentrale.de/pics/MT8_London_ens.png
Lots of mini northerlies on offer there. Even if no cold spell comes out of this, a succession of cold snaps seems very possible.
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So the promise of a persistent block to the north has been backed off on both GFS and UKMO by T144. Quite shocking how quickly it gets crushed actually. Will it reappear? I guess there will be some fluctuations run to run for a few days. The good news for winter lovers is that the air to our north and east is now cold, so opportunities for cold may not need such a big lead-in in the next couple of weeks. In short, winter is round the corner, but will it actually come around that corner?
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I think any lessons to be learnt for those disappointed is not to hang hopes on what the operationals show but to draw a much nearer reality outcome by looking at the ensembles and to date despite some mouthwatering operational charts at no point have the ensembles shown any deep shift downwards into serious cold territory in their mean for any run which I have regularly reported in my summaries and that to me is indication enough to suggest at no point soon would their be any significant cold
That is true, although sometimes the Op run can act as a 'leader' of the pack and a few cold/mild solutions end up being right with the rest being wrong. I think the lack of agreement in the ensembles merely indicates the volatility of the situation, as indeed it still does - a few 06Z ensembles still going for something colder late next week, a sign that the Atlantic isn't going to win this one without a fight.
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but looks like you hold last nights record low localy 
South West/Central Southern England Regional Discussion 13/01/13 ---->
in Regional
Posted
Light snow in Portsmouth, not settling apart from on a few surfaces