The op run is again the mildest option in the short ens, most runs bring the low close but keep it all snow across the south

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I may have said this before but wish it went Feb 29th - So I could include the coldest day of the winter in winter for winter 17/18 stats but it looks like the coldest day would be the start of spring on 1st March. - As fate would have it! Alas it could be the coldest start to spring in a long time!?

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http://old.wetterzentrale.de/pics/MT8_London_ens.png

BIG flip in the 18z Ensembles early in FI with a majority now looking to end this earlier.

I sense the end will be nigh shortly.....but I can't wait for spring to arrive tbh.

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I wouldn't call it a big flip at all. That would suggest the 12z ens had a much lower mean but in reality its only about 1c warmer by the end of the run. 

There is clearly much uncertainty surrounding the track and intensity of the low to the SW by Friday and until next week we don't have much of an idea where we go from there. The default would always be a return to near average conditions but there is much scatter and much to be resolved.

Can we have a short term model snow potential thread to keep away from the doom mongers looking for a breakdown??i

Well, as you know meteorological spring is in 6 days time so you don't have to wait too long!?

Did you not want to see a few dustings of snow followed by a good covering of snow before this winter is out?

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No! They have rarelyagreed it would continue well into March. Depends on your starting point. I don't think we can even take one ensemble set in isolation atm. I saved Monday's 06z ensembles and this would be an upgrade from them. Deep cold consistent starting point of Monday but mean was just -12C. Mean was back to -5C by March 1st. Obviously there was more uncertainty after that into F1 but the theme was milder still. I just think a couple of excellent sets have raised expectations and they still exceed our early expectations in my opinion. 

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For contrasting purposes - i thought of comparing the 06Z run of the ensembles for London to the very latest 18z run: First thing to notice is the increase spike in precipitation - So this could be rain or snow or pure snow etc. The 18z ensembles shows more precipitation spikes for 2nd/3rd March denoting a breakdown is becoming more likely around Friday than it was during the 06z run.

06z

 

Latest 18z

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Maybe this ECM precip chart sums things up. On the other hand, maybe it doesn't.

18z..
80cm over my house. :/

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Talk of record lows and blizzards seem a little OTT with BBC forecasters not on board ?

Hmm, interesting to see this morning that GEM, MetO and GFS all show something not far off a blizzard as a low moves up from the south at the end of next week. I would suspect they won't get it right at this range, but it's a remarkably strong signal.

It'll be interesting to see if ECM this morning is on board, too, as its ensembles last night showed a great deal of scatter around then.

(We all know about returning polar maritime airmasses, but this would contain returning polar continental air - so rare I don't think that term even exists!)

Also, here's one for the archives:

http://old.wetterzentrale.de/pics/brack4.gif

First time in decades that a large pool of sub 510-dam air is shown over England on a "fax" chart.

EDIT: The German model shows an alternative whereby the low is kept away to the south, instead a low move south and effectively keeps deep cold over us until at least Saturday.

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Lot of risk though, Darren. It's bringing milder air. Looks marginal in the south.

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TBH, if it happened I would expect large amounts of snowfall followed by rain down here. I have my doubts, though, despite the "big guns" so far all showing it this morning... not least because it's still a week away.

 

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GFS ops have been quite insistent about this so not surprising to see it shown elsewhere this morning. I’m sure some will see negatives but it could lead to an epic (by recent standards) spell of snow for everyone if it lands just right,   No complaints from me.

Yes.

I'm ignoring it, for the moment.  ICON NAVGEM CMA all have the low slicing through the middle of France (as do a good proportion of the GEFS) like a hot knife through butter, leaving the UK in cold E or NElies, so not a hugely strong signal, even if later backed by the ECM op.

One of the reasons they model this is  that they have the upper cold pool shooting further south over S England on Weds, that seems to be the key, amongst other variables.

http://www.meteociel.fr/modeles/navgeme_cartes.php

http://www.meteociel.fr/modeles/icone_cartes.php?&ech=162&mode=0&map=0&archive=0

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=168&code=19&mode=0&carte=0

http://www.meteociel.fr/modeles/cmae_cartes.php?&ech=144&mode=0&carte=0

 

FI is around t72 as very small differences in angles of isobars make massive differences in weather on the ground - the difference between dry as a bone and powder snow drifted in a streamer.  The difference between frontal blizzard that gives way to rain, or continued threat of cold and snow from the North Sea.

More runs are needed.

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The Cresta award goes to ICON, but whichever way you look it’s incredibke output and it’s on our doorstep now.
A severe spell of late winter weather starts tomorrow night, and the focus now is on how much snow, where and what follows on Friday - blizzard and thaw, blizzard and more snow or just more snow ☃️

I’m guessing more yellows today with an amber for the east coast taking us to Tues.

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Things starting to look extremely cold for the northern half of the Country for the next two weeks according to the 0z GEFS with plenty to entertain us southerners in the meantime!! These are the ensembles for Aberdeen.
http://modeles7.meteociel.fr/modeles/gens/runs/2018022400/graphe3_1000___-2.32641543982_57.3684210526_.gif 

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Yes, although the nature of the beast is that we will always be looking to see how the cold will break down, the cold air is now embedded and there's a heck of a ride to come over the next few days. As usual, I've been archiving various charts each day and will doubtless look back at them with nostalgia in years to come - I mean, really, -12C 850s for several days, 510 lines etc haven't been seen down here at least for decades in midwinter, let alone in the dying days of winter.

FWIW, the GEFS seem to have around a 75/25 split in favour of milder air making it here at the end of next week, favouring a more northerly track of the low. I'll be interested to see what the split is like in this morning's EPS.

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It is far from decided and (see my previous post) there is plenty of evidence other than the GEFS to the contrary.

We shall see what the ECM Op makes of it soon, along with its 50 or so members later on.  

My view is that the interaction of the deep cold and the warmer air to the south is going to take many attempts to model correctly, I expect volatile output in this aspect as we go through the weekend.

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Yup, I'd agree wholeheartedly with that. Despite the ops so far and the GEFS, I wouldn't be at all surprised if that low instead went through France instead, as per the ICON. The models always have problems in these situations, it seems, and I daresay they'll still be faffing around with it even by Tuesday... albeit I suspect by then the snow falling will have stolen much of the attention on here!

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I agree. The biggest snowfalls are almost always associated with marginal setups (with the exception of lake effect snow). With such a cold pool in place over the UK next week it would almost be a shame if we DIDN'T get a mild snowmaking low smashing into it. Yes some people would probably get rain but it would be an epic blizzzard, one for the history books. 

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I agree.  I'm hoping its resolved by Sunday evening but I have a feeling that it could even take as long as you say.

In the meantime the focus of the snow showers appears to be forecasted for north Kent northward on an ENE or Ely.  You are in with a shout Darren, as am I in terms of my workplace in Faversham.

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Indeed, my location is one that used to do very well back in the day, as did much of the north Kent coastal strip.

Something worth mentioning is that the raw forecasts from the GFS have been slowly ramping up snow volumes here. I find XCWeather's presentation to be really nice, so here's the link to MBY:

http://xcweather.co.uk/forecast/leysdown

Of note is that from Sunday night snow is forecast even though it doesn't show a snow symbol - it seems anything under 0.5mm rainfall equivalent is just shown as cloud.

As we know, the models struggle to resolve shallow cumulus/cumulonimbus clouds and thus tend to underestimate convective snowfall. Yesterday was a prime example. The models showed unbroken sunshine all day, yet shallow cumulus built up during the morning and by afternoon the sky was mostly obscured.

I've been keeping the senior team at the school where I work updated these past few days. The Head was most sceptical, believing it'd just get cold and sunny (as the automated forecasts at the time were showing), but they've ordered in extra salt as a precaution. Not, as the site team say, it'll do much good with blowing powder snow!

I've got Monday off work, booked that day off ages ago, so should miss the first round of traffic chaos. I'm not much looking forward to Tuesday's commute, though!

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UKMO has the 0C isotherm hugging the south coast by 144, so considerably earlier than GFS. It would likely be all snow at that point but southerners would want to see that low heading east rather than north.

Starting to look increasingly likely that some part of the country could see an epic dump of snow at the end of the week, even after whatever convective goodies get served up before then.

(Automated weather app update: now showing snow for Fri, Sat, Sun and Mon here!)

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