Just Before Dawn

Well the 18z GFS operational is quite a run - a little, very minor potential hiccup on tuesday with some annoying dewpoints progged above 0c for a time in coastal areas and a light westerly wind until later tuesday afternoon, but from there on in, it's a remarkable chart with lots of cold, unstable air. No problem with snow showers there, and some pretty beefy ones at that. From Late Wednesday into early evening Saturday we get strong to gale-force north-easterlies, peaking on Friday. I'm not generally one for hyperbole, but if the GFS 18z operational were to verify, then Friday could see whiteout conditions across the North York Moors, Yorkshire Wolds and Lincolnshire Wolds, with snow showers and blowing snow. We haven't seen that here in over 20 years. I've been in two genuine white-outs in my life, one in Slovakia, one on Glacier National Park, Montana, and they are genuinely frightening. Exceptional synoptics in one sense, but also concerning in another, were they to verify.

GFS 12z output Dewpoint maps showed the 0-1C flirting with the east coast through much of Monday until early Tuesday am, from which point it's much better. As the 18z GFS output is now coming up, we'll see if that's different.

Actually, you're right. Re-reading the output it looks fine by Tuesday late morning.

Certainly too early to worry about much, but the 12z GFS does flirt with +c dewpoints at times along the coast until the middle of the week. Will no doubt change, but thats what it showed.

8 miles away and all we have is sleet too. Very disappointing. Dew Points obviously too high along the coast - we'll need to watch that going into next week, at least according into the 12z GFS output.

Unless of course you also looked at predicted dew points, dry bulb and 500-1000hPa thickness. I guess we'll see, soon enough.

Underwhelming overnight with temps too high for anything other than a bit of sleet. NMM on Netweather extra also suggests much of the ppn later today will be of wintery-mix type, perhaps with some snow on the back edge, which is also disappointing if it verifies. Probably better for snow the further west or the higher you are, though as we move into the overnight period, dews and thicknesses look better, though ppn reduces. Enjoy it if you got it.

Pretty much North-South now - the shower cluster that gave snow earlier today over Donny/Scunny etc might catch you on its very eastern edge.

Cheers John, along the western edge of the Lincolnshire Wolds by the look of it then.

As a (very) recent Net Weather Extra subscriber, the 5 minute radar is marvellous for situations like this. This particular shower cluster is hugging the low ground almost - I wouldn't be surprised to see places like Market Rasen, Coningsby & Woodhall Spa next in the firing line.

Cold, dry and bright here all day - clouded over a couple of times but it has remained cold all day and the light dusting we had overnight has remained largely intact. Tomorrow evening looks more promising.

Good morning all - and a happy 2010 to you all. Very light dusting here this morning, not much, but probably better than I was expecting given the distribution of shower activity yesterday. Hopefully a bit more expected throughout the day for this location, though I think next week could be a lot more interesting.

I'll be having haggis for tea, that's about as close as I'll be getting. Good UKMO this evening. The little cluster of showers south of Middlesbrough only making agonisingly slow progress south at the moment, with no real sign on the radar of much further south even out over the North Sea.

Predicting snow is always a bit of a black art isn't it? (Actually it should be white art, but you get the point) - and it's a stage-by-stage process in my experience, and some of the stages are based on personal experience.As you say John, Dry Bulb and dew point critical, even more so precipitation estimates, which can be a bit dicey when trying to get a grip on convective shower activity. Obviously the direction of flow is critical, but local topography also plays a role - the {insert place name here} snow shield gag is only a half-joke, and it's an experience-based thing taking into account things as diverse as local topography, heat-island effects (in slack air), coastal sea temps. That's why I never predict snow depths. I do admire those who are prepared to stick their neck out though, particularly if they explain why they think the way they do. Radar watching, and a close eye on dry-bulb and dew point and that'll do me. That's one of the reasons why I'm not too worried about lack of MetO warnings - 12 hours from now, we can have an idea of what the ppn situation might be, but it will only be an idea, so there's no sense in getting worked up about it, one way or the other. Besides which, I don't want to be greedy - the 6 consecutive days of falling snow here before Christmas already marks this winter as outside the ordinary for recent years, so if this next phase is perhaps not quite as good as hoped (not that this is pinned down by any stretch) well then, I can't complain too much. The shower activity over Tyne & Wear and Teeside is creeping very slowly south, but it is very slow, and the bits and pieces that are coming ashore between Mablethorpe and Super Sunny Skeggy in Lincs seem to be hail/graupel. Air flow direction is largely ENE at the moment and we'll need that to change to a more North-Easterly flow for the east of the region to benefit tonight and early tomorrow. The showers are penetrating a fair way inland - the irony might be that places in the NW of our patch, along with the North York Moors will see some falling snow before South and East Yorks and Lincs do! Not often you can say that in an easterly focussed event (at least at the moment)!

I think that's right Lewis - we're in the timescales now where radar-watching will be the best way to assess where ppn is likely. 06z GFS looks good in terms of thicknesses and dew points for North and East Yorkshire from later this afternoon and for Lincolnshire by later this evening, so anything overnight should be snow except perhaps right on the coastal fringe. By tomorrow, even that should be OK. The more northerly flow is a bit of a pain, but it's still east of due north, which offers some hope. Due north and it really would be 5-10km from the coast except traditionally favoured spots like the North York Moors. I expect that the 06z is off a bit here too - and that there will be a more easterly component to airflows, but even if the 06z verified, I still think it wouldn't be a disaster - the longer sea track would at least generate more instability, potentially heavier showers with the potential for these to retain ppn longer over land, meaning that this might offset less favourable wind direction in terms of inland snow potential, at least in part. SUFC, the 6z GFS run has ppn over us until 12pm today, however it's been dry and bright all morning. The outputs for tonight and tomorrow do draw ppn closer to the coast, but for you it's only 10 or so km from where the edge of the ppn is expected to extend to, on the basis of the 6z output - with that sort of fine detail, I'd not yet write off the possibility of showers pushing that far inland.

John's willingness to engage, explain and often explain a second, third and fourth time is a big reason why Net Weather is the community it is. I look forward to seeing what it is you'll be doing next. Thanks, John.

SSTs are water temps, not air temps and vary based on mixing (including freshwater inputs), surface air temps, location, depth of water etc. Current SSTs in the North Sea vary between 10c in deepwater areas, to between 6-8c in more shallow parts. It's dropped in the last week or so, especially along coastal fringes and in embayments, with 8c water more extensive than in the week before Christmas. Still warm enough to moderate low level air, but less than it would have done last week.

If 12z ECM verfies as is, then temps and dew points would be Ok inland from early pm thursday, perhaps late on thursday night for coastal areas, but looks fine for all after that. ECM ensembles for Holland are out and the operational run is on the colder side of the ensembles certainly, but does have some support too, and isn't the coldest run either!

The 12z ecm is a spectacular run - were it to verify (and that's a humongous if) then there would be substantive convectional snowfall and some potentially frigid night-time minima in rural areas over snowfields. Ensembles should be interesting. Pits comments about the patchiness of convective snowfall is a well made point, and although North Sea SSTs are still good for convection, the last weeks low temps have moderated the high ssts a bit, though still warm enough to make convective snowfall marginal in coastal areas until fairly late on thursday, by which time dews and temps should be right side of marginal even on the coast.

Agreed - good synoptics for much of the east coast - including all of Lincolnshire *cough cough* and much of the East Coast from Teeside to The Wash at first, before broadening out to the whole of Eastern Britain south to about Lowestoft. Nice eye candy, but it'll all change by the 18z run, probably. EDIT - The 18z run is exceptional for eastern parts of our patch, keeping a snow risk going from early Thursday through to well into Saturday.

Some shots of the snowfields over the Lincolnshire Wolds.

Heavier snow falling now - whiting out the roads (which had largely cleared earlier) and giving us a fresh dusting.

As the ppn peps up a little, we too have snow again - fairly light but with more perky ppn to our west, it might be that we have an hour or so or more heavy snow. That's six successive days with falling snow here, and I can't remember the last time that happened.

Hi TETIS, I can confirm that there's snow falling across Central Lincs all the way out to the coast. I'm right on the N edge of it so our snow has been V light and intermittent, but further south it's been a bit more persistent. Lincoln on the back edge of the PPN now as the risk transfers east with the cold front.

Very light drizzle here now - The precip will certainly need to pep up in order to give anything significant.