Chris.R

I am personally going for a top down transition rather than a bottom up one. I mean I'm expecting snow to melt higher in the atmosphere first before it starts to become marginal at the surface. I'm not doing a forecast until tomorrow but at the moment I'm thinking much greater accumulation Might be possible.

iand61 I'd kill to be in your location right now. You're going to do very well. You will likely see a transition to freezing rain/ice pellets from early hours Friday though and then regular rain by Friday lunchtime. Not sure there's anything we can do about it eventually turn to rain south of Cumbria.

The boundary layer is not a problem here it's the inversion above it. Once that gets close to 0 then it's dodgy but the air below it remains mostly below freezing. It's not your simple case of greater altitude = colder.

Latest WRF not much different. there does seem to be less precipitation though and there is a deeper warm layer on Thursday night. Raw data for Wigan below. Meteociel - Prévisions météo fines WRF heure par heure neige pour Wigan ( Grande-Bretagne ) WWW.METEOCIEL.FR Prévisions météo gratuites et précises à 3 jours heure par heure pour Wigan ( Grande-Bretagne ) basées sur le modèle WRF. Graphiques horaires de températures et pluie.

Day 10 i'm beginning to think it could all stay as snow or ice pellets throughout in most of the region now. even where the air is above freezing it's only just so a bit of very heavy precip would easy mix that out.

GFS this morning is very close to being epic. North of Preston all levels remain at or below freezing throughout. South of Preston though there is a layer above freezing between Thursday afternoon and Friday morning, the top of the boundary layer remains below freezing throughout so that would suggest increased risk of ice pellets And suppressed surface temperatures which could allow any snow cover to remain. It is the GFS though and it's just one run. Going to check WRF now.

Joe Bloggs yeah it's probably true I'm not aware of why that is the case but if he says that is something to look out for then it will be. They seem quite low to me anyway.

If when people say low heights they mean low geopotential heights then you can't get much lower than what's coming up.

iand61 if I do I think I'll need more than an email address to log back in!

The Northern Ramper Oldham: 3 H light snow followed by 2 H heavy snow (to end of forecast). T850 -4.0°C at 12Z.

I'm not even going to dip a toe into the mad thread. Apart from the fact I'll probably get bitten, after that WRF I think it's going to be more fun in here.

WRF now out to 12Z Thursday. Let's have a look what it shows Thursday morning four different locations south – north. Worcester: Initial light rain... followed by 4 H heavy snow... followed by 3 H ice pellets... followed by rain. Shrewsbury: 8 H heavy snow... followed by 1 H ice pellets (to end of forecast). Chester: 2 H light snow... followed by 5 H heavy snow (to end of forecast). Wigan: 2 H light snow... followed by 3 H heavy snow (to end of forecast). Lancaster: 3 H light snow (to end of forecast). 850 temps at 12Z Thursday: Worcester: +4.2°C Shrewsbury: +0.4°C Chester: -2.9°C Wigan: -4.2°C Lancaster: -4.1°C Carlisle: -6.7°C

GFS 12 is a little bit better but still I hope it's wrong as it shows a snow to rain to snow event except for Northern cumbria where it might stay all as snow on that.

GFS/WRF need to change for the better.

Biggest improvement is cold air digs further south before the low on Thursday and is mixed out slower.

18Z another improvement Wednesday – Friday. A bit dodgy after that but things seem to be improving as they come closer.

543 dam and T850 0 or below will be enough, obviously it's not as simple as that though but Good as a rough guide. Thickness not as important this time.

Latest runs of GFS and WRF are really starting to increase the risk for back edge snow on Tuesday night as they keep the precip going after the cold air starts to under-cut.

Snow line perhaps 20 miles further south on 6Z. Still going right direction.

Day 10 Yep SST at Crosby today is 6.2°C, this is 1.2°C below the long-term February average.

Much better GFF 0Z. Wednesday night event much better angle now... Would be a big snow event before turn to ice pellets and then rain. The snow line for Friday and Saturday is further south as well. 18 Z had it north of the border, now it's Around Carlisle. Like to see further southerly corrections on that.

Rob 79812010 Yep December 17th 2010... Best snowfall in my life. 25 cm in Crosby... Ice flows on the Mersey estuary... Banks of ice on the beach feet deep.

Out for a walk in Freshfield today on the Fisherman's Path. Cloudy but dry there though was sunny at home when I left.

Sunny

Day 10 can't remember about the warning but it was when we had snow all day but it didn't settle, and then did overnight then Melted in next day's sun.