South West/Central Southern England Regional Discussion 15/01/13 12z---->

[EGHH]

I know Met Office have dismissed the NAE for now, but I see it as a little concerning.

It is a high res model that's designed for short term forecasting. IIRC it did alright (in the sense of other models) in predicting the weekends weather so its definetly a model I would like to see switch sides quickly.

Other than that, good output tonight as has been said. We are still very much in the game and at this stage, that's all we can ask for.

Lets hope the ECM doesn't let us down. Get this on our side too and we can all go to bed happy for now!

It doesn't hurt to stay grounded.

I tend to look at the short range meso models like this: They are initialized using a subset of one of the Global Models' data but after that they pretty much ignore what's happening outside their little 3d box of the atmosphere. The global models model the whole atmosphere (with small exceptions), over the whole globe so have a better chance of modelling the differing interactions between the broad macroscale features. The little mesoscale models don't need to know what's going on outside their "box" but as the time increments, this causes added error as features from outside their "box" that later should be inside the "box" aren't included in the modelling. So pretty accurate at T0 to T12, generally accurate T12 to T24 and starting to potentially become inacurrate T24 to T48. This is the main reason they go no further. That and the fact that increased resolution isn't always helpful, depending on the instability of the modelling system etc.

In effect T48 on the NAE can be like T168 on a global model - getting very FI-ish

Well that's wot I fink anyway!!!

[Lynxus]

Wow, just seen the latest GFS today.

Looks like the SW / W could be in for some great snow potential on Thurs,Fri,Sat & Sun.!

Lets hope it doesnt vanish

[Frosty_wsm]

Wow, just seen the latest GFS today.

Looks like the SW / W could be in for some great snow potential on Thurs,Fri,Sat & Sun.!

Lets hope it doesnt vanish

Somebody's in a better mood today I see lol

[Dorsetbred]

Oblix not a problem, I think you'll find every answer you could care to wish for in here, let alone the MOD thread. I posted my thoughts days ago, and I'm refraining and waiting for something closer to the time, as everything is just this way and that, and then back. Didn't want to appear abrupt, it's just a tad early yet to really be sure.

[Lynxus]

Somebody's in a better mood today I see lol

Mildly better ( no pun )

Im still very worried about how this will turn out though. While its not quite as marginal ( so far ) as i expected. Its still got room to be a complete washout.

Fingers crossed

[Iceberg]

Well heres the latst meto forecast for me for friday and saturday......Couldnt really wish for much more.

[AWD]

Long run and ECM is actually alright. Any snow cover in northern and eastern counties of our region could stay into next week.

All to play for still but still a large degree of uncertainty.

[Frosty_wsm]

Mildly better ( no pun )

Im still very worried about how this will turn out though. While its not quite as marginal ( so far ) as i expected. Its still got room to be a complete washout.

Fingers crossed

Or possibly a freezing rain event, I remember the last time the happened from a similar setup to this Friday, god it was lethal out there!

[Lynxus]

Or possibly a freezing rain event, I remember the last time the happened from a similar setup to this Friday, god it was lethal out there!

That certainly would be interesting.

While I would love the best snow event for years, Im trying to stay open to the idea of nothing happening.

Its looking better and better as time goes by, but the GFS has a horrible tendency to give with one and take with another.

1foot of snow can quickly change to a drizzle day or a clear sunny day.

[snowlight robbery]

Up against it even before the usual Poole Harbour snow shield has been deployed!. Going to be a nowcasting Friday I think!

[philglossop]

Come on David Braine- you know you wanna say snow don't you!!!

[Dorsetbred]

Jeez, I've been in here for days, can somebody point me to the exit please, I need to get out more

[Bristawl Si]

Lovely graphics right now from Ian.

Snow, snow Friday and Sat across much of our region.

Edited January 15, 2013 by Bristle boy

[philglossop]

DOOOOOOOOOOOOOOOOOOOOHHHHHHHHHHHHHHHHHH.

East Devon............ again on Friday

[TimMB]

Very interesting report by Ian!

[AWD]

Lovely graphics right now from Ian.

Snow, snow Friday and Sat across much of our region.

Did he give any hints of accumulation depths at this stage?

[philglossop]

Actually on reflection- it was a tad general from David on Spotlight.......but looks good for the east of our BBC region.

[Frosty_wsm]

Great forecast there by Ian, snow on Friday and Saturday on that forecast, uncertainty of course but I hope it turns out to be accurate

[Bristawl Si]

Did he give any hints of accumulation depths at this stage?

I dont think so. I was typing my post at the time!

Still a bit of uncertainty i think, as he did mention threat of slightly milder air poss changing the forecast.

Edited January 15, 2013 by Bristle boy

[Bumpkin]

Really think Devon/Cornwall will get a significant snow event before this winter says adios. Can feel it in me water

EDIT: and Dorset:-)

Either that or you've got an infection

[Sainsbo]

Did he give any hints of accumulation depths at this stage?

2-5cm's at low levels, with 10cms on high ground. I'm guessing just a rough estimate and details will firm up nearer the time.

Edited January 15, 2013 by Sainsbo

[chris55]

If I have time I might put a bit more detail around this but to very quickly show why the 528 line is pretty useless in this set up for Friday and why I think the meto would be heavy snow for most in the sw.

I've chosen charts for midday on Friday as its a nice central point in the day, without any diurnal cooling.

Both charts are for the gfs 12z since we don't have freezing levels etc for meto gm output.

First chart shows the 528 line which is off in the North Sea, seeing this you would assume rain for nearly all of the country. However 528 refers to a thickness gradient across a big chunk of the lower atmosphere and not really the surface or the layer that contains the precip.

If we look at the freezing level we get a very different picture.

A freezing level of 100m or less equal certain snow in reality, 100-200 Indicates snow above 50-100m or under evaporative cooling. 200-400 indicates snow above 200-300m, sleet at 100-200m but this is effected by evapo cooling.

Anyway the picture is very very different and I don't see why the meto would be any different to be honest.

Excellent post Iceberg, I was going to do something similar.

Edited January 15, 2013 by chris55

[divadee]

Why do some posters feel the need to completely poopoo the event they COULD happen Friday in the SW in the mod disc?

I know we are largely forgotten by people on there but it makes me laugh, tha they just skirt over it and look at the models from another point of view.

I know a lot of people look at models from IMBY view, but it makes it hard to read and understand the posts in the mod thread.

First sub zero night in quite a while here. Now -1.7 with dp of -2

[Blizzardof82]

Why do some posters feel the need to completely poopoo the event they COULD happen Friday in the SW in the mod disc?

I know we are largely forgotten by people on there but it makes me laugh, tha they just skirt over it and look at the models from another point of view.

I know a lot of people look at models from IMBY view, but it makes it hard to read and understand the posts in the mod thread.

A lot of eastern bias in there and too many people looking at FI and reaching for razor blades

[PompeyFC]

nice graphics on south today - snow right across the south coast