18z Model discussion - snow but how much and where?

[nick sussex]

Its bite your finger nails time as if this low verifies a lucky location that remains on the cold side of this throughout the precip could receive some significant snow,again its impossible to call this until within 24hrs as small distances could see heavy rain whilst a location 50 miles further north some very large snow totals.

Someones going to be very happy come the day and someone else really peeved off, of course as it clears areas that may have had a wintry mix may see this turn back to snow before clearing. The model drama continues!

[The Eagle]

You probably are; except in the southern quarter of England the wintry prospects are no less on the 18Z than the 12Z.

Yes its also worth remembering:

You dont need the 528 DAM line over your head

You dont need sub -5 850s

And you dont need the warm sector not to make some inroads as you can still have evaporative cooling etc.

Im very happy with this evolution but things are still going to change. The trend is what matters and its excellent and hopefully this is the final nail the ECM coffin

[Evo]

Although the first low loses the warm sector on the 18z, just a small change North makes quite a big difference:

12z:

18z:

The 18z pushes it through faster, hence further North. I thought the 18z would go the other way and either lose the shortwave or push it South - shows what I know

[Matty M]

No point looking any further on this run really.. that second low looks like giving Blizzards to Scotland though!

But seen as 72hrs is uncertain at this point no point looking after 120!!

[Paul]

This is where using the half degree stuff on netweather rather than the 1 degree low res stuff on wz comes into it's own. That temp drop is over dartmoor/exmoor, so it's also about height..

GFS has different ideas about snowfall.

Look at WIB location.

http://www.wetterzentrale.de/pics/Rtavn10817.png

http://www.wetterzentrale.de/pics/Rtavn1082.png

Cause of such low temps??

Snowfall and clear skies!.

[kippure]

No point looking any further on this run really.. that second low looks like giving Blizzards to Scotland though!

But seen as 72hrs is uncertain at this point no point looking after 120!!

Mighten be able to get to them exams matty?

[Yeti]

Hopefully the trend has reversed eh? Even still I've just about given up on seeing any significant snow next week here. The south always gets it anyway.

In the 6z the prospects were good for here, but the last two runs not so. Tbh I'm not so bothered about the longer term prospects because I won't be here Saturday onwards, and so all I want is one of the lows to produce prolonged snowfall here before then and I'll be very happy :lol: . I would be more disappointed to see the cold spell prolonged without the lows tracking across than to see a 3 hour snow-to-rain event . I know the rest on here wouldn't, but I can see me missing the only snow event of the year while I'm on holiday if the lows track too far S!

:lol:

[Nick F]

Oddly, the 18z and 12z before seem more certain on the track of the second low across the South early Saturday, little difference between the two runs with position, though deeper on 18z. Colder air further North second time round though on both runs.

[Snowly does it]

LPs tracking across but the Scandi High looks good still, can the cold get drawn back in?

[January Snowstorm]

It's going to be a week of margins I think.

Scotland looks odds o though for a whiteout

Looks like the rugby will be a no go next wkd in Murrayfield

Edited February 4, 2007 by January Snowstorm

[The Eagle]

Looks like another snow event progged for the Weekend on this run for Wales, Ireland and the midlands area. To good to be true I think

EDIT: Maybe not actually. Thought surface temps reflected that but the precip type charts dont.

Edited February 4, 2007 by Darkman

[PB22]

Two channel lows in one run...we are being spoilt! Fascinating set up here. A very interesting week to come for sure.

[TEITS]

This is where using the half degree stuff on netweather rather than the 1 degree low res stuff on wz comes into it's own. That temp drop is over dartmoor/exmoor, so it's also about height..

I shall have to save some money to purchase NW Extra for a year.

Im beginning to think that come the day in question we would all be better off using other members reports to decide what will fall out of the skeis. Like Nick Sussex says someone 50 miles S of me could see rain whilst I see blizzards (I wish).

Having said this I would still head for Aberdeenshire to see the full force of this cold spell.

[Evo]

Oddly, the 18z and 12z before seem more certain on the track of the second low across the South early Saturday, little difference between the two runs with position, though deeper on 18z. Colder air further North second time round though on both runs.

Yes, it is a bit odd. Also both troughs seem to lose any warm pockets on the 18z:

12z:

18z:

[Paul]

I shall have to save some money to purchase NW Extra for a year.

Im beginning to think that come the day in question we would all be better off using other members reports to decide what will fall out of the skeis. Like Nick Sussex says someone 50 miles S of me could see rain whilst I see blizzards (I wish).

Having said this I would still head for Aberdeenshire to see the full force of this cold spell.

Don't forget all the free charts in the datacentre are the high res ones - am going to whack some extras in there tomorrow (and have some extra free ensemble charts too.

If you are thinking of extra - now is a great time - we have some real ground breaking features heading in there this year to go with the 5 minute radar - which everyone should be subscribing to for this cold spell

[nick sussex]

I think we need to have a reality check in here! even the fact that we're talking about the chances for snow and perhaps lots of it for certain locations is a major victory given the crap winter so far. Also events further north may mean an extension of the cold with a large swathe of high pressure building from russia all the way to iceland.

This is all still up in the air and anyone looking at output past 96hrs for definite answers is going to find this all turns into even more of a car crash of emotions than it is already!

And can we all at least celebrate one thing that this does not support the ecm!

Edited February 4, 2007 by nick sussex

[Snowyowl9]

Another fantastic run.

http://85.214.49.20/wz/pics/Rtavn961.png

http://85.214.49.20/wz/pics/Rtavn964.png

http://85.214.49.20/wz/pics/Rtavn1261.png

http://85.214.49.20/wz/pics/Rtavn12617.png

[Snowly does it]

In what was once border-reliable and is now the distant reaches of FI T162, warm air pushing in from the Atlantic with some +5 850s coming into the South

[tom_f123]

carol kirkwood just said this there may be a wee touch of snow for southern areas whats she talking about not another mild lover is she

[davehsug]

I think the best thing at this moment Dave is to use our memories of the events in the golden era to determine what may happen. Back then, it would usually be for my area, and probably yours too, a fair dumping of snow before the milder air slowly crept in, but how oftern have we seen the models have to handle this sort of set-up in the christmas pudding ? Very rarely.

Pretty much what I said last night Ian. We've never seen the evolution of a "proper" cold spell in these model days. I'm not saying that this will be one of course, but all we have in archives are charts of what actually happened, not the model forecasts that led up to them.

I doubt that this can become the real thing as there are no real height rises over Scandi, but by God it's putting up a good scrap for a flimsy old thing

Dave

[Simon SWales]

I shall have to save some money to purchase NW Extra for a year.

Im beginning to think that come the day in question we would all be better off using other members reports to decide what will fall out of the skeis. Like Nick Sussex says someone 50 miles S of me could see rain whilst I see blizzards (I wish).

Having said this I would still head for Aberdeenshire to see the full force of this cold spell.

TEITS, PM me, i'll sort you out for 3 months on extra.

Edited February 4, 2007 by Simon SWales

[Evo]

18z bringing in a deep trough out in FI at T168, obviously doesn't mean anything yet but worth keeping an eye on perhaps.

Scratch that, it's cut-off so it's going nowhere.

Edited February 4, 2007 by Evo

[January Snowstorm]

Pretty much what I said last night Ian. We've never seen the evolution of a "proper" cold spell in these model days. I'm not saying that this will be one of course, but all we have in archives are charts of what actually happened, not the model forecasts that led up to them.

I doubt that this can become the real thing as there are no real height rises over Scandi, but by God it's putting up a good scrap for a flimsy old thing

Dave

I think this is indeed key.

We need a much stronger scandi high to what's showing.

Maybe it will upgrade but we need it to for a more prolonged cold spell.Flimsy has hit the nail on the head

[Nick F]

Pretty much what I said last night Ian. We've never seen the evolution of a "proper" cold spell in these model days. I'm not saying that this will be one of course, but all we have in archives are charts of what actually happened, not the model forecasts that led up to them.

I doubt that this can become the real thing as there are no real height rises over Scandi, but by God it's putting up a good scrap for a flimsy old thing

Dave

It seems as ever the UK is always on the knife edge of things, particularly S'ern UK wrt to the lows progged to move in late in the week - where working out where will be make or break is futile atm.

I do remember in Jan or Feb 2001 while staying in the higher parts of Brighton there being a channel low that brought an afternoon of heavy snow that wasn't followed by a thaw and milder air straight away, so even in the modern era of winters it isn't out of the question, so gives me all the more hope for some seeing a good fall on Thursday.

[johnholmes]

I had promised another blog this evening into the weekend.

Having seen the 18z I'm even more unsure on what the outcome will be so I'll hold off until tomorrow am and look at both the 00z and 06z run before I give it a try.

As someone has mentioned, for such a small cold spell it certainly is putting up one hell of a fight before it lets go.

Remember this cold spell was unti Wednesday, AT THE MOST, when this first started. Its now looking like it will be Thur Fri before it begines to lose its grip in the more southern areas and perhaps into next Sunday before it finally gives up in the north.

John

ps

the comments in blog 7 about Scotland N Ireland then ne England and some counties of E Anglia for now into late Tuesday still hold, and it may extend to other eastern parts. East Yorks area and east Lincs, just a cover on ground away from the coast, chiefly on ground above about 300ft I would estimate for Yorks/Lincs.

Edited February 4, 2007 by johnholmes