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

[tom_f123]

slightly off topic but how much is net xtra

[johnholmes]

talk to Paul, go to the link and its all explained in there, from the Front Page

[stratty]

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 christmas pudding of winters it isn't out of the question, so gives me all the more hope for some seeing a good fall on Thursday.

Yes looking at the dew points later in the week from the 18z they are around 0 and +1 for most of southern England, this is going to be soooooo border line (at the mo).

[Paul]

slightly off topic but how much is net xtra

Hi Tom, there are various options - the 5 minute radar for instance is just £19.50 a year (less than 40p a week, so no reason for every member of the forum not to have this!)

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[nick sussex]

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 christmas pudding of winters it isn't out of the question, so gives me all the more hope for some seeing a good fall on Thursday.

I agree with you Nick F who knows where that low is going to track, in these situations you need a bit of luck to remain on the right side of the low and have a good spell of snow. It could still just as easily track into France and miss most of the uk or conversely it might track further north, however a track too far north will have implications for the next low pressure and will signify a weaker scandi high and hence worse longer term prospects.

It depends what you're willing to risk in these circumstances, a short term spell of snow then likely back to rain or take your chances on perhaps a drier start to proceedings and a longer cold spell with perhaps snow chances later.

[davehsug]

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

A few memories of the 70s John, when we would see on the BBC weather a few troughs stuck in the North Sea, whilst we were in mild air which was forecast to win, only for the troughs to be eventually forced back west by an unexpected rise of pressure from the East. Not sure that's as likely these days though with so much more info available from satelites & the like.

Dave

[PB22]

I would strongly recommend NW Extra to everyone with an interest in the weather. You cannot go wrong with it, its brilliant!

Back to the models, the FAX charts are out, and crucially they are going with thier own model.

T+96 chart:

http://weather.noaa.gov/pub/fax/PPVmate9.TIF

T+120hr chart:

http://weather.noaa.gov/pub/fax/PPVO89.TIF

[January Snowstorm]

You know the charts are good when JS hasn't had one moan today

[johnholmes]

A few memories of the 70s John, when we would see on the BBC weather a few troughs stuck in the North Sea, whilst we were in mild air which was forecast to win, only for the troughs to be eventually forced back west by an unexpected rise of pressure from the East. Not sure that's as likely these days though with so much more info available from satelites & the like.

Dave

yes, a lot on here understandably have no idea how little was known beyond 48 hours maximum in those days. Surface charts every 3 hours into Scandinavia and much of Europe, all hand plotted, then analyzed by the forecaster. upper air from a similar area every 6 hours, and that was your lot.

sorry an Atlantic hand plotted chart, often with only about 6 ships over the total area every 6 hours as well.

Radar ??

sat pics ??, just beginning to come in, and you had to make an educated guess, IF you could see a piece of coast line, just where the template fitted on the fax chart from bracknell in turn from NOAA.

Computers ?? not until about 1978, I think did the Met office run its first fully operational forecast model.

ah they were the days.

Edited February 4, 2007 by johnholmes

[BristolBaggie]

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

So why is there people on here who wish to be in Aberdeenshire for this cold spell when the action will be in the south ?

[ukmoose]

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 must agree - the Scandi high is essential if this is to come to anything. Without it, the lows will march straight through with little resistance and milder air will undercut the colder air very quickly resulting in rain and higher temps. Sadly, this look quite likely now to my untrained eye. Best prognosis is for lows to move further south and leave the UK in colder air but without the block...hope I'm wrong.

Moose

[grab my graupel]

You know the charts are good when JS hasn't had one moan today

I'm going to moan instead J.S.

I don't think the 18z has made any difference, as none of us are still any

wiser about what's going to happen.

The positioning of the lows tonight have just added to the confusion.

and things still look as marginal as ever.

[johnholmes]

jus about sums it up gmg

[Roger J Smith]

There was some other thread where I discussed this a couple of days ago, something entitled "Atlantic coming back in?" or such ... holding to what I said there, which was roughly as follows.

The "Greenland high" on this occasion is actually more than the usual Greenland high, it is also a more surface-based (and therefore real) arctic high that has been drifting across the north polar region from far northern Canada towards northeast Greenland.

For that reason, I somewhat tend to distrust the weak resolution of the models concerning this high as it transfers south and merges with a weak (as some said flimsy) ridge already lingering around in Scandinavia. So it would not surprise me if the models begin to upgrade this cold spell due to a higher centre of pressure in this developing high, which is also likely to be unusually cold due to the transfer of -35 C air from over the polar ice cap (which is still there contrary to some news reports, if a few cms thinner).

I think a high of 1032-1035 mbs may well develop as there won't be as much weakening of the feature due to this more genuine surface high being attached to the more obvious Greenland high (but then I am looking at it from this side).

Then if the general plot of troughs and lows is essentially accurate, then a very strong easterly gradient is possible by Wed and Thurs with colder air at higher levels than currently indicated and much better prospects for a widespread snowstorm in all but the far southwest and parts of Ireland essentially south and west coasts.

Even on the current model run, I would think there is a good chance of a heavy snowfall of perhaps major proportions over large parts of the central and northern U.K. and Northern Ireland and especially at somewhat higher elevations away from the North Sea coast, but there is also potential here for sleet, freezing rain and various other unpleasantries in parts of south central and southeast England. Some maps that I am seeing for Saturday have the look of a freezing rain event across parts of the Midlands, for example.

Whatever happens Wed to Friday, I don't expect the cold spell to linger past Saturday morning, as the Atlantic will slowly return to a more vigorous state from then to about the next weekend following, with potential for some very strong winds and heavy rainfalls during that week

[Matty M]

All the 18z GFS Ensembles out to 120hrs are cold and snowy for many areas of the UK bar 2

so were running at 12/14 going for something pretty god damn special!

[BristolBlizzard]

Going by what people have been saying about the high to the southwest, is it looking like rain/sleet for peeps in the SW? Please put me out my misery

[Rustynailer]

yes, a lot on here understandably have no idea how little was known beyond 48 hours maximum in those days. Surface charts every 3 hours into Scandinavia and much of Europe, all hand plotted, then analyzed by the forecaster. upper air from a similar area every 6 hours, and that was your lot.

sorry an Atlantic hand plotted chart, often with only about 6 ships over the total area every 6 hours as well.

Radar ??

sat pics ??, just beginning to come in, and you had to make an educated guess, IF you could see a piece of coast line, just where the template fitted on the fax chart from bracknell in turn from NOAA.

Computers ?? not until about 1978, I think did the Met office run its first fully operational forecast model.

ah they were the days.

Does this mean that no propper experience exists model wise(GFS, etc') of the 70s-80s cold periods, just what was programmed into them at start up from our less well developed technology of times past?

Russ

Sorry i may have asked in a confusing manor , basically has GFS etc' truly been there before?

Edited February 4, 2007 by Rustynailer

[stratty]

All the 18z GFS Ensembles out to 120hrs are cold and snowy for many areas of the UK bar 2

so were running at 12/14 going for something pretty god damn special!

GEFS no.13 takes cold up to T174!

ps. Excellent read Roger!

[West is Best]

Seems to me that the GFS 18Z is backing up the GFS and UKMO 12Z runs, and continuing to go against the ECM.

What should be concerning people is not so much that the ECM is sticking to its guns, but that it has full backing from the 12z GEM. Here's the GEM chart for midday Thursday:

For what it is worth, the two lesser models JMA and NGP are also very progressive and more in line with the ECM in their 12z runs with upper temps much too high for proper snow.

I don't agree that the ECM has been wayward, but that aside to have GEM alongside is a powerful force. If it weren't for the UKMO (which is arguably the least trustworthy of the serious models) GFS would actually be on its own.

This is dodgy, and all talk of snow certainties (even in the title of this thread, tut tut) must be withheld until this model dispute is resolved! It's getting close to the alleged event and one or more of the models is going to fall from grace over this.

[grab my graupel]

jus about sums it up gmg

I think I'm going to sit back a bit and take each day as it comes regards

this cold spell.

I think there is a lot of speculation right now, and possibly a lot of false hopes

with it.

I feel some will be pleased with this spell and some maybe hugely dissapointed,

as it has the potential to go anyway still.

[Paul]

This is dodgy, and all talk of snow certainties (even in the title of this thread, tut tut) must be withheld until this model dispute is resolved! It's getting close to the alleged event and one or more of the models is going to fall from grace over this.

Lol WIB - I 100% guarantee there will be snow this week and I can't see how you can disagree with that!!! (scotland)

I would say though, on current form I'd back the GFS - the ECM hasn't performed strongly of late and as for the GEM, it was only a favourite model earlier this week because it was showing the second ice age for a bit!! It's always been poor...

[BristolBlizzard]

Edited as off topic - please post into the will it snow thread with this type of question.

Edited February 4, 2007 by Paul

[The Eagle]

Great faxes - great GFS - great big smile on my face I feel very confident that the snow drought will come to an end next week for most of us and I agree with Roger that the only places that look on the wrong side of Marginal are Southwest England and Southwest Ireland. The rest are well in with a shout here of a frontal event so lets hope the upgrades continue and we are sick of snow by Friday! B)

[Thundery wintry showers]

What should be concerning people is not so much that the ECM is sticking to its guns, but that it has full backing from the 12z GEM. Here's the GEM chart for midday Thursday:

For what it is worth, the two lesser models JMA and NGP are also very progressive and more in line with the ECM in their 12z runs with upper temps much too high for proper snow.

I don't agree that the ECM has been wayward, but that aside to have GEM alongside is a powerful force. If it weren't for the UKMO (which is arguably the least trustworthy of the serious models) GFS would actually be on its own.

This is dodgy, and all talk of snow certainties (even in the title of this thread, tut tut) must be withheld until this model dispute is resolved! It's getting close to the alleged event and one or more of the models is going to fall from grace over this.

I sense a bit of mild bias in there (maybe the old saying, 'if it can go wrong for cold/snow lovers, it will'?). The ECM having full backing from the GEM doesn't mean a great deal as, in fact, the GEM has been easily the worst-performing model over the past few weeks. JMA and NOGAPS are certainly closer to the ECM than the GFS is, but I wouldn't say that they back the ECM- rather, they're midway between GFS and ECM, and JMA in particular backs up the GFS on the persistence of the initial northerly, including winds switching over to an E'ly on Wednesday.

ECM has GEM alongside it, but GFS has UKMO alongside it, and while I generally think of ECM as, on average, being slightly more reliable than GFS, UKMO is nearly always far more reliable than GEM. Also, ECM has not been more reliable than GFS since around mid January.

[Just Below Zero]

This is dodgy, and all talk of snow certainties (even in the title of this thread, tut tut) must be withheld until this model dispute is resolved! It's getting close to the alleged event and one or more of the models is going to fall from grace over this.

I tend to agree to an extent WiB already the SH has been described as flimsy.

It has about the same heights as Brighton Pier and has to face a full rampant SW gale at high tide. We shall see!! B)