Model Output Discussion

[Nick L]

I can see Scotland being cold & wintry all next week at the very least with the track the lows are taking, just bumping into the cold air up there before the lows move east and allow a cold backwash to pull south behind it but in other parts of the uk it also looks rather cold to cold with a snow risk although lower than in the north, if I was in scotland I would be highly delighted with the current model output for the next seven days and possibly longer.

I wouldn't be so confident, over the past 24 hours it has gone from a south only event to a north only event to a Midlands only event and back to a north only event. Last night us Midlanders were delighted with the output, not so this morning. Far too early to call IMO.

[kold weather]

The problem is Karl some of the ensembles take the LP up too far west so instead of a cold shot on the backside that cold shot goes into the Atlantic instead and it becomes just rain for even Scotland. I'd say 30-40% of the ensembles show that pattern to one extent or another, though some still manage to drag some colder air back in.

Further south if we have to have this pattern we need the LP to be as strong as possible, the evolution could well end up being somewhat like what we saw Monday-Tuesday this week and that would open the way for another possible snow event if the cold air can dig down enough.

[karyo]

I am slightly disappointed with this morning's UKMO and 6z GFS, as they gradually take the lows more north. As a consequence milder, rainy weather affects England and Wales next week. The ensembles also show this trend.

The ECM looks much better however, with everything further south.

The 12zs will probably show who is right.The met office further outlook should also show whether this is a new trend!

Karyo

[Frosty.]

The problem is Karl some of the ensembles take the LP up too far west so instead of a cold shot on the backside that cold shot goes into the Atlantic instead and it becomes just rain for even Scotland. I'd say 30-40% of the ensembles show that pattern to one extent or another, though some still manage to drag some colder air back in.

Further south if we have to have this pattern we need the LP to be as strong as possible, the evolution could well end up being somewhat like what we saw Monday-Tuesday this week and that would open the way for another possible snow event if the cold air can dig down enough.

Hi Darren,

I was really just taking the models at face value this morning rather than looking in depth at the ensembles, the actual op runs from the gfs, ecm and ukmo all look very wintry for the north at the moment although I realise we are always one run away from a huge downgrade but i'm fairly confident that somewhere in the north will be battered by a blizzard or two based on the op runs.

[Matt12]

I hate to say it, but the ensembles seem to currently be indicating rain next week (and plenty of it!) for most of England at least! I thought it was too good to be true when I say how much precip we are forecasted going to get in the next 7 days.

Matt.

[TEITS]

I hate to say it, but the ensembles seem to currently be indicating rain next week (and plenty of it!) for most of England at least! I thought it was too good to be true when I say how much precip we are forecasted going to get in the next 7 days.

Matt.

Yes based on the ensembles its only the far N of England/Scotland that remains cold. However according to the latest Met O update this disagrees with the GFS as they refer to snow for Central parts which of course means the Midlands.

[BLAST FROM THE PAST]

Looking back I think the winter pattern was set in December with regards to the lows sitting to the west

of Norway as we saw with the northerly before Christmas.

I am sure this has a lot to do with SST'S and the differential between the warmer seas to the north

of Scotland and cooler water in the north sea.

I went negative for my CET guesstimate this month and with a tweak here and there it could so easily

have come off and I must admit with the record breaking AO and prolonged negative NAO I am very

disappointed at the return the UK has seen in regards to winter weather this month.

If you look back through the archives and AO and NAO records you will see some classic bitterly cold

spells in February with nothing like the northern blocking we have seen this month.

The bitterly cold weather to the northeast would certainly bring a proper freeze and it would be great

to show some younger members that very potent wintry outbreaks are possible in late February or

even early march even down in southern England.

The Jet stream is so far south its stopping a ridge being thrown up to connect with the northern blocking

and bringing the block and cold southwards yet we still have these spoiler lows to contend with.

I am still convinced we will see a potent cold spell of weather within the next two weeks but I must admit

to being very surprised that greater blocking to the northeast is not being shown on the models in the

extended outlook. Hopefully this will soon change.

That isn't going to happen IMO CC. You have been calling for that right through Feb and it still hasn't materialised...and won't. Deep widespread cold has gone but cold reamins and thus gives very good snow chances for favoured locations. The bit about the jetstream is very interesting and I believe it is the jetstream's positioning that has again controlled the winter like it did for 08/09 allowing for northern blocking to develop, and not northern blocking forcing it south. I think there lies the difference and why 'classic' easterlies never arose and persisted. The charts continue to show the IMO 'embedded' longterm trend for the jetstream to remain on a more southerly track especially compared to past 20-30 years and as many have been saying we have seen and still are seeing synoptics more akin to 60s and 70s. This is why IB's even larger teapot theory is failing, lots of it was right but the reasoning behind it and the belief that it was very unlikely to reverse is why its failing.

This winter has been and still is a real corker and has matched IMO many of the greats I have lived through and enjoyed...and there's more to come.

Calm before the storm here, beautiful day but chilly. I think there will be the need to to do nowcasts for the next week as slight changes in track could make a big difference...although I think I'll be rain only. Midlands northwards for me re snow and mountains of Wales.

BFTP

Edited February 19, 2010 by BLAST FROM THE PAST

[Matt12]

Hey, go easy on me guys, this is my first post, haha! I have been following these forums (this thread in particlar) for a while now (lurking) and only just made an account.

So, going by the models, what are the chances of Scotland seeing some snow over the coming week?

Extremely high, I'd say. Although I'm no weather expert (far from it!), the temps look favourable at the mo for Northern England and Scotland for some serious snowfall.

Perhaps, someone much more knowledgeable than myself can help with a forecast more. XD

Edited February 19, 2010 by Matt12

[StewieEatWorld]

Extremely high, I'd say. Although I'm no weather expert (far from it!), the temps look favourable at the mo for Northern England and Scotland for some serious snowfall.

Perhaps, someone much more knowledgeable than myself can help with a forecast more. XD

Hmmm, sounds good for the northern half of the UK anyway. Just gotta hope the models keep the cold air over us. Never know, the cold air could creep southwards on the next output.

[grab my graupel]

Maybe something to discuss in the Met Office outlook thread rather than this one but

Thanks Kev, I'll pop these posts into that area :huh:

[StewieEatWorld]

Ive always wondered, why do the models not "come out" until a good few hours than their time? Like, I notice the "12Z" obviously means 12:00, but we don't see it until around 4pm. Just a newbie being curious :huh:

[kold weather]

Also one final thing from the ensembles that maybe worth noting is they all are more agressive with the strength of the low, if it weakens then it wil lnot shot that far north as fast, what we need is for it to stay as far east as is possible, because if it goes too far west it will make even Scotland marginal for a time and blow any other risks of snowfall down the line, whilst if its further east, it could bring a lot more of the country into play plus bring down colder air again which could set-up for another attempt.

For Ireland, its a sorta win-win set-up in many ways...

[trevw]

Ive always wondered, why do the models not "come out" until a good few hours than their time? Like, I notice the "12Z" obviously means 12:00, but we don't see it until around 4pm. Just a newbie being curious

had always assumed that 12z refered to the time of taking the data sample on which the run was based/time of starting model run - then you have the time to run the model against the data and produce the output..

[MR EXTREMES]

nice suprise here on the southcoast snow falling from deep convection most likely the last of time for awhile but still good to see it one last time before the less cold air come i on depressions,

as for the models still looking pretty good for the north pretty poor for the south.

to tell the truth more of a wintry mix.

Edited February 19, 2010 by badboy657

[kold weather]

Big differences between the 12z GFS and the NAE, the NAE takes the frontal system across the south Midlands with just very light precip further north whilst the GFS develops a low pressure system which gives snow to northern England on Sunday instead.

So one of those models is going to be rather wrong, somewhere is going to get a snow event on Sunday though from the looks of things!

[Iceberg]

Yep KW, absolutely no agreement inter run, or inter model atm even within the next 48 hrs.

[Cheese Rice]

Crazy model outputs, everything changing, nothing is even certain 48 hours out, what happened to that low that was going to hit Scotland?!?!

Edit: If it came of (which it wont judging by the inconsistent model output) there would be quite a difference in temperatures.

Edited February 19, 2010 by 10123

[cooling climate]

That isn't going to happen IMO CC. You have been calling for that right through Feb and it still hasn't materialised...and won't.

BFTP

Dear oh dear rather silly to make such a bold statement, especially after some of your calls this

winter although you have not been that far out as you change your mind as often as the weather.

The block to the north and northeast will most likely happen around the turn of the month now I

feel although we should start to see this in the models anytime now.

Terrible run to run continuity again, I would not like to even guess where the low on Monday is

going to end up. Some areas are likely to see some appreciable falls of snow though by the looks

of things.

[Iceberg]

At T84 GFS 06 had a 970 LP centre of the north coast of Scotland, the 12Z GFS has a 975 low off the IOW for the same time Monday 18GMT.

Next to worthless.

[Higher Ground]

Crazy model outputs, everything changing, nothing is even certain 48 hours out, what happened to that low that was going to hit Scotland??

Centred over S Coast instead at T+78. (Or to be more precise, secondary low pressure centre failed to form to north on this run hence less deflection of jet stream to north?)

Edited February 19, 2010 by Higher Ground

[kold weather]

A better run for the Midlands this one, the angle of attack is a little better and the front that develops in the south coast lifts northwards but only gets so far and hits the wall of colder air, then the LP comes up BUT is just about far enough east to drag colder air into Wales and possibly West Midlands to still have snow...

A step in the right direction IMO for a good chunk of the country.

[kev238]

Well- a slightly better track for the low pressure on Monday. All very borderline though for areas North and West from a line from the Wash to the Bristol Channel. This track is likely to oscillate right until the last minute. On the face of it the 850s look too high but in this sort of situation is that important?

The updated text forecasts (Met Office site) for E Midlands and Yorkshire region mention possibility for snow and there are still moderate warnings out for Monday across a large swath of Central UK so potential still there; I think looking at the NAE when it comes into range will give the best clues as to what to expect.

[kold weather]

At T84 GFS 06 had a 970 LP centre of the north coast of Scotland, the 12Z GFS has a 975 low off the IOW for the same time Monday 18GMT.

Next to worthless.

Well this is run almost as good as the 18z last night in some parts of W.Midlands...plus the angle of the low pressure system also allows a far greater shot at backedge snow as well for those further south.

Still your right there is just no inter/intramodel agreement at all, the models are having big problems with what LP is going to be dominant.

This run has the LP to our south taking longer to develop and therefore everything develops down the chain so to speak.

[Cheese Rice]

A better run for the Midlands this one, the angle of attack is a little better and the front that develops in the south coast lifts northwards but only gets so far and hits the wall of colder air, then the LP comes up BUT is just about far enough east to drag colder air into Wales and possibly West Midlands to still have snow...

A step in the right direction IMO for a good chunk of the country.

Is it really though as the models keep changing, we keep going back and forth. So much so that I don't think we are going in any direction at the moment, stuck in the middle with no clue as to what will happen.

[Ben_Cambs]

This is evidence for the model volatility that some members were predicting, if the models cant sort out Monday's LP then theres little point going anywhere further than Monday! The angle of the LP looks better on this run = snow for a bigger chunk of the country, but because of the changes we may have to wait another 24 hours or so before there is some sort of agreement. UKMO is coming out now, lets see what it says about Monday...

Edited February 19, 2010 by Snowman0697