General Model Output Discussion:

[Freezing-Point]

I think FP missed a year and should of said the change to seeing more of these type of charts again

were from 2005 late february.

http://www.wetterzentrale.de/archive/ra/2005/Rrea00120050220.gif

That was a potent N-ly considering I remember it like the back of my hand that time.

http://www.wetterzentrale.de/archive/ra/2005/Rrea00120050222.gif

Yes you are right, I originally typed 2005 but changed it to 2006. I was not sure as I typed that in 5 mins of the top of my head, but the point remains the same.

[Cloud 10]

18zat120hrs>> ecm12zat120hrs>>

So far so good from the 18z,surely it couldn't go the same way as the rest of the ecm?

[Geordiesnow]

Very snowy run for parts of Scotland, could see quite large totals up there if this run came off as it is shown now, Northern Scotland is certainly the place to be for this cold shot.

This run also starts to show why people should never carried away with cold charts either. This is a cold run but for alot of people, it is so far not a snowy run.

[Richard Lake]

Within the 120h timeframe pools of -10 air on the 850hpa playing with the Shetland Islands. If there is widespread snowfall on Friday as per shown would any extensive snowcover assist -10c air falling South or is it not as simple as there?

I am sure I read somewhere snowcover isn't factored into the models?

Edited January 26, 2010 by rikki

[Lewis]

18z is less progressive, with the HP a little further West, colder 850 uppers pushing further W of Western Coast of Ireland.

12z

18z

Edit:

Mid-term is still up in the air regarding the track of the LP, the blocking and the High to the West, i think the block breaks on this run..

Edited January 26, 2010 by Storm Force Lewis

[andymusic]

Within the 120h timeframe pools of -10 air on the 850hpa playing with the Shetland Islands. If there is widespread snowfall on Friday as per shown would any extensive snowcover assist -10c air falling South or is it not as simple as there?

I am sure I read somewhere snowcover isn't factored into the models?

GFS does show lower temps after it thinks that a particular area has had a snow covering

[January Snowstorm]

I think the 18z is going off on one after Monday

Upgrades the short-term which is good.

Synoptically a mess so best ignored for what's showing after Monday

[Bobby]

Within the 120h timeframe pools of -10 air on the 850hpa playing with the Shetland Islands. If there is widespread snowfall on Friday as per shown would any extensive snowcover assist -10c air falling South or is it not as simple as there?

I am sure I read somewhere snowcover isn't factored into the models?

850hpa is upper air temperatures and snow cover has very little effect on these. Snow cover can affect the surface temperatures though and this I believe is factored into the models.

Synoptically a mess so best ignored for what's showing after Monday

Can't say that just because you don't like what it's showing.

[damianslaw]

Lots to talk about if your looking for cold and snow in the short-medium term.

UKMO fax charts are showing a trough feature/short wave moving into western and southern scotland on Thursday moving down the country through the night and into southern england on Friday, good chance that places to the east of this feature will see some snowfall especially higher ground. The BBC think so too, though they remain quite cautious, showing some snow in north england and also central england. One to watch, Wales and Ireland will probably see rain due to the mild flow to the west of the front - its a developing situation.

Beyond, many northern and eastern coastal parts will see some snow showers on Saturday courtesy of a bitter N wind.

Then just when many of us were thinking the high would topple into the country, the models are beginning to show development stirring over the Norweigian Sea, with lower heights transferring down towards the North Sea with associated fronts, this is certainly a feature many in the east should be keeping an eye on,if it transpires we could be about to see a major widespread snow event, many central parts would probably join in aswell.

Beyond, northern blocking all the way it seems, ECM is showing a mighty cold pool moving in and indeed if things pan out as shown by ECM a more severe spell of weather than what occured in early Jan seems highly likely. Its still way beyond the reliable timeframe, but increasing signs the atlantic is just dead in the water and once again heights will develop robustly to the NW.

[Slinky]

I think the 18z is going off on one after Monday

Upgrades the short-term which is good.

Synoptically a mess so best ignored for what's showing after Monday

Why is it a mess? Looks no less plausible than the 12z ....

[nick sussex]

The GFS 18hrs tries to overcomplicate things with that low off the nw of Norway which stops the block pushing sw'wards and almost scuppers the easterly however it looks a mess. Putting this run aside the key period is around 144hrs, preferably you don't want the high to the west getting so far eastwards and want the trough over Europe to dig its heels in. It's crucial that the trough is blocked from moving eastwards until the ridge has backed westwards.

[cold snap]

Very snowy run for parts of Scotland, could see quite large totals up there if this run came off as it is shown now, Northern Scotland is certainly the place to be for this cold shot.

This run also starts to show why people should never carried away with cold charts either. This is a cold run but for alot of people, it is so far not a snowy run.

Agreed.Just had a good look at 18Z

Points to make regarding possible Easterly of next week

1.Not as cold

2.Not as snowy

3.A lot slower evolution to ECM

But this maybe a good thing just shows us how cautious we all must be.however its still a very decent run

Now in closer timeframe.Northerly for weekend

1.Topple happens quicker

2.High pressure to the west pushing east

3.Flow is slacker

So to conclude a slight downgrade tonight.very slight.but some dream outputs earlier

Edited January 26, 2010 by cold snap

[Geordiesnow]

Can't say that just because you don't like what it's showing.

JS post may have an hint of lets not look too far ahead because its not showing what the ECM is showing but i think it says that the outlook is uncertain. That low which would deliver alot of snow to parts of Northern and eastern Scotland seems a bit of a spoiler as it takes such an age for it to move southwards. Until the models firm up what happens with this low, then any easterly is not guranteed.

Like i said, its not a bad run for cold weather, but for alot of people, its not a snowy run.

[Jason T]

is it true though that alot of PPN did not show from quite a bit of the last spell untill the last minute so to speak.

[swilliam]

Very poor run for FI - we only get to this!

[cooling climate]

I think the 18z is going off on one after Monday

Upgrades the short-term which is good.

Synoptically a mess so best ignored for what's showing after Monday

Yep me thinks so to but there again it is the 18z.

That will do till tomorrow and I wonder what ice age scenario awaits in the morning.

[J10]

Lots to talk about if your looking for cold and snow in the short-medium term.

UKMO fax charts are showing a trough feature/short wave moving into western and southern scotland on Thursday moving down the country through the night and into southern england on Friday, good chance that places to the east of this feature will see some snowfall especially higher ground. The BBC think so too, though they remain quite cautious, showing some snow in north england and also central england. One to watch, Wales and Ireland will probably see rain due to the mild flow to the west of the front - its a developing situation.

Beyond, many northern and eastern coastal parts will see some snow showers on Saturday courtesy of a bitter N wind.

While you are right that it does look very marginal for Western areas on Friday. The wind direction for late Friday into Sunday, look west of north, so this looks very good indeed for the potential for snow showers for many western coastal districts into the weekend.

Thereafter the prospects are good for further wintry weather.

[cold snap]

Very poor run for FI - we only get to this!

Disagree the evolution just seams to be a bit slower to what was on offer from ECM.

ECM may off been overdoing.Or GFS is undoing it.

All to play for

[Cloud 10]

The weather is broken!:lol:

The finer details beyond 168 hrs on the 18z are pretty un-important as the trend remains the same,and that trend is COLD.

[cold snap]

I THINK he may have been sarcastic with his remark

I thought he was talking about time it took for the evolution to take shape.lol

Its still a little behind ECM.

But thats being very very picky

[nick sussex]

JS post may have an hint of lets not look too far ahead because its not showing what the ECM is showing but i think it says that the outlook is uncertain. That low which would deliver alot of snow to parts of Northern and eastern Scotland seems a bit of a spoiler as it takes such an age for it to move southwards. Until the models firm up what happens with this low, then any easterly is not guranteed.

Like i said, its not a bad run for cold weather, but for alot of people, its not a snowy run.

JS is right it's a mess, its very unlikely that you'll see that low hanging around the nw of Norway when the block is pushing sw'wards. The GFS has a habit of overdoing these features, putting that aside the models seem unsure of what to do with that piece of energy off the trough to the west around 132hrs to the west of Iceland, they look like developing it into a shortwave but then back away, we either want to see this run quickly ne'wards or head se to the west of the uk, we don't want a halfway house here with that feature.

Again though the outlook is made much simpler if the models hold the Atlantic trough further west, theres more margin for error then and everyones nerves won't become shredded with the tension!

[andymusic]

Disagree the evolution just seams to be a bit slower to what was on offer from ECM.

ECM may off been overdoing.Or GFS is undoing it.

All to play for

Just wait for GFS ens - 18z may have been an outlier in parts of it's run (if that's at all possible given these amazing potential synoptics)

[Jason T]

Please forgive me if i sound stupid,but the models produced today show that the last cold snap was nothing compared to this.

[Kentish Kiwi]

The weather is broken!

The finer details beyond 168 hrs on the 18z are pretty un-important as the trend remains the same,and that trend is COLD.

:lol: The anti-Bartlett?

That's just about as good as it gets for us, isn't it? Lower than -15 850's and the dam down into 504 for the South-East!

[andymusic]

Please forgive me if i sound stupid,but the models produced today show that the last cold snap was nothing compared to this.

IF (and that's a big if) the reality pans out the way the models are predicting then yes - the last cold spell will seem a slight small affair - but add these two together and you've got quite an amazing winter! - Only IF mind it comes off!