Model Output Discussion

[Eugene]

Excellent T+84 hrs fax and i am very confident that would deliver snowfall for the midlands, looks very similar indeed to GFS 00Z T+84 hrs which has temps near 0C monday daytime, all indicates snow to me, you need some moisture air moving in to get heavy snowfall anyway so the 528 dam line is in the perfect place to me running through northern england

http://www.wetterzentrale.de/pics/brack2a.gif

[Cymro]

Could people clarify on this, I personally see atm the snow being from mid Wales onwards and not the whole of Wales that is suggested here am I right(stupid question because no forecaster is ever correct as in spot on) just seems a little vague saying Wales and the Midlands because they're a vast area. NAE did well with the showers today as always had some hefty snow showers here this morning.

[Eugene]

Anyone looking for Spring, the latter stages of FI show +10 850's for the first time

http://www.netweathe...ction=nwdc;sess=

Big outlier though, ages away and with no support, looking through meteociel for around the same timeframe there are some TEITS specials

I will say this again some people including the pro's are underestimating the potential for heavy snowfall for next week big time

Edited February 19, 2010 by Eugene

[TEITS]

Could people clarify on this, I personally see atm the snow being from mid Wales onwards and not the whole of Wales that is suggested here am I right(stupid question because no forecaster is ever correct as in spot on) just seems a little vague saying Wales and the Midlands because they're a vast area. NAE did well with the showers today as always had some hefty snow showers here this morning.

Yes sorry I should of said Central/S Wales as N Wales look to escape the snow tomorrow.

Like I said yesterday im suffering from model fatigue and I don't even bother looking at each ensemble member anymore. Another reason is the inconsistency between the model runs is making looking beyond +48 a pointless excercise at the moment.

[Cymro]

Yes sorry I should of said Central/S Wales as N Wales look to escape the snow tomorrow.

Like I said yesterday im suffering from model fatigue and I don't even bother looking at each ensemble member anymore. Another reason is the inconsistency between the model runs is making looking beyond +48 a pointless excercise at the moment.

Yeah chopping and turning every five seconds, I must say however that enhances the excitement of watrching the models and then seeing them come into fruition or fall into despair hehe how very poetic of me, I personally think the chances of snow are much higher tomorrow than the met office seem to suggest but its potential so lets just wait and see.

[TEITS]

I personally think the chances of snow are much higher tomorrow than the met office seem to suggest but its potential so lets just wait and see.

At the moment tomorrow looks like bringing only around 1-3cm. There are two reasons why amounts should be small and these are the timing of the precip i.e arriving during the day and the precip totals only suggest around 7mm. So taking into account the snow ratio, surface temps, air temps is why I feel only 1-3cm is likely.

However in saying this next week could bring a snowstorm to the UK. I always class a snowstorm in the UK as one that brings over 20cm of lying snow. Now there is a real threat of at least 30mm of precip possible with these LPs systems pushing up from the S so snowfalls of between 20-30cm is possible in some areas.

[Duane S.]

I have taken a few days away from the madness of viewing these charts and come back today to see a very interesting 7 days ahead of the UK. As somebody posted quite correctly earlier, for most heavy snow events marginality is normally involved.

I fancy that the NE track of some of the systems up through the UK, shown by some models, is wrong and that they will take a more lateral route as they come through. If I had to stick my neck out and say where is going to see the biggest accumulations then the Midlands would be favorite but it wouldn't take much for the emphasis to swing to North Yorkshire or conversely, South Somerset.

With a bit of luck I would like to think even I will see the odd spell of snow. The bottom line is though that there is potential for snow anywhere.

[cooling climate]

At the moment tomorrow looks like bringing only around 1-3cm. There are two reasons why amounts should be small and these are the timing of the precip i.e arriving during the day and the precip totals only suggest around 7mm. So taking into account the snow ratio, surface temps, air temps is why I feel only 1-3cm is likely.

However in saying this next week could bring a snowstorm to the UK. I always class a snowstorm in the UK as one that brings over 20cm of lying snow. Now there is a real threat of at least 30mm of precip possible with these LPs systems pushing up from the S so snowfalls of between 20-30cm is possible in some areas.

Looking at the 06z coming out it is frustrating at how close we are to a proper freeze up

where we would be looking at daytime max of 0c at best and probably lower than this.

Instead because of a persistance of low to the west of Norway we are held in this rather

cold set up with daytime temperatures in the region of 3 to 5c for the majority of England

and Wales.

[Ben_Cambs]

The models this week have been so fascinating to watch and there is so much potential for snow next week, and potential for a snowstorm like TEITS mentioned. There is no sign of a Early Spring and this shows how terrific this winter has been for cold lovers, I personally have only had one 10C day this winter since 9th December. I agree with Nick S from yesterday that the model output is going to be quite volatile over the next few days! ECM the pick of the bunch this morning for snow potential..

[mountain shadow]

Sunday morning is looking interesting for parts of Northern Ireland to say the least...

http://charts.netweather.tv/gfsimages/gfs.20100219/06/51/ukprec.png

http://charts.netweather.tv/gfsimages/gfs.20100219/06/51/prectypeuktopo.png

METO have it a bit further south at the moment though.

[cuckoo]

Looks like the really cold pool over Southern Scandinavia feeds some cold air into Poland and the Baltic states before being blown away by the low coming up the North Sea on the 06Z GFS output.

Looks like the Shetland Isles will be in a Northerly flow.

Edited February 19, 2010 by cuckoo

[Lewis]

After looking at the 06Z it's a short term upgrade, although a lot of uncertainty in the medium/long term simply due to the evolution of these low pressures, a lot more chart viewing to come.

Tonight and overnight into the early hours of tomorrow there's the potential for NE areas, N Yorkshire, E Yorkshire and NE lincs to get a decent covering with a trough developing in the North Sea and pushing South. Could be some very heavy bursts tied up with these organised showers.

Monday seems to be downgrading as we come nearer, as is Sundays possible event, which is clearly shown by the MetOffice removing the advisories.

A contrasting pattern really over the coming 8-10 days, colder in the North with wintry showers, falling mainly as snow on Northern Hills, with milder weather in the South with occasional heavy rain from fronts moving in.

Lewis

[Nick L]

After looking at the 06Z it's a short term upgrade, although a lot of uncertainty in the medium/long term simply due to the evolution of these low pressures, a lot more chart viewing to come.

Tonight and overnight into the early hours of tomorrow there's the potential for NE areas, N Yorkshire, E Yorkshire and NE lincs to get a decent covering with a trough developing in the North Sea and pushing South. Could be some very heavy bursts tied up with these organised showers.

Monday seems to be downgrading as we come nearer, as is Sundays possible event, which is clearly shown by the MetOffice removing the advisories.

A contrasting pattern really over the coming 8-10 days, colder in the North with wintry showers, falling mainly as snow on Northern Hills, with milder weather in the South with occasional heavy rain from fronts moving in.

Lewis

Advisories are still there for Monday Lewis:

http://www.metoffice...t_warnings.html

Updated this morning.

Edit: Misread what you put - apologies.

Edited February 19, 2010 by nick2702

[nick sussex]

The operational model runs seem reluctant to edge the pattern eastwards in line with the expected upstream changes. The ridge over the western USA is expected to be replaced by troughing here, the AO is expected to remain deeply negative this should result in pressure rising to the north and the Scandi trough edging east with less phasing with energy to the south of the UK, however we don't really see this replicated in the model output.

So I'd be dubious of any later output trying to retrogress the pattern or dropping heights to the north. Earlier on still alot of uncertainty going into next week with the track of low pressure which of course makes a big difference to who gets any snow.

Edited February 19, 2010 by nick sussex

[Lewis]

Advisories are still there for Monday Lewis:

http://www.metoffice...t_warnings.html

Updated this morning.

Edit: Misread what you put - apologies.

I do that a lot Nick. No need to apologise :unsure:

Edited February 19, 2010 by Storm Force Lewis

[snowmadchrisuk]

Well IMO the warnings for Sunday/Monday are way to far South , I can not see how you can get Snow under these conditions , Apart from the North the Midlands / East (apart from Northern England) and South the conditions are not even close to marginal Mon/Tue . the 6z is worse than the 00z . Some of these upgrade comments must be location based . The only way the Midlands and further South will see an upgrade is if that Low moves further South . If it wasn't for the rain on Sunday and Monday some places would be looking at double figures.

Edited February 19, 2010 by snowmadchrisuk

[D KARLSON]

The models this week have been so fascinating to watch and there is so much potential for snow next week, and potential for a snowstorm like TEITS mentioned. There is no sign of a Early Spring and this shows how terrific this winter has been for cold lovers, I personally have only had one 10C day this winter since 9th December. I agree with Nick S from yesterday that the model output is going to be quite volatile over the next few days! ECM the pick of the bunch this morning for snow potential..

Snow will be the theme over the weekend and into next week ,and as temps start to edge down ,temps will edge to the cold side of marginal which will allow the snow to be more widespread, when and where ??????

Whats been a surprise looking at the charts is how some of that very cold air over scandinavia is sneeking its way back in on the back of these lows ,you only have to look at those night time lows in Scotland -15 in places i believe and some -6 s further south.

Now i dont believe these temps were progged at all and that is down to the exact synoptics not being progged ,the slightest error in position of these lows will have a disproportionate effect simply due to the intensly cold air over scandinavia and how much this cold air is tapped into by the synoptics.

If we look at the synoptics progged ove the coming days there is low confidence certainly in detail and this will cause a large margin for error in forecast and as these lows appear to be pushing up on a more southerly track with each output this will allow more of this very cold air to be dragged in to the equation.

TO SUM UP; There is a lot of potential for heavy snow just about anywhere over the coming week and this may have been underestimated by some of the forecasts and february is Known for being the most treachorous month, keep an eye on this one !!!!

[bluearmy]

The operational model runs seem reluctant to edge the pattern eastwards in line with the expected upstream changes. The ridge over the western USA is expected to be replaced by troughing here, the AO is expected to remain deeply negative this should result in pressure rising to the north and the Scandi trough edging east with less phasing with energy to the south of the UK, however we don't really see this replicated in the model output.

So I'd be dubious of any later output trying to retrogress the pattern or dropping heights to the north. Earlier on still alot of uncertainty going into next week with the track of low pressure which of course makes a big difference with who gets any snow.

the NAEFS ensembles pick this up towards the end of the run nick which is a lifetime away (>T348). pressure builds towards iceland as the anomolies over eastern canada and nw siberia come together and push the trough back to the west atlantic and south east europe. the ens may be a bit slow to pick this up - lets hope so anyway.

getting rid of the energy northwest scandi is vital if we are to advect any deep cold this way although by early march, it will result in marginal oportunites the further south one goes. CC comments on this earlier - story of the month i'm afraid. so close to something astonishing if it hadnt been there, going all the way back to the end of the northerly that started the month and the failed easterly that followed.

[ANYWEATHER]

Well IMO the warnings for Sunday/Monday are way to far South , I can not see how you can get Snow under these conditions , Apart from the North the Midlands / East (apart from Northern England) and South the conditions are not even close to marginal Mon/Tue . the 6z is worse than the 00z . Some of these upgrade comments must be location based . The only way the Midlands and further South will see an upgrade is if that Low moves further South . If it wasn't for the rain on Sunday and Monday some places would be looking at double figures.

Yep, but youre basing your conclusion on just the gfs. Certainly fine line, but these marginal events can bring some surprising and heavy snowfall. Im not sure the gfs has the synoptics right at all and indeed because of so much model uncertainty, t48 is FI.! Expect some subtle changes on the next run/s :unsure:

[nick sussex]

the NAEFS ensembles pick this up towards the end of the run nick which is a lifetime away (>T348). pressure builds towards iceland as the anomolies over eastern canada and nw siberia come together and push the trough back to the west atlantic and south east europe. the ens may be a bit slow to pick this up - lets hope so anyway.

getting rid of the energy northwest scandi is vital if we are to advect any deep cold this way although by early march, it will result in marginal oportunites the further south one goes. CC comments on this earlier - story of the month i'm afraid. so close to something astonishing if it hadnt been there, going all the way back to the end of the northerly that started the month and the failed easterly that followed.

I agree even though this winter has been very good in terms of the length of cold there have been several missed opportunities which could have taken it to an altogether different level.

The problem of course heading into March is we need a much colder source of air to deliver and bog standard -5 uppers just won't cut it, we've even seen during this week how marginal conditions are, I think people sometimes forget its difficult now to develop embedded cold at the surface in these slack flows and so much depends on timing of any precip.

Early March can still deliver but as you said we need those low heights to disappear from nw Scandi.

[Buxton Codge]

Great models for snow lovers this morning!

[Frosty.]

Stunning GFS 00z & 06z output for the north this morning, several snow or even blizzard events are being indicated for central and especially northern britain during next week with the low tracking into scotland on mon/tues looking very interesting for a potential blizzard with strong winds. The ECM 00z also looks very wintry next week for most of the uk, as does the UKMO 00z. The north does look like taking a battering from the snow and ice but the south should also get it's fair share although there are signs the weather will turn milder beyond next week but there could be a wintry reload from the east as the 6z shows. :unsure: not much sign of spring. :unsure:

[cooling climate]

the NAEFS ensembles pick this up towards the end of the run nick which is a lifetime away (>T348). pressure builds towards iceland as the anomolies over eastern canada and nw siberia come together and push the trough back to the west atlantic and south east europe. the ens may be a bit slow to pick this up - lets hope so anyway.

getting rid of the energy northwest scandi is vital if we are to advect any deep cold this way although by early march, it will result in marginal oportunites the further south one goes. CC comments on this earlier - story of the month i'm afraid. so close to something astonishing if it hadnt been there, going all the way back to the end of the northerly that started the month and the failed easterly that followed.

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.

Edited February 19, 2010 by cooling climate

[kold weather]

Amazingly though Karl a lot of the ensembles are marginal even for Scotland with a snow-rain change happening...

The evolution though is a good one for Scotland and does need to be watched, if the low is strong enough it will allow colder air back southwards again and we once again go back to square one with regards to this pattern which is where we are at now.

Even if the system does end up only hitting Scotland...hopefully it ends up as strong as the 06z because the threat would stil lbe there for the Midlands northwards.

[Frosty.]

Amazingly though Karl a lot of the ensembles are marginal even for Scotland with a snow-rain change happening...

The evolution though is a good one for Scotland and does need to be watched, if the low is strong enough it will allow colder air back southwards again and we once again go back to square one with regards to this pattern which is where we are at now.

Even if the system does end up only hitting Scotland...hopefully it ends up as strong as the 06z because the threat would stil lbe there for the Midlands northwards.

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.