Model Output Discussion 12z 18/10/2012

[Alan Medlock Valley]

quite a large percentage did though,so not sure where you get the 90% from.some of us just sat back in awe and watched things unfold.

I think at a stretch it was 20% of people on here that knew considering lets face it there isn't many knowledgeable members on here tbh apart from Gibby, Steve Murr, Thundery Wintry showers, BFTP, Chino etc, some contributions are good from others though has to be said and thanked.

Edited October 22, 2012 by Alan Medlock Valley

[Summer Sun]

Well in FI but there is still some snow showing

Thats it for tonight the rest is rain

Edited October 22, 2012 by Summer Sun

[peterf]

there's a lot of very knowledgeable folk on here,and the majority don't post.

anyway back to the models.

[phil nw.]

A few posts again wandering off topic and have been deleted.

If members wish to widen discussions to previous Winters or indeed general opinions on the up and coming season then we have plenty of other threads for this.

[A Winter's Tale]

Evening folks.

Tonight is setting up to be a mostly overcast one away from the far north western regions, but most significantly fog should become very widespread across England and Wales and parts of southern Ireland and highland Scotland could also have some fog patches. Tonight's minima should be 9 to 12C for cities, but in the highland glens it could get close to freezing at a few spots. The fog should continue into the morning and should have largely diminished by lunchtime, thereafter largely overcast conditions and some drizzle with the Scottish highlands north and west of the Great Glen being the exception but a few sunny breaks could develop across a few western areas away from the north west highlands. Temperatures should max at 11 to 16C. Tuesday night should remain largely overcast with a little drizzle, clear skies restricted to the far north west once more, lows of 8 to 13C.

On Wednesday there could be some more sunny spells, particulary across the south of England and the sunshine across northern Scotland could spread a little southwards and eastwards. From London to Dundee, skies are more likely to be overcast with some drizzle. Maximum temperatures of 11 to 16C. There should be less drizzle during Wednesday night but still overcast in the familar areas and some clear skies down the very western areas. Minima should be 5 to 12C.

There should be less drizzle on Thursday and sunny spells could become a lot more widespread across northern Ireland, the south west and some parts of Scotland although northern areas this time could be overcast with some light rain before the cold front arrives. Maximum temperatures of around 10 to 13C. As the cold front makes it way south, some light rain should spread southwards overnight, some breaks in the cloud cover south of the front and north of it more widespread clear skies away from northern coasts. Minima should be at 5 to 9C across England, Wales and Northern Ireland but in Scotland and widespread frost should develop with lows below freezing in the highlands and around 2 to 4C in cities.

On Friday, a cold sunny day seems likely for the north with some showers around the northern coasts. Cloudier conditions across England and southern areas in particular as the front brings rain to southern Ireland and England before clearing into the sea. Maximum temperatures in Scotland and northern England and Ireland should be 5 to 8C but closer to 10C further south in England and Wales. Friday night looks like being a very cold one, especially for northern areas with a widespread frost and minimum temperatures mostly below freezing. Some cloud cover may remain across the south of England and Wales and little cloud cover in Ireland. Down eastern and north coastal regions there could be a few showers. Minimum temperatures in cities should range between -1 to 6C in cities.

Although the significance of the cold spell that was been somewhat downgraded, it seems very likely now that for a while at least at the end of the week, things will turn much colder and there should be widespread frosts - for the north in particular - and some low temperatures plus some lovely crisp conditions and sunshine, particulary north of Manchester. And on the coastline around the north of Scotland and the north sea may be prone to a few showers and these could be wintry in nature, especially a little inland and with some elevation. So my word for the next few days is take care with the foggy start tomorrow, enjoy the rare occasions when the sun decides to come out - unless you live in north west Scotland where here sunshine shouldn't be as illusive - make the most of the mild temperatures as you can even if it's cloudy and drizzly and for the end of the week enjoy the colder, sunny and crisp conditions and I'm sure that a lucky place or two might see some wintryness. But it's worth following what the models do with this cold spell later this week as there is still time for adjustments and we'll gain a much better idea of what sort of temperatures and weather we could get as the finer details begin to firm up. I think that beyond this weekend, we may see the beginning of a change to more unsettled conditions but further northerlies remain possible but there's a lot of things beyond this week that remain to be confirmed so at this stage, I suppose everything is still up for grabs, although I expect a fairly normal outlook for this time of year to follow.

[Frosty.]

Don't lose hope people, just because of a few dodgy op runs showing a wishy washy nw'ly, the met office tv forecast still shows an ARCTIC BLAST digging in for the weekend with snow showers in the northeast of the uk and widespread frosty nights, perhaps that snow risk will upgrade for some others areas too. In the meantime, the major hazard is fog, some dense fog tonight which will again be slow to thin tomorrow with another dull day for most areas, the far north of scotland looks clearer and sunnier, on wednesday it looks a lot brighter in the areas previously dull but by thursday, patchy rain beginning to push south, then colder air arrives by friday and digs in at the weekend from the arctic.

[summer blizzard]

Far too much despondency here, a simply look at the theta-t's indicates that it will be pretty cool at the surface right until Nov 6th from this run, no real tropical air.

[UV-RAY]

Don't lose hope people, just because of a few dodgy op runs showing a wishy washy nw'ly, the met office tv forecast still shows an ARCTIC BLAST digging in for the weekend with snow showers in the northeast of the uk and widespread frosty nights, perhaps that snow risk will upgrade for some others areas too. In the meantime, the major hazard is fog, some dense fog tonight which will again be slow to thin tomorrow with another dull day for most areas, the far north of scotland looks clearer and sunnier, on wednesday it looks a lot brighter in the areas previously dull but by thursday, patchy rain beginning to push south, then colder air arrives by friday and digs in at the weekend from the arctic.

What do the Met Office know Frosty.

[Frosty.]

What do the Met Office know Frosty.

they know enough to keep me onboard with the arctic blast until at least the 00z tomorrow

[UV-RAY]

they know enough to keep me onboard with the arctic blast until at least the 00z tomorrow

Same here Frosty, I'll take their word over our resident doomsday and wind up merchants any day.

[Gavin Hannah]

Same here Frosty, I'll take their word over our resident doomsday and wind up merchants any day.

It will never snow again in the UK.... Mwah-ha-ha!

I'm looking forward to the 18z, lets see if the cold can dig in on the next run!

[Alan Medlock Valley]

Far too much despondency here, a simply look at the theta-t's indicates that it will be pretty cool at the surface right until Nov 6th from this run, no real tropical air.

Indeed - it's not even classed as late Autumn until 1st November , whether we have a cold blast this week or in the weeks ahead it will arrive at some point - this isn't the South of Spain.

[Geordiesnow]

I thinkt here has been a short term upgrade on the GFS in sending the colder air southwards and westwards quicker than first thought, there was some GFS runs which seemed to suggest will the -5 upper air temp will even reach most of the UK and whilst it did, it was not as quick as today's GFS 12Z run.

The bad news is that whilst the alignment of the isobars look good at 72 hours on the UKMO chart, it seems pressure wants to rise from the NW but not as quick as yesterdays GFS runs. I was reading this thread on me phone earlier and fearing the worse going by the posts but the Northerly for the end of the week is still there hence the forecasts.

The length on any colder spell has been downgraded but the detail is subject to change and I said that yesterday regardless what happens to the Northerly on Friday.

Edit: Another inspection of the GFS seems to suggest that low running up the Labrador sea has entered Greenland which kills the block off quickly and reduces height rises quite quickly, so there is still some differences between the GFS and UKMO outputs I feel with the UKMO still offering the coldest set up.

Edited October 22, 2012 by Geordiesnow

[IanM]

Can we please try to stick to discussing the models? There are other threads better suited to general winter chat, thanks.

[cold snap]

the models are diverting the cold east not a bad thing at this time of year.we can tap into later.hoping for a decent ecm

Edited October 22, 2012 by cold snap

[Summer Sun]

Dispite the doom and gloom of one bad day from the models the beeb are getting more confident of a blast of artic air come the weekend they have issued another video in the website day time highs reach just 2c for some in the north with glasgow seeing a high of -1c factor in the wind chill and your looking at -4c to to 0c in the south

ECM is out to Thursday now, the cold air is coming

Edited October 22, 2012 by Summer Sun

[Geordiesnow]

At 72 hours, everything on the face of it looks really promising but that pesky low pressure in the Labrador Sea should enter into Greenland and by 96 hours, we should see the block starting to collapse and shunt the Northerly eastwards, one is hoping the UK can still remain in the flow long enough to deliver some cold air as per the UKMO set up and not the GFS set up.*

I don't think its a case the cold air has been shunted eastwards, if anything its been shunted westwards but I'm pretty sure yesterdays outputs shown that pesky low pressure system not advancing as far North as it did and it most certainly did not enter Greenland like it has on today's outputs.

* Of course I could be proven wrong here and I hope I am wrong!

[Summer Sun]

Out to the 26th now and its getting colder

If the HP could shift a bit further west that would be perfect

[cold snap]

its a near miss .il take it .pulling are hair out in dec.jan of course.ecm looks like it may go same way

out to 120 ecm and cold air starting to get cut off .

Edited October 22, 2012 by cold snap

[Summer Sun]

High pressure moves in it remains chilly though

[Geordiesnow]

Out to the 26th now and its getting colder

If the HP could shift a bit further west that would be perfect

The high has collapsed thanks to the low in the Labrador Sea/Baffin Bay area, it won't head westwards, the only thing that will keep any potential colder snap going is if a shortwaves dives SE'wards and we see a ridge pulling up and the ECM sadly does not really show that.

[SMU]

Evening All-

A couple of days of mixed fortunes on the model front-

on the whole we have moved from extreme charts back to a more representative charts of a polar outbreak in October-

Perhaps a pity- but still a high end northerly for this time of year-

http://www.meteociel...212/ECH1-72.GIF

http://www.meteociel...CH1-96.GIF?22-0

However the allignment of the energy over the states has just over run the pattern & taken the sting out of the meridional jet- so the pattern relaxes away to a weaker northwesterly after 48 hours-

http://www.meteociel...H1-120.GIF?22-0

Within the moderate NW flow we see a shortwave developing off the polar front & sliding south/south East-

Good for the north & the early season hill snowcover- but ultimatly the chances of any white stuff a little deminished today.-

the only perk from the 120 chart is some nice cold frosty air- coming from a cold high- maxima up to 10c.( still low singles in the north)

A case of close but no cigar this time-

The mid term sees heights over the whole pole lowering a little ( contrary to the mid term outlook 2 days ago) so the AO will bounce back towards a low level of negative.- As a result the depth of the cold over the mid lattitudes will drain away, however the UK may see the benefit of a light rise in pressure behind the shortwave allowing us to stay cold-

In looks as though in the 'mean' the flow remains in the chilly NW quadrant...

After that - no clarity just yet...-

S

Edited October 22, 2012 by Steve Murr

[Isolated Frost]

The ONE major difference in todays and yesterdays 12z ECM is the small upper low in the Labrador Sea. There are notably lower heights N and W of Greenland and this is causing heights on a whole to fall across Greenland- pushing that HP cell just a touch further SE. This touch eliminates the chance of snowfall on Friday and Saturday in Northern and Eastern areas, for the most part. The ECM 12z today is another good run for cold prospects, but the pattern has been touched a tad eastwards as the upper heights N and W of Greenland fall. This is the crucial detail in the future of this cold spell, GS has got it spot on, it pays to look at the whole picture in situations like this.

At +120 we have the same problem, the heights have fallen dramatically and we have an upper low developing around Baffin Island- whilst yesterday heights were in comparison rather large, ensuring that the upper ridge was in place and we had a long-stretch northerly as a result.

All in all the area around NE Canada is the difference between a ripping northerly or a nw'ly toppler. The Met Office obviously disagree with the ECM and GFS with there more extreme solutions to it, so perhaps it's a battle for the NWP's, the strat certainly gives the NWP's the answer.

On the left is today's 12z ECM, on the right is yesterday's. There's your answer, put simply.

[Gavin Hannah]

UKMO still maintaining more of a northerly flow out at t.120. Hoping the rest of the models trend towards the UKMO for some prolonged cold and high level snow come the weekend.

[cold snap]

not so bad at 168 from ecm.could of been worse next frame should be of more intrest i was expecting atlantic to take control not yet anyway