Model Output Discussion 12z 18/10/2012

[Cloud 10]

Quite a change in today's 12z ECM compared to yesterday for Saturday,which won't

impress north sea convection fan's!

yesterday.. today..

Still a decent cold snap coming for the end of the week though,especially for the time of

year with some widespread frost and still a chance of some wintry showers.

LOL,just seen I.F's post!

Edited October 22, 2012 by Cloud 10

[ANYWEATHER]

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 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

Ummgghh, not sure Steve that a few wobbles from the models dictate the end of the week, there is so much info out there that it boggles your mind. Im looking for trends and we have been here before, I expect tomorrows models to reinfirm the cold, Im certainly not dispondent on todays models, the way I see it computer models are really struggling with some new trends in our weather over the last few years and to have this initial cold at this time of year as I have said before is something really unique

[Frosty.]

The euro's tonight give us something to work with, a much colder snap than the gfs is showing and it's only monday so still lots of time to fine tune the pattern in the next few days before we know for sure, little pesky lows that appear on one run can disappear on the next run.

Edited October 22, 2012 by Frosty039

[cold snap]

cant believe not more comments about ecm by no means epic .its show another possible outcome

[Geordiesnow]

Ummgghh, not sure Steve that a few wobbles from the models dictate the end of the week, there is so much info out there that it boggles your mind. Im looking for trends and we have been here before, I expect tomorrows models to reinfirm the cold, Im certainly not dispondent on todays models, the way I see it computer models are really struggling with some new trends in our weather over the last few years and to have this initial cold at this time of year as I have said before is something really unique

What makes you so sure that the models will switch to a more longer cold shot?

Too me, its amazing/frustrating how much difference the low pressure over the Labrador Sea has on the output because imo the GFS has swung towards the Euros in a more perfect alignment in the Northerly but we had a "joker in the pack" so to speak which just completely collapsed any proposed height rises in the space of 24 hours!

The details of each run will vary but the main trend from tonight is that it appears any Greenland block is not going to last very long, the UKMO only offers something a little bit more of a straw to clutch.

That said it may swing tomorrow but the timescale suggests this would appear to be unlikely.

[Gavin Hannah]

The euro's tonight give us something to work with, a much colder snap than the gfs is showing and it's only monday so still lots of time to fine tune the pattern in the next few days before we know for sure, little pesky lows that appear on one run can disappear on the next run.

Exactly, I pointed out earlier that one run from the GFS a few days ago had the LP in the Atlantic kick out a shortwave which completely toppled the Cold spell prospects. Next run, it was gone. ECM also had a shortwave above the UK a few days ago. It too is gone now.

[bluearmy]

i haven't relooked at the ecm runs from the weekend but there was a theme for the scandi trough to push energy sw towards us as a result of the greeny ridge being sharper and more defined. maybe a good time to reflect that ecm op seems to have a bias towards greeny ridges being overstated which has a consequence of more wintry charts for nw europe. i have a feeling this could be a recurring theme this winter so possibly a good time for us to be reminded of this bias. lets hope when winter comes we have a more meridional flow off the eastern seaboard to blow up the ridge.

[Gavin Hannah]

i haven't relooked at the ecm runs from the weekend but there was a theme for the scandi trough to push energy sw towards us as a result of the greeny ridge being sharper and more defined. maybe a good time to reflect that ecm op seems to have a bias towards greeny ridges being overstated which has a consequence of more wintry charts for nw europe. i have a feeling this could be a recurring theme this winter so possibly a good time for us to be reminded of this bias. lets hope when winter comes we have a more meridional flow off the eastern seaboard to blow up the ridge.

Am I right in thinking that if that LP in the Atlantic can migrate North West(ish), it would be beneficial for the HP sticking around for longer, producing a longer lasting northerly?

Edited October 22, 2012 by IBringTheHammer

[SMU]

http://www.meteociel...H1-240.GIF?22-0

A satisfactory run from the ECM tonight- in terms of the context of moving in towards late Autumn-

Never mild, the 0c isotherm 'generally' south of the UK, persistence with blocking around southern greenland & the southern arm of the jet staying south towards Spain.

the emphasis of blocking looks slightly -NAO west based, so to get the trough east of the UK is good news.

in summary- Turning much colder from the north then the pattern relaxing, but seemingly at worst easing back to a chilly NW origin, oscillating back to Northerly-

For the entire run the indications of the polar vortex gathering strength is still muted especially when you see bursts of WAA heading North out of the states-

Also worth a final look is the cat 4 hurricane heading towards NY at day 9...

much to be satisfied about, just not quite as extreme as a few of the earlier runs....

S

Edited October 22, 2012 by Steve Murr

[tinybill]

if thiis comes off there wont be much moving in the uk !!!

[I remember Atlantic 252]

if thiis comes off there wont be much moving in the uk !!!

Bloody 'ell tinybill thats a wild chart, a cherry pick thing, but away from Scotland, temps wont be that cold, but Scotland, Pennines, Peaks a snowfest

[ANYWEATHER]

What makes you so sure that the models will switch to a more longer cold shot?

Too me, its amazing/frustrating how much difference the low pressure over the Labrador Sea has on the output because imo the GFS has swung towards the Euros in a more perfect alignment in the Northerly but we had a "joker in the pack" so to speak which just completely collapsed any proposed height rises in the space of 24 hours!

The details of each run will vary but the main trend from tonight is that it appears any Greenland block is not going to last very long, the UKMO only offers something a little bit more of a straw to clutch.

That said it may swing tomorrow but the timescale suggests this would appear to be unlikely.

Whatever way you look at it, ecm and gfs share a cold outlook, really no point in looking at too much detail, The "TREND" in the synoptics is the key to whatever is forecast in the days ahead. These charts show what I said above.....!

[Geordiesnow]

Whatever way you look at it, ecm and gfs share a cold outlook, really no point in looking at too much detail, The "TREND" in the synoptics is the key to whatever is forecast in the days ahead. These charts show what I said above.....!

Not disputing that we will see our first proper cold shot of the season so far but sadly some small changes has put an real dent into the cold shot lasting longer and the trend does look like to my eyes is for lowering heights across Greenland, hopefully any shortwaves can bring a re-load set up with a better angled ridge into Greenland, something like the UKMO.

[January Snowstorm]

You have to say hats off to the gfs over the last week or so.

First to spot the Northerly and first to spot the Greeny high not being as dominant.

I mean last night it was every model v gfs and the gfs was right!!

[Gavin Hannah]

You have to say hats off to the gfs over the last week or so.

First to spot the Northerly and first to spot the Greeny high not being as dominant.

I mean last night it was every model v gfs and the gfs was right!!

We don't know that is right yet. They could all change tack by tomorrow. But it was the first to spot the cold shot.

[Fozfoster]

You have to say hats off to the gfs over the last week or so.

First to spot the Northerly and first to spot the Greeny high not being as dominant.

I mean last night it was every model v gfs and the gfs was right!!

YES first to pick up the cold spell but not right YET!! Edit.

IBTH got there first, bit like GFS.

Edited October 22, 2012 by Fozfoster

[Methuselah]

You have to say hats off to the gfs over the last week or so.

First to spot the Northerly and first to spot the Greeny high not being as dominant.

I mean last night it was every model v gfs and the gfs was right!!

In ten days you will...

[Fozfoster]

In ten days you will...

That far out is pretty safe bet Pete, how about 5 days?

[Paul White.]

You have to say hats off to the gfs over the last week or so.

First to spot the Northerly and first to spot the Greeny high not being as dominant.

I mean last night it was every model v gfs and the gfs was right!!

I don't quite understand what you are saying and I have read other posts like this one. You seem to be saying hats off to gfs because it picked up the northly and it'd now picked up a watered down version bearing in mind none of the forecasted Synoptics have have actually happened as yet. Surly best to wait until after the events have taken place and then credit models and posters with back slaps later

Paul

[Timmytour]

Well no one knows what is going to happen, but the GFS is looking less like a sheep and more like a shepherd among the models at the moment

[peterf]

it's all still to play for,too early for congrats or commiserations just yet.

[Fozfoster]

I don't quite understand what you are saying and I have read other posts like this one. You seem to be saying hats off to gfs because it picked up the northly and it'd now picked up a watered down version bearing in mind none of the forecasted Synoptics have have actually happened as yet. Surly best to wait until after the events have taken place and then credit models and posters with back slaps later

Paul

Yes and to add if i may,not as good 4-5 days out but good to spot a trend (8-10).

[Gavin Hannah]

Video blog from MetO today regarding forecasted Cold Spell

http://metofficenews.wordpress.com/2012/10/22/turning-colder-this-weekend/

[Zakos]

Still small variations in the forecast northerly each run, but I think we can safely discount the occurrence of a widespread snow event to low levels. as has been clear by many on here we would need a direct and potent northerly at this time of year.

This is not going to happen, the coldest of the air is going to move over Scandinavia, leaving most of the uk in only -5 t850s. However, there are some indications of a possible cold reload from the north again, perhaps we may be more lucky on this occasion. At present it is too far to out to tell if the reload will even occur.

In terms of the bigger picture, still continued signals from the models of a weak polar vortex, and a fairly disorganised jet stream. positive signs then it seems, as winter draws ever closer.

[bluearmy]

just gave myself a geography lesson and the mean ridge the other side of the hemisphere over the next two weeks is more kamchatka based than aleutian.