Winter Model Discussion 18Z 19/1/13 onwards.

[The Eagle]

strong signal on the GFS and CFS for heights stretching across from Greenland to Scandi, initiating 1st week of February

We are struggling to know the weather 48 hours in advance. I'd take anything post 120 with a massive dose of salt. Can't say the charts are in any way impressive in the medium term or different to a typical Atlantic setup - high pressure to the south, low pressure to the north. As for the SSW lark - what happened to all that? Not hearing much about it now. The PV was going to be pulverised we were told. Back very healthy by the end of the week. What we have had the last week was a run of the mill flukey situation that by all accounts and according to met agencies had little to do with SSW and more to do with typical deviations that just happened to somehow drag out a period of cold weather. I'm not confident at all we can return to these conditions any time soon once the jet stream gets going.

Hope i'm wrong though.

Edited January 21, 2013 by The Eagle

[Cheshire Freeze]

I'm really just learning all this stuff so if this is nonsense please feel free to tell me but doesn't the GFS show a shortish northerly/northeasterly blast around the 4th/5th Feb followed by the HP setting up shop over the UK and channelling the colder air into Europe? For those that want cold/wintry weather wouldn't that HP need to be further North and West to deliver? These are the charts I'm referring to, hope they link correctly:

Short blast:

http://modeles.meteo...nh-1-360.png?12

HP setting up shop over UK:

http://modeles.meteo...0-384.png?12?12

It's all about trends....

Recent mid-late FIs have featured a weakening vortex, little or no Canadian/Greenland PV to speak of, a southerly jet and a high latitude block setting up somewhere between Scandi and Greenland. All things we want to see. Werreting about the exact location of such blocks at this range is futile.

[ABCD]

It's all about trends....

Recent mid-late FIs have featured a weakening vortex, little or no Canadian/Greenland PV to speak of, a southerly jet and a high latitude block setting up somewhere between Scandi and Greenland. All things we want to see. Werreting about the exact location of such blocks at this range is futile.

Lol my follow up question was going to be about focusing on trends rather than specifics but you've already answered it so cheers.

[Cheshire Freeze]

We are struggling to know the weather 48 hours in advance. I'd take anything post 120 with a massive dose of salt. Can't say the charts are in any way impressive in the medium term or different to a typical Atlantic setup - high pressure to the south, low pressure to the north. As for the SSW lark - what happened to all that? Not hearing much about it now. The PV was going to be pulverised we were told. Back very healthy by the end of the week. What we have had the last week was a run of the mill flukey situation that by all accounts and according to met agencies had little to do with SSW and more to do with typical deviations that just happened to somehow drag out a period of cold weather. I'm not confident at all we can return to these conditions any time soon once the jet stream gets going.

Hope i'm wrong though.

You're wrong.

What we've seen is a quick (immediate) response from the troposphere in accordance to the SSW that inititated a couple of weeks ago. This reversed the zonal winds and enabled us to acheive a block (albeit relatively weak). This has allowed the Canadian vortex to become detached and is being shoved towards us and firing up the jet (hence the zonal looking weather next week). However, with continued warming around the Greenland/Canada sector this segment of PV is forecast to lose its intensity fairly quickly and with the warming event continuing to propagate into the troposphere I think we're looking at a realistic chance of a cold pattern re-establishing first week of February (roughly 4 weeks after SSW initiation) which fits in with general SSW lag time for tropospheric impact.

[godber]

Long time "lurker", on this superbly informative thread. Big thankyou to all the "big hitters", GP, JH, Chiono, Steve murr, Nick sussex, etc... Would just like to ask. Do we not need to go through a breakdown in this current cold spell, to a more mobile pattern to get us to the next phase?

[weatherguy]

Long time "lurker", on this superbly informative thread. Big thankyou to all the "big hitters", GP, JH, Chiono, Steve murr, Nick sussex, etc... Would just like to ask. Do we not need to go through a breakdown in this current cold spell, to a more mobile pattern to get us to the next phase?

Well unless the see some undercutting episode of ridiculous proportions (very unlikely), that PV segment over Canada has no other route towards Siberia (where it is forecast to shift to) other than ploughing through our weak block. Therefore I'd say an unsettled spell of milder weather is fairly necessary, yes.

[Jonan92]

Lol, crazy ensemble in this run

[jason75]

clutching at straws i know but perb no 10 looks wot could happen i suppose lol

[Djdazzle]

Lol, crazy ensemble in this run

Trendsetter!

[MillinMan1]

Although the SSW at beginning of January could have helped towards our current cold weather, i still think it has a lot more to offer for us in the near future.

[nick sussex]

Long time "lurker", on this superbly informative thread. Big thankyou to all the "big hitters", GP, JH, Chiono, Steve murr, Nick sussex, etc... Would just like to ask. Do we not need to go through a breakdown in this current cold spell, to a more mobile pattern to get us to the next phase?

Well unless we can order ensemble no 10 from the GEFS then yes!

To get to a blocking scenario its likely that we'll need to go through a milder spell but it might just be a short interlude. As the pattern resets though expect some wild swings in the model output.

[Jaffusmaximus]

Could someone please post a link to GP's and RJS forecast for Feb, would be much appreciated!

[Catacol]

I think this may be a tady IMBY given that most parts of the UK have had an absolute pasting over the last week or so...

The initial statement was about the SW of England so of course my answer will relate to the same. More rain will be bad news down here - fact. We have had little or no snow - fact. We would prefer it to be dry to avoid more flooding - fact. Poor output therefore for the SW from the end of the week. What's your point?

[weatherguy]

The initial statement was about the SW of England so of course my answer will relate to the same. More rain will be bad news down here - fact. We have had little or no snow - fact. We would prefer it to be dry to avoid more flooding - fact. Poor output therefore for the SW from the end of the week. What's your point?

Looking back I misread your post I think, my "IMBY" remark was regarding the apparent tone in your comment regarding snowfall for your area. I may have read that in the wrong context though, so no problem

[Yarmy]

You can tell the medium term model output ain't great when this thread actually gets shorter each time I refresh.

Anyway, three GFS runs in a row with Greeny Heights in lala land. Shame the other models don't go out that far.

[ChartViewer]

Well unless we can order ensemble no 10 from the GEFS then yes!

To get to a blocking scenario its likely that we'll need to go through a milder spell but it might just be a short interlude. As the pattern resets though expect some wild swings in the model output.

Ill take that Nick

[SMU]

http://meteocentre.com/models/get_panel.php?mod=gemglb&run=12&stn=PNM&map=eur〈=fr

If tonights GEM lands it would be a MAJOR coup-

It would turn a reasonable cold spell into a major one- although it does go against the ENTIRE ECM 00z suite-

& just for the stats out there-

UK snow Falling days for January AVERAGE-

http://www.metoffice.gov.uk/climate/uk/averages/6190_1km/SnowFall_Average_1961-1990_1.gif

4-6 for the south of England, 6-10 for the central belt...- 10 -14 for scotland-

Its a sad thing that we have become used to much lower totals in recent years.,...-

S

[allenar]

I remember an event shown in December suddenly get scrapped. I also remember someone saying the models aren't all that reliable at the moment. If got a feeling plenty more twists to come yet. Saturday is a long time to go..

[Tim Bland]

We shouldn't assume a return to cold is a given. Even GP can get wrong at times. Sorry to pour water on the fire but it should be said. Also the ensembles are not onboard yet http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

[Timmytour]

Lol, crazy ensemble in this run

<adopts Delboy tone and posture> well....that is my most favourite perforation....

Edited January 21, 2013 by Timmytour

[shaky]

Ecm lookin very similar to gem at 72 hours

[Continental Climate]

It's game over for this cold spell on saturday guys http://www.wetterzentrale.de/pics/Recm1201.gif!!! However i am firmly of the opinion that by monday next week the models will look a lot better from a coldies pov. Look for blocking in the iceland/SE Greenland area.

[nick sussex]

Looking at the 850's on the ECM at 120hrs there looks like just enough cold air ahead of the front to bring some snow for eastern areas but its quite unusual to see a positive tilt to troughing not mix out the cold beforehand.

Earlier at T72hrs it almost looks like you're going to get some trough disruption with a shortwave forming to the west off the main trough but then at T96hrs much more energy heads over the top.

It does look like it will turn milder around the weekend or soon after but the models aren't really convincing me with exactly how the breakdown occurs.

Edited January 21, 2013 by nick sussex

[Tom D]

Ecm lookin very similar to gem at 72 hours

Unfortunately the ECM has a much greater data input than the GEM (or so I would have thought).

http://176.31.229.228/modeles/gem/archives/2013012112/gem-0-120.png

Same old story. GEM vs the world.

[Blizzardof82]

Unfortunately the ECM has a much greater data input than the GEM (or so I would have thought).

http://www.meteociel...M1-120.GIF?21-0

http://176.31.229.22...2/gem-0-120.png

Same old story. GEM vs the world.

Although GEM has performed very well at handling this cold spell.