General Model Output Discussion:

[kold weather]

I'm surprised it is so quiet in here. That GFS run would deliver buckets of snow to the SW - classic stuff. It will invariably change between now and then but a nice trend nonetheless. In reality I can see the low being too far south to have any influence. Something to watch in the next few days anyway.

Yep, the UKMO takes it further south though even then the SW would have a fair threat of snow.

I suspect the models will again take the low a little further south but this time we will have a much stronger surface cold pool to lay with and a proper continetal feed as well, so if the low does get far enough south a big snow event would be probable.

Nick, totally agree, the one thing that could be of help though is if the PV comes far enough south, doesn't have to have a direct role here, just enough to stop the low from going too far NE.

Edited December 29, 2009 by kold weather

[Guest North Sea Snow Convection]

Evening Tamara

Personally i dont like the ukmo or the gfs, preferably its better to have a stronger ridge backing west so that low pressure runs ene and then be deflected away this is safer, part of the problem with the gfs is the block edges west too far, people are assuming that the low will do as the gfs says, and eventually head away se again but this is fraught with danger, with the block having edged so far west the scenario could play out in an altogether less favourable way. The UKMO at 96hrs has that shortwave stopping a stronger ridge from the east, then its down to the low to the sw not heading too far ne. I'm hoping the ecm will stick to its guns driving lower heights into the Med and edging towards the GEM where the block is further east and the Scandi trough better aligned.

I don't want to spoil everyones fun here but the angle of attack of that low and the complications of that small shortwave IMO are not a gamble worth taking but again like I've said before its a risk reward thing, people will of course have different views on this.

I agree nick. I think my positive comments regarding the UKMO were mostly geared to the end of this week. And like you, I am not so sure about the start of next week with regard to the GFS. Rain to snow scenarios are of course fine by me - but a snow to potential rain is rather different! Getting the cold bedded in and sustained via the synoptic route you have suggested earlier today, and again just now, is certainly better imo.

I suppose that there might be the advantage this time that there should be at least some cold air in place, unlike this week. That might also hinder the progress of the low further NE.

Edited December 29, 2009 by North Sea Snow Convection

[SMU]

http://91.121.94.83/modeles/gens/run/gens-21-1-150.png?12

Ensemble Mean 12z GFS-

PERFECT PERFECT- dont move it- snow moving into the SE-

Infact people remember this- with established cold you are move likely to get heavy snow from the SW with a SURFACE SE Flow in -5 air than you are from an easterly with -8 air-!!!

All about the dry dewpoints.....

S

[Frosty.]

I'm surprised it is so quiet in here. That GFS run would deliver buckets of snow to the SW - classic stuff. It will invariably change between now and then but a nice trend nonetheless. In reality I can see the low being too far south to have any influence. Something to watch in the next few days anyway.

It's a good run for everyone who loves snow and frost, even after T+192 when the high builds, it remains cold and frosty for a while. Most favoured areas for snow showers once the current frontal rain/sleet and wet snow clears the south will be northeast & eastern scotland, northeast england and maybe further down the east coast once the weakening front across the south clears off. Still the chance of a Northerly by the beginning of next week but hopefully it will last longer than shown. I think today's meto update was closely linked to the GEM 00z and the ECM 00z. Possible snow event for the sw late weekend into early next week?

Edited December 29, 2009 by Frosty039

[SMU]

Last one from me for a while-

Ensemble 20 is where its at for sustained cold & heavy snow a la 85 for the SE-

S

[nick sussex]

I agree nick. I think my positive comments regarding the UKMO were mostly geared to the end of this week. And like you, I am not so sure about the start of next week with regard to the GFS. Rain to snow scenarios are of course fine by me - but a snow to potential rain is rather different! Getting the cold bedded in and sustained via the synoptic route you have suggested earlier today, and again just now, is certainly better imo.

I hope people don't think i'm being a misery here! the gfs in a sense does a party trick, it drives the low far enough ne to deliver some snow, then says okay i'll let you enjoy the snow now i'm off se, how very nice of it! However the scenario could play out like this the low drives ne, the block backs west the Scandi trough heads sw because of this, the low phases with low heights to the ne and the flow backs to the south as everything gets shunted to the nw!

We should never expect the models at that range to follow the nice festive route but have to account for margin for error and variables, of course any attack from the sw comes with risks but this one is now looking very complicated. Perhaps i'm just grumpy today as this current low is driving mild mush sw'erlies right into France with lots of warm rain for now the second day, with the Pyrenees looking particularly sad with the snow cover fast disappearing,the sooner it just takes a hike se the better, there is snow expected by Thursday thankfully so hopefully my mood should slowly improve!

[winter watcher]

http://91.121.94.83/modeles/gens/run/gens-21-1-150.png?12

Ensemble Mean 12z GFS-

PERFECT PERFECT- dont move it- snow moving into the SE-

Infact people remember this- with established cold you are move likely to get heavy snow from the SW with a SURFACE SE Flow in -5 air than you are from an easterly with -8 air-!!!

All about the dry dewpoints.....

S

Steve tried sending you a pm but it says your in box is full just a quick one regarding your joe b quote do you agree with him with that statement?

[TEITS]

Very nice +144 UKMO for the simple reason the core of the HP remains over Greenland. The period between +144 & +192 is definately trending towards keeping the block over Greenland as the GEM ensembles suggest.

As for the LP hitting the S/SE next weekend? At the moment it may fringe the far S but I feel this will be kept away due to the block.

[phil nw.]

Good output for cold and snow again.

The NH pattern is good as long as the upper high stays to our North West and the Scandi trough orientates towards us.

This more west based -nao set up does bring the mild air close to our South at times but the chances are there for more widespread snow events with low pressure nearby.

As i said earlier a Jan.1987 would be perfection but i think this pattern will be cold enough to satisfy most.

http://www.meteociel...&mode=0&carte=1

http://www.meteociel...&mode=1&carte=1

Let`s appreciate what we have in front of us.

Edited December 29, 2009 by phil n.warks.

[Archie_Lewis]

http://91.121.94.83/modeles/gens/run/gens-21-1-150.png?12

Ensemble Mean 12z GFS-

PERFECT PERFECT- dont move it- snow moving into the SE-

Infact people remember this- with established cold you are move likely to get heavy snow from the SW with a SURFACE SE Flow in -5 air than you are from an easterly with -8 air-!!!

All about the dry dewpoints.....

S

looks great. BUT it's 6 days away! If still showing Saturday then game on but until then ...............

Edited December 29, 2009 by Archie_Lewis

[swilliam]

Last one from me for a while-

Ensemble 20 is where its at for sustained cold & heavy snow a la 85 for the SE-

S

Surely 3 is better in general? A brief milder period for the SE admittedly

but worth having because then look what happens.

then we end up with a picture perfect Greenland Scandi high block

Shows what could happen if things go well for us!

[phil nw.]

I hope people don't think i'm being a misery here! the gfs in a sense does a party trick, it drives the low far enough ne to deliver some snow, then says okay i'll let you enjoy the snow now i'm off se, how very nice of it! However the scenario could play out like this the low drives ne, the block backs west the Scandi trough heads sw because of this, the low phases with low heights to the ne and the flow backs to the south as everything gets shunted to the nw!

We should never expect the models at that range to follow the nice festive route but have to account for margin for error and variables, of course any attack from the sw comes with risks but this one is now looking very complicated. Perhaps i'm just grumpy today as this current low is driving mild mush sw'erlies right into France with lots of warm rain for now the second day, with the Pyrenees looking particularly sad with the snow cover fast disappearing,the sooner it just takes a hike se the better, there is snow expected by Thursday thankfully so hopefully my mood should slowly improve!

Blimey Nick you are into mental gynastics with the output today

I can see where it may go wrong but i am just seeing the overall Hemisphere pattern as v.good for cold and snow here.

Yes there are risks with the trough so close but as you well know Nick getting and keeping cold in the UK is always an edgy situation.

Glass half full Mate

Edited December 29, 2009 by phil n.warks.

[danm]

Surely 3 is better in general? A brief milder period for the SE admittedly

but worth having because then look what happens.

then we end up with a picture perfect Greenland Scandi high block

Shows what could happen if things go well for us!

Looks great but that is way too far off, and fraught with even more risks as the milder air sweeps in on the 6th on those charts. At least the low from the SW (although being 6 days away) is in a semi-reliable time frame.

Edited December 29, 2009 by danm

[TEITS]

GEM is very nice aswell.

http://91.121.94.83/modeles/gem/run/gem-0-144.png

Im beginning to wonder whether the flow might start changing from a N,ly to a NE/ENE,ly in future outputs. I wonder if this is the reason the Met O forecast said "snow showers becoming more persistant and widespread from the middle of next week"?

Back to the LP at the weekend and although I think it will be a near miss. I've had a look at the rest of the ensembles and I have to say there is a risk of a snow event occuring. However I don't have the stamina to follow another LP at the moment.

[danm]

GEM is very nice aswell.

http://91.121.94.83/modeles/gem/run/gem-0-144.png

Im beginning to wonder whether the flow might start changing from a N,ly to a NE/ENE,ly in future outputs. I wonder if this is the reason the Met O forecast said "snow showers becoming more persistant and widespread from the middle of next week"?

Back to the LP at the weekend and although I think it will be a near miss. I've had a look at the rest of the ensembles and I have to say there is a risk of a snow event occuring. However I don't have the stamina to follow another LP at the moment. :o

Lol agreed. Its not good for the health following these low's. Any subtle shifts means a whiteout for one area and a washout down the road. Always better to have a frigid easterly with convection off the north sea. Less widespread snow, but you know it will be snow.

Edited December 29, 2009 by danm

[swilliam]

Looks great but that is way too far off, and fraught with even more risks as the milder air sweeps in on the 6th on those charts. At least the low from the SW (although being 6 days away) is in a semi-reliable time frame.

I knew somebody would say that. Yes it is only extreme FI - but shows what could happen

[john mac]

GEM is very nice aswell.

http://91.121.94.83/modeles/gem/run/gem-0-144.png

Im beginning to wonder whether the flow might start changing from a N,ly to a NE/ENE,ly in future outputs. I wonder if this is the reason the Met O forecast said "snow showers becoming more persistant and widespread from the middle of next week"?

Back to the LP at the weekend and although I think it will be a near miss. I've had a look at the rest of the ensembles and I have to say there is a risk of a snow event occuring. However I don't have the stamina to follow another LP at the moment. :o

Yeah i dont blame you TEITS, absolutely knackered after this one, 12z still has things looking good for EA &SE from thursday night into friday

[clark3r]

Hi i see on the fax charts there is a couple of troughs on the charts so there could be a bit more precipitation

http://www.meteociel...h=48&carte=2000

thursday night fri morning i would say at the moment 2 - 5 cm snow at best! really am not expecting much if any from the weather front thursday night/fri

[TEITS]

Whats driving me loopy is the sheer amount of uncertainity for every timeframe.

For example.

How much precip will be left on this front with the colder air undercutting?

http://www.meteociel.fr/ukmo/fax/fax48s.gif

How much convection will occur on Friday?

http://www.wetterzentrale.de/pics/Rtavn661.png

Where exactly will this LP go?

http://www.wetterzentrale.de/pics/Rtavn1201.png

What happens after this? Do we see a N,ly/ENE,ly or does the block back W?

http://www.wetterzentrale.de/pics/Rukm1441.gif

I cannot answer any of these questions. The only thing I do know is its going to get colder!

Edited December 29, 2009 by THE EYE IN THE SKY

[john mac]

That might explain why it is so quiet on here tonight, i dont think anyone really knows what is going to happen next. Are you about SM could yopu give us your thoughts for the rest of this week and into the weekend?

[on the coast]

Whats driving me loopy is the sheer amount of uncertainity for every timeframe.

For example.

How much precip will be left on this front with the colder air undercutting?

http://www.meteociel.fr/ukmo/fax/fax48s.gif

How much convection will occur on Friday?

http://www.wetterzentrale.de/pics/Rtavn661.png

Where exactly will this LP go?

http://www.wetterzentrale.de/pics/Rtavn1201.png

What happens after this? Do we see a N,ly/ENE,ly or does the block back W?

http://www.wetterzentrale.de/pics/Rukm1441.gif

I cannot answer any of these questions. The only thing I do know is its going to get colder!

You certainly get the feeling that this cold spell is going to be a day by day thing. So many options shown

on many of the runs.

[Snow storm]

Wales could have the heaviest snowfall for years tomorrow-

click here for snow chart

In actual fact Wales may have continuous snow for the next 30 hours!!!

Not to ramp, but you may have the heaviest snow in 20 years.

Meanwhile, down South, the fun starts Thursday midday when the cold air creeps in, and precip. from the channel flirts with the South-

chart

If the ppn moves North by only 50 miles the South could be in for a surprise.

Next Monday looks phenomenal, but I am completely disregarding it as FI- for the moment.

ppn chart

2m temps at 0c midday

Edited December 29, 2009 by Snow storm

[john mac]

The ECM will be out shortly probs with an absolute stunning set of charts. I think we need some sort of clarification to get this forum going again.

[ANYWEATHER]

Well if this synoptic situation early next week does not provide snowstorms for the south ..."I WILL FLASH MY ASS IN THE NEAREST WINDOW OF A SUPERMARKET"!!! :o

[BarnetBlizzard]

Well if this synoptic situation early next week does not provide snowstorms for the south ..."I WILL FLASH MY ASS IN THE NEAREST WINDOW OF A SUPERMARKET"!!!

You shouldn't have said that it could move south or north by 50-100 miles though, more likely to move south because of the cold blocking, but it will defintly move over the following days.