General Model Output Discussion

[Yeti]

I notice some ensemble members building HP over christmas, while others keep it rather cold and slack

http://91.121.94.83/modeles/gens/run/gens-5-1-228.png?6

http://91.121.94.83/modeles/gens/run/gens-0-1-264.png?6

http://www.meteociel.fr/modeles/gefs_cartes.php?code=7&ech=240&mode=0

　

Surprised i haven't read more about this must be bored of the cold weather by now

Actually that's something I had noticed, quite a lot of the models are hinting at pressure and even height rises over Scandinavia later on, and whilst this might not necessarily lead to a full easterly reload it would at the least make the cold air harder to budge.

GEM: http://www.wetterzentrale.de/pics/Rgem2281.gif

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

ECM: http://www.wetterzentrale.de/pics/Recm2401.gif

As well as the nice GEFS members you posted

Obviously not all of those would lead to cold in the short term but seeing heights and pressure to our NE is rarely a bad thing!

On the other hand this would need to occur late enough so as not to prevent the Atlantic low moving far enough NW.

[Eugene]

Yuck GFS 12Z FI is a horror show, atlantic system after atlantic system giving copious amounts of rain, people in wales and cumbria must be praying it doesn't come off, i`ll be joining them

[eyeofthestorm]

Much better UKMO; keeps the cold over the UK for longer. Heights rising over Northern Scandinavia with Lows remaining further south and the milder air further east. A Good UKMO. :lol:

http://www.wetterzen...n/fsukmeur.html

Edited December 17, 2009 by eyeofthestorm

[Frosty.]

Yuck GFS 12Z FI is a horror show, atlantic system after atlantic system giving copious amounts of rain, people in wales and cumbria must be praying it doesn't come off, i`ll be joining them :lol:

Plenty of wintry weather before then though, scotland cold & wintry most of next week and temps only slowly recovering further south, even by the end of FI there is still some cold air around in the north but snow mostly on hills by then. Some very sharp frosts for a time next week.

Back to today, there seems to be a lot more snow around than was publicly forecast this morning :lol: I suppose everyone is lamp post or radar watching...probably why I couldn't get on there myself.

[Barb]

Yuck GFS 12Z FI is a horror show, atlantic system after atlantic system giving copious amounts of rain, people in wales and cumbria must be praying it doesn't come off, i`ll be joining them

It's not nice. But Fantasy Island begins after the weekend I think. The amount of chopping and changing in the models is crazy at the moment - anything further than +72 is to be taken with a shovel of salt.

Yes much better looking UKMO.

[Frosty.]

Much better UKMO; keeps the cold over the UK for longer. Heights rising over Northern Scandinavia with Lows remaining further south and the milder air further east. A Good UKMO.

http://www.wetterzen...n/fsukmeur.html

Yes the ukmo 12z is much better for prolonging the cold over the uk, a nice upgrade on the 00z..hope it continues showing similar tomorrow.

[mushymanrob]

Yuck GFS 12Z FI is a horror show, atlantic system after atlantic system giving copious amounts of rain, people in wales and cumbria must be praying it doesn't come off, i`ll be joining them :lol:

lol...i think its great! but no doubt itll be dismissed as an 'outlier' as it doesnt show the synoptics some...most, would desire. outlier or trend setter?... i know what my monies on... of course things could go either way but gradually the seeming unstoppable cold looks like being a short lived blip.

[oldsnowywizard]

i would have thought that somewhere E mids to the south will get about 5-6 hours of snowfall as the low over holland turns into the NE wind and stalls against the HP.. twisting on its apex is what i want to say but im not sure if thats the right term lol.. it should pep up a little as it picks up some moisture over the north sea.. im not entirley sure i buy the 12z after sunday, it has the low, moving south, then back north and then west? i would imagine this will be very hard to predict until the day itself..

Edited December 17, 2009 by oldsnowywizard

[mushymanrob]

Yes the ukmo 12z is much better for prolonging the cold over the uk, a nice upgrade on the 00z..hope it continues showing similar tomorrow.

hi frosty :lol:

is it? at t120 theres a very mild drift off the mid atlantic via spain ... a trend the gfs suggests too..

[Shiny_Bottom_1]

Interesting that whilst we still look for the cold spell to continue (and I for one would love that), it really must be emphasised how consistant the GEFS has been in bringing in higher 850's around the 23rd. This has been shown in general (when looking at the average of the ensembles, and to some extent the op run) for around 4-5 days now. Like the cold spell trend it picked up on, this is for me another trend the GEFS has picked up on.

For me, at the moment, the GEFS is leading the way for trend spotting in the mid to long term.

[disco-barry]

So whats happened to the weather front which was meant to be coming down from Scotland on Saturday ?

[Frosty.]

hi frosty

is it? at t120 theres a very mild drift off the mid atlantic via spain ... a trend the gfs suggests too..

hi mushy,

i'm not so sure, the ukmo 12z trough has a better shape, for the northern half of the uk at least with an easterly or NE'ly tilt but much of the uk still seems to be in a generally arctic originated cold and unsettled flow although perhaps it's mixing out slowly across the south, doesn't look very mild to me but i'm sure your mild weather will return soon. Glad to see you are full of christmas spirit and goodwill to all coldies.

Edited December 17, 2009 by Frosty039

[phil nw.]

Interesting that whilst we still look for the cold spell to continue (and I for one would love that), it really must be emphasised how consistant the GEFS has been in bringing in higher 850's around the 23rd. This has been shown in general (when looking at the average of the ensembles, and to some extent the op run) for around 4-5 days now. Like the cold spell trend it picked up on, this is for me another trend the GEFS has picked up on.

For me, at the moment, the GEFS is leading the way for trend spotting in the mid to long term.

In a way yes the trend in the ens. is for a warming around 23-24th Dec but recently the mean 850`s have leveled off and even gone below 0C today.

This,if you like,is another trend,so an end to the cold is not a done deal yet,inspite of 12z GFS.

My Warks Ens. in fact show the op. was one of the warmest runs around Christmas for the 850`s.

http://charts.netweather.tv/ensimages/ens.20091217/12/t850Warwickshire.png

And for the 2m temps was the warmest over Christmas.

http://charts.netweather.tv/ensimages/ens.20091217/12/t2mWarwickshire.png

I think there will be a moderation of the cold,more so the further South,around Christmas but nothing is firmed up on the sypnotics this far away.

[Nights King]

Has the weather front that is moving into eastern england been moved slightly further west? National forecast just made it look like stretching into the west country abit with regular showers over bristol area?

Could it move any further west than expected?

[Shiny_Bottom_1]

In a way yes the trend in the ens. is for a warming around 23-24th Dec but recently the mean 850`s have leveled off and even gone below 0C today.

This,if you like,is another trend,so an end to the cold is not a done deal yet,inspite of 12z GFS.

My Warks Ens. in fact show the op. was one of the warmest runs around Christmas for the 850`s.

http://charts.netweather.tv/ensimages/ens.20091217/12/t850Warwickshire.png

And for the 2m temps was the warmest over Christmas.

http://charts.netweather.tv/ensimages/ens.20091217/12/t2mWarwickshire.png

I think there will be a moderation of the cold,more so the further South,around Christmas but nothing is firmed up on the sypnotics this far away.

Hi Phil.

Of course, i'm not indicating mild, but the set up is to high (in theory) for any real snow. Average is probably what I would call it.

Regarding the 2m temps, ignore the GEFS Op run after (I think) about 7 days. As it hits low res, it does what the attached does, every (or about 95%) of the time. Not sure if the charts reflect the ensemble run though.

[nick sussex]

My model headline tonight would be chaos breaks out at 96 hrs! it's a mess synoptically because in the current set up the smallest detail changes could mean the difference between snow and rain. The ukmo in typical model fashion switches at 144hrs to bring an interesting set up, its gone from Scrooge to Santa in 12hrs!

FI starts at 96hrs, I wouldn't take notice of any output at this point or beyond.

Edited December 17, 2009 by nick sussex

[J10]

Indeed both UKMO and ECM far better than GFS in keeping conditions cold for Christmas.

But nothing decided as of yet.

[Frosty.]

Even with my cold hat on, I think the very cold spell is on borrowed time as next week progresses and the best we can hope for is to maybe buy an extra day or two at the most. It's inevitable that the arctic air will be slowly mixed out from the south, probably by the middle of next week and then the erosion of the remaining cold air further north will continue with the uk in near average temps either by boxing day or soon after.

Edited December 17, 2009 by Frosty039

[Yeti]

Even with my cold hat on, I think the very cold spell is on borrowed time as next week progresses and the best we can hope for is to maybe buy an extra day or two at the most. It's inevitable that the arctic air will be slowly mixed out from the south, probably by the middle of next week and then the erosion of the remaining cold air further north will continue with the uk in near average temps either by boxing day or soon after.

It's such a shame - there's such a huge easterly just a few hundred miles to the N!

http://www.wetterzentrale.de/pics/Recm1681.gif

[Barb]

GFS 12z op = mild outlier:

[wellington boot]

Even with my cold hat on, I think the very cold spell is on borrowed time as next week progresses and the best we can hope for is to maybe buy an extra day or two at the most. It's inevitable that the arctic air will be slowly mixed out from the south, probably by the middle of next week and then the erosion of the remaining cold air further north will continue with the uk in near average temps either by boxing day or soon after.

Sadly I suspect you're right. However, there has still got to be a 10% chance that the surface cold will hang on, everything will be just far enough east that no southerly flow really gets going, and that everything falls away southeastwards and resets. With the ensembles a mess and some fairly serious disagreement between models, it is just about on the cards. But I agree, a return to mild is the likely outcome here.

[phil nw.]

Hi Phil.

Of course, i'm not indicating mild, but the set up is to high (in theory) for any real snow. Average is probably what I would call it.

Regarding the 2m temps, ignore the GEFS Op run after (I think) about 7 days. As it hits low res, it does what the attached does, every (or about 95%) of the time. Not sure if the charts reflect the ensemble run though.

Hi SB,

You`re right re.not taking those 2m temps. as gospel,but with a stagnant setup in that complex low nr.Christmas we have the cold air on the ground and those ground temps will take a while to pick up inspite of warmer uppers.

Just looking now at ECM along with the others it is a right dogs breakfast sypnotically around T144hrs.

http://www.wetterzentrale.de/pics/Recm1441.gif

http://www.wetterzentrale.de/pics/Rtavn1441.png

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

All the jet energy well south and we just stagnate.

As Nick S said everything beyond T96hrs.is very uncertain.

[Cloud 10]

The AO (arctic oscillation) ensembles are just flatlining at the moment,never seen that before.

Also an interesting chart for christmas day from tonights ecm!

Maybe we should be looking to the north/east again in the longer term.

[nick sussex]

Hi SB,

You`re right re.not taking those 2m temps. as gospel,but with a stagnant setup in that complex low nr.Christmas we have the cold air on the ground and those ground temps will take a while to pick up inspite of warmer uppers.

Just looking now at ECM along with the others it is a right dogs breakfast sypnotically around T144hrs.

http://www.wetterzentrale.de/pics/Recm1441.gif

http://www.wetterzentrale.de/pics/Rtavn1441.png

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

All the jet energy well south and we just stagnate.

As Nick S said everything beyond T96hrs.is very uncertain.

Evening Phil

Yes it's a dogs dinner with disagreements a plenty in terms of the detail, in terms of the general pattern though there is decent agreement but because there is such a small margin for error in terms of who gets snow or rain then it's just not worth looking at the model output at T-96hrs or beyond until we have model agreement on the detail, even then though given the set up it wont be till 24hrs out that we can make a good call. In these situations where lows head ne we often see a slowing down as they hit the cold air, for the models the complication is that the AO is still going to remain in negative territory with decent heights to the north so they have to factor this in and probably poorly.

I would tonight be intrigued to see the ecm ensembles,perhaps a few more colder solutions might be on offer.

[Frosty.]

Sadly I suspect you're right. However, there has still got to be a 10% chance that the surface cold will hang on, everything will be just far enough east that no southerly flow really gets going, and that everything falls away southeastwards and resets. With the ensembles a mess and some fairly serious disagreement between models, it is just about on the cards. But I agree, a return to mild is the likely outcome here.

The ECM 12z does slow down the change to less cold with quite a potent looking easterly for a time, even christmas day has snow potential in central and northern areas but I just get the feeling it's a last swipe before the atlantic air filters in. I quite like the ukmo 12z as well which also delays the change, in the north at least.