General Model Output Discussion

[cooling climate]

With the weather coming up it seems silly looking way out to next week but the

ECM t216 chart is a corker.

Fantastic run tonight.

The t 240 chart would surely bring the coldest weather so far.

Edited January 4, 2010 by cooling climate

[SMU]

Steve - what's your take on tom eve and Wednesday - has it become a nowcast event? Latest charts suggest South Midlands, Central S.England and into the S.W. I suppose by this time tomorrow it could've shifted back east. A nightmare for the UK weather forecasters, i'd imagine.

Slightly off topic so I will make it quick-

Despite access to 4 local models- NAE, UKMO,GFS & soon to be ECM ( IMO link) every model has different locations for the heavy snow- however the key is there will be HEAVY snow

Its a TOTAL nowcast & radar watch im afraid-- which is where the MET office warnings generally become useless & out of date-

Also- for the countless people who complained about how dry its going to be- WELL- some by the end of TUES will be up to 10/20cm of snow- IF ECM varifies then the country has the prospect of further heavy snow from T96 to T 168 which is another 4 / 5 days after- ( heaviest being in the East & SE)

Finally- the model consensus is swinging heavily to an undercutting scenario in the mid term- which given the recent storm track of this winter will NO DOUBT be progged to far North.....

ECM 216 SUMS IT UP-

ACtually edit that as well- ECM goes for snow risk out to t240 for the SE & indeed the risk of heavy snow as well transfers to the SW for a time-

S

Edited January 4, 2010 by Steve Murr

[TEITS]

I just want to add that our local forecast is suggesting the band of snow to the SW will move across the E Anglia region during Tues night. The GFS 12Z does indicate this snow band returning especially into W parts of E Anglia.

Considering the changes today I would highly recommend following this evenings model output and even then come tomorrow it might change!

[phil nw.]

Interestingly the NAE is a outlier with regards to what the other models show, the GME, GFS and the UKMO all focus the precip core further east...however the NAE has a better resolution so that balances that out very nicely indeed...therefore gotta be 50-50.

Anyway the ECM is a stonker of a run for Friday+Saturday, bitter cold with the perfect flow for driving the showers far inland...

GFS on its own with regards to the easterly tonight...

Regarding the precip. Kold it could well be that few if any will miss out altogether tomorrow/weds. the way the low appears to be developing.

http://expert.weathe...010518_0412.gif

http://www.meteociel...ax/fax36s.gifIt

Definitely a radar/nowcasting event coming up for next 48hrs.or so.

If some of 12z output was to be believed locations like TEITS and myself could get 24hrs. of this,but i wouldn`t think that will be the case,although i wouldn`t rule out a 4-6hrs. spell for some places.

It`s still a developing situation as you know.

Yes the Easterly looks stronger ,with GFS playing catch up again,i reckon.

Iroically it was the GFS a couple of days ago that first went with a really strong Easterly,it was that 18z the other night when Steve M nearly fell of his chair after viewing it.

Just going back to my first point about the next 48hrs.or so.

We always said that when the cold was properly in place then look for snow as these little disturbances often crop up at the last minute and this looks like the first in this pattern.

We mustn`t forget that many Scottish and Northern members have had many days of lying snow already and it`s mainly members in the Midlands and further South that have seen little or no lying snow.

Edited January 4, 2010 by phil n.warks.

[Stoxs]

I just want to add that our local forecast is suggesting the band of snow to the SW will move across the E Anglia region during Tues night. The GFS 12Z does indicate this snow band returning especially into W parts of E Anglia.

Considering the changes today I would highly recommend following this evenings model output and even then come tomorrow it might change!

Good point TEITS

but i would like to add that with this type of set up don`t be surprised to see the next run putting the center out in the north sea again!

All comes down to the Lampost and ruler , what will be will be !

There will be some dissapointed people on here by wednesday morning and it could be ME! or it could be Kold or TEITS, who knows.

[grab my graupel]

Folks, there are plenty of threads for discussing other topics, so let's stick to the models please

Thanks

Brian

[DEYS(Kent)]

http://en.vedur.is/weather/forecasts/atlantic/#type=prec

ECM to 72 for those that want to...

ECM following NAE and latest forecasts re, snow tomorrow night. If anything the snow risk maybe further N. No much to the E/SE.

[Frosty.]

What on earth has happened to the new so called improved gfs model, it looks just as bad as it did before the upgrade. Great euro output tonight, the ecm 12z holding back the atlantic with lows stuck to the west of the BI thanks to a solid scandi anticyclonic block which looks as though it could hold all the way through next week as well with an E'ly breeze and some snow flurries with severe frosts continuing.

[kold weather]

I'm actually not too bothered about this snow set-up, already had 7 days of snowcover which is better then most winters so I'm content on that front.

Steve, yeah the undercut solution is the way to go IMO, I also suspect the GFs putting way too much energy into it as per normal but we shall see. Should shift our winds SE which will give SEVERE cold with Europe by this point under a big blanket of snow, daytime maxes widely down to -2/3/4C...look at the archive charts and look at the coldest days and I bet at least a few had a SE airflow in the middle of a embedded cold spell.

[danm]

http://en.vedur.is/weather/forecasts/atlantic/#type=prec

ECM to 72 for those that want to...

ECM following NAE and latest forecasts re, snow tomorrow night. If anything the snow risk maybe further N. No much to the E/SE.

That covers a pretty large part of the Midlands and South if you ask me. Maybe not getting to eastern Kent and eastern parts of EA, but a fairly wide area looks to be at risk from that.

[kold weather]

http://en.vedur.is/w...ntic/#type=prec

ECM to 72 for those that want to...

ECM following NAE and latest forecasts re, snow tomorrow night. If anything the snow risk maybe further N. No much to the E/SE.

Pretty similar I agree!

Worth noting the easterly airflow is not showing much BUT the models are quite frankly useless when it comes to easterly convection, these models really can't handle L-E-S convection at all (lake effect snow)

[Ian Fergusson]

That covers a pretty large part of the Midlands and South if you ask me. Maybe not getting to eastern Kent and eastern parts of EA, but a fairly wide area looks to be at risk from that.

I'll post the latest NAE frames if I get a chance later (bed at 21Z, up at 03Z!!) but I suspect most or all of you have seen the last set of NAE modified frames and WBFL/PPN discrimination run I posted on the SW thread, which clearly show the key change to earlier runs in terms of the W versus E bias. It's evolving into a nowcast story effectively for tomorrow, as others have alluded to here, and I've been at pains to stress that irrespective of the (quite spectacular, if NAE is to be trusted = 20cm+) snow totals into eastern districts of the westcountry by late Tues / early Wed; the profound here-and-now hazard looming for tomorrow up to 12Z is ice on the roads, and it cannot be overstated.

[Neilsouth]

Pretty similar I agree!

Worth noting the easterly airflow is not showing much BUT the models are quite frankly useless when it comes to easterly convection, these models really can't handle L-E-S convection at all (lake effect snow)

Agreed like last night , alot more precipitation filtered in from the north sea than the models picked up.. Also the models didn't pick up the streamer affecting this local area.

[nick sussex]

NOAA are happy with the ecm operational runs and ensemble means and have added to their slating of the gfs 00hrs by also slating the gfs 06hrs run, they're not using the gfs at all today for their extended outlook which isn't surprising. Looks like the new gfs run is fast sinking and it's the same old problem with this model.

[Neilsouth]

NOAA are happy with the ecm operational runs and ensemble means and have added to their slating of the gfs 00hrs by also slating the gfs 06hrs run, they're not using the gfs at all today for their extended outlook which isn't surprising. Looks like the new gfs run is fast sinking and it's the same old problem with this model.

Pretty much the general feeling on two aswell , not sure whats going on with the new gfs... I thought that model was in testing for ages?

[Ian Fergusson]

Agreed like last night , alot more precipitation filtered in from the north sea than the models picked up.. Also the models didn't pick up the streamer affecting this local area.

? the 4km NAE did, refer to the graphic I posted yesterday showing the predicted streamlines and convergence zone forecast.

New UKMO modified fields tells the story into Wed, or at least the suggestive version...

[Devon-Nelly]

Looks pretty awesome for Weds morning for many areas across the midlands and the south and we may get some heavy fluffy stuff too looking at the latest runs.

But overall staying very very cold, will be keeping my fingers crossed.

[TEITS]

Right after spending a bit of time looking at all the models I think I have tomorrow pretty much sorted (until later!).

If we look at the Fax chart for tomorrow lunchtime we see the front situated around Lincs to the SW.

http://www.wetterzentrale.de/pics/brack0.gif

So around Lincs/E Midlands a light dusting is possible but regions to the SE will remain dry.

What happens during Tues is an area of snow develops across S/Central/W parts of England. Look at the links below and you will see the ECM/Fax are similiar at +36hrs.

http://en.vedur.is/photos/atlant_evr_urkomuspa/100104_1200_36.png

The band of snow across S/Central England moves NE during Tues night into much of the Midlands and probably as far N as Lincs with the E extent being W Norfolk. After this the band of band of snow returns S.

This ties in with the GFS and also my local BBC forecast. However this can easily change as we have seen today.

[SussexmarkyMark]

? the 4km NAE did, refer to the graphic I posted yesterday showing the predicted streamlines and convergence zone forecast.

New UKMO modified fields tells the story into Wed, or at least the suggestive version...

Is there any chance you could interpret that a little please, as I'm not sure what all the colours mean ? Not helped by the fact that I'm colour-blind ! Thanks

[kold weather]

Yeah Ian I agree with regards to Tuesday set-up ,is the type that could quite easily give 6-9 inches in the bullseye spot...have to admit though I suspect the NAE is a little too far west and will adjust back eastwards again a little (probably say 50 miles) because as I've said before in a developing low situation the models tend to be too far west, of course thats only a guide and not always the case!

Also very interesting modified chart, suggestive that the second band could be stronger then some are expecting...

[Stoxs]

Right after spending a bit of time looking at all the models I think I have tomorrow pretty much sorted (until later!).

If we look at the Fax chart for tomorrow lunchtime we see the front situated around Lincs to the SW.

http://www.wetterzentrale.de/pics/brack0.gif

So around Lincs/E Midlands a light dusting is possible but regions to the SE will remain dry.

What happens during Tues is an area of snow develops across S/Central/W parts of England. Look at the links below and you will see the ECM/Fax are similiar at +36hrs.

http://en.vedur.is/photos/atlant_evr_urkomuspa/100104_1200_36.png

The band of snow across S/Central England moves NE during Tues night into much of the Midlands and probably as far N as Lincs with the E extent being W Norfolk. After this the band of band of snow returns S.

This ties in with the GFS and also my local BBC forecast. However this can easily change as we have seen today.

Thanks for that TEITS

A question to you or anyone else who would care to answer

Why does this trought develope into a LOW?, Usually this would pass through and diminish not develope over land.

unstable air mass i guess but why and where has it come from, if you have any charts to show what to look for it would be appreciated

[nick sussex]

Right after spending a bit of time looking at all the models I think I have tomorrow pretty much sorted (until later!).

If we look at the Fax chart for tomorrow lunchtime we see the front situated around Lincs to the SW.

http://www.wetterzentrale.de/pics/brack0.gif

So around Lincs/E Midlands a light dusting is possible but regions to the SE will remain dry.

What happens during Tues is an area of snow develops across S/Central/W parts of England. Look at the links below and you will see the ECM/Fax are similiar at +36hrs.

http://en.vedur.is/photos/atlant_evr_urkomuspa/100104_1200_36.png

The band of snow across S/Central England moves NE during Tues night into much of the Midlands and probably as far N as Lincs with the E extent being W Norfolk. After this the band of band of snow returns S.

This ties in with the GFS and also my local BBC forecast. However this can easily change as we have seen today.

That's a good forecast Dave but given the big changes on a local level between runs you'll probably have to update that later after the gfs 18hrs run and the latest NAE! very complicated for tomorrow but i'm sure no one would begrudge southern areas if they got lots of snow especially as they have largely missed out so far, i'm hoping that the snow can be shared around so at least people will look back at this spell with fond memories, IMO if the ecm keeps up with this trend then certainly this could be better than anything since the 60's.

[Altohumorous]

Sorry but I only have time to concentrate on the main risk area. If I concentrated on the whole of the UK I would be here all night.

Fair enough, but I would have thought the troughs progged for further north and west are worthy of more comment. Perhaps they will just be weak affairs, that's what the MetO over here think anyway, but the UKMO precipitation charts beg to differ

[Devon-Nelly]

Thats looks stunning Thanks Ian, Can i just ask are the different coloured snow flakes the difference in how heavy it will be E.g. Blue = light, Green = Moderate ect?

It looks as though there could be alot of snow for some areas on Wednesday and maybe a few flakes here too lol.

[tinybill]

Yeah Ian I agree with regards to Tuesday set-up ,is the type that could quite easily give 6-9 inches in the bullseye spot...have to admit though I suspect the NAE is a little too far west and will adjust back eastwards again a little (probably say 50 miles) because as I've said before in a developing low situation the models tend to be too far west, of course thats only a guide and not always the case!

Also very interesting modified chart, suggestive that the second band could be stronger then some are expecting...

our girl to-night on BBC local said we can expect Tuesday night appox 4 inches and Wednesday in the east we can expect 8 -appox then that leaves Thursday , Fri ,sat mind how the models are going at the moment for the end of the week all eyes will be on the low coming from France and how far north its going to go

,