Model Output Discussion

[TEITS]

now it would seem this cold snap is not going to last but i sopose its a start for winter lets hope nino loses its effect but im sure by end of december things wont be as good.

Crikey lets worry about the cold spell arriving let alone the end of the cold spell.

Besides this the general theme of the ensembles is a huge block over Greenland with the LP systems having no other option than to travel underneath the block. If this happens then a prolonged cold spell is plausible.

How good is the GEM model though, it hardly ever gets a mention on here unless we are grasping at straws.

If it was only the GEM showing this cold spell then I wouldn't take much notice. However this mornings GEM is exactly like the GFS which is encouraging.

Come Thurs 12Zs we should know whats going to happen!

[Methuselah]

Apart from February 1986, I can't recall a single protracted spell of cold and snow that's demise wasn't expected long before it ever arrived...IMO, talk of a breakdown before Xmas is a tad pessimistic? It could happen, probably even will happen; but, as yet, it's all out in FI...

In the mean time, many parts of Eastern and southeastern England look to be in-line for a bit of dumping come Tuesday and Wednesday; the North Sea (in Tamara's words) looks like becoming a 'snow machine'...Just enjoy it???

[snowmadchrisuk]

How good is the GEM model though, it hardly ever gets a mention on here unless we are grasping at straws.

The GEM Ensembles paint a better picture than the GEM it self I think Frosty. Also it isn't just the GEM , NO GAPS Is almost identical to GFS as well.I'm still looking at some high heating bills next week with some significant cold and very low night time Mins . IMO .

Chris

Edited December 8, 2009 by snowmadchrisuk

[D KARLSON]

Well the basics are are set in stone now ,its now more a question of severity of cold ,duration and the amount of snowfall this does have an 80s classic look to it, all the hallmarks are there and no this could not have happened a few years ago but on this occasion the bias is towards it being likely as opposed to unlikely.

If this comes off, its going to cause a hell of a lot of disruption even one to tell the grandkids WHY ?

You probably would be hard pressed to find a bigger temperature contrast than is forecast in the these synoptics ,this is a rare beast very cold arctic continental air crossing what is still a relatively warm north sea ,very high convection from this and widespread thundersnow giving impressive accumulations.

If these charts can continue to be verified then the above remains a possibility if not then a watered down version perhaps , very exciting nonetheless i think the odds have increased now to at least a 60% chance of something fairly severe occuring ,just a case of how the models handel these shortwaves nuff said.

just one thing is Steve Murr related to Frank .... call my blufff :lol: :lol: :lol: :lol:

[ribster]

im happy but very dissapointed id like this to be a christmas to remember by being a white one but as you have suggested BFTP,

now it would seem this cold snap is not going to last.

but i sopose its a start for winter lets hope nino loses its effect but im sure by end of december things wont be as good.

models are very consistent now and cold snow looks like for a little while gfs is stunning but still anything can happen.

Dear oh dear, not sure the longetivity can be commented on yet, lets get there first shall we? It wasn't so long ago you were banging on about wind and rain all winter

[Frosty.]

If it was only the GEM showing this cold spell then I wouldn't take much notice. However this mornings GEM is exactly like the GFS which is encouraging.

Come Thurs 12Zs we should know whats going to happen!

Thanks TEITS,

As you rightly say, in 2 days we will have the answer, let's hope it's the answer 99.9% of us are looking for

The ECM is niggling me though, we never seem to get across the board agreement do we.

[Iceberg]

I probably wouldn't trust the GFS ENS Mean as it would tend to fudge any short wave development.

However a quick look though the ENS shows roughly 70/30 split in favour some cold, potentially snowy weather.

The ops run and alternative are too good to wish for re the start of the cold and the snow potential, however there are a few runs that are even better.

[Cal]

Well, well, the Parallel run clearly gives a superb southerly tracking jet in F.I. giving a cold spell right through the run with some good snow accumulations into the mix.

[TEITS]

Blimey i've never seen the AO ensembles with an index of -4!

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

NAO index of -2.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

The blocking forecasts tell the story though with blocking to our N and LP systems taking a trip to the Med.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_nh/forecast_3_nh.gif

[NorthantsSnow]

ECM not very keen, but 4 spectacular GFS runs in a row can't be ignored. UKMO looks closer to the GFS than the ECM at +144.

Better agreement at 12z? Hope so. The cruellest thing would be the ECM coming on board with the GFS at the same time as the GFS backs away. I've seen that happen a few times.

Overall, still a lot of uncertainty. I wouldn't say chances of a cold easterly followed by a cold Nly/NEly have increased or decreased today, probably still 50/50. But we need to see a better ECM run either tonight or tomorrow.

[phil nw.]

How good is the GEM model though, it hardly ever gets a mention on here unless we are grasping at straws.

Hi Frosty,

Here`s the link for latest model performances.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz6.gif

Canadian model seems to be up there with the others for the NH.Looks to be better than GFS at present.

Cheers,Phil

[Polar Continental]

How good is the GEM model though, it hardly ever gets a mention on here unless we are grasping at straws.

My personal model preference based on overall performance.

1 GFS

2 ECM

3 GEM

4 UKMO

5 JMA

6 NOGAPS

I rarely look at the other models.

it may be a good idea for someone to start a poll on this!

[Cecil Hogmanay Melchett]

Blimey i've never seen the AO ensembles with an index of -4!

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

NAO index of -2.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

The blocking forecasts tell the story though with blocking to our N and LP systems taking a trip to the Med.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_nh/forecast_3_nh.gif

only trouble is Dave they are forecasted to bounce right back up very abruptly.

El nino regions 3.4 now at 1.84 apparently . That is very strong.

[TEITS]

My last post until later.

Remember when I first started following this potential cold spell I commented on the Iceland SLP ensembles and how the mean was increasing. Well at first the mean was around 1010mb but has now risen to 1025mb on the 06Z.

http://charts.netweather.tv/ensimages/ens.20091208/06/prmslReyjavic.png

The 850hpa mean for Cambs stands at -7C.

http://charts.netweather.tv/ensimages/ens.20091208/06/t850Cambridgeshire.png

If the runs continue with a similiar output then I expect that mean will drop to -10C!

[NorthantsSnow]

Well, well, the Parallel run clearly gives a superb southerly tracking jet in F.I. giving a cold spell right through the run with some good snow accumulations into the mix.

I must say this parallel run seems heavily biased towards cold solutions! I could see this "new GFS" breaking more hearts than the current one when it arrives.

[Megamoonflake]

Ensembles suggesting a bitter 10 day cold spell! http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=306&y=141&ville=Londres

Bring it on

Edited December 8, 2009 by Megamoonflake

[kold weather]

ECM still going for a high to stick out just to our west, something I remember GP saying was highly unlikely. Its still an ok run in other circumstances but compared to what we could have, its pretty poor.

Saying that its got a completely different jet stream oreintation as soon as 96hrs to all the other models with a far flabby PV to our NW, the GFS makes less of this featue.

Still for now the UKMO is on the GFS side, granted it is about 24hrs slower then the GFS and there is still agreement with other models which is key...however the 12z runs really are going to be so vital and until the models decide on the situation of the jet/PV between 96hrs and 144hrs we are not going to get any closer.

Knowing the UK, the ECM will have spotted a new trend...

[Cecil Hogmanay Melchett]

Those NAO/AO projections Dve posted are actually of concern to me!!

The negative AO/NAO looks according to those charts to be VERY shortlived,i wonder if ecm has progged this

into its output because we see heights falling very quickly to the North on that 0z run.

[Frosty.]

Hi Frosty,

Here`s the link for latest model performances.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz6.gif

Canadian model seems to be up there with the others for the NH.Looks to be better than GFS at present.

Cheers,Phil

Thank you phil

I must admit to not paying much attention to the canadian model before but I will from now on. There are plenty of positives so far today but now all eyes on the meto update.

My personal model preference based on overall performance.

1 GFS

2 ECM

3 GEM

4 UKMO

5 JMA

6 NOGAPS

I rarely look at the other models.

it may be a good idea for someone to start a poll on this!

NOGAPS is where I thought it would be

The GFS 06z is not as good for the Northerly which follows the E'ly, everything looks a bit further east so it's not so good news for more northern parts of scotland but very good news elsewhere, the 00z gfs was just about perfection though

[Eugene]

http://www.wetterzentrale.de/pics/MT8_London_ens.png

OMG GFS 06Z wasn't even the coldest run with a few almost hitting -15C hPa, astounding

LOL@ those moaning about the warmer hump in the more reliable timeframe with an anticyclone over us 850's aloft are meaningless at the surface and translate to the same temps as before so no downgrade, oh dear back to weather school for them :lol:

[MR EXTREMES]

Well, well, the Parallel run clearly gives a superb southerly tracking jet in F.I. giving a cold spell right through the run with some good snow accumulations into the mix.

now this is absolutely stunning:o

[kold weather]

Either way we are going to likely know one way or the other in the next 24hrs exactly how this will evolve IMO, you don't often have synoptic discord at just 96hrs on quite the scale the models are showing at the moment. The biggest concern is the ECM ens have also backed away somewhat from the cold solution...however as GP said if we get a phase 4 of the GWO soon then the ECM pattern is a total opposite to what you'd expect.

Ian, its not just the shortwaves, the whole pattern on the eCM is skewed differently to all the others as it makes a much bigger deal of the Canadian PV and slots it further east. I can see where your coming from and past experience is stopping me from getting excited at the moment thats for sure.

Edited December 8, 2009 by kold weather

[mountain shadow]

It does look as though an easterly is on the cards. I would have good confidence based on current output that the south east of England as a minimum will see cold and snow next week. The further north and west you go confidence diminishes and is based on exactly how far north west the block can get before tipping over towards scandi.

The County Down pressure ensembles show are very wide range of outcomes with a divergence occuring as little as three days away. Despite this the 850's mean is at or around -5oC from 6 days away to the end of the run.

Every run is crucial now, but if I lived in the south east i would be a happy bunny at the moment.

[snowmadchrisuk]

Either way we are going to likely know one way or the other in the next 24hrs exactly how this will evolve IMO, you don't often have synoptic discord at just 96hrs on quite the scale the models are showing at the moment. The biggest concern is the ECM ens have also backed away somewhat from the cold solution...however as GP said if we get a phase 4 of the GWO soon then the ECM pattern is a total opposite to what you'd expect.

I agree with you the synoptic's won't change , but as to weather we get deep cold or not all in all depends on the shape and position of the high . I doubt this will be sorted out tomorrow. It is still a week before we are even going to get into -5 850's .

Edited December 8, 2009 by snowmadchrisuk

[Frosty.]

Regardless of the shortwaves issue on the ECM, I’m afraid I don’t buy the GFS synoptics that produce the easterly. It’s typical of the model to be over aggressive in developing the trigger low at this range of it’s resolution.

Talk of ignoring past disappointments is like continuing to back a horse that should win but doesn’t – there are reasons for continous failure and I think we will be picking the bones out of another sorry episode come tomorrow night.

As kevin keegan once said, I will absolutely love it if you are wrong, ok, I changed it a bit but you get the idea.

I'm sure the gfs will get it right one of these days..this might be it

Excellent ensemble support for a bitterly cold spell