Model Output Discussion

[Cecil Hogmanay Melchett]

120+FAX chart has a very potent Icelandic low.I think we need to see whats in store in the morning before

convincing ourselves we are home and hosed.

http://www.meteociel.com/ukmo/fax/fax120s.gif

A few more twists and turns to come?

Nighty night!!!!

[cooling climate]

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=192&code=0&mode=0&runpara=1&carte=1

You can view the parallel run from this link.

It is actually showing the paralle run now.

[Guest North Sea Snow Convection]

Obviously there are still major hurdles to be overcome, but the idea of Cold arriving, be it inversion related or true cold is now pretty much guaranteed - the vast uncertainty relates to the potency of the cold etc.

However, if it was to evolve as shown on the 18Z Parallel, there would be dangerous amounts of snowfall from T+192, witht that trough moving down from Scandi.

Given that we are approaching the period of the year with the least amount of daylight, any snow could persist for quite some time & serious cold could be the result.

All hypothetical as of yet but it's certainly trending in the right direction. I think that if we can get enough warm upper air due north and then cut off, then there will be almost inevitably a blocking scenario with significant cold.

No doubt there will be many more ups and downs

Hi - good to see you back posting again. Nice summary earlier I just read

We have been here before many times - but how times of late has it been early Dec and a big -AO scenario in front of us??

[Snowaddict]

18Z Ensembles:

Control Run brings 850's of -5 into the SE at T+138

Another excellent ensemble mean out to T+168, with mean pressure of 1020mb - 1025mb over Iceland and cold air filtering into eastern districts.

All in all, quite simply excellent but everything is still far from resolved, so caution to be strongly advised.

Edited December 7, 2009 by Snowaddict

[cooling climate]

120+FAX chart has a very potent Icelandic low.I think we need to see whats in store in the morning before

convincing ourselves we are home and hosed.

http://www.meteociel...fax/fax120s.gif

A few more twists and turns to come?

Nighty night!!!!

That looks very similar to the GFS etc.

[Tom Montalbano]

Very good run on the whole again and quite like the 12z at times but more messy and highs rather flabby.

Has the look of Jan/Feb 1985 at times, thats the kiss of death now!

http://www.wetterzentrale.de/pics/archive/ra/1985/Rrea00119850106.gif

http://www.wetterzentrale.de/pics/archive/ra/1985/Rrea00119850107.gif

http://www.wetterzentrale.de/pics/archive/ra/1985/Rrea00119850209.gif

Its interesting to note how some of these charts look very similar to those analogue charts G.P. used in his LRF.

If you're around Stewart, you were probably not expecting to see this sort of set-up just yet but of course a lot could still go wrong.

If these sort of charts are still in the offing come the end of the week I will feel more confident of a decent cold spell. As a lot of you have stated, we've been here so many times and we seem to be far more sceptical than a few years ago, not such a bad thing!

I for one will not be convinced, right up until the last moment, almost until I see that first snowflake against the light of my nearest lamp-post.

Regards,

Tom.

[NorthantsSnow]

The parallel run is an absolutely extraordinary run, it truly is.

The operational itself is excellent as well, mind you. We have truly been spoilt by the outputs today.

[Frosty.]

If this run really does happen, very cold upper NE/E winds across an above normal warm North Sea........

.....equals one huge snow machine.

A bit like lake effect snow in the us, I think tonight's 18z is an upgrade on last night. The eastern half of the uk would be badly affected if these charts were to verify but of course they won't, with a week or slightly more still to go!

[winter watcher]

Parallel run is simply amazing in F.I. talk about re-loads !!

I am not saying that nobody is dismissing the parallel run but replying to the above comment i would not dismiss the parallel run so quickly as i have stated over the past three days it has been showing consistency run after run. This to me has been on par with the gfs.

[SP1986]

At first the operational does not bring particularly cold air at the surface into the country, cloud could be a spoiler in that sense, and although there could be inversion we dont know that just yet, these things are notoriously difficult to forecast this far out.

I'm not even going to talk about FI because it goes over the top in my opinion

The realistic outlook is one where we can be sure that a cooler pattern is on the way, an easterly or northeasterly pattern. At the moment we can't say for sure if fog or frost will occur, although in all likeliness fog will occur somewhere. I don't think we'll know of inversions until the day it happens, it's easy to assume there may be an inversion but the upper air to me is on the borderline state for inversions at least on the operational.

I think as much as the pattern dictates at the moment, thing are looking fairly optimistic from my point of view now.

Still plenty of time for it to go wrong though, and if it can, it will.

[NorthernRab]

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=0&runpara=1

NB, it's working really slowly as the whole of the NW forum has descended on meteociel...

Cheers for that Yeti, long time no speak - hope you are well!

And aye, that is one monster of a run - we can dream.

[Snowaddict]

Hi - good to see you back posting again. Nice summary earlier I just read:)

We have been here before many times - but how times of late has it been early Dec and a big -AO scenario in front of us??

Hi Tamara & thanks for the welcome back

Some of the latest NWP output is indeed spectacular!

It certainly is a very interesting setup. The cynicism amongst all is very understandable because of the amount of times that such cold spells have vanished in the space of one suite of runs. However, as you say, the background signals overwhelmingly support the evolution on this occasion.

Fingers crossed that any shortwaves that do develop don't hinder but instead aid the advection of the cold towards us!

I think that there may be multiple opportunities for cold incursions if the evolution becomes established correctly.

[bluearmy]

120+FAX chart has a very potent Icelandic low.I think we need to see whats in store in the morning before

convincing ourselves we are home and hosed.

<_<

http://www.meteociel.com/ukmo/fax/fax120s.gif

A few more twists and turns to come?

Nighty night!!!!

that shortwave is the one that brings in the cold on ECM T240 having travelled all the way around our block and set up residence n italy

[Geordiesnow]

120+FAX chart has a very potent Icelandic low.I think we need to see whats in store in the morning before

convincing ourselves we are home and hosed.

<_<

http://www.meteociel.com/ukmo/fax/fax120s.gif

A few more twists and turns to come?

Nighty night!!!!

I can't really read the FAX charts all that well but we are getting to the time where shortwaves could well indeed spoil things, let's hope not but tomorrow morning's runs will be quite important although they certainly won't decide anything as of yet. This thread tomorrow morning will either be a very jolly happy place or it will be the most depressing thread on any internet forum.

Too much talk of the FI charts which probably won't happen so if you are going to get carried away with them, make sure you take these charts as a pinch of salt.

[SMU]

120+FAX chart has a very potent Icelandic low.I think we need to see whats in store in the morning before

convincing ourselves we are home and hosed.

<_<

http://www.meteociel.com/ukmo/fax/fax120s.gif

A few more twists and turns to come?

Nighty night!!!!

That is not a bad fax- if the jet was going underneath then the flow over the isobars would be moving towards that small low, however they are moving away indicating that the jet has moved west & its becoming cut off-

Also note how the front changes direction along the occlusion indicating a inflection point!!!- come on peeps keen eyes!!!

Of course it gets picked up when the loop jet comes back south-thats the plan anyway-!!!

S

Edited December 7, 2009 by Steve Murr

[Absolute Zero]

The experienced people should be trying to work out how fantastic winter charts like these evaporate into a 6 hour toppler!

[Guest North Sea Snow Convection]

Hi Tamara & thanks for the welcome back

Some of the latest NWP output is indeed spectacular!

It certainly is a very interesting setup. The cynicism amongst all is very understandable because of the amount of times that such cold spells have vanished in the space of one suite of runs. However, as you say, the background signals overwhelmingly support the evolution on this occasion.

Fingers crossed that any shortwaves that do develop don't hinder but instead aid the advection of the cold towards us!

I think that there may be multiple opportunities for cold incursions if the evolution becomes established correctly.

I've just looked at the parallel!

If that is a fanfare for the new GFS then bring it on!!!

[Tom Montalbano]

Just had a quick look at the ensemble members from the 18z on Meteociel, there are some stonking runs in there, as well as a few dodgy ones. Its going to look pretty special in graph form, quite a few runs around -5 and some even below, I would've thought.

Heres some of the mean grabs, at certain points.

http://91.121.94.83/modeles/gens/run/gens-21-1-144.png?18

http://91.121.94.83/modeles/gens/run/gens-21-1-168.png?18

http://91.121.94.83/modeles/gens/run/gens-21-1-216.png?18

Regards,

Tom.

[swfc]

Great runs today so i guess a slight dip is on the cards tom.When does the parallel run start.Sorry take over on gfs. <_<

Edited December 7, 2009 by swfc

[damianslaw]

Some mouth watering charts modelwise today for those who love deep rooted cold and snow, however, I will remain cautious until such charts begin to show in the reliable timeframe.

Must say the upstream signals look conducive to a sustained cold period setting in from the end of this week onwards, a major player being the very negative AO which will ensure some form of very strong northern blocking is about to set in.

I'm not too concerned about the prospect of a shortwave developing to the north as I feel it would likely be a weak affair and if anything would be the trigger for the bitter arctic continental air to stream downwards, in fact its the best sceanrio I feel for developign widespread cold for the whole country and setting us up for further re-loads, better dare I say it than an easterly.

Still won't know for sure until probably Thursday whether we are on the verge of a sustained very cold and potentially snowy period or just a cold dry period, whatever way you look at it the outlook will be a settled one and far from mild, which is great in my book after all the rain we have had and very mild weather.

[weather eater]

Yet again another run that backs the earlier output, small changes in detail but nothing major, all to the good, A bit of a mess later on, GFS up to its usual habit of plonking in shortwaves where ever possible, although one thing I would say about them is they up the ante for snowfall, so not necessarily a bad thing. Next hurdle the 00z in the morning, yet again as long as these are pretty much on the mark out to 144hrs then that will be fine.

[Frosty.]

Great runs today so i guess a slight dip is on the cards tom.When does the parallel run start.Sorry take over on gfs. <_<

I'm sure the 00z will make more sober viewing, I don't see how this level of wintryness can be maintained run after run.

Edited December 7, 2009 by Frosty039

[snowmadchrisuk]

Great runs today so i guess a slight dip is on the cards tom.When does the parallel run start.Sorry take over on gfs. <_<

It takes over on December 15th , a week tomorrow.

[SMU]

I've just looked at the parallel!

If that is a fanfare for the new GFS then bring it on!!!

Last one from me

2 histoic charts from the archives- take note of the dates & what historic weather occured just days later-

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870107.gif

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850101.gif

http://www.wetterzentrale.de/archive/slp/1947/Rslp19470118.gif

Now look at this......

http://www.wetterzentrale.de/pics/Rtavn841.png

This is why we are hoping & praying this doesnt fall apart-

S

Edited December 7, 2009 by Steve Murr

[reef]

Pretty good ensembles too tonight with the majority of the ensembles now going for some sort of cold spell in the south:

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

Further north and its delayed slightly but theres better agreement. Less potent overall however:

http://www.wetterzentrale.de/pics/MT8_Aberdeen_ens.png

I have to stress though, we've been in situations where theres been 100% ensemble support at this range and its still not come to fruition. I wont be happy until its inside T+96.