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Model Output Discussion 23/11/2012 18Z onwards


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Posted
  • Location: Pontypridd, Wales 240m asl
  • Location: Pontypridd, Wales 240m asl

marginal I know - but a little wintry entertainment certainly could be on the cards for us welshy types - tuesday/wednesday morning

gfs-2-108.png?18

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Posted
  • Location: Near Keele, North Staffs
  • Location: Near Keele, North Staffs

JS, it's not possible to say at this stage, we need more runs tomorrow. I would say we are trending away from an easterly but until there is more consistency in the NWP medium term it is impossible to determine how long anything that does come our way will last.

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Posted
  • Location: Morecambe
  • Location: Morecambe

Well the silence from the pro's is noticeable tonight

Having just seen the 18z I must say am disappointed.

On the face of it what does it show, a 2 day cold spell ?

Very fragile ground at the moment so we are and far away from 2 nights ago when we were viewing perfect synoptics.

Still I do think the models have not got this right by a country mile and things will improve tomorrow

We need to see that arctic high further south and much stronger height rises towards Greenland

What you on about JS? Those height rises are very strong but the problem we have is the blocking is not as in a favorable position as say the UKMO/GFS12Z runs hence we see the charts as they are and hence why I don't want to see the trough heading into Scandinavia.

The GFS 18Z is quite close to being the perfect run but of course, all the major players have to be in the right place for this to occur. I got criticized by some on here for being too negative to suggest if the blocking is not perfect then we may not get much in the way of cold at all!

Tomorrow runs won't be decisive but hopefully they will give a better indication what the models wants to do with that trough.

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Posted
  • Location: Liphook
  • Location: Liphook

A much better 18z run, has a far more reasliatic handling of that shortwave, as I said its pretty rare such features don't sheared and end up weakening and being absorbed into the already in situ trough.

Whilst never bitterly cold, its pretty cold throughout, probably averaging 2-3C for the first 10 days of December, which is decently below average.

Also, this is likely to be a long lasting event, no real signs of a warm-up from what I'm seeing and the longer we keep importing some sort of cold, the easier it'll be to drag in the colder 850hpa temps and the cooler the surface temps will go, which as we've seen, really helps us out in any marginal set-ups.

I think GP is right, little if any mildness before Xmas...so even if this first 7-10 days doesn't do an awful lot, its going to help cool things down further and I suspect come the 2-3rd week of December the set-up aloft will be more condusive for a stronger cold shot. Thats my call, book it!

Edited by kold weather
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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

Well the silence from the pro's is noticeable tonight

Having just seen the 18z I must say am disappointed.

On the face of it what does it show, a 2 day cold spell ?

Very fragile ground at the moment so we are and far away from 2 nights ago when we were viewing perfect synoptics.

Still I do think the models have not got this right by a country mile and things will improve tomorrow

We need to see that arctic high further south and much stronger height rises towards Greenland

slightly contradicting yourself there i think. the trends are beyond doubt now- the pro's have been calling them for days, even weeks now. the lack of comment from the "pro's" - just shows how much uncertainty there is in the details. i certainly wouldn't want to stick my neck out and make a definitive forecast right now! (not that i could!)

cold? yes. where, when and how much? nobody knows for certain...... yet....

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Posted
  • Location: st albans
  • Location: st albans

The 18z fi is a good example of how tough it will probably be to get away from a cold solution once we get past next weekend. of course we could get an evolution as per the gfs 12z op but that was so out of kilter with the anomolys that it can be ignored. someone mentioned model fatigue earlier. The 2010 spell was so consistent in its countdown that we just knew where we were going. Wondering if we can stand several weeks like this??

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Posted
  • Location: Bedford
  • Location: Bedford

Well the silence from the pro's is noticeable tonight

Having just seen the 18z I must say am disappointed.

On the face of it what does it show, a 2 day cold spell ?

Very fragile ground at the moment so we are and far away from 2 nights ago when we were viewing perfect synoptics.

Still I do think the models have not got this right by a country mile and things will improve tomorrow

We need to see that arctic high further south and much stronger height rises towards Greenland

yes agree heights around Greenland don't look as strong on this run, i don't like the look of that powerful low near Greenland at T192 but thats FI so things will change again

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Posted
  • Location: Leicestershire (hinckley)
  • Location: Leicestershire (hinckley)

The pros as you say haven't commented because as said before anything past +72 is open to quite large variations. The last 3 gfs runs have all been different. Until we start seeing consistancy there's not really much to comment on because you can guarentee itl change

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

A much better 18z after the shortwave explosion on the 12z, I'm guessing SM and Nick S will be less keen on this evolution as it's a northerly route, the important thing is to not to have shortwaves breaking thru around Iceland going forward from T192.

I'm less keen on this route as it has more chance to go wrong, take a look at a few of the ECM ensemble maps to see how it could all end in tears.

The problem here is the interaction pulling the European trough further north which could just sit there for days.

Theres no guarantee that this will eventually sink away especially if heights build too far to the nw.

If the trough was further east and south you'd have more margin for error. This isn't about me preferring a particular scenario for my neck of the woods, as it is a northerly delivers lots of snow to the Pyrenees and even a bit lower down here in the valley.

I always like cold patterns that have high margins for error, we may get there even with the ECM and GFS eventually, but I've seen too many eventualies that implode!

So I'd ask you to not start up hinting at a se bias as you have in the past when I don't even live in Sussex anymore!

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Posted
  • Location: Liphook
  • Location: Liphook

The 18z fi is a good example of how tough it will probably be to get away from a cold solution once we get past next weekend. of course we could get an evolution as per the gfs 12z op but that was so out of kilter with the anomolys that it can be ignored. someone mentioned model fatigue earlier. The 2010 spell was so consistent in its countdown that we just knew where we were going. Wondering if we can stand several weeks like this??

Spot on, providing we don't end up with the mean trough to the SW of us like the 12z GFS, its going to be very difficult to shift the SURFACE cold once in place, we'll either see what we did on the 06z this morning, a version of the 18z where we eventually get a reload from the Atlantic, or a frosty and cold HP build over our shores. The PV is on the ropes and I see NO reason why it should rebound that strongly in the near future.

Think of this one as a slow burner, and remember many great winters only had teasers at this stage, including the legendary winters...

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Posted
  • Location: Dunstable 446ft ASL
  • Weather Preferences: cold with frost & snow in winter; hot and dry in summer
  • Location: Dunstable 446ft ASL

What you on about JS? Those height rises are very strong but the problem we have is the blocking is not as in a favorable position as say the UKMO/GFS12Z runs hence we see the charts as they are and hence why I don't want to see the trough heading into Scandinavia.

The GFS 18Z is quite close to being the perfect run but of course, all the major players have to be in the right place for this to occur. I got criticized by some on here for being too negative to suggest if the blocking is not perfect then we may not get much in the way of cold at all!

Tomorrow runs won't be decisive but hopefully they will give a better indication what the models wants to do with that trough.

Agree with this and Ians comments above. Not sure we will know where we are finally going with this until Monday/Tuesday and then we will be starting to restle with the 'second phase' of cold - hopefully !
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Posted
  • Location: CARDIFF
  • Location: CARDIFF

Evening again all

quick question about the Surface Pressure charts (fax charts) at 120hrs

The 528 dam line appears to be North of UK, however it says 528 between North Wales and ireland

Is that an error or correction?

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

The 18z fi is a good example of how tough it will probably be to get away from a cold solution once we get past next weekend. of course we could get an evolution as per the gfs 12z op but that was so out of kilter with the anomolys that it can be ignored. someone mentioned model fatigue earlier. The 2010 spell was so consistent in its countdown that we just knew where we were going. Wondering if we can stand several weeks like this??

Is it still only November?It seems like we have been following this build up to the long heralded -AO/-NAO changeover for an age Nick.

In spite of the operational runs variations at quite short range we can take a lot of positives-if looking for cold- from the mean Ht 500hPa anomls in the ensembles and naef`s outputs and of course from the Stratosphere.forecasts.

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

Compared to the 12z the 18z is a good run. Surface cold never leaves the UK and there's the potential for some snow events in there.

On a seperate note, rainfall looks really excessive for some areas in the next 96 hours.

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

When is GP's forecast coming out? I am getting impatient...

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Posted
  • Location: Ribble Valley
  • Location: Ribble Valley

Compared to the 12z the 18z is a good run. Surface cold never leaves the UK and there's the potential for some snow events in there.

On a seperate note, rainfall looks really excessive for some areas in the next 96 hours.

Short term pain for long term gain, more so if the 18z comes about for locale CC.
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Posted
  • Location: Leeds (Roundhay) 135m
  • Location: Leeds (Roundhay) 135m

As others have noted, some concerning rainfall charts in the near term, not good for those areas that have already suffered from recent flooding. Already posted, but this would be particularly nasty for the north Midlands if it came to fruition.

108-777.GIF?23-18

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Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

Out of all the charts today I think the UKMO 144 has it right,

http://www.meteociel...44-21.GIF?23-18

I know it also happens to be the best for getting the coldest 850s to the UK but both ECM and GFS look to have the trough to far north, I can't seem to find anything like it in the archives. And ECM is especially odd with this boomerang high idea.

http://www.meteociel...H1-168.GIF?23-0

Of course UKMO may well join the ECMs ideas tomorrow but it wouldn't surprise me if the trough was corrected southwards over the next few runs. And instead of this "strange" northerly type set up we see more of an easterly influence again.

Edited by chris55
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Posted
  • Location: Bedworth, North Warwickshire 404ft above sea level
  • Location: Bedworth, North Warwickshire 404ft above sea level

Not a bad end to preceedings tonight????

Where's 'Cyclonic Happiness' when you need him?.............lol.......Paul??......Stop robbing them Holly Bushes!!

Rtavn3842.png

Hey GS, how's you doing? I just did my first holly wreath today as it happens lol.

Deep down I'm stupidly excited about all the models are showing, but I can understand why everyone is being so cautious, we haven't had one run the same as the other for over a week.

So, there's small wonder no-one is willing to commit to anything, but I'll say this...........everything looks and feels right for a decent snowy 'spell' not snap.

There was exactly this sort of errant wobbling going on just before the last epic winter spell of 2010/11, and IMO, so long as the back end of the model are showing everything under the sun, we don't need to worry about them, just look up to 144+, at least before there, there's a resonable amout of agreement.

The 18z is certainly a good enough in anyone's books, we'd have killed for this sort of setup 5 years ago, but I think it's a damn site more trustworthy to believe in since the synoptic shift of 2007.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Evening again all

quick question about the Surface Pressure charts (fax charts) at 120hrs

The 528 dam line appears to be North of UK, however it says 528 between North Wales and ireland

Is that an error or correction?

it is correct

a small area of 528 just ahead of the trough they have marked with the main 528 line further north-nothing wrong with it assuming the idea of the trough and a patch of colder air is correct.

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Posted
  • Location: Epsom, Surrey, 100 Meters above sea level
  • Weather Preferences: Anything Extreme
  • Location: Epsom, Surrey, 100 Meters above sea level

I would expect the lack of posting from the 'pro's' is more likely because they are unknw.gif scratching their heads trying to figure it all out.

From an IMBY perspective the 18z doesn't offer me very much at all in the way of a snow, but then again I've yet to see a single run (bar that infamous 18z run a few weeks ago).. that has.

But the prospect of having the entire UK under -5 uppers on the first day of Winter proper, it a mile away from what I was expecting at the beginning of November , I'll settle for that for now in the hope that things can progress from there.

GFS

h850t850eu.png

ECM

ecmt850.192.png

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Posted
  • Location: Bedworth, North Warwickshire 404ft above sea level
  • Location: Bedworth, North Warwickshire 404ft above sea level

As others have noted, some concerning rainfall charts in the near term, not good for those areas that have already suffered from recent flooding. Already posted, but this would be particularly nasty for the north Midlands if it came to fruition.

108-777.GIF?23-18

You can bet your life there won't be any rainfall accumulation charts showing up like that when the upper air is cold enough for snow this coming cold spell, if we did, it would be more 'epic' than even 1947!! (does this classify as a ramp?rofl.gif )
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