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General Model Output Discussion Tuesday December 22Nd:


Methuselah

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Completely off topic i know, but talking of one of the south west posters - what's happened to Jemtom this winter?- last year he was a very frequent poster. Anyone know?

No idea. Maybe the lack of mild charts has put him off posting.

Back to the models and its fastinating looking at +120. How much cold air will be moved S? What track will the next LP take? Will it engage the cold air to the N and bring colder air as it tracks E?

So many questions that cannot be answered yet!

Edited by THE EYE IN THE SKY
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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

I tell you what synoptically the 18Z is a stunner.

http://www.wetterzentrale.de/pics/Rtavn1621.png

I shall have to check the archives but im pretty sure in Dec 1978 it wasn't the first set of S,ly tracking LPs that bought the blizzards but the next one.

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Posted
  • Location: Mid Welsh/English Border
  • Weather Preferences: Snow! Exciting weather!
  • Location: Mid Welsh/English Border

18hr GFS continues to bring in the cold around the 144hrs - a lot quicker than any before :lol:

Nice Greenland block rebuilding!!!

Edited by stratty
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Guest North Sea Snow Convection

I think the point is that if you look at the major models for the same timeframe there is not a lot of difference to the smaller model output trying to suggest a change to milder weather, so it is not as if there is much disagreement in the shorter term with the lesser models that apparently are showing a change to the said milder weather.

The extent of any milder incursion just after xmas has definitely been quite significantly scaled down today on a countrywide basis - and there is good agreement (again at this time of writing) for the cold air to stay very close by and increasingly looking at the present time to extend back across the whole country just before the New Year.

Tomorrow is another day - but I don't think anyone is ignoring the complete range of possibilities at all. I posted myself yesterday about the chance of the jet stream moving further north in accordance with some model output - especially the ECM. Again, at the time of writing here, that suggestion has quite markedly decreased and signals look in favour of a cold outlook once more

Edit :GFS 18z consolidates the cold further. The models are having to keep backtracking on the northern extent of any milder air into the UK. The mild air keeps being put back and downgraded.

Edited by North Sea Snow Convection
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Time to get the shovels out! Very close here to some major snowfall for areas on the northern flank of these lows but it's just too early to get excited, still concerns here about any possible phasing of the low to the north and the low to the sw, basically if you want a cold and snowy outlook you want these to remain separate systems, this run does look great but there are a few moments when you could end up with something like the gme!

It could still eventually reload to cold but would take alot longer, so in a nutshell almost within touching distance of some synoptics that would blow even larger teapot era talk into the stratosphere! but still a few hurdles to overcome.

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Posted
  • Location: G.Manchester
  • Location: G.Manchester

Lets just keep things in perspective, accept others view are valid even if they don't fit our own desires and hope that the 18GFS does not trend towards GEM/GME.

The GEM and GME are renowned for being pretty poor. Infact I've never seen them set any trends, just follow on from the GFS and ECM. Why you suddenly start using the least reliable charts to prove a rather baseless point is beyond me....

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Posted
  • Location: G.Manchester
  • Location: G.Manchester

I tell you what synoptically the 18Z is a stunner.

http://www.wetterzentrale.de/pics/Rtavn1621.png

I shall have to check the archives but im pretty sure in Dec 1978 it wasn't the first set of S,ly tracking LPs that bought the blizzards but the next one.

Yep good point.

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Posted
  • Location: Peterborough, Cambridgeshire
  • Weather Preferences: Thunderstorms and snow
  • Location: Peterborough, Cambridgeshire

LOL - http://charts.netweather.tv/gfsimages/gfs.20091222/18/312/h850t850eu.png

FI of this run redefines "Cold" Zonality - every depression brings with it blizzards beneath a persistent Greenland High.

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Posted
  • Location: Ware, Herts
  • Location: Ware, Herts

This run is fantastic; cold never really leaves the UK and a long, snowy winter for much of Scotland looks to be underway. After a breif mild spell over the southern UK, it looks likely now that colder air will push down from the north starting as early as this Sunday.

The interesting part is the place where this cold air meets the mild, wet air from the south. GFS shows a band of heavy precip over the far south of the UK, and as the cold air undercuts and the uppers become colder, there's the potential for a lot of snowfall across the south by next Tuesday.

I know it's a week off, but the GFS is adamant such a situation will occur.

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Posted
  • Location: Cambridge (term time) and Bonn, Germany 170m (holidays)
  • Location: Cambridge (term time) and Bonn, Germany 170m (holidays)

http://www.wetterzentrale.de/pics/Rtavn3001.png

This must be one of the most exceptional charts the GFS has ever produced!

Iceland is freezing with snow showers, Scandanavia is frigid and a huge snowstorm sits over the UK, the Low Countries, Germany and the Alps.

We can but dream :(

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Posted
  • Location: st albans
  • Location: st albans

The GEM and GME are renowned for being pretty poor. Infact I've never seen them set any trends, just follow on from the GFS and ECM. Why you suddenly start using the least reliable charts to prove a rather baseless point is beyond me....

GEM has proved itself a very strong model since its upgrade earlier in the year. it often verifies infront of GFS. i find it a pretty decent model for pinning down a change within T180 which GFS has sniffed at but forgotten about.

by the way, anyone notice the repeating trend in fi of the polar low diving down to nw scotland leading to a west based -NAO : i'd take another 2 months of this pattern.

Edited by JACKONE
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Posted
  • Location: Cambourne Cambridge 70M ASL
  • Weather Preferences: Blizzards,Hot Thundery nights.
  • Location: Cambourne Cambridge 70M ASL

This run is fantastic; cold never really leaves the UK and a long, snowy winter for much of Scotland looks to be underway. After a breif mild spell over the southern UK, it looks likely now that colder air will push down from the north starting as early as this Sunday.

The interesting part is the place where this cold air meets the mild, wet air from the south. GFS shows a band of heavy precip over the far south of the UK, and as the cold air undercuts and the uppers become colder, there's the potential for a lot of snowfall across the south by next Tuesday.

I know it's a week off, but the GFS is adamant such a situation will occur.

Yes good temperature difference between the 2 airmasses,and lots of moisture= very heavy snow

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Posted
  • Location: High Wycombe, Bucks
  • Location: High Wycombe, Bucks

http://www.wetterzen...s/Rtavn3001.png

This must be one of the most exceptional charts the GFS has ever produced!

Iceland is freezing with snow showers, Scandanavia is frigid and a huge snowstorm sits over the UK, the Low Countries, Germany and the Alps.

We can but dream :(

:( 980mb Azores Low anybody, with 1055mb Greenland High? Can we bank this run! :lol:

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

[And so the upgrades continue to gather momentum, a comment earlier from worzel about the charts just being full of potential is very true but, in the build up to the current cold spell there was similar potential and look what happened. It can happen again and this 18z run is stunning with most of the uk not even becoming less cold before the reinforcements arrive from the north or northeast with a sustained attack of Arctic air beginning during the weekend and continuing all of next week, quite incredible synoptics but I have a feeling the gfs has turbo charged the cold on this run and the reality won't be quite as extreme but we shall see...it looks odds on for cold to continue and intensify during the next week after a less cold interlude in the far south & southwest. This run is so extreme it would lead to widespread severe blizzards which would dwarf what most of the uk has seen so far.

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

I banked after the second blizzard.

Don't usually comment on individual runs, but what a stunner. People might get the hang of driving in the snow with all that practice.

On the more serious side, a consistent enough theme showing up with ridging in the Atlantic rebooting our Greenland ridge.

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A bit chilly to bring in the new year!

h850t850eu.png

Seriously though, these charts over the past few weeks are ones i hoped for but never thought i would see. Before last winter the best we could usually hope for was a 24hour northerly toppler. Now we have around 10 days of bitter cold and heavy snow, with a fair chance of more being on the way after this 'mild' interlude. Enjoy the output, we may never see the likes of this again, or it could be the start of the new even larger teapot!

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Speaking of 1978/79 but didn't the E coast of the USA suffer dreadful blizzards like they have done recently. The reason im asking is the 18Z GFS is very similiar to that period.

Back to the 18Z and like Nick S says you would certainly need a shovel. Now if this was to verify the track of the LP is so important. You want to the track of the LP to be far enough N to bring the precip but you don't want it too far N otherwise your on the wrong side. Having said this it will always turn colder as the LP clears to the E.

Just checked 1978 and I was right.

26th Dec.

http://www.wetterzentrale.de/archive/ra/1978/Rrea00119781226.gif

31st Dec.

http://www.wetterzentrale.de/archive/ra/1978/Rrea00119781231.gif

Now im not daring to suggest this will happen but crikey these models have upgraded compared to a few days ago.

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Posted
  • Location: Melbourne, Victoria
  • Location: Melbourne, Victoria

LOL - http://charts.netweather.tv/gfsimages/gfs.20091222/18/312/h850t850eu.png

FI of this run redefines "Cold" Zonality - every depression brings with it blizzards beneath a persistent Greenland High.

Plus, to the North of us, extreme mid winter cold is developing !

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

GFS 18Z has a similar distribution of precipitation on Christmas Eve as the 12Z, but introduces a slack easterly flow, meaning that coastal areas of north-east England may be pushed to the wrong side of marginal, initiating a thaw. Inland, it should still be snow over northern England and a marginal mix over the Midlands.

The latter part of the run verifies as such because the low pressure to the S is projected further south than on earlier runs, keeping the British Isles on the poleward side of the PFJ and continuing the theme of cold Arctic regimes with sunshine and snow showers. It is only one of a range of possibilities at this range, but one which I feel has a fair chance of verifying, though it's unlikely to sustain for quite as long as the 18Z shows (IMHO).

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

Speaking of 1978/79 but didn't the E coast of the USA suffer dreadful blizzards like they have done recently. The reason im asking is the 18Z GFS is very similiar to that period.

Feb 1978 not Jan/Feb 1979

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Posted
  • Location: leeds
  • Location: leeds

Speaking of 1978/79 but didn't the E coast of the USA suffer dreadful blizzards like they have done recently. The reason im asking is the 18Z GFS is very similiar to that period.

Back to the 18Z and like Nick S says you would certainly need a shovel. Now if this was to verify the track of the LP is so important. You want to the track of the LP to be far enough N to bring the precip but you don't want it too far N otherwise your on the wrong side. Having said this it will always turn colder as the LP clears to the E.

Just checked 1978 and I was right.

26th Dec.

http://www.wetterzen...00119781226.gif

31st Dec.

http://www.wetterzen...00119781231.gif

Now im not daring to suggest this will happen but crikey these models have upgraded compared to a few days ago.

good luck with the snow, it looks like we would stay mostly dry compared to the souths massive dumpings, wouldn't i?closedeyes.gif

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Posted
  • Location: Chapmanslade, Wiltshire + Charente, France
  • Location: Chapmanslade, Wiltshire + Charente, France

It does seem that the colder synoptics are actually happening rather than staying in FI never to occur in reality.

I'd have to say the snowfall so far has been localised and moderate - if we get a proper frontal snow event which we are being tempted by in the models many people will simply not know what to do. Even with 'Global warming' a severe snowstorm event will occur, just not very often. This winter does have a real feeling of 81/82 about it.

I posted this link last week - for those that missed it ...

http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=6681&start=1

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Posted
  • Location: st albans
  • Location: st albans

good luck with the snow, it looks like we would stay mostly dry compared to the souths massive dumpings, wouldn't i?closedeyes.gif

SL - those charts are a lifetime away considering how early FI has become. as much chance of leeds being the battlefront as the south, the midlands, scotland or indeed Paris.

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