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WInter Model Output Discussion 12z- 28/01/2013


phil nw.

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Posted
  • Location: Keyingham, East Yorkshire
  • Weather Preferences: Spanish plumes, hot and sunny with thunderstorms
  • Location: Keyingham, East Yorkshire

UKMO following GFS by rising pressure this weekend over the UK nice to see some decent agreement at the t144 range

UW144-21.GIF?28-17

gfs-0-144.png?12

A very welcome sight Gavin. In the latter stages the GFS 12z turns more unsettled but rainfall looks to be showery in nature and restricted to the northern half of the UK.

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Posted
  • Location: st albans
  • Location: st albans

Just a brief comment but this repeated 'tumbling' mid atlantic high is something we see modelled every winter and i dont recall it ever verifying for more than 1 or maybe 2 cycles at most. it will either evolve to a very cold or mobile scenario and given the week 2 anomolys at the moment i know where my dosh is going.

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

So now we seem to have three options; all of which point towards increasingly northerly-dominated scenarios: a mid-Atlantic anticyclone that tends extend a ridge northwards possibly extending to Greenland; a slightly less-likely (IMO) Arctic anticyclone building southwards; a quasi-stationary, misplaced Azores High, with the ever-present threat of intermittent attacks from the N or NW...

So I wouldn't be writing-off winter just yet...good.gif

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

Just a brief comment but this repeated 'tumbling' mid atlantic high is something we see modelled every winter and i dont recall it ever verifying for more than 1 or maybe 2 cycles at most. it will either evolve to a very cold or mobile scenario and given the week 2 anomolys at the moment i know where my dosh is going.

... and just to put this into pictorial expression, those two options are for a fall in angular momentum or for continued cycling back and forth in the global wind oscillation at high angular momentum values.

post-2478-0-80666500-1359392577_thumb.jp

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

... and just to put this into pictorial expression, those two options are for a fall in angular momentum or for continued cycling back and forth in the global wind oscillation at high angular momentum values.

post-2478-0-80666500-1359392577_thumb.jp

Taking your quote from previous thread...

''The real insight here is this. Longer range modelling failed to pick this amplification. There is more to come as angular momentum is sky high at the moment and we're likely to see the GWO flick through phases 5-6-7-8 and back again. That builds further amplification into the system, so temperatures 3-4C below normal as a starting point''

I'm guessing you don't foresee the 'winter over' route.

Edited by CreweCold
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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

Indeed CC. Taking Joe Bs theory from 2009/10, increased angular momentum (El Nino type) during a cold PDO phase (low angular momentum) is a recipe for cold outbreaks in the middle latitudes. What we have in front of us is a microcosm of that theory.

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Posted
  • Location: st albans
  • Location: st albans

Indeed CC. Taking Joe Bs theory from 2009/10, increased angular momentum (El Nino type) during a cold PDO phase (low angular momentum) is a recipe for cold outbreaks in the middle latitudes. What we have in front of us is a microcosm of that theory.

but to clarify that not all the mid latitudes can be cold at the same time ! i think we got quite lucky earlier in the month given the generally weak blocking signal to our north that divrted the jet nw/se. can we be lucky twice in two months after being 'unlucky' in mid december?

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

Game on...

Shame its at 336!

h500slp.png

Timing looks about ok CC for the main event, maybe more of a retrograde taking place by then with cooler/colder seeping over us as pattern amplifies next weekend . Watch for HP to our ENE to back west and not GHP to start?

BFTP

Edited by BLAST FROM THE PAST
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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Certainly the ens are trending colder next week with the mean falling to around -4 to -5C 850hPa for London

http://modeles.meteo...ndres&runpara=0

The GFS/UKMO.12z runs both model the Euro trough digging deep into Europe which brings the first incursion of deeper cold at aaround T120hrs.

http://modeles.meteo...nh-1-120.png?12

The mean Ht anomols. show the AH gradually edging west with some ridging north after day 10-00z NAEF`s

http://176.31.229.22...-0-0-300.png?12

showing a blocked Atlantic and a developing cold pattern for the UK around the same time frame as 12z GFS Op run.

It` looks more a gradual change rather than a quick switch but it is a consistent trend in recent runs.

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

Modelling seems to be following a very similar path to early December: a deepening Euro trough, shortwaves cutting NW-SE across the UK.

I wonder how soon before models begin to develop heights to the NE, and what if any will the fate of any attempted easterly ? Will it share the same fate of the mid December one ?

The sun has been spokily quiet of late.

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I think those chasing the cold still need to point out that 90% of the output is average ( born out of milder & cooler periods)

there is no cold within 10 days. The GFS is still trying to get cold at day 15, meanwhile the days tick by...

& just above for GP- the signals maybe thus- ie AAM state etc, however your posts seem to be getting shorter & shorter with teleconnection patterns that are lower & lower in direct correlation to the UK itself-

Maybe that in itself correlates to the state of the output V your postings over the last week around reload of cold- IE- SSW blocking pattern reloading, then GWO pattern driving amplification & now AAM driving mid lattitude cold.

At some point maybe someone should chip up with the 'persistence' factor of this winter... persistence is a royal PITA ( Pain in the A) however this years persistence has defied the teleconnective signals but the removal of any greenland blocking.

Without that the chance of anything sustainedfrom the North or EAST of North is remote.....

S

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

I know lots are looking for cold but lets get one thing out the way

The longer the Azores stays by the chances of a sustained cold spell are low this is the truth with the Azores so close by it can easily drift over the UK as its shown to do this weekend

h500slp.png

Now we do see the odd colder snap I think is best to describe it based on the 12z run but again the Azores is so close to the UK it quickly pushes back in

h500slp.png

h500slp.png

Now I'm not saying we wont see colder snaps from time to time but any sustained cold in the next 10 days looks very slim and it will remain like that until the Azores high either gets pushed well out into the Atlantic and allows a northerly flow of some sort to set up or it heads back south like it was for the last cold spell until that happens winter will remain on hold

Edited by Gavin.
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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

Modelling seems to be following a very similar path to early December: a deepening Euro trough, shortwaves cutting NW-SE across the UK.

I wonder how soon before models begin to develop heights to the NE, and what if any will the fate of any attempted easterly ? Will it share the same fate of the mid December one ?

The sun has been spokily quiet of late.

I guess we see how it plays out. Some on here don't seem convinced.

The ensembles look good.

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Posted
  • Location: st albans
  • Location: st albans

Modelling seems to be following a very similar path to early December: a deepening Euro trough, shortwaves cutting NW-SE across the UK.

I wonder how soon before models begin to develop heights to the NE, and what if any will the fate of any attempted easterly ? Will it share the same fate of the mid December one ?

The sun has been spokily quiet of late.

Cue 'that ecm' !!!

on a serious note, the ecm modelling pre the spell just ended was rife with a southerly undercutting jet in fi on the ops. not so far away with the verified pattern given the general poor nwp at the time. we are yet to see the model playing with a proper deep cold scenario but now that any prospective cold is coming within a 10 day timeframe, we should expect some stellar fi's from the model over the next few days.

and dont worry about steve's negativity. the more he posts thus, the better the nwp gets !! (actually, its not exactly negative but fairly realistic given the precise modelling within a reliable timeframe). that assumes the models are right.

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

& just above for GP- the signals maybe thus- ie AAM state etc, however your posts seem to be getting shorter & shorter with teleconnection patterns that are lower & lower in direct correlation to the UK itself-

S

Quality not quantity.

What has post length got to do with the price of fish?

I've seen some lengthy posts on this forum in my time spouting nowt but a load of half baked claptrap.

Edited by CreweCold
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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

The ensembles continue to look a lot drier than of later as we move through the first 13 days of February which will be welcomed by many hit by flooding I'm sure

MT8_London_ens.png?6767676767

MT8_Aberdeen_ens.png?6767676767

Edited by Gavin.
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Posted
  • Location: Sunderland
  • Weather Preferences: cold
  • Location: Sunderland

EC 0z analysis-

NAtlantic_2013012800_thgt850_216.png

-25c t850s into the US via a northerly at D9.

Europe_2013012712_thgt850_240.png

Yesterday's 12z analysis- comparison will be the D9 from the upcoming output- here's hoping we manage a stalled, intensified and most importantly amplified trough... SSE-NNW would do nicely- see if the EC can provide any notable retrogression...

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20

You are relentlessly negative.

More like realistic - nothing in the NWP points to a "big freeze". Of course, things can change but at the moment slightly below average temperatures are likely in the medium term as reflected in the Met Office's 30 day forecast.

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

More like realistic - nothing in the NWP points to a "big freeze". Of course, things can change but at the moment slightly below average temperatures are likely in the medium term as reflected in the Met Office's 30 day forecast.

I don't think anyone has predicted the biggest freeze up since '47 though have they. A cold spell, yes, but who mentioned a 'big freeze'. I think most people would be content with some falling snow and cold days?.........On second thoughts maybe not!

I don't see where all this fixation on bone shakingly cold has come from? Surely people would settle, would be happy, with some snow producing synoptics?

Oh damn...look, I'm repeating myself now! Nurse!

Edited by CreweCold
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Posted
  • Location: Near Keele, North Staffs
  • Location: Near Keele, North Staffs

The models are in agreement for a slightly displaced Azores High into the mid-Atlantic, what then becomes important is the timing and track of Lows off the Eastern seaboard, if we can amplification over the US, then we should see heights rise towards Greenland and then as long as pressure stays low over Europe that pattern can repeat.

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

I think most of us accept that the real cold is not within 10 days-unless -4C uppers qualify.

The consistent ens outputs just beyond that period wrt pattern evolution are trending for a colder setup-see my post above(Post 35).

Unless the medium term ens switch away from that then i believe there`s enough to be optimistic for coldies.

Edited by phil nw.
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Posted
  • Location: Wildwood, Stafford 104m asl
  • Weather Preferences: obviously snow!
  • Location: Wildwood, Stafford 104m asl

ECMWF 120 looks a bit like the legendary 19th Nov 1996, only with much less cold uppers, so hope it dosent come off

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

The track of this little Low pressure system on Friday is still open to much change, could potentially be a potent feature, and not your average Atlantic Low. One to watch, not for the snow but for the unusualness of the synoptics and the risk of some high winds and heavy rain.

Recm961.gif

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

Big differences between the ECM and UKMO in terms of the weekend. The ECM develops that shortwave into a deep feature with a strong ne flow as it clears. It looks cold enough for some snow as that clears away and snow showers into the east and se afterwards at 120hrs.

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