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Model output discussion - 16th Nov onwards


Paul

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Posted
  • Location: Cork, Ireland.
  • Weather Preferences: Storms frost snow heatwaves
  • Location: Cork, Ireland.

As we say goodbye to that crisp Arctic air the pattern is now reverting to a more typical westerly type as the Atlantic high flattens out later in the week.

Those low heights modeled to sit over Greenland is never a great sign if looking for prolonged cold but with the jet running across our latitude we will sit on the cold side from time to time.

What we don't want is to see the Atlantic high becoming a Euro high such as shown in later frames as this will mean milder air becoming more dominant from the sw as the jet realignes to a more sw-ne angle.

Gfs 12z and the southwest/northeast jet stream realignment would seem to suggest the possibility of some copious rainfall totals. Not to mention the possible rapid formation of some secondary lows. Doesn't look benign by any means.  

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Posted
  • Location: Loughmacrory, Co Tyrone. 170m asl
  • Weather Preferences: snow
  • Location: Loughmacrory, Co Tyrone. 170m asl

Cheers Yarmy and Phil, that'll keep me going for the foreseeable future!

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Models showing a very typical outlook for the time of year - text book atlantic dominance with frontal attacks easing easily across the country and fluctuations in temps between mild and cool thanks to quick exchanges between polar maritime and tropical maritime air.

 

On average the next 3 weeks are the most westerly of the year, blocked scenarios always have a hard time in influencing things...

 

For me its always a grin and bear it time of year, when I least expect 'colder' than normal conditions to surface.. such conditions are always a bonus.

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire

I don't know why but I do like the look of the GFS 18z. Oh, wait a minute :) I do know why I like it. It reminds me of a much more amplified pacific jet in the 8 - 10 day range as predicted by Glacier Point last night :) I know I keep saying it but mid December looks very interesting. I also think Fergie's comments earlier tonight are very enlightning for the coldies out there.

Edited by blizzard81
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Posted
  • Location: Head in the clouds somewhere near Avondale, West Auckland
  • Weather Preferences: Storm-force northeasterly(with a high tide!).Blizzards.Sunny summer
  • Location: Head in the clouds somewhere near Avondale, West Auckland

Typical November fare, some hopeful signs of a cold snap or two in the offing. I feel we are in a seasonal transition period that has disrupted the pattern that held for several months but I don't think it's a radical change of pattern. I think we could see a return to northern blocking within 3 weeks.

 

On the other hand the November pattern bore some similarities to last year but locally and certainly hemispherically I think there are enough differences to be hopeful of a different winter at least, and if you want cold the overall signs are good in my view. Last year never convinced me for cold patterns to emerge, regardless of the drivers and downstream indicators, the mid-lat blocking pattern was consistent and consistent patterns usually don't change quick. The current and recent patterns have not been there long enough and have looked transitional.

 

The cold lobe that shifted en-masse out of Greenland this week reminded me of episodes at the start of very mild winters in the late 80s. But those episodes ended up with very cold anticyclones drifting from these parts into central and south Europe and setting up intense blocking

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Posted
  • Location: Boar's Hill, Oxon
  • Weather Preferences: Interesting weather
  • Location: Boar's Hill, Oxon

Lorenzo, is anyone still trying to make use of the OPI, and if not, did anyone work out what was being used to calculate it, and if so, is it possible last year was a blip for UK/Europe and maybe this year it would have more usefulness? I couldn't find anything recent by searching online myself, but maybe someone knows?

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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

Lorenzo, is anyone still trying to make use of the OPI, and if not, did anyone work out what was being used to calculate it, and if so, is it possible last year was a blip for UK/Europe and maybe this year it would have more usefulness? I couldn't find anything recent by searching online myself, but maybe someone knows?

 

For OPI,I do not know what Riccardo and team are doing now, I do know there is a stratosphere monitoring thread at meteotoscana.it so ther is something of a legacy there.

 

Genuinely I think they were onto something as the timing of the wave activity was excellent, where they missed out was how it impacted the vortex. Naturally something we have learned from are looking at in hi -def so to speak this season, hence the concentration on the Siberian high among other factors.

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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

those who are worrying about the output from the models should take some comfort from this-

November 22nd 2015 (today)

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November 22nd 1962

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it could happen....

 

This made me think of a great question - you said It could happen, am wondering - How did it happen?

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

This made me think of a great question - you said It could happen, am wondering - How did it happen?

well, i dont know but when you look at the archive charts in the lead up to it (probably the most famous winter in living memory), it seems to pop up out of nowhere. the weather seemed to change from standard zonal to epic winter very quickly. the notable point was the strong siberian high at the same timeframe it is showing today. it would be interesting to look back at the ENSO state and solar output etc back then. i might do so when i get time.

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

The reality is that blocking and cold often pop up when the models have been forecasting zonal out to next winter - predicting winter cold for our little Island surrounded by warm waters is even more difficult.

 

ECM 12z ensembles have some interest in that there are now some cold runs showing though they are very much in the minority. Still, small acorns and all that...

 

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

GFS 12z first showed an Arctic high and it is back on the 00z and more impressively on the GEM - remains to be seen if it will be of any use to us.

 

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Posted
  • Location: st albans
  • Location: st albans

GFS 12z first showed an Arctic high and it is back on the 00z and more impressively on the GEM - remains to be seen if it will be of any use to us.

 

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So early in the season? Of course it will mucka. patience peeps. The coldies have been both lucky and unlucky over the past half dozen winters. we have a hybrid type pattern on the week 2 models at the moment. Typical Nino responses in parts of the NH and not in others. given that, one would perhaps move against the analogues. however, I know weatherbell are very comfortable with where the current modelling and their winter forecast are going and they are very keen on using analogues.

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Posted
  • Location: Carlisle, Cumbria
  • Weather Preferences: Atlantic storms, severe gales, blowing snow and frost :)
  • Location: Carlisle, Cumbria

Was hoping to wake up and find this idea had been dropped but no, it appears to be worse this morning with a big fat high centred over Spain/Biscay giving us SW'lys, that would be a terrible start to winter!  :help:

 

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

If I remember correctly the models did the same thing before settling on what we got.  There were some beauties for cold then they showed a flattening then upgraded again nearer to the time.  I think the flattening shown on last couple of runs will amplify a bit more again...but I do see that theme happening towards end of 1st week of Dec.  Nice to see GFS maintain the pM air flooding the UK end of the month.

 

BFTP 

Possible signs that happening again, the runs reently erred too mild and flat for me.  Small steps towards more seasonal set up

 

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BFTP

Edited by BLAST FROM THE PAST
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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

We are still on track for a colder and windy Pm blast next weekend with gale force wly / nwly winds, wintry showers and snow on northern hills according to the Ecm 00z. :)

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Edited by Frosty.
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Posted
  • Location: Camborne
  • Location: Camborne

Both the gfs and ecm ops runs tell a familiar story this morning which is a westerly air flow and the usual interplay between the Pm and Tm airmassess resulting in a N/S split over the UK  with much of the wintry stuff confined to the north  A pretty mobile scenario. So at the grave risk of bringing disapprobation down on my head what do the GEFS anomalies say? Much as they have for a few days,

 

Low pressure Siberia/Alaska and Greenland. Ridging Alaska and Russia and a suspicion to the S/SE of the UK. Which broadly speaking translates to the surface outlook as noted above.

 

 

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Posted
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.
  • Weather Preferences: Winter synoptics.Hot summers.
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl.

We are still on track for a colder and windy Pm blast next weekend with gale force wly / nwly winds, wintry showers and snow on northern hills according to the Ecm 00z. :)

A scenario reinforced by the UKMO today

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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

A scenario reinforced by the UKMO today

And the GEM...the gfs 00z mild high pressure build from the south early next week doesn't have much if any support from the other models i'm pleased to say. :D

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

Looking decidely average for the time being, with a strong jet meandering between NW/SW influenced weather. Windy with heavy rain at times, though also with drier interludes. Perhaps a slight bias towards more milder than colder weather, though nothing much in it.

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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

Is the GFS running behind this morning? Could have sworn it should start rolling out at 09.30.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

npsh500.pngnpsh500.216.png

 

I'm not keen on the GFS 00z det. run (left), as it drives low pressure from the Atlantic right through Scandinavia and on toward Siberia, which interferes with the Siberian High and interrupts the wave breaking process.

 

The ECM 00z det. run, on the other hand (right) stalls out that low west of Siberia as the jet pattern becomes more meridional. This actually enhances the Siberian High's efforts ridging toward the pole and leads to a fascinating +240 chart:

 

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Just look at that jet meandering (as implied from 500 mb contours), and that 1036 mb ridge from Siberia is causing the polar vortex some real trouble.

 

 

Of course, I'm looking outside the reliable again (as the conditions later this coming week are being well covered by other members), so the usual caveats apply. Given GFS's over-progressive tendencies and ECM's habit of getting carried away with jet meridionality and pattern amplification, a halfway house is, as usual, the safest bet when considering det. output in isolation.

 

 

The ridge from Siberia is impressive on the +240 ECM 00z ensemble mean though, at just over 1025 mb peak, which lends good support to the det. run. The spreads do reveal enough uncertainty to incorporate something not far from GFS, but I imagine there are few if any runs that are quite as progressive (only someone with paid access can know the true story, of course).

 

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Worth noting the lack of Azores High displacement into Europe, too. It's a bit more like a CP El Nino so perhaps a reflection of the hybrid El Nino characteristics we see in the Pacific at the moment, whereas a Euro High is more a characteristic of a 'classic' (EP) type event. This is, however, an idea that's just popped into my head and requires scientific verification!

Edited by Singularity
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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

A mild second half to the week looking likely, with temps back into double figures. But, 06z GFS indicating a sharp cold front moving east later this Friday, with a wedge of sub -5C T850s / sub 528dam air sweeping across most parts Friday night into Saturday, so another cold Saturday possibly on the way. Though as the air is Pm rather than Am, it maybe more of a struggle to get snow falling to lower levels on the back edge of the rain in central and southern areas, as the cold/dry air to undercut trails too far behind. Wintry showers following the cold front likely to bring snow in the north though, particularly over the hills. 

 

I can see this being the same rinse and repeat pattern as we head into early December too, a strong and progressive flow pattern over the Atlantic back across N America and the north Pacific, typical of El Nino climo, though with some transient troughs and ridges pushing east which will allow brief cold shots across the UK in between milder interludes. Unless we knock the strengthening trop vortex from its perch over Greenland then assume this pattern will continue. 

Edited by Nick F
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