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Model output discussion - heading into 2018


Paul
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Posted
  • Location: Hertfordshire
  • Location: Hertfordshire

GFS strat forecasts lend some support to the synoptics seen on the H500 charts with warming and geopotential heights from pacific and European side stretching the vortex. Of course could be gone in a couple of runs time we will see. Certainly height rises our side of the pole could be very beneficial so long as they are strong enough otherwise a euro slug may be all that's on offer.

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
8 minutes ago, Ross Andrew Hemphill said:

Not really sure why people are being a bit pessimistic after this 12z. To me, it shows various snow chances for loads of us, the closest being just 36 or so hours away. 

You have to remember that you don't need -10 850s for snow and cold, and that things may have to be milder for a while before the real cold arrives. :)

Living in Scotland at 200m asl cannot be compared with living in lowland S.E England viz. snow chances in a polar maritime flow.  

Marginality just doesn't cut it where I live - give me -15 uppers with a moisture laden easterly please!

Edited by mulzy
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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

Having not viewed the charts since Christmas Eve I would also say that things are not as bad as feared, at least from tonights run in that the Arctic profile does improve from day 5 to 10. The vortex stays in control but it's not a huge hemispheric flat as a pancake like vortex. Indeed tonight's run has a new assault by days 7/8 amplifying the pattern somewhat.

Not a great picture but it's more 1984 than 2007.

gfsnh-0-240.png?12?12

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

Whilst the search for crunchy snow and ice days continues the current pattern could be a lot worse .

At least the jet is tracking further south which will allow for some colder air at times .

Day ten looks currently where the pattern might offer something more interesting. The Euro trough and some pull back in the PV  might allow a high pressure cell to form to the ne and then it’s whether there’s enough trough disruption to the west.

 

Edited by nick sussex
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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
2 minutes ago, nick sussex said:

Whilst the search for crunchy snow and ice days continues the current pattern could be a lot worse .

At least the jet is tracking further south which will allow for some colder air at times .

Day ten looks currently where the pattern might offer something more interesting. The Euro trough and some pull back in the PV  might allow a high pressure cell to form to the ne and then it’s whether there’s enough trough disruption to the west.

 

Yes broadly speaking, the EPS and GEFS in the same ballpark at 240, mean NW'ly but within that patten, there's a signal for some more continuous snowfall via lee flows with lows clearing and not just for the North either, in fact this is what I have in mind.

 

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Posted
  • Location: uxbridge middlesex(- also Bampton oxfordshire
  • Weather Preferences: blizzard conditions. ice days
  • Location: uxbridge middlesex(- also Bampton oxfordshire

Taking gfs/ukmo/gem/jma-96hrs 12z snaps..(jma-84)..

Im alarmed myself by how content ifeel will pm flow this season?!..

There is a descript' tone of a classic winter setting up now. And as some will know the american depth of cold would usualy be non-descript for increase in trigger lows on seaboard eject' firing into the pond and aligning the jet at ourselves' while inter water warmth act to assure the moblie mild/milder regime!..

But this is of big contrast this year and pm flows are of major interest-and continue to be(perhaps more as we evolve)?

The northern hem-shape is prime for exating on-flow and us gaining-not only on intial bursts from the v-cold embeded shelf...but the notable eastern continental/russian-peninssula warmth...with our current nw/atlantic cool/cold and MLBS -on occasion' may have actualy done ourselves a favour in terms of mlb allowing colder than usual pm shots as the fridged cold steers into the US-and holding for the continuation, of the warmer heights to our east...thus; allowing disregard of higher lattitude block forming that on collapse...takes an waful lot longer to re-acheive.

So in a nutshell keep taking these suprise pm shots with perhaps' some decent snowfalls to anywhere in the uk 'given' correcting of placements...and await what looks to be possibly building for our not so bad current situ...

And yes the mjo will be a player...but all-in all....its preety promising if you take the basics into account...

I have left the ecm out as a purpose..as i'd like to see the offering..as to my point making overal....

I'll flag that after 240 12z upcoming...then i think my post and its decipher may become a lot clearer!?..

Edit:

The operationals have been the defining factor by a wide-mile this season...

So notes taken seriously run-run now...

J84-21.gif

gem-0-96.png

UW96-21.gif

gfs-0-90.png

Edited by tight isobar
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Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.
32 minutes ago, Polar Maritime said:

The GFS again showing a very mobile N/W flow with plenty waves of cold air passing over the UK bringing cool/cold sometimes wintry and windy with severe gales for some especially the North. Not looking bad at all as we head into January I don't think..

viewimage-25.thumb.png.36ffa9dc80e901143dd5c278a5d61762.pngviewimage-32.thumb.png.d996eac8f62c928b4a7b012a7317a167.pngviewimage-29.thumb.png.1597a83f8dacb5cbb8fb6a585eecc1be.png

 

Good news. Ridge/Depression/Ridge and Rain/Sleet/Snow all in the mix alongside some drier spells as we head into 2018 then. Happy with that, as I'm not one to set my targets too high. Despite my doubts, when going off to bed yesterday evening with Air Temperature at 6.5c, we even ended up with a temporary accumulation of snow in Costa Del Newbury, so who knows what might come our way soon.

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

JanuaryPhase3gt1500mb.gif

If the MJO makes it to phase 3 with reasonable amplitude, it will lend some credence to the GFS 12z idea of a Scandinavian blocking high.  The run doesn't dig the Atlantic trough sufficiently down into Europe to be a great match overall though - which is not surprising given that GEFS aren't looking keen on taking the MJO beyond phase 2 (in contrast to ECM ensembles, which are).

Quite a big IF at this time, though!

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

The end of this cold snap looks very messy and complicated for northern areas .

The big 3 have differing views at T72 hrs. The Euros bring a better chance of some snow.

Then both the ECM and GFS develop a shortwave which could run into the UK looking at the formers T96 hrs output which is similar upstream.

 

Edited by nick sussex
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

The ECM building more amplification upstream at T168hrs.

This should help drive low heights into Europe and this looks better going forward than the GFS.

Nice T192 hrs from the ECM , the following could get this room buzzing if that low to the nw can clear se and detach from low heights near Greenland .

Edited by nick sussex
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

I’m underwhelmed , three lengths clear and the ECM unseated the rider at the final hurdle .

Putting aside what it did on day 9 and 10 the upstream pattern has improved and still a chance we might see a high pressure develop to the ne.

 

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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
2 hours ago, sebastiaan1973 said:

Catacol, your comments about the MJO reminds me of this research http://onlinelibrary.wiley.com/doi/10.1002/2017GL072832/abstract

Yes - I have encountered this research before. Looking forward to winter 19/20 and 21/22 :-)

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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
1 hour ago, Singularity said:

JanuaryPhase3gt1500mb.gif

If the MJO makes it to phase 3 with reasonable amplitude, it will lend some credence to the GFS 12z idea of a Scandinavian blocking high.  The run doesn't dig the Atlantic trough sufficiently down into Europe to be a great match overall though - which is not surprising given that GEFS aren't looking keen on taking the MJO beyond phase 2 (in contrast to ECM ensembles, which are).

Quite a big IF at this time, though!

Interesting how different composite reanalysis models see it differently. The JMA composite for phase 3 in MJO amplitude >1 looks even better... if we can get there.

z500_p3_01_1mon.png

Given time lag this would take us to mid Jan....

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

Just had a glance at the gefs 2m average temperature charts for differing UK locations and this stark variation between the colder Winter climate of Aberdeenshire and the mild of Cornwall stands out quite well at the moment.

viewimage.pbx?type=ens;date=20171227;timviewimage.pbx?type=ens;date=20171227;tim

Magnified with this Atlantic pattern of the jet wavering north and south over the UK.These expected readings show that the far north would be found on the north(polar)side of the jet for much of the time whereas the far south and south west experiencing mainly milder air.Many locations between seeing the day to day variations between the two under this mean westerly ridge /trough pattern.

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset
50 minutes ago, nick sussex said:

I’m underwhelmed , three lengths clear and the ECM unseated the rider at the final hurdle .

Putting aside what it did on day 9 and 10 the upstream pattern has improved and still a chance we might see a high pressure develop to the ne.

 

Exactly how I'm seeing it Nick. D9 / 10 trending the right way.

Get the jet south enough at that juncture and the PV should pull back with a developing Pacific ridge. 

ECM didn't quite play ball this time but you get the feeling there is a stonkingly good op run around the corner, that develops an influential NE block after that period.

Edited by s4lancia
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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

Some weak heights to N/NE I assume the low will sink away south east into Europe bringing some lower heights fitting with main cluster from EC ENS 00z that will be beneficial, first I’ve seen from a ECM op run with some form of blocking to N/NE a reasonable timeframe to look for IMO. It has been a lot worse than this I can tell you that.

CD482225-ED7F-4154-8232-C6C6FFC4C593.thumb.gif.e724724c86d688914ff7193c31a07ee9.gif8215E42D-911D-413B-B622-3CE2A6F88FC0.thumb.gif.dd08799d82f741bb0c162ab4d9759cb7.gif

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Posted
  • Location: st albans
  • Location: st albans

The op ec and gfs are both keen on a very neg epo by day 10

now that should drive another eastern USA trough which keeps the Atlantic jet strong - this is why I can’t currently see any Greenland or Icelandic blocking taking hold but the jet is certainly keener than recently modelled in the extended to drive se into Europe.  

For the first time on the extended eps there seems to be some interest in rising heights nw Russia/svaalbard and edging into ne Scandi 

 

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
10 minutes ago, bluearmy said:

The op ec and gfs are both keen on a very neg epo by day 10

now that should drive another eastern USA trough which keeps the Atlantic jet strong - this is why I can’t currently see any Greenland or Icelandic blocking taking hold but the jet is certainly keener than recently modelled in the extended to drive se into Europe.  

For the first time on the extended eps there seems to be some interest in rising heights nw Russia/svaalbard and edging into ne Scandi 

 

Interesting Blue :)

FWIW i suspect the heights way to the NE are actually assisting forcing the jet just about SE enough to maintain interest for Northern Britain-

Think cold zonality is about the best we can hope for into January,i  don't see much hope of any blocking where we would want it in an ideal world.

The EC mean days 9 and 10 looks reasonable tonight- but the problem here from my viewpoint is twofold- as we get nearer to zero hour the models tend to push the jet north- diminishing the snow chances, secondly, yes , Exeter have been quite bold in their updates but their update for January sounds more traditional zonal than cold zonal, which kind of re-enforces the first concern.

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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

There will be brief milder interludes but primarily looking average to below average. To the north largely below average with wintry precipitation quite abundant over hills, sometimes to lower levels. 

The far north seeing the best of the wintry weather as you would expect, eyes on heights to N/NE in NWP a nice wedge will do, an unsettled chilly regime doesn’t fill me with joy, not down here. 

ECM 12Z mean at day nine..

ACCEFCD4-641D-44E3-A05C-9BCD7F2967AC.thumb.png.0d888cb26f53de11e15601f7b88e932d.png

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)

The gfs is more amplified at 186 compared to it's 18z 210 from last night with heights starting to biuld behind that big low to our NW.

gfsnh-0-186.png?18gfsnh-0-210.png?18

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

The GFS has a more favourable elongated PV running ne/sw through Greenland .

This is normally well correlated with a pressure rise to the ne.

Edited by nick sussex
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