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Model output discussion - late November


Paul

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex
5 minutes ago, Ali1977 said:

Not so good at 144

C3F8EB66-FB5F-49DA-9892-A9518DF40170.png

No not good, incredible the difference in just 12 hours, compared to its 00z run at just D6.

 

And at D7, spot the difference.

icon-0-168.png

icon-0-174.png

Edited by snowray
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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
19 minutes ago, Faronstream said:

We already know that the GFS 06z run is an EXTREME outliner, it won't verify

Based on what exactly ?tia

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Posted
  • Location: leicester
  • Location: leicester
5 hours ago, IDO said:

...yes, variation on the theme, just the wrong variation in the medium term. See where FI goes with this plot.

By the way icon 12z goes the same way as the gfs 06z!looks absolutely identical!!!like i said i had a feeling this would happen yesterday!!if the atlantic low doesnt slide its an issue!!if it doesnt deepen enough and help a wedge in the atlantic then know good!!what do we get we get we get the middle ground which is absolutely what we dont want!over to the ukmo and gfs...

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex
7 minutes ago, ICE COLD said:

So annoying just hope ECM and UKMO hold steady . Hope @Steve Murr is right . 

I was getting excited when I saw the agreement between the models on the 00z runs, can things really change that much in 6/12 hours at T120?

Guess I have a very short memory.

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Posted
  • Location: st albans
  • Location: st albans
36 minutes ago, Faronstream said:

It still looks extremely cold in both GFS/ECM even the 6z was cold so below zero degrees at daytime temperatures for whole western europe and NAO is still negative for the whole period so no possibilty for any  milder temperatures than normal

At the surface or at 1500m??

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Posted
  • Location: Hertfordshire
  • Weather Preferences: SNOW AND FREEZING TEMPS
  • Location: Hertfordshire
1 minute ago, Weathizard said:

ICON with the hard no, usual story with phasing Atlantic lows, never get the clean break!

E7DC6398-D850-49F9-B523-89BD60CE9B2A.png

4F19F883-498D-47A5-852C-123F791A78B3.png

Yes the earlier attempts fail but think we’re gonna get a second bite of the cherry further down the line . 
 

Here the ICON at T180 

659EE7CC-E918-4CD4-A504-B32C59AEB0FB.png

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Posted
  • Location: leicester
  • Location: leicester
2 minutes ago, ICE COLD said:

Yes the earlier attempts fail but think we’re gonna get a second bite of the cherry further down the line . 
 

Here the ICON at T180 

659EE7CC-E918-4CD4-A504-B32C59AEB0FB.png

Dont worry buddy that will flatten out aswell!!it always does lol!!!

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Posted
  • Location: London, UK
  • Weather Preferences: MCC/MCS Thunderstorms
  • Location: London, UK

Very interesting over at the WPC Extended Forecast Discussion.  Models are struggling somewhat post Day 4, as I said last night - taking anything post 96 hours with the finest pinch of salt. 

Quote

 

The medium range period begins with a vigorous shortwave/surface low exiting the Northeast, with various shortwaves rotating through broad troughing across the remainder of the CONUS. For Day 3-4 (Mon-Tues), models overall show very good agreement and thus a majority deterministic model blend sufficed, between the 18z/Nov 21 GFS, the 12z/Nov 21 ECMWF, and the 12z/Nov 21 UKMET. Beyond this, one of the biggest forecast concerns continues to be regarding the evolution of a shortwave as it digs southward through the Western U.S. and ejects into the Central U.S. by day 4. Models continue to struggle with respect to both timing and intensity of this system, which looks to spin up a surface low in the south-central Plains on Tuesday, and track it quickly towards the Northeast by Wednesday/Thursday.

The GFS has been very consistent in deepening this surface low early on as it tracks through the Midwest, while the ECMWF shows much more run-to-run variability ranging from a solution close to that of the GFS to maintaining a rather weak wave through the Midwest and not showing much intensification until the low reaches the Northeast on Wednesday. The CMC also continues to exhibit high variability with each new model run and the latest run barely shows a shortwave at all and is so widely different from any other model solution and the ensemble means that it was not considered. Timing of this system also remains in question with the GFS on the faster side of the guidance envelope and the ECMWF/UKMET on the slower side. In addition, scatter plots of various ensemble member surface lows shows better clustering towards the slightly faster GFS. Based on this, and given the uncertainty remaining with this system beyond day 5, a blend of the ensemble means (ECENS/GEFS) was preferred which results in a moderately intense storm and a slightly faster track much closer to that of the GFS.

This also maintains very good continuity with the previous WPC forecast. Meanwhile, another vigorous shortwave follows on the heels of this first one reaching the West coast by late Tuesday. Models agree that this wave should become quite amplified by mid to late next week, with some solutions wanting to close off an upper low somewhere along the Southwest coast. Run-to-run variability in the deterministic models, both with respect to timing and closed low vs amplified troughing, remains high with this system and thus more of the better clustered ensemble means was used in the blend for days 6-7.

Reference: 

WWW.WPC.NCEP.NOAA.GOV

Anything after this period I think should be looked at, but not through rose tinted glasses.   Appears to be some variability regarding the Alaskan ridge and the cutoff low which assists the building of a ridge to our west.  Either way, it's an interesting period for sure.

image.thumb.png.f9410de5185f36afae5919139a8b98fd.png

 

image.thumb.png.3b23dd3bcd9e3ae88ede8e6b97c34fe6.png

 

The next 96 hours look relatively straightforward, but with the prime concern the evolution of the shortwave into the Central US.   It's pretty obvious that 

 Bank this chart of a Northern Hemispheric disruption at it's finest and see what the outcome is next Friday.

ECMOPNH12_192_1.thumb.png.732660ca23936d63beb17ec1a18abd57.png

 

 

 

 

Edited by Robbie Garrett
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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
6 minutes ago, bluearmy said:

At the surface or at 1500m??

I think he's looking at the 850s BA

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL

UKMO much better at 144 than the last GFS, but not as good as earlier 

85B354AD-0EE9-4E85-8A9B-6BB41E01FB8B.png

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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
6 minutes ago, Ali1977 said:

UKMO much better at 120

08481F30-4673-4399-8A64-C42E711B1E44.png

Much better indeed at T+144 with ridge to the NW and trough to the east with arctic air flooding south!!❄

UW144-21.thumb.gif.d9dd4bd0173c722c300deb5e2ca5ee39.gif

Edited by JON SNOW
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Posted
  • Location: Hertfordshire
  • Weather Preferences: SNOW AND FREEZING TEMPS
  • Location: Hertfordshire
4 minutes ago, Ali1977 said:

UKMO much better at 120

08481F30-4673-4399-8A64-C42E711B1E44.png

And beautiful at T144 . Get in there . A lot better than gfs and icon 

3AD25841-885A-440F-9C4F-D7AE70AF9AC9.gif

Edited by ICE COLD
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Posted
  • Location: leicester
  • Location: leicester
3 minutes ago, Ali1977 said:

UKMO much better at 144 than the last GFS, but not as good as earlier 

85B354AD-0EE9-4E85-8A9B-6BB41E01FB8B.png

Prime example of what i was saying earlier!!if that low dont slide then we want it to wind up to such an extent so it sends a ridge into the atlantic just like the ukmo 12z!!

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL

GFS still says no albeit slightly better ,  if ECM back tracks I won’t be happy.!! FINGERS are crossed the UKMO has it.

643BA75E-673A-4DD8-8945-C4E5877E7F27.png

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

Well the 12zgfs looks very much like this morning's Oz at 144 hrs.is it wrong I've know idea.second chance maybe coming up?

Edited by swfc
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Posted
  • Location: Lincs
  • Location: Lincs

Big differences by day 6 so little point looking beyond then, 12z GFS has the Atlantic low further east thus a bigger wedge between them, better than the 6z run, might be just enough to get the Greenie high but a close run thing

Yep its there, this evolution is better for getting the proper cold in IMO, but very tight margins, those lows CANNOT phase. UKMO very different 

 

GFS NOV.png

Edited by coldwinter
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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL

UKMO looks on a knife edge for me at 144

image.thumb.png.a1c1bd35ac4b835ed9c6e712f3d40d7c.png

The low in the west Atlantic looks a real pain, is there enough of a wedge of heights around Iceland to direct enough energy south?

METO seem to think its game on judging by the upgrade in their outlook today.

 

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