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Model output discussion - mid January


Paul
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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

Its not as bigger downgrade as I thought either - yes less frigid 91 style runs but the pattern is very good - a mean Easterly flow at the end of the run.

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Posted
  • Location: Orpington Kent
  • Weather Preferences: Snow freezing rain heat waves
  • Location: Orpington Kent
36 minutes ago, mulzy said:

FWIW, the 12z GFS is a UK High borefest from day 8 to 16.  It nearly gets there in deep FI though...

I must be looking at completely different model then..:D

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

Day 15 GEFS 500Mb Mean Heights Anomaly chart is decent.  Let's see if the EPS agrees with it...

gensnh-21-5-360.png

Edited by mulzy
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Posted
  • Location: Wildwood, Stafford 104m asl
  • Weather Preferences: obviously snow!
  • Location: Wildwood, Stafford 104m asl
42 minutes ago, mulzy said:

FWIW, the 12z GFS is a UK High borefest from day 8 to 16.  It nearly gets there in deep FI though...

better than zonal wet and windy Atlantic sick bucket charts, 

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

NCEP extended forecast discussion:

...MODEL GUIDANCE/UNCERTAINTY ASSESSMENT/PREFERENCES...

THROUGH DAY 4/JANUARY 26...OPERATIONAL/ENSEMBLE GUIDANCE APPEAR TO
BE IN SOLID AGREEMENT WITH THE EVOLVING SYNOPTIC-SCALE PATTERN.
TOWARD THE END OF THE WORK WEEK...THE BIGGEST SHIFT IN THE
GUIDANCE IS TO BE QUICKER WITH THE NORTH-CENTRAL SURFACE LOW PER
MULTI-DAY ENSEMBLE LOW COMPARISONS. MARKED DIFFERENCES APPEAR OVER
THE WEEKEND AS THE GUIDANCE STRUGGLE WITH THE DEGREE OF
AMPLIFICATION ACROSS THE EASTERN U.S. CONSIDERING MODELS FROM THE
OVERNIGHT SHIFT...RELEVANT OPERATIONAL SOLUTIONS AS WELL AS
ENSEMBLE SPAGHETTI PLOTS SHOWED AN UPPER TROUGH DIGGING THROUGH
THE OZARKS ON 28/1200Z. HOWEVER...THE 00Z SUITE OF MODELS HAS MADE
A SIGNIFICANT EASTWARD/FLATTER ADJUSTMENT WITH THE LONGWAVE
PATTERN. IT IS WORTH NOTING THERE ARE A SIGNIFICANT NUMBER OF 00Z
ECMWF/CMC ENSEMBLE MEMBERS WHICH FAVOR THE SLOWER/DEEPER SOLUTION
SO NOT COMPLETELY SOLD ON THIS LATEST FORECAST TREND. REGARDLESS
OF MODEL CHOICE...LOWER HEIGHTS DO APPEAR TO BE FAVORED INTO EARLY
NEXT WEEK ACROSS THE EAST COAST CHARACTERIZED BY VARIOUS LEVELS OF
AMPLIFICATION

That will effect the downstream pattern in the Atlantic. And you can see by looking at the GFS versus the UKMO at T144hrs the differences upstream around the Ozarks which is the area around Kansas and Missouri.

Edited by nick sussex
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Posted
  • Location: st albans
  • Location: st albans
2 minutes ago, mulzy said:

Day 15 GEFS 500Mb Mean Heights Anomaly chart is decent.  Let's see if the EPS agrees with it...

gensnh-21-5-360.png

I doubt the eps mean with 30 more members is going to show anything like that at T360 !  especially given the rather varied clusters from earlier.

note that 3 or 4 gefs runs end up two or three days short of wintry nirvana so the 12z suite is probably better than it looks on the diagrams

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Posted
  • Location: Hertfordshire
  • Location: Hertfordshire
3 hours ago, bluearmy said:

can you expand on the strat forcing and how it will influence the pattern ?

Was at work so could not reply immediately but yes basically the strat forcing that we are seeing in the charts will precondition if you like the strat  so that IF we do get a strong MJO phase seven - eight - one response instead of minor ridging we would likely see strong HLB's that would last for several weeks perhaps with the Uk very likely to see some potent cold spells. The 06z run showed split vortices up to 10mb. Have not looked at the 12z yet.

Also if you pop along to the strat thread you will find much, much more helpful information to get you started.

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

The ECM and UKMO similar upstream at T144hrs. Both engage southern stream energy as opposed to the flatter GFS.

The ECM also splits the energy in the Atlantic which clears a path for the high to the south to be pulled further west.

Edited by nick sussex
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Posted
  • Location: st albans
  • Location: st albans
17 minutes ago, comet said:

Was at work so could not reply immediately but yes basically the strat forcing that we are seeing in the charts will precondition if you like the strat  so that IF we do get a strong MJO phase seven - eight - one response instead of minor ridging we would likely see strong HLB's that would last for several weeks perhaps with the Uk very likely to see some potent cold spells. The 06z run showed split vortices up to 10mb. Have not looked at the 12z yet.

Also if you pop along to the strat thread you will find much, much more helpful information to get you started.

The MJO analogues for 7-8-1 have no adjustments for the state of the strat,. are you simply saying that because the strat is looking fairly benign, it wont interfere with the HLB signature which would follow MJO 7-8-1???  the split mid strat vortex showing on the gfs op post day 13 is certainly not reliable.  one thing i've noticed over the past weeks is the trop signature sometimes mirrored right up to 30hpa on ecm days 8/10. at 50hpa, its often. the next run, if the op is different in the trop, the mid strat pattern is also different. that's not something which in previous winters is so evident above 70hpa outside of the sustained big features (like a Aleutian ridge) 

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

What a cracker of a mean at T+384 the unproblematic easterly. :spiteful: 

21E25E91-3FD3-4CCC-A8A5-FF88DFC80969.thumb.png.3acdfd8b7439bdc6fb70c4319695561d.png

It appears to me fairly good evidence it will turn benign and anticyclonic with MLB.

31341528-4C4D-4C5E-9A4F-1DDB65A705CC.thumb.png.8f7b13060b35d756d87094709e350f13.png

...thereafter it may stretch N/NE resulting in much colder conditions. GEFS very decent again..

DCA8BDDD-EF75-45CF-86A0-F9414F67BC4B.thumb.png.f57ef5c2c939a74e4e25d7eb87ba13bb.png81219389-5E97-47CD-ADEF-DB49602E197F.thumb.png.015191ff616c979113f34422e4a4e608.png

BD9F6F62-E900-4CF3-9EB0-1E5C4F7A5A32.thumb.png.0ca74e59da45804060ef53f943eb0b62.png0FB7012A-7761-47EF-BECA-BE9B04870834.thumb.png.dec5ba5f1d0b575d504ccbe2f1e9e4c9.png

 

Edited by Daniel*
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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
16 minutes ago, bluearmy said:

The MJO analogues for 7-8-1 have no adjustments for the state of the strat,. are you simply saying that because the strat is looking fairly benign, it wont interfere with the HLB signature which would follow MJO 7-8-1???  the split mid strat vortex showing on the gfs op post day 13 is certainly not reliable.  one thing i've noticed over the past weeks is the trop signature sometimes mirrored right up to 30hpa on ecm days 8/10. at 50hpa, its often. the next run, if the op is different in the trop, the mid strat pattern is also different. that's not something which in previous winters is so evident above 70hpa outside of the sustained big features (like a Aleutian ridge) 

While there's a good chance of an amplified phase 6 and 7 i caution against the belief that the MJO will be of any real strength in phases 8 and 1.

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Posted
  • Location: Hertfordshire
  • Location: Hertfordshire
8 minutes ago, bluearmy said:

The MJO analogues for 7-8-1 have no adjustments for the state of the strat,. are you simply saying that because the strat is looking fairly benign, it wont interfere with the HLB signature which would follow MJO 7-8-1???  the split mid strat vortex showing on the gfs op post day 13 is certainly not reliable.  one thing i've noticed over the past weeks is the trop signature sometimes mirrored right up to 30hpa on ecm days 8/10. at 50hpa, its often. the next run, if the op is different in the trop, the mid strat pattern is also different. that's not something which in previous winters is so evident above 70hpa outside of the sustained big features (like a Aleutian ridge) 

Rightly or wrongly I believe that without the strats c/o ie the top down forcing and warming we are seeing to weaken the vortices you would not see strong HLB's even with a phase 7-8 MJO response.

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Posted
  • Location: st albans
  • Location: st albans
8 minutes ago, comet said:

Rightly or wrongly I believe that without the strats c/o ie the top down forcing and warming we are seeing to weaken the vortices you would not see strong HLB's even with a phase 7-8 MJO response.

no discussion that a strong strat vortex and consequential zonal flow will make sustained HLB nigh on impossible. i'm just not sure if you are saying the strat is part of the cause of HLB or just not interfering destructively with the trop developing them. one is passive and one isn't.

the ec op is evolving exactly as suggested yesterday evening re the mean and anomaly.  I hope we aren't headed towards another 'warm easterly' !

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

Too many differences between the outputs to have much confidence in the outlook.

Its clear some changes are likely as both the ECM and GFS point to that but even at T144hrs hrs the evolutions can’t develop similarly over the UK because of the different view upstream.

The ECM splits Atlantic energy which allows the high an easier path to the west. The GFS doesn’t do this but tries to amplify the flow later.

 

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

UKMO extended keeps the high nearby had to trawl through the files to find it whilst NOAA is shut down along with the rest of federal government

ukm2.2018012912_168_lant.troplant_prp_fcst.gentracker.thumb.png.1be8a73077dd59d201f71d7f3b75bd00.png

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Posted
  • Location: Wyke regis overlooking Chesil beach.
  • Weather Preferences: Snowfall
  • Location: Wyke regis overlooking Chesil beach.

Certainly enough going on in the output today to keep us interested as to where the High pressure decides to go next week and beyond. Some absolute stonkers in the Gefs.Just fo fun at this range of course, but certainly not outside the realms of possibilty going forward.

It would be nice to get the chance of at least one decent fall of snow down here in deepest south Dorset before winter is out. 

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Posted
  • Location: Evesham/ Tewkesbury
  • Weather Preferences: Enjoy the weather, you can't take it with you 😎
  • Location: Evesham/ Tewkesbury

Evening :hi:Another week and more drama!  Wednesdays cold front needs keeping an eye on with perhaps some dramatic weather along the front with winds and rain, then it turns colder, then at T+144 both ecm and gfs diverge greatly . Gfs builds a big area of high pressure so cold with perhaps problems with frost and fog , ecm on the other hand shows PMr air with cyclonic synoptics with problems with snow and ice....:cc_confused: It looks like the Boxing Gloves are out again for the two main Rivels:rofl:

brindel.png

brindelx.png

brindelxx.png

brindelxxx.png

brindelxxxx.png

brindelxxxxx.png

BOXING GLOVES.jpg

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

As posted previously the episodic winter continues, any hint of a prolonged SW long drawn atlantic fetch quickly cast aside, with shots of polar maritime air ready to pounce, a 48 hr mild spell, then back to average conditions Thurs-Fri, then a marked divergence between ECM and GFS, both indicate heights to the south becoming an influential player and the atlantic going into freefall somewhat - we either end up with a mid atlantic ridge and weak PM shot/cyclonic conditions from the NW, further snow potential for the north, or a ridge building through the UK and stretching towards the atlantic and eastwards, with the jet well deflected from our shores - a settled spell to start Feb, cold at night, frost and average temps, but likely trending colder.

The main theme from the models is a weakening of the atlantic as move towards the new month, and heights over the country seems a good call, with every chance thereafter for something colder to the east to arrive, probably best chance of the winter so far, and far more likely to happen in Feb than Dec-Jan, not saying it will, but chances much higher.Just a hunch but I sense an evolvement to cold and settled will take hold - atlantic hitting a brick wall.

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

Too much of a toppler feel to the modelling, especially the ops. Too much energy in the northern arm yet again. I notice that there doesn't appear to be any 'very' cold runs showing in the ecm ens for debilt. 

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Posted
  • Location: Hertfordshire
  • Location: Hertfordshire
1 hour ago, bluearmy said:

no discussion that a strong strat vortex and consequential zonal flow will make sustained HLB nigh on impossible. i'm just not sure if you are saying the strat is part of the cause of HLB or just not interfering destructively with the trop developing them. one is passive and one isn't.

the ec op is evolving exactly as suggested yesterday evening re the mean and anomaly.  I hope we aren't headed towards another 'warm easterly' !

Yes of course it is part of the cause of HLB. Strong forcing Pacific side with heights, MJO forcing contributing aiding ridging on Atlantic side. Continued strat forcing ( warming) helping to force split ( IF we are really lucky). Thinking of Jan 2012/13 warming here and subsequent blocking although this time round HLB may be more robust.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
8 minutes ago, comet said:

Yes of course it is part of the cause of HLB. Strong forcing Pacific side with heights, MJO forcing contributing aiding ridging on Atlantic side. Continued strat forcing ( warming) helping to force split ( IF we are really lucky). Thinking of Jan 2012/13 warming here and subsequent blocking although this time round HLB may be more robust.

But this time unlike 2013 there is no suggestion of the top-mid strat vortex getting completely shredded, any split in the output (if you can even call it that) has been trop led so no more reliable that trop output. not saying we cant get a decent trop pattern but it will be because the upper vortex isn't strong enough to stop the trop doing what it wants, not because a strong over the top warming has shredded the trop vortex through downwelling of -ve zonal winds or not yet anyway.

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