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Focussed Model Discussion


Paul
Message added by Paul

This is the focused model discussion - please only post about the model output. 

For a more laid back, bantery model discussion please use the Cold hunt - models and banter thread.

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Posted
  • Location: Camborne
  • Location: Camborne

Comparing tonight's ext EPS mean with two days ago does show the consistency and also the east European ridge gaining some traction with the trough a tad further south which portends temps a fair bit below average and an interesting surface analysis to sort

8-13.thumb.png.06f50acad5b72179c6fcd035f1673625.png10-15.thumb.png.481ea09309a32bd729784cadc36b4dc5.png

 

Edited by knocker
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Posted
  • Location: East Ham, London
  • Location: East Ham, London
6 minutes ago, bluearmy said:

It’s the growing trend on the eps mean ......

Yes and it's something I'll be looking out for tomorrow and beyond. IF we see heights emerging and most likely as an extension westward of the Eurasian HP, the question will be what will happen to the Atlantic in response.

The 12Z ECM OP tonight showed the Atlantic LP slowing and stopping in situ to the west and filling which would then allow the HP to push westward.

if we were really lucky, the HP pushing westward might encourage the Atlantic to slide SE but with pressure rising over Europe I'm doubtful about that.

The battleground scenario wouldn't be atypical for February.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
25 minutes ago, stodge said:

but with pressure rising over Europe

This is another puzzling feature, as the upper waveguide ought to be locked into a form that keeps refreshing the Euro trough with little in the way of relaxation periods.

Obviously big implications if the modelling has gone awry there.

I feel we really need to see more ‘success’ cold-wise in the 6-8 day range in order to bolster confidence in getting anywhere much thereafter. There comes a point when repeated derailments or moderations (as with the current spell) become hard to keep attributing to bad luck.

Edited by Singularity
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Posted
  • Location: Liphook
  • Location: Liphook
17 minutes ago, Singularity said:

This is another puzzling feature, as the upper waveguide ought to be locked into a form that keeps refreshing the Euro trough with little in the way of relaxation periods.

Obviously big implications if the modelling has gone awry there.

I feel we really need to see more ‘success’ cold-wise in the 6-8 day range in order to bolster confidence in getting anywhere much thereafter. There comes a point when repeated derailments or moderations (as with the current spell) become hard to keep attributing to bad luck.

Could the fact that the PV is so much larger in the area it is in than normal that its distorting what would be the usual tropical forcing pattern? I'm not sure, its certainly an interesting dilemma, and as you say if we keep failing then clearly something has gone awry somewhere. No doubt if it goes wrong, it will find a way out during April or something when its of no use! ;) 

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Posted
  • Location: West Sussex
  • Weather Preferences: Extreme cold & snow
  • Location: West Sussex

After wandering around phases 4 and 5 the MJO has shown signs of staying slightly amplified and moving across phases 6 and 7 as we get towards the end of the month and into February. (More favourable for -NAO)  The latest ECM modelling demonstrates this. The GFS only moves it across Phase 6 and then it loses amplification.  Something to bear in mind with the decent ECM trop eNS tonight. 

image.thumb.png.6281c37d680e8e27c85f3fa4973910d8.png

Edited by Purga
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Posted
  • Location: Crawley
  • Location: Crawley

Isn’t there going to be a massive cold plunge next week in the US which will fire up the jet? Wouldn’t this jet stop any height rises in the Atlantic? Or will this new cold plunge actually help us this time! Thanks

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Posted
  • Location: st albans
  • Location: st albans
2 minutes ago, Tony Cassidy said:

Isn’t there going to be a massive cold plunge next week in the US which will fire up the jet? Wouldn’t this jet stop any height rises in the Atlantic? Or will this new cold plunge actually help us this time! Thanks

Let you know in a fortnight ..........  but seriously, the jet is predicted to stay strong but to dive se into the euro trough ..... there is a transient Atlantic ridge predicted as a downstream consequence of the deep n American trough 

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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
2 hours ago, snowray said:

JMA looking great tonight at D8.

 

Still no consistency in the models although looking generally cold with some snow chances for most of us.

No deep freeze though, just yet.

JE192-21.gif

JE192-7.gif

JMA continues its fantastic run, I love the JMA....even if it's wrong!

But it might not be!;)

JE216-21.gif

JE240-21.gif

JE264-21.gif

JE264-7.gif

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

18z GFS is a bit strange too; it has more trough  disruption as I’d expect to feature, but the polar jet is quite a way further north relative to NW Europe than would be typical for the forcing at hand.

Possibly the models aren’t properly resolving the downstream response to the Pacific developments. We’ll know by the weekend I expect.

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Posted
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
  • Weather Preferences: Winter: Snow>Freezing Fog; Summer: Sun>Daytime Storms
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
On 22/01/2019 at 21:48, The Enforcer said:

Meanwhile, who wants to join us in time for Sunday lunch?

T+144: image.png.0d8066f2b47b0c8368f2d26e835714T+120: 81134C21-105F-4235-B08C-61EBFD1D545E.pngT+96: ?

T+96: image.png.4463b72e7dc06b02d0cb31bcb79114

The air source has changed from North-Atlantic to Scandinavia to Arctic. This looks like a wintery Jet trajectory to me. I wouldn't mind if this NW-SE pattern kept repeating over the next few weeks.

Edited by The Enforcer
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Posted
  • Location: Liphook
  • Location: Liphook
20 minutes ago, Singularity said:

18z GFS is a bit strange too; it has more trough  disruption as I’d expect to feature, but the polar jet is quite a way further north relative to NW Europe than would be typical for the forcing at hand.

Possibly the models aren’t properly resolving the downstream response to the Pacific developments. We’ll know by the weekend I expect.

Once again just wondering whether the larger/more intense than normal PV lobe is forcing the jet to arch more to the north than you'd expect given the usual forcing.

I note the MJO phase 5 does have a lower pressure anomaly over E.Canada, but this looks way more intense and larger than the normal you'd expect for that pattern sand that is forcing the jet more northerly than would otherwise be suggestive with the tropical forcing?

Edited by kold weather
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Posted
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
  • Weather Preferences: Winter: Snow>Freezing Fog; Summer: Sun>Daytime Storms
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
8 hours ago, knocker said:

A continuation of the wintry showers in the north west this evening, and even the wintry precipitation in the far south east, and as the temps starts to plummet  icy conditions will become widespread. But the complication could be through tracking south down the country which could bring some snow to lower levels

PPVE89.thumb.gif.06ae7aba0634df73d80afe9bb99ce6c9.gif1508835951_min21.thumb.png.990a0a9cd609ace737172ace02ec284a.png786641509_min04.thumb.png.48930730909aebbc6e74a93dd2ef240b.png

Good spot. Even if the mid-long term northern hemispheric pattern doesn't play out as many have been anticipating, these localised troughs that seem virtually impossible to model (e.g. heavy lowland snow in the South this Tuesday afternoon) are on a mission to stick two fingers up at the eternal "winter is over brigade". Who knows what tonight's feature will do? Watch that radar, boys.

Edited by The Enforcer
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Posted
  • Location: .
  • Location: .

The 0z GFS has a predominately westerly flow with northerly incursions. There's no sign of sustained blocking for the UK.

Ironically, however, the less cold setup might produce considerably more snow. The two boundary events of 30/1 and 1/2 do look pretty interesting but I'd still urge great caution. That's a long way out, GFS tends to exaggerate lows and they're quite marginal. Still some cause for excitement, even if the overall trend is not one of deep freeze.

30/1:

1217442746_ScreenShot2019-01-24at06_03_18.thumb.png.7d01983838e5fe2f0148b9662748b7a9.png

1901626841_ScreenShot2019-01-24at06_04_03.thumb.png.2b3a4270779c16bf43c3c0a89fa4955c.png

1127226141_ScreenShot2019-01-24at06_04_36.thumb.png.1123570845096c94b84814f0db00623f.png

 

1/2:

1617863033_ScreenShot2019-01-24at06_03_34.thumb.png.0a91dd82c8a6c189edc92c401b26e6c2.png

1021763047_ScreenShot2019-01-24at06_04_19.thumb.png.529b65d89f969f39ed6ab501f5c5d463.png

125413571_ScreenShot2019-01-24at06_04_46.thumb.png.fd7693019a14686127f54789a4a3cbf9.png

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Posted
  • Location: Camborne
  • Location: Camborne

Following on briefly with the gfs. The front clears quickly and by T144 a trough covers much of central and the eastern Atlantic with cold showery conditions effecting the UK, And this is the story over the next two or three days as the upper trough remains the dominating feature with perturbations within it bringing bands of rain, sleet and snow and remaining very cold

gfs_z500_vort_natl_25.thumb.png.cbb22e090aac2661c8dc70db06e4079a.pnggfs_z500_vort_natl_29.thumb.png.f2a42018b16ef5e9d3ba5c4a42fde32e.pnggfs_z500_vort_natl_33.thumb.png.2e4aa0f41f6c589e8d6493849327b51f.png

gfs_t850a_natl_33.thumb.png.a602d18432da8841eb6b2712fc6ab5ae.png

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Posted
  • Location: Camborne
  • Location: Camborne

According to the ecm the main feature during the middle part of next week, as the main trough slips south, is the severe frosts Wed/Thursday as slack low pressure resides over the UK. But during Thursday cloud and mixed precipitation on a front associated with the next trough tracking south east west of Ireland arrives in south western regions And the trough ends up south of the UK initiating a chilly easterly which is transient

t156.thumb.png.e474b1e7b0bd40662cec9eb47038a5a9.pngt192.thumb.png.05f52f527a6d218fd5b3ba8fcee05007.pngt192.thumb.png.1e349d28787240377bd1917c6416b484.png

Some signs this morning of the det run not adverse to the direction of travel as indicated by last night's ext EPS

Edited by knocker
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Posted
  • Location: Isle of Lewis
  • Weather Preferences: Sun in summer, snow in winter, wind in Autumn and rainbows in the spring!
  • Location: Isle of Lewis

I love your charts Knocker!

It does indeed look like a similar setup to last winter (Nov, Dec, Jan). When the jet was having a Tango!  

It does look very wintry over the next few weeks at times. Every chart is pointing towards that trend. 

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Posted
  • Location: Camborne
  • Location: Camborne

As mentioned last evening, more traction from the east European ridge, energy diversion mid Atlantic and trough slipping south equates to temps below average and a tricky surface analysis

9-14.thumb.png.f2c95448091d5f23a43cdb82ec6e6958.png

 

Edited by knocker
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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

So this morning the GEM and ECM move, at D10 move towards the GFS Pacific profile of any wave being interfered with by troughing so no real progress as to a Pacific Ridge, in fact, now like the GFS a big step towards a Pacific trough. 

So at D10 the three models:

1055199417_ECH1-240(9).thumb.gif.744ea7ad25a9733fb3f449e6b8d4386d.gif1517081857_gfsnh-0-240(2).thumb.png.6dc5ec898ef6071930304e0518969b95.png1599653818_gemnh-0-240(2).thumb.png.feb39dddcc8b1c96cd80fa60a5d0b2fe.png

Upstream a much flatter pattern, this means that we will have a faster influx of HP cells flowing west-east. The net effect will be a gradual easing of the trough east and/or warming out, fewer chances for ridges to develop to higher latitude and the possibility of the jet to split near the UK sending some of the energy east rather than SE.

We see the three models in the UK region having variations of this outcome, the GEM more zonal, the GFS split energy, more cold-zonal, and the ECM in its early stages of handling this upstream pattern change, so still trying to be more progressive with heights ridging north. Unfortunately, at D10, we know the ECM bias, so we can have low expectancies of that being repeated at 12z, the mean D8-D10 highlights this.

It does appear that the failure of the models with their MJO signal means we will get no help from there, the opposite in fact, and with downwelling really not showing its hand even at D16 on the GEFS, little productive help there. The D9-D16 development of the Pacific lobe:

Mean D9-D16>>>anim_fny4.gif  Mean D0-D9>>> anim_nea9.gif

We can see the wedge move from the Pacific to Siberia draining the Canadian lobe towards the Asian/Pacific side. The routes for the Canadian lobe are split so less energy filling the euro trough, compared to the above D0-D9 where the Arctic High and wedge forced the NW-SE flow over the UK. 

No way to sugar coat this, a bad trend. Hopefully, by then the downwelling would have reset the pattern and this scenario will not bear fruit. Still on the colder side of the climate, so the further north and higher ground could still be interesting...

 

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Posted
  • Location: st albans
  • Location: st albans

Good analysis @IDO  -

i think the Canadian stays just strong enough to keep the euro trough fed out to the end of eeek 2 and the developing scandi ridging should mean the uk is in the battle ground area - by that time the wild card of downwelling is thrown into the mix 

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

It’s not a Pacific ridge we should look out for as such; rather a western USA/Alaska one as part of the PNA pattern. Some suggestion of this in the D8-D16 but not as much so as would be typical of the MJO behaviour depicted for that time. Makes me wonder if the upper divergence above the Maritimes is really being got rid off; that’s were a lot of interference with the Nino pattern has come from in recent weeks.

Models are often just too broad with troughs in the longer-range though, so I might be reading too much into it; the Pacific one just needs sharpening up.

An added complication in the mid-range is the cutting off of what could have been a powerful PNA ridge into an Arctic high with the jet passing south of it into the US. Models may give this too much eastward momentum based on historical bias but this is not a dependable error.

 

Overall I see scope for blocking to set up more toward N than NE of the UK and hold it’s own for at least a few days - but not enough evidence yet to really expect such adjustments. Hopefully some will emerge over the next few days.

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