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Model output discussion - 5th December 2016 - Into Winter we go

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1 hour ago, Glacier Point said:

12z data showing a shift in Equatorial low level westerly winds and convective anomalies much further east compared to 00z and 06z data. Be interesting to see what if any difference this makes to tonight's models.

Upper level winds still more easterly dominated but two out of three tropical forcing facets demonstrating an eastward trend [and therefore less likely to be destructively interfering on the downstream pattern].

Sorry for being thick, but what's the net result of this?

cheers

Karl

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1 minute ago, karlos1983 said:

Sorry for being thick, but what's the net result of this?

cheers

Karl

Looking at the 12z so far....chuff all.

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UN144-21.GIF?05-17

The UKMO continues to show a wedge of heights developing to our north, that should disrupt low pressure upstream as cold air pushes south and then south west into Europe from Russia. GFS still not interested though.

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Shortwave drama on the GFS 12hrs run, it wasn't so good early on but its later output is better. All depends on those shortwaves over the UK if they head se and detach cleanly from the mothership upstream and allow that weak Scandi ridge sw.

Edited by nick sussex
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Well the UKMO and GFS are completely different at 144, with high pressure building back in on the UKMO.

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Not much really going on with the gfs again. Or ukmo for that matter. After reading Steve murrs post I think we are along way from any decent output. Think I may take a break. Hopefully something in Jan may pop up. Because that post earlier just makes very grim reading indeed. 

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2 minutes ago, warrenb said:

Well the UKMO and GFS are completely different at 144, with high pressure building back in on the UKMO.

Just to illustrate...

UN144-21.GIF?05-17  gfsnh-0-144.png?12

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h850t850eu.png

Loving that miniature Scandi High - a comical nod by GFS to the idea that height rises could occur in that area :laugh:

 

h850t850eu.png

Going forward from this point, if GFS responds to an amplification signal from the MJO, the trough would tend to elongate south. Otherwise, it will probably become a large, well-rounded feature that overruns the Scandi High. Any bets? :p

Edited by Singularity
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1 minute ago, Singularity said:

h850t850eu.png

Loving that miniature Scandi High - a comical nod by GFS to the idea that height rises could occur in that area :laugh:

It was there on the 6z too, but not a "closed off" high then. 

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Big questions to answer at just +120 to +168 range;

  • Will the major Atlantic trough hold on long enough receive reinforcement by shortwave lows merging with it, or will it disintegrate before that can happen?
  • How strong will the localised response to stratospheric ridge be in the Iceland-Scandinavia region? The stratospheric ridge is weakening as it arrives, but the rate of weakening has trended down over the past 4-5 days, opening the door to a more pronounced tropospheric response. Fine margins could make a lot of difference going forward.
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Looking at the Gfs 12z so far, at least the daffodils will be happy :D becoming pretty mild indeed.

ukmaxtemp.png

hgt500-1000.png

ukmaxtemp (1).png

hgt500-1000 (1).png

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gem-0-138.png?12

Looks like GEM prefers UKMO's take over that of GFS.

GFS just seems too aggressive with the shortwaves rounding the base of the parent trough.

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11 minutes ago, Paul_1978 said:

It was there on the 6z too, but not a "closed off" high then. 

blink and you will miss it it ends up as a euro slug with al the energy going over the top but im not to concerned with the GFS the way it is handling this its always super progressive in the lower resolutions anyway better to watch the euros if this a future scenario

Edited by igloo
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Looking at the above charts posted the issue seems to be getting low heights into Europe that would potentially prop up the Scandi High enough to draw the cold air westwards.

Higher pressure seems rather stubborn in this area and we could do with it disappearing sharpish!

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3 minutes ago, warrenb said:

Looks like GEM maybe going Scandi as well

With the environment north and west I doubt it's going to be anything other than a brief amplification of the Euro ridge 

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Just now, warrenb said:

Looks like GEM maybe going Scandi as well

gem-0-168.png?12

It sure is thinking about it.

I have a feeling that a setup where you have an amplification signal battling against a strong thermal gradient in the far-western N. Atlantic is about as optimum as it gets for magnifying any zonal bias within models.

The knock-on effects are huge because you remove the disruptive forcing on the lower stratospheric vortex from the Atlantic- W. Eurasia side. So if GFS is wrong in the +120 to +168 range then the rest of the run is rendered invalid.

However, the fact that it's still been trying to raise pressure across the UK in the face of the zonal flow does at least indicate that the signal is in there, somewhere.

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GFS parallel (that's the new version- coming soon...) maintains the blocking theme

gfsnh-0-240-5.png

gfsnh-0-348-1.png

gfsnh-0-384-5.png

This is of course the 06z but it's consistent with the 00z...

Edited by bobbydog
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14 minutes ago, Nick F said:

So, 12z GFS op offers us the tease of a Scandi High as the  jet splits invof UK/NW Europe, but because of the strengthening jet upstream coming out of N America, the high gets pushed east too quickly to be of much use for us.

GFSOPEU12_186_21.pngGFSOPEU12_228_21.png

However, the ops may not have the amplification ahead of deep storm coming out of NE Canada correct, nor speed or direction of the storm ... this could have consequences on how ridging downstream near/over UK evolves IMO.

In spades upstrem with the very cold upper trough swinging east across America and the very strong jet. I cannot see anything changing much downstream

gfs_z500a_noram_38.pnggfs_uv250_noram_38.png

 

Edited by knocker

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