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phil nw.

Model Output Discussion 01/09/17

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ukm2.2017112000.168.lant.troplant.prp.fcst.gentracker.png

Not sure what to make of UKMO 168- most of the precip is in the biscay region- :)

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1 minute ago, northwestsnow said:

ukm2.2017112000.168.lant.troplant.prp.fcst.gentracker.png

Not sure what to make of UKMO 168- most of the precip is in the biscay region- :)

It has a northeasterly flow for us but probably not a long lasting one. Could be worse.

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For all the attention on the UK, if one looks at the whole northern hemisphere you can see we aren't that far away from a "deluxe" vortex split that brings weather to us from the middle of the Arctic. And that's at D7 not D17:

gfsnh-0-162.png?6  ECH1-168.GIF?13-12  

The million dollar question is "where's the Atlantic low going?" Looking at the EC clusters this morning, pretty high confidence that a ridge will get in ahead of it:

ec-ens_nat_z500scenarios_2017111300_168.

but will it then undercut by T192? Five clusters - one says "yes" (the third one), others "no" or "maybe"

ec-ens_nat_z500scenarios_2017111300_192.

The key is going to be the speed at which heights push north. The centre of any North Atlantic high needs to get far enough north quickly to allow lower pressure freedom to push through. If that can happen, then a northerly will have freedom to push down to the UK undisturbed. But if no undercut happens, the eventual result will probably be a collapsed high like the ECM op run, albeit a very cold one initially.

As Bluearmy has indicated, nothing really conclusive to go on when looking in the D10-D15 timeframe.

So in summary, a full Arctic plunge looks out of reach at the moment but only just, and there's still room for an upgrade. Even without it, some very cold and frosty weather may result anyway.

EDIT: In my opinion, it looks like the UKMO D7 achieves the undercut too.

Edited by Man With Beard

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Absolutely dyer GEFS mean has a positively tilted surface low to the WNW of us.

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Morning! Impressive block developing by late week over the artic ,with some massive temperature fluctuations to the north and south of the UK. Expect computer models to become gridlocked in there handling of the up coming synoptics in the days ahead....

h850t850eu.webp

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8 minutes ago, feb1991blizzard said:

Absolutely dyer GEFS mean has a positively tilted surface low to the WNW of us.

There is a split, the op was in the milder/wetter pack but there really isnt a halfway house-

 

Edited by northwestsnow

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Not the best of means  on the ensembles.  However there really is a large scatter so very much up in the air   on a side note  one as the magical mystical -10 breached  i also think that particular perb is the trail blazer 

graphe3_1000_234_80___.gif

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2 minutes ago, northwestsnow said:

There is a split, the op was in the milder/wetter pack but there really isnt a halfway house-

MT8_London_ens.png

The thing is, if you look at all of the Purbs for the 21st as an example, every single last one of them has Blocking over Greenland and the pv in really bad shape. I'm not sure how much use the ENS are going to be at the moment.

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1 minute ago, karlos1983 said:

The thing is, if you look at all of the Purbs for the 21st as an example, every single last one of them has Blocking over Greenland and the pv in really bad shape. I'm not sure how much use the ENS are going to be at the moment.

Yes im sure your right, btw that was yesterdays 12z ens from GEFS im having probs updating charts for some reason.

The 6z ones are not great, the slight majority look very wet/zonal.

Guess we will have to wait and see..

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I think a reasonable assessment of where we currently sit is that the medium term (6/10 days ) remains uncertain re the NAO being too west based or not and the longer term out to two weeks, is now trending average whereas up until yesterday it would be described as a cold outlook. I suspect that the ‘average’ look to the period 10/15 days allows for any pattern to become established. 

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Lot's of scatter still but the mean only seems to be going one way at the moment and that is less cold with each run

00z

5647654.thumb.jpg.a3f711618af754133a96f6f6762b2112.jpg

06z

gefsens850London0.thumb.png.23f95bddb63ff2aaaaf922347e85d11a.png

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6 minutes ago, bluearmy said:

I think a reasonable assessment of where we currently sit is that the medium term (6/10 days ) remains uncertain re the NAO being too west based or not and the longer term out to two weeks, is now trending average whereas up until yesterday it would be described as a cold outlook. I suspect that the ‘average’ look to the period 10/15 days allows for any pattern to become established. 

Whats your take on the GFS/EC standoff Blue- ok 6z moved a little but its still really quite a long way from EC- and we know EC has a tendency to over amplify..

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Can we keep meto updates to the correct thread. Ta

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3 hours ago, snowray said:

The Sun has been spotless for the last two weeks after being quite active last month, seems that we might be entering a prolonged minimum phase early and could be on the cusp of the next grand minimum.

SDO_HMIIF_512.jpg

sc5_sc24_1-2.png

The sun was quite inactive last month as well. September saw an active month but since then it's crashed.

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For those wanting a visual between the 00 and 06z means from the GEFS.

Captură de ecran din 2017.11.13 la 14.56.02.png

Captură de ecran din 2017.11.13 la 14.55.53.png

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What are we really concerned about..... I know I said ENS probably aren't much help t the moment, but......... it does seem fairly obvious which model might not quite be onto the correct hymn book,never mind hymn sheet 

ensemble-tt6-london.thumb.gif.4813924f5a2764bb1985c736bc422126.gif

 

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52 minutes ago, northwestsnow said:

Whats your take on the GFS/EC standoff Blue- ok 6z moved a little but its still really quite a long way from EC- and we know EC has a tendency to over amplify..

It’s a bit delicate to call - my best guess would be that that the undercutting will happen but whether it gets far enough east without phasing to prevent west based NAO is my issue. Thereafter I would be concerned for coldies looking for a wintry last week of November that there is no strong extended signal but it wouldn’t be a shock to see a renewed amplification crop up to our west 

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The Ukmo charts again look positive. The 0z t120 chart almost identical to the 12z 144 chart yesterday when i said the high closest to the UK would slide away southeast with delayed Atlantic heights then building. This can clearly be seen on the 0z t144 chart this morning with post t144 looking very promising. Nothing to get hung up about I would expect a good afternoon and evening model watching to come.

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