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Paul

Model output discussion - proper cold spell inbound?

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Just now, terrier said:

And this is a reason people shouldn’t just think because we have a ssw taking place means cold and snowy for our little island. It all depends we’re the blocks ends up. Even with a ssw we could end up in a southerly flow. And wouldn’t that just be Sod’s law for us if that did transpire. 

reasonable point terrier but probably worth looking at all the ensemble runs before drawing too many conclusions on something which is still at least a week away.

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24 minutes ago, ICE COLD said:

Let's hope the GFS 6z is off the mark . 

IMG_1300.PNG

Whilst many are thinking the nwp doesn’t have a decent handle on the likely pattern post SSW, one does need to consider that perhaps it does. The models have been upgraded significantly over the past few years and the fact the eps don’t show wintry nirvana for nw Europe within 2 weeks may well be because it won’t happen !  Whilst I do expect to see more blocked runs appearing and deep cold bleeding into e Europe and Scandi during week 2, it doesn’t mean that this will happen - the eps could well turn out to be doing a decent job. the first indicator for me that things are to change will be to see if the ec op begins to correct se with the Atlantic trough extension at days 7/9. 

Certainly isn’t tedious !!

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What doesn't make sense is it looks primed for HLB at T240 . IMG_1301.thumb.PNG.8faf1f6dc6cb1f127ed829bf8ab92223.PNG

and then it just all disappeared. There's not really any blocking any where by day 15 ?? 🤔IMG_1302.thumb.PNG.a19a7f654c9da7b0382b6f6bd676feb1.PNG

A SSW and you should see HLB but there isn't any across the hole globe ? 

Edited by ICE COLD

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Yes it's no good of the Atlantic troughs don't play ball but to be honest at this point I was thinking 'really GFS?' as the trough stringing out that much without a clean split away of the secondary low into Europe is seriously strange. The trough out west also seems unreasonably progressive, perhaps relating to the model taking AAM down a bit but even so...! 

h850t850eu.png

It does remind us though that the first tropospheric height rises in response to the SSW will be east and northeast of us, meaning we are dependent on a reduced zonal flow in the N. Atlantic to get something quickly from that. Otherwise, we have to wait for the second bout of height rises which occur in response to the warming hitting the Canadian daughter vortex; those affect the Greenland area and give a means for blocking to advance west even with the Atlantic being a total twit. You can see that process right at the end of the GFS 06z.

ECM 00z on day 10 appeared to be producing the second phase response (Greenland height rises) before the second warming has even completed, so most likely that's a coincidence?

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2 minutes ago, ICE COLD said:

What doesn't make sense is it looks primed for HLB at T240 . IMG_1301.thumb.PNG.8faf1f6dc6cb1f127ed829bf8ab92223.PNG

and then it just all disappeared. There's not really any blocking any where by day 15 ?? 🤔IMG_1302.thumb.PNG.a19a7f654c9da7b0382b6f6bd676feb1.PNG

Most likely a dodgy run as charts try to find a common ground!

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1 hour ago, johnholmes said:

A request please.

However great you think a post is please try not to include it all when it is a long one, simply give a link to the post.

thank you

 

Hi John,

You can click the little white arrow in the black box next to the time of post in the quoted post and this collapses the whole quote, this saves you scrolling all the way down to read the reply to the post.

On to the models and it certainly is some exciting times ahead and lets hope we all get some Snow.  This thread has certainly been top notch the last couple of days with some excellent analysis and detailed descriptions of what we can expect - this certainly helps people like myself who do try to understand what the models say but ultimately it confuses me more if I try and understand them too much!!

 

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15 minutes ago, Summer Sun said:

GFS 06z gives temps of 13c for some for a very short period

GFSOPEU06_300_1.thumb.png.e0a0b4b2103c55508095e7e532d452fc.png06_300_uk2mtmp.thumb.png.68f7e5bfdcaab54f678d99eca5b4c123.png

Quite a temperature contrast 

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19 minutes ago, bluearmy said:

Whilst many are thinking the nwp doesn’t have a decent handle on the likely pattern post SSW, one does need to consider that perhaps it does. The models have been upgraded significantly over the past few years and the fact the eps don’t show wintry nirvana for nw Europe within 2 weeks may well be because it won’t happen !  Whilst I do expect to see more blocked runs appearing and deep cold bleeding into e Europe and Scandi during week 2, it doesn’t mean that this will happen - the eps could well turn out to be doing a decent job. the first indicator for me that things are to change will be to see if the ec op begins to correct se with the Atlantic trough extension at days 7/9. 

Certainly isn’t tedious !!

I have noticed the strength of reversal trending stronger and toward GFS/GEFS so it would be surprising not to see more of a response on the 12z suite. 

I do wonder if there are issues with the influence of the Canadian daughter vortex prior to it being taken down; either in terms of what it will actually do or in terms of how the model attempts to resolve the balance of play between that and the reduced zonal signal across W. Eurasia.

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The Gfs 6z op has a happy ending!:D:cold:

06_384_preciptype.png

06_384_ukthickness850.png

06_384_ukthickness.png

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GFS 6z, looks Atlantic dominated right through out. Lots of cold zonal air, usual places seeing wintry stuff. In the main pretty wet and windy.

Edited by Chevron12345

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Bound to be a few variances on the effects of the ssw at the range especially with gfs coming out 4 times a day you're going to get every little nuance that only last only a few hours being picked up as a possible influence. At this range its the trend that is important and without doubt that trend is for northern blocking. Exact postioning and its effects for the UK won't be sorted for another week with any real accuracy.

Edited by Broadmayne blizzard

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GFS 06Z Control gets there in the end.

gens-0-1-384.png

Fascinating to see this develop at this stage and of course caution is required.

As I've said repeatedly, the split vortex and the SSW buys us a seat at the table, not a winning hand. The modelling of the pressured PV is I think an area of uncertainty in extremis.

 

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1 minute ago, Broadmayne blizzard said:

Bound to be a few variances on the effects of the ssw at the range especially with gfs coming out 4 times a day you're going to get every little nuance that only last only a few hours being picked up as a possible influence. At this range its the trend that is important and without doubt that trend is for northern blocking. Exact postioning and its effects for the UK won't be sorted for another week with any real accuracy.

There maybe northern blocking, but to my very untrained eye all I see is a big strong chunk of PV sat over Canada/Greenland sending weather systems off the Atlantic to the UK. Until that big chunk of PV does something else or disappears it just looks windy, wet with snow over high ground. Of course its not as simple as that due to the SSW, which I'm sure someone will point out. But if the SSW was not happening it just looks like good old english wintry weather, cold and damp down south and wintry in the the north.

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15 minutes ago, Frosty. said:

The Gfs 6z op has a happy ending!:D:cold:

06_384_preciptype.png

06_384_ukthickness850.png

06_384_ukthickness.png

Well if that comes off on my birthday (24th) I'd be gutted..........will be sitting on a beach in Mexico!!!

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18 minutes ago, Broadmayne blizzard said:

Bound to be a few variances on the effects of the ssw at the range especially with gfs coming out 4 times a day you're going to get every little nuance that only last only a few hours being picked up as a possible influence. At this range its the trend that is important and without doubt that trend is for northern blocking. Exact postioning and its effects for the UK won't be sorted for another week with any real accuracy.

Totally agree, runs will vary quite markedly IMO

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The GFS 06z mean actually manages to make it slightly above the long-term average towards the end of the run for a few days few runs at the coldest get to around -12 the 'warmest' get to around +6

gefsens850London0.thumb.png.03a20c3d7e5b4494ad3e7230bebd93a5.png

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There's plenty to encourage those (including me of course!:D) hoping for a freeze later this month within the GEFS 6z..some peachy charts!!:):cold-emoji:❄❄❄❄❄❄❄❄❄❄❄❄❄❄❄

0_384_850tmp.png

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11_384_850tmp.png

13_342_850tmp.png

13_366_2mtmpmax.png

13_366_850tmp.png

14_384_850tmp.png

Edited by Frosty.

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Hopefully the models will starting showing what the latest meto further update says.

Very encouraging.

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1 hour ago, bluearmy said:

Whilst many are thinking the nwp doesn’t have a decent handle on the likely pattern post SSW, one does need to consider that perhaps it does. The models have been upgraded significantly over the past few years and the fact the eps don’t show wintry nirvana for nw Europe within 2 weeks may well be because it won’t happen !  Whilst I do expect to see more blocked runs appearing and deep cold bleeding into e Europe and Scandi during week 2, it doesn’t mean that this will happen - the eps could well turn out to be doing a decent job. the first indicator for me that things are to change will be to see if the ec op begins to correct se with the Atlantic trough extension at days 7/9. 

Certainly isn’t tedious !!

Yes you maybe right BA . But the GFS 00z had this for Day 10 -IMG_1303.thumb.PNG.6684bd3fd3fb079069fd689b3abc0964.PNG

And the GFS 6z had this for day 10IMG_1310.thumb.PNG.a8d2968bec750e7ee862c3ec77eb051c.PNG

so I really don't think it does have a handle on the SSW , It's completely different . 😁

Edited by ICE COLD

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30 minutes ago, KyleHenry said:

“How I learned to stop worrying and love the SSW” Dr Strangelove. 

 

I have always attempted to keep my explanations of the atmospheric processes in the most basic of terms. Simplistic, yes but wanting them to be very understandable too.

SSW creates a split at the 10hPa level commencing over the next 24 hours. As seen below.

 

 6519734A-267E-49A9-A4F5-38953D9A9614.thumb.png.26252249349470611d33416da29b7a1c.png

 

Inside the gap of the split vortices there becomes an opening for High pressure to locate to that position. 

We have seen several times this winter, the development of a -AO. Displacement of the PV off its natural peg hole- Greenland. 

The wave energy burns out and we see a return of the PV back to its natural position.

What we have now is not only displacement but also destruction of the PV and no return to its default position.

The SSW downwells enough that it allows upwelling from the surface (wave 2) access to an altitude and position that would be unattainable without the SSW.

That easterly winds exist in all levels from Mesopause to the surface. Firstly at the pole= -AO and the lower latitudes. 

16676616-FA11-4380-AA21-12EE54856F6C.thumb.gif.1c80ed4c84141a1293ff39a12fcf4563.gif

Above see how the HP moves into the gap of where the upper Trop PV existed. We have a cross polar link up. 

Allow 2 day lag to make the same positions at 500 mb level. 

A0FD6C59-7DEE-474E-95FB-B663079900DC.thumb.gif.14445dda54625273e908006372a2ae4d.gif

 

Then by the 17th Feb the -AO acts as an elbow into the face of the US daughter vortex and pins in down. While at the same time the vortex is attacked again leaving more certainty that the PV will not reform or reposition at its default for approx 4 weeks. That is if it can recover from such a brutal assault. 

The ECM has a better handle on the upcoming surface reactions. Strat/Trop PV is gone and so the -AO opens the way for a -NAO to develop. 

As seen below

 

C2EBE542-1BF4-4C18-BB23-DD907806D5C4.thumb.png.7b3d69ccbb660dc865c81f6386592e2f.png

I feel the GFS is struggling to interpret to upcoming developments and is messy in comparison. 

Hope this explains the quiet confidence of the SSW effects and the incoming surface responses based on logic, physics and the process.

 

 

 

 

0F518BBE-9AB9-4428-A75F-FA3D5B90E898.gif

Magnificent Kyle. That's one hell of a sub Chiono just sent on to win the game:hi:and yes I have included all the post.

Edited by winterof79

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I think I'll reserve judgement on the possible ramifications (viz the models) of the upcoming SSW until after the newfangled Net Weather Wormhole App comes online!:cold:

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