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Hunt For Cold: Model Discussion - Heading Into Christmas

Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

  • Some topic drift, humorous responses etc are fine
  • Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
  • Posts which start with something like 'I know this is off topic but ...' are not ok.
  • Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

Message added by Paul

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48 minutes ago, Steve Murr said:

Atlantics hit the wall...

Awaits undercut

DD700A64-DB51-4783-9303-28E02ECD07D6.thumb.png.751fd32a79286b44e61deb619bd3e46f.png

NB again QTR to strat....

 

 

Not a chance from that...heights remain over Spain/SW Europe, looks good at 144 - 198 but the fly in the ointment is still that main low which doesn't advect northwards (near Greenland) followed by the feature developing from near the Azores and then 'balloons' ...another near miss on the cards or the building blocks?

Edited by Froze were the Days

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3 minutes ago, feb1991blizzard said:

Strat or trop?

Strat , just trying to get my head around what you guys are looking for when looking for colder forecasts.

Sorry for all the questions and i know i should research it more before coming in here but you lot got me hooked.

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2 minutes ago, Sparky68 said:

Strat , just trying to get my head around what you guys are looking for when looking for colder forecasts.

Sorry for all the questions and i know i should research it more before coming in here but you lot got me hooked.

You could combine the two and just call it a strop

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16 minutes ago, FiftyShadesofSnow said:

In a word. No.

The Ecm has already reverted back 1 frame from its 0z op. It has no backing from the gfs, Met office etc. The Ecm is progressive as usual and will jump to the gfs solution by its 12z tmw. 

Gfs also models that area far better. Unfortunately. 

Under normal circumstances yes, not when a disruption to the vortex has happened. During the last two SSWs ECM went for cold and GFS went for mild, ECM won both times. GFS is just wrong at d8-d12. The Iceland/East Greenland area is where our gap in the split vortex will be during the next few days. ECM is beginning to see this in its tropospheric output by starting to rapidly weaken lows that approach this area. GFS bringing a huge polar vortex over the East Greenland region in the mid range is going to be way off imo.

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h500slp.png h500slp.png

The 12z GFS did feature a significant gain of heights across Scandinavia compared to the 06z and 00z. Perhaps this represents a nod of sorts to what ECM's produced this eve.

The more the ridge through the UK stays amplified and resists the Atlantic, the greater the potential to drive some stratospheric wave-breaking right where we need it to open the door for the reversal downwelling process. GFS' instance on flattening the ridge quickly is closely tied into it's bleak lower-stratosphere evolutions.

 

Important to bear in mind that the MJO composites only go so far in isolation; the atmospheric response beyond the tropics must also be considered by looking to the GWO. If the MJO propagates on east as per ECM/EPS, AAM will surge upward, with the GWO heading through P5, and the ridge through the UK will have much more of a fighting chance against the Atlantic trough than the MJO P6 composite suggests.

Currently, it seems to me that GFS' huge amplification of the MJO in P5-6 is causing it to 'drown out' the extratropical component of the response.

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18 minutes ago, Sparky68 said:

Strat , just trying to get my head around what you guys are looking for when looking for colder forecasts.

Sorry for all the questions and i know i should research it more before coming in here but you lot got me hooked.

image.thumb.png.11b80e329f83627f9d5c07968607bb0e.pngimage.thumb.png.82ab958b9a1b053e9094abc6882bb4ea.png

January 13 and Janoary 09

See the distance between the lobes and no residual energy in the Atlantic.

Edited by feb1991blizzard

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Can anyone clarify what actually causes a SSW?  I know the stratosphere is stratified with cooler air closer to Earth and warmer air higher up near the ozone layer (UV light from the Sun is absorbed in this region) but I am puzzled by what mechanism could cause such a dramatic change in temperature.

EDIT: Okay so after a little search on the Met Office site they mention the breaking of waves in the Polar Jet that then cause the air in the stratosphere to collapse.  Quite strange how this doesn't occur every winter.  

Edited by Evening Star

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15 minutes ago, Sparky68 said:

So the residual energy is heat from the Atlantic?

Any residual chunk of the vortex, thats why i dont think the current one is necessarily as good as previous split SSW's

See here, its in Eastern Canada, this can translate to a residual bit of trop vortex firing up, where as in the other examples, the split is wide and far and nice clean heights right where we want them.

https://www.instantweathermaps.com/GFS-php/strat.php?run=2018122712&var=HGT&lev=30mb&hour=228

 

Edited by feb1991blizzard

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12 minutes ago, Steve Murr said:

Just for reference what area are you referring to as the GFS doesnt model any area better than the Euros blended

In this scenario the NOAA write the GFS off saying its to too far East - so your betting on the heavy underdog...

😉 👍

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I haven't posted much recently, and if I have it's largely about the uncertainty in the strat.  That uncertainty is reducing now, but it doesn't seem to be helpful in resolving what happens down here in the 10+ day timescale.

Main models at T144 tonight:

image.thumb.jpg.526851d295296c03dda5b056fcf3fe67.jpgimage.thumb.jpg.52f4b5c1f488695ed45603c340f46c80.jpgimage.thumb.jpg.d26356f4d4e51e4f93e053654f1395f9.jpgimage.thumb.jpg.0d3501769329828421ba1bad93c7162c.jpgimage.thumb.jpg.3a700dd364055225f981647f84ad6a3a.jpg

ECM best, GFS and ICON runners up, no point going beyond T144, they haven't a clue.

Still maybe a couple of days before the fog clears, but if we are indeed talking about a not perfect downwelling of the strat pattern, coupled with MJO forcing from the trop, then as I said in a post a few days ago it's squeaky bum time, but the sphincter holds tonight, in my view!  I think 48 hours from now should confirm this post SSW spell as a goer or not, I'm still 60% for goer!

Edited by Mike Poole

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ECM Mean 144 V GFS 144 Mean shows the eastward bias of the GFS, also if you scroll through the GFS at 144 they are all over the shop!

0450D22C-98AE-41D2-91B3-DC8CF710C25C.thumb.png.444f6b7ff4395fe9349f64d27b9f58af.pngE05AE5F3-9045-42FF-9301-CC5794C801D0.thumb.png.e2267fc171dd8ba9e64e623a2bbefcf0.png

Edited by Steve Murr

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A definite drop down from the ECM mean tonight compared with the 00z for the first few days of Jan

graphe_ens3_php.thumb.png.70bc2c4f1dff4b437af394bb29c545a4.png

 

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45 minutes ago, Evening Star said:

Can anyone clarify what actually causes a SSW?  I know the stratosphere is stratified with cooler air closer to Earth and warmer air higher up near the ozone layer (UV light from the Sun is absorbed in this region) but I am puzzled by what mechanism could cause such a dramatic change in temperature.

EDIT: Okay so after a little search on the Met Office site they mention the breaking of waves in the Polar Jet that then cause the air in the stratosphere to collapse.  Quite strange how this doesn't occur every winter.  

Nobody seems to mention the Brewer Dobson Circulation any more, its a model (not a computer one) to show how Ozone is produced at the equator and is transported to the poles, the stronger the circulation and more Ozone, means a warmer stratosphere (i think).

 

 

Edited by feb1991blizzard

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6 minutes ago, feb1991blizzard said:

Nobody seems to mention the Brewer Dobson Circulation any more, its a model (not a computer one) to show how Ozone is produced at the equator and is transported to the poles, the stronger the circulation and more Ozone, means a warmer stratosphere (i think).

 

 

Never heard of that but looks like it could be a good bit of stuff to study.

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Certainly a less vigorous Atlantic on the 12z ecm suite .... we still end up with a broad low euro mslp  anomoly ........but the clusters will reveal more ......the end week 2 on both gems and eps look unsettled with a capital U ....a few well placed wedges wouldn’t go amiss ........

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TBH EC 46 tonight is a real biggie- it will almost certainly play a big part in Exeters update tomorrow, finger crossed..

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The overide/modeling of trop/strat responces..being miss-interp imo..

The warming and placements of the disolving pv-at the layers..are confused and miss aligned..as the basis are fraught..as the notions of asian/siberian/alaskan, geop pots are missing the format..by way of position!

And with ckear and concise secondary warm @the strat  are also not being fed through..YET!..

DOWNWELLING is indeed of rapid responce..and troughing..'again' imo miss-placed via action and pulses.

The polar vortex is under increadable strain...already..

And with melt flux happenings, and a paused reckoning of a forming 2nd'ery warm even the polar notes..wafz are confused!..

The massive amp..of hp format and missing of a link...are not noted..im sure!!!..

And as the gain cements..im sure so will 2 outs....

Through cross..

And on a euro window...the ssts..are playing ball now ..also!!!

gefs_ensemblemean_wafz_2018122400.webp

gefs_ensemblemean_pch_2018122400.webp

figure5_12242018.webp

figure1_12242018 (1).webp

Wassertemperatur_EU_NA.png

gefs_ensemblemean_wafz_2018122400 (1).webp

Edited by tight isobar

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1 hour ago, More Snow said:

Anybody else get that feeling that the GFS is about to perform a massive flip in about 3hrs time and this place will go into melt down once more. its normally the way with real deep cold in the UK, the big guns run around blind as a bat for days only for ECM to pick up the baton and then the others jump in line just in time for the ECM to have a wobble before the way forward emerges, and then we all start the uppers debate the shift west shift east with each run then about when the cold spell is 3 days out the hunt for the breakdown starts. 

The SSW promises some snaw to some for sure 👍❄️❄️ The ensembles look promising too for snaw ❄️❄️❄️

A14E256B-CB45-40FF-8089-E94B079FFE27.png

Edited by prolongedSnowLover

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5 minutes ago, bluearmy said:

Certainly a less vigorous Atlantic on the 12z ecm suite .... we still end up with a broad low euro mslp  anomoly ........but the clusters will reveal more ......the end week 2 on both gems and eps look unsettled with a capital U ....a few well placed wedges wouldn’t go amiss ........

Not convinced 120-168 is a done deal yet..

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14 minutes ago, northwestsnow said:

TBH EC 46 tonight is a real biggie- it will almost certainly play a big part in Exeters update tomorrow, finger crossed..

It won't determine what actually happens though. The real biggies always get to t+72 with cross model support. 

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