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Hunt For Cold: Model Discussion - Heading Into Christmas


Message added by 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)

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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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Last one from me for 6 weeks before I leave in the morning for Canada . Our experts we use in resort have told me that todays upper air soundings over the Russian Arctic are showing Easterlies now est

After a health scare I have had the best news ever and been given the all clear. What a year it has been weather wise.Just like to take the opportunity to wish Paul,all The moderating team a

Afternoon so 2 hours on the train should be plenty of time for a post- The last 2 weeks the projected SSW has gradually worked through the models & is now 'imminent' ~ 30hours away is when we

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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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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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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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19 minutes ago, carinthian said:

Last one from me for 6 weeks before I leave in the morning for Canada . Our experts we use in resort have told me that todays upper air soundings over the Russian Arctic are showing Easterlies now established at 10mb level.  They expect this flow direction to run down to the troposphere in the coming days ( the start of the reversing the westerly flow for much of Northern Europe including the British Isles ). This will impact on the models in the next 48 hours. So hopefully some good looking winter charts for you lot just around the corner.  Will be watching from far a field with great interest. Bye for now and a happy New Year to all our forum members, young and old ! 

C

Thank you buddy for this information. We can only hope for the best.

In the evening runs I find the UKMO model quite interesting at 144 h. Statistical comparision has shown us that if we compare the GFS, ECMWF, UKMO models together, that UKMO model was even the second on the list right behind the ECMWF model. The GFS came just third on the list. It also depends on the situation.

UW144-7.thumb.GIF.36a9fc9a445f0ec3ebdb4d9fe865c4a9.GIF

Edited by Redbull165
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42 minutes ago, Steve Murr said:

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

maybe ECM's westward bias? Let's be honest, we would have had a lot more snow over the years if the GFS could just be ignored or it always simply caught up with the ECM.

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State of flux is the best term to apply to the models at the moment = so expect further probable wild swings in the days ahead as they get to grips with the projected flushing out of the zonal winds - which are forecast to collapse. 

GFS has flipped quite a bit in the past few runs, 12z forecasts showing significant amplification with a southerly tracking - plausible, but perhaps too must gusto to it, and too much easterly bias. ECM showing a 13-15 Dec scenario with the block holding firm against a weakening trough to our west. A middle ground scenario would bring fairly typical January fayre, temps about average with something wintry for the north.

The atlantic is very fragile right now at the time of year when it should be most rampant, and typically we turn a corner come early Jan, when high pressure has an easier time in overriding it - and ever more so as we move further through winter..

 

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1 minute ago, damianslaw said:

State of flux is the best term to apply to the models at the moment = so expect further probable wild swings in the days ahead as they get to grips with the projected flushing out of the zonal winds - which are forecast to collapse, from a very weak base state relative to the time of year anyhow.

GFS has flipped quite a bit in the past few runs, 12z forecasts showing significant amplification with a southerly tracking - plausible, but perhaps too must gusto to it, and too much easterly bias. ECM showing a 13-15 Dec scenario with the block holding firm against a weakening trough to our west. A middle ground scenario would bring fairly typical January fayre, temps about average with something wintry for the north.

The atlantic is very fragile right now at the time of year when it should be most rampant, and typically we turn a corner come early Jan, when high pressure has an easier time in overriding it - and ever more so as we move further through winter..

 

 

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2 minutes ago, Redbull165 said:

Thank you buddy for this information. We can only hope for the best.

In the evening runs I find the UKMO model quite interesting at 144 h. Statistical comparision has shown us that if we compare the GFS,ECMWF,UKMO models together, that UKMO model was even the second on the list right behind the ECMWF model. It also depends on the situation.

UW144-7.thumb.GIF.36a9fc9a445f0ec3ebdb4d9fe865c4a9.GIF

Yes it is interesting. Certainly has the coldest air massing just to the east. Where the high relocates will be important. GFS/ECM seem likely it to sink it a bit and cut off further cold air advection into Europe /Eastern Britain. UKMO positioning looks the best placed for it to develop further towards Scandinavia , then Bingo. However, we know this can change in the morning.

C

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