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Stratosphere and Polar Vortex Watch


Paul

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Posted
  • Location: Coniston, Cumbria 90m ASL
  • Weather Preferences: wintry
  • Location: Coniston, Cumbria 90m ASL
58 minutes ago, feb1991blizzard said:

This is more a snapshot of current status but still worth a look, especially when any warming wave does appears.

https://earth.nullschool.net/#current/wind/isobaric/10hPa/overlay=temp/orthographic=-7.61,83.89,360

Apologies if I'm teaching anyone to suck a festive egg!!

 

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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

Whilst the rest of us relaxed on Christmas Day, Dr. Cohen was busy updating his weekly blog! His final sentence below is not what many of us want to read, but atm model output seems to support his thinking. The latest GEFS (26th Dec 0z) have 15 out of 21 members with a stronger-than-average strat vortex by 10th Jan. I also note CFS has backed off from its' thoughts about a January SSW.

Here's some extracts:

The dynamic event that I am most focused on is the predicted increase in poleward heat transport or increased vertical component of the Wave Activity Flux (WAFz) activity for the end of December and the first week of January.
But the critical question in my mind is will this predicted WAFz pulse and possibly subsequent pulses be of sufficient magnitude to disrupt a strengthening stratospheric PV?  If not then the stratospheric PV will likely remain relatively strong for much of January and exert increasing influence on the tropospheric circulation with similar strengthening of the tropospheric PV and an increasingly mild pattern across the mid-latitudes of the NH.  Alternatively, if the predicted WAFz pulse and possibly subsequent pulses are of sufficient magnitude to disrupt the stratospheric PV, then the weakened stratospheric PV will exert increasing influence on the tropospheric circulation with similar weakening of the tropospheric PV and an increasingly cold pattern across the mid-latitudes of the NH.  My interpretation of the model trends is that the models favor the former milder solution.

5a42165bb7d0d_AERGEFSWAFz25Dec.thumb.jpg.da30828cbf7c120cbf0aefab513dd743.jpg

Full blog: http://www.aer.com/science-research/climate-weather/arctic-oscillation

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Posted
  • Location: Wakefield, West Yorkshire
  • Location: Wakefield, West Yorkshire
1 hour ago, damianslaw said:

Interesting post - but the models do tend to struggle a bit over christmas and could easily revert to the other scenario in the days ahead. We shall see..

Do models really struggle over Christmas? And if so, why?

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex
33 minutes ago, Paul_1978 said:

Do models really struggle over Christmas? And if so, why?

Is it not the usual lack of data over the Christmas period that we hear about, weather balloons and weather professionals generally being a bit merrier and jolly at this time of the year which leads to a little carelessness and some data just gets missed or mislaid down the boozer after a festive drink or two. All sorts of things get unintentionally left behind some place and cannot be found over Christmas, quite often they have been left in pubs. :laugh:

Edited by snowray
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Posted
  • Location: st albans
  • Location: st albans
5 hours ago, Don said:

I think the fact of the matter is we are likely to see another mild January. 

Not sure how that’s ‘likely fact’ yet don ???

i would have thought MLB is just as likely and that could deliver cold periods 

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Posted
  • Location: US / IL
  • Location: US / IL
On 12/24/2017 at 13:26, Paul_1978 said:

T+384 charts never verify. Ain’t gonna happen!

I've seen it said that if all the GFS+240 outputs were to verify, the planet would be uninhabitable. /s

Another expert in this field is Tormer Burg, who suggests that
" Yesterday's bombogenesis over the Sea of Okhotsk & ridge amplification downstream is leading to major cyclonic wavebreaking over the WPAC, resulting in an anomalous block developing over E Russia. This will be a shift in E Russia which spent most of the month under a trough. In conjunction Alaska & W Canada return to near-normal heights as poleward heat flux temporarily decreases in the N PAC. " <twitter.com/burgwx/status/945750648015982592>
 

Me, ..... I'm still trying to learn.

 

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

Late January is still all to play for too.:)

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
6 hours ago, bluearmy said:

Not sure how that’s ‘likely fact’ yet don ???

i would have thought MLB is just as likely and that could deliver cold periods 

A MLB is an even more shudder inducing thought than the alternative of wild and wet. If I'm not going to get any snow, I'd rather get some actual weather (I'm thinking severe gales, squall lines etc).

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19 hours ago, Don said:

I think the fact of the matter is we are likely to see another mild January. 

Not sure how you can jump to that extreme a conclusion, the models are not great at all at forecasting more than a week ahead. However, despite no SSW we still had substantial cold in December and already here in South Wales we are well below average temps again for a few days. In December we spent about two weeks with sub zero temps, now considering Met Office data shows average low through Jan and Feb for much of the UK (including here) is only zero degrees, our -9 was substantially below usual temps, and as colder here than it was in 2010, although not as cold for as long we still had two weeks of -2 and -3 with wind chills much lower which is again for December well below even the Jan and Feb average lows. Snow was good, not as good as 08, 09 and 2010 but was near a foot at about 200m which lasted days.

Today it will be down to -2 and tomorrow about -3 (forecasts keep changing), so we don't need an SSW event to get cold and snow, considering we had all that before winter technically started on 21st of December we still have plenty of time and as I said, as for the models they ain't got nothing nailed for more than 5 or 7 days so January is far from written off.

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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

No disagreement amongst the GEFS members in the overnight output (0z 28th Dec), with all 21 members now forecasting a stronger-than-average Vortex (10hPa 60N) by 12th Jan. The zonal mean zonal wind is currently 43.8 m/s and the forecast for 12th Jan is 59 m/s.

Today: 5a449d4da7a3f_WICGEFSZonalwindtemp0z28Decfor28Dec.thumb.png.2950cd4973cda97294074a9f75de1956.png 12th Jan: 5a449d67f189b_WICGEFSZonalwindtemp0z28Decfor12Jan.thumb.png.80858b95948dcb1f9ed675bb866d06ff.png

Wave 2 activity forecast for around the 8th Jan, but on this occasion this doesn't seem enough to disturb the upper strat at 10hPa? (Any comments/views on this last point would be welcomed please).

5a449d9933715_WICGEFSWave2byLat0z28Decfor08Jan.thumb.png.12a1a75a962efd5ba977ce4c32130696.png5a449da694f01_WICGEFSWave20z28Decfor08Jan.thumb.png.bb9160e7a1a5a66ad7284c96fc4ecac1.png

Charts http://weatheriscool.com/

 

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Posted
  • Location: st albans
  • Location: st albans

Doesn't look good does it! The ec does show the zonal flow relaxing somewhat up top by day 10 but so does the gefs and they then reboot it.  Lower down and the flow to 100hpa looks pretty solid. 

the trop output at day 16 doesn't show too many compact hemispheric raging vortices so coldies have to hope that the same is true post the second surge or that some strategically placed wedges do the trick for nw europe

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Posted
  • Location: Hertfordshire
  • Location: Hertfordshire
4 hours ago, Blessed Weather said:

No disagreement amongst the GEFS members in the overnight output (0z 28th Dec), with all 21 members now forecasting a stronger-than-average Vortex (10hPa 60N) by 12th Jan. The zonal mean zonal wind is currently 43.8 m/s and the forecast for 12th Jan is 59 m/s.

Today: 5a449d4da7a3f_WICGEFSZonalwindtemp0z28Decfor28Dec.thumb.png.2950cd4973cda97294074a9f75de1956.png 12th Jan: 5a449d67f189b_WICGEFSZonalwindtemp0z28Decfor12Jan.thumb.png.80858b95948dcb1f9ed675bb866d06ff.png

Wave 2 activity forecast for around the 8th Jan, but on this occasion this doesn't seem enough to disturb the upper strat at 10hPa? (Any comments/views on this last point would be welcomed please).

5a449d9933715_WICGEFSWave2byLat0z28Decfor08Jan.thumb.png.12a1a75a962efd5ba977ce4c32130696.png5a449da694f01_WICGEFSWave20z28Decfor08Jan.thumb.png.bb9160e7a1a5a66ad7284c96fc4ecac1.png

Charts http://weatheriscool.com/

 

Perhaps the theory that a negative or easterly QBO = weaker vortex, needs to be re-examined along with the idea that a stronger vortex would lead to greater significance or impact when split etc. The trouble with this theory is that a much stronger vortex is of course that much harder to disturb.

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4 hours ago, Blessed Weather said:

Wave 2 activity forecast for around the 8th Jan, but on this occasion this doesn't seem enough to disturb the upper strat at 10hPa? (Any comments/views on this last point would be welcomed please).

The vortex is going to grow in size. Wave heights increase as the zonal winds increase up to a point but if the wind is too strong they can't penetrate the vortex. It will take sustained pressure and wave breaking (beyond the modeled time period) to reduce the vortex area and zonal winds to make it vulnerable.

Edited by Interitus
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Posted
  • Location: st albans
  • Location: st albans
2 hours ago, knocker said:

 

If the gefs don't soon begin to hone in on a pretty compact strong vortex then will seem a bit odd?? Plenty of 12z members show either HLB evident or v amplified patterns

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
33 minutes ago, chionomaniac said:

HNY to all.

I may just throw it out there, but the day 10 pattern (mean EPS) is a classic precursor - Alaskan and Scandi high - for a wave 2 type SSW. It seems that the GEFS are starting to show similar H500 anomalies.

If so, then I suspect the chances for a strat warming and vortex split will increase.

Timing wise that would probably lead to significant strat PV disruption by the end of the month and a possible SSW too.

If it is going to happen then we should keep a check on the temps at 1hPA from around the 20th Jan onwards as the first signs of the vortex disruption will occur from then onwards and in this case start at the top of the strat and downwell.

Keep an eye on the EAMT graphs as well.......

Happy new year Chino :)

I had a feeling there might be movement on this front - and right on cue the maestro returns!!

 

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Posted
  • Location: st albans
  • Location: st albans
53 minutes ago, chionomaniac said:

HNY to all.

I may just throw it out there, but the day 10 pattern (mean EPS) is a classic precursor - Alaskan and Scandi high - for a wave 2 type SSW. It seems that the GEFS are starting to show similar H500 anomalies.

If so, then I suspect the chances for a strat warming and vortex split will increase.

Timing wise that would probably lead to significant strat PV disruption by the end of the month and a possible SSW too.

If it is going to happen then we should keep a check on the temps at 1hPA from around the 20th Jan onwards as the first signs of the vortex disruption will occur from then onwards and in this case start at the top of the strat and downwell.

Keep an eye on the EAMT graphs as well.......

Don’t upset Judah again ed ...........

he seems a bit precious sometimes ! 

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
9 minutes ago, bluearmy said:

Don’t upset Judah again ed ...........

he seems a bit precious sometimes ! 

I found that a bit odd. Anyway, it will be interesting to see how the strat behaves if these trop HL blocks do develop. I know what I expect to see but predicting a possible SSW 4 weeks in advance is a risky business, lol.

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