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Stratosphere and Polar Vortex Watch


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Some useful tropospheric developments upcoming which are likely to have stratospheric impacts towards the end of November and more particularly into December. A strong convectively coupled tropic

so after many days the GFS & FNMOC & canadian finally now follow the Euro with 44 out 64 Members with a split at day 9- The ECM is day 8. We will call it - SSW & Split for 1st Ja

For all that watch the zonal winds. Let me urge you to look at the geopotential heights more. At least as far as weakening/strengthening trends go. Because as the polar vortex cries for help, you migh

Posted Images

The gfs ensemble now goes for a reversal at 10 hPa 60N. Z_temp_30hpa_384.thumb.png.5f8fbb88b63e9d647ac5d64f0e7d9f95.png

Still very far out in the forecast and latest GFS not as extreme, but it seems to be good agreement regarding the increased wave 1 activity, latest gfs shown below.336.thumb.png.78f5fee53f38e1b25211e6adece55583.png

216.thumb.png.d3c31a961c5915b5917933560d88613f.png

 Interesting times ahead!

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Brewer Dobson Unit analysis.

 

IMG_4538.thumb.GIF.fe779b6af2787ca87c9924e489eb229a.GIF

24/11/2017.

IMG_4536.thumb.GIF.bcc6f7c60492dbeb577e1f7992b4e7e4.GIF

25/11/2017.

IMG_4540.thumb.GIF.b3c9b1d836ef3b2e4b80ab26b57aece4.GIF

30/11/2014.

IMG_4538.thumb.GIF.fe779b6af2787ca87c9924e489eb229a.GIF

24/11/2010.

IMG_4538.thumb.GIF.fe779b6af2787ca87c9924e489eb229a.GIF

IMG_4541.PNG.3f35bfeedf4ebff847ecf1a1d597bdd6.PNG

 

Deviations of Ozone % in key geographical areas during both cold and mild NW European winters, I will let the reader decipher the differences on their own. 

 

IMG_4539.GIF

Edited by KyleHenry
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The obvious question from this is which leads which. Pattern is clear - but my knowledge of ozone impact on trop pressure patterns or the vortex above is weak. Does ozone concentration provide a forcing that helps alter the pattern, or is it simply reflective of a dominant pattern that shifts the ozone to suit?

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47 minutes ago, Catacol said:

The obvious question from this is which leads which. Pattern is clear - but my knowledge of ozone impact on trop pressure patterns or the vortex above is weak. Does ozone concentration provide a forcing that helps alter the pattern, or is it simply reflective of a dominant pattern that shifts the ozone to suit?

I'm observing ozone concentration in terms of relationship to other ongoing key factors. 

There is currently no Stratosphere/Troposphere coupling. 

Tropopause has extended In height through Autumn.

Low solar.

Northern Hemispheric Ozone concentration percentage is up in comparison to years without key factors.

Ongoing wave activity which will displace PV off default position.

Most significantly, less BDU above PV default position in atmosphere above Greenland results in less cooling, lessens convection at heights inside PV and in turn the PV is weakened by being unable to anchor at its default position. 

Noted that in years without these factors ozone transfer from Southern Hemisphere doesn't occur until mid Jan onwards. 

Ozone is not an overriding factor but in a specific alignment of key components, it becomes an assisting factor.

* Not inferring this winter will be like 2010. Using it as an extreme example. 

 

Edited by KyleHenry
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26 minutes ago, KyleHenry said:

 

Most significantly, less BDU above PV default position in atmosphere above Greenland results in less cooling, lessens convection at heights inside PV and in turn the PV is weakened by being unable to anchor at its default position. 

 

Ah - ok - this bit is particularly relevant. So it is a specific driver that impacts on vortex intensity and position. Best I add that to my teleconnective forecasting arsenal - I've rather ignored BDC when looking at pattern development. Rather good news then - and considerably better than 2010 especially if we want to see scandy heights rise also.

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Still rather impressive output this morning (GFS 06z in FI). Does anyone have any info on December SSWs? I believe there are rare and FU Berlin reports such events only in '87, '98, and 2001. These were not exactly impressive winters...

Edited by Ruben Amsterdam
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https://esrl.noaa.gov/csd/groups/csd8/sswcompendium/majorevents.html

Butler, A. H., J. P. Sjoberg, D. J. Seidel, and Karen H. Rosenlof, A sudden stratospheric warming compendium, Earth Syst. Sci. Data, doi:10.5194/essd-9-63-2017, 2017

Event Name NCEP-NCAR ERA40 ERA-Interim JRA-55 MERRA2 ENSO QBO 50mb
               
DEC 1965 8-Dec-65 16-Dec-65   18-Dec-65   E E
               
DEC 1981 4-Dec-81 4-Dec-81 4-Dec-81 4-Dec-81 4-Dec-81 N E
               
DEC 1987 8-Dec-87 8-Dec-87 8-Dec-87 8-Dec-87 8-Dec-87 E W
               
DEC 1998 15-Dec-98 15-Dec-98 15-Dec-98 15-Dec-98 15-Dec-98 L E
               
DEC 2001 2-Jan-02 31-Dec-01 30-Dec-01 31-Dec-01 30-Dec-01 N E
               
Total Events 36 29 24 37 23

Frequency: Events/Decade

6.2 6.4 6.5 6.4 6.4
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2 hours ago, Ruben Amsterdam said:

Still rather impressive output this morning (GFS 06z in FI). Does anyone have any info on December SSWs? I believe there are rare and FU Berlin reports such events only in '87, '98, and 2001. These were not exactly impressive winters...

Check out the SSW compendium for a full list of dates from reanalyses - https://www.esrl.noaa.gov/csd/groups/csd8/sswcompendium/majorevents.html

Since 1958 there have been 5 with 1981 perhaps most well known - winter 1981/2 was famously cold for the UK.

FWIW this forecast event is very similar to 1998.

edit: pipped to the post, lol

Edited by Interitus
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17 minutes ago, Interitus said:

1998

dec98.thumb.gif.c2c116dc97c1f9032d0edd7e2a7c3167.gif

 

That was a really sucky winter, as were 1960, 68, 77, 88,  and 2004 (winters with december or early to mid January warmings) 

Edited by ArHu3
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2 hours ago, Interitus said:

Check out the SSW compendium for a full list of dates from reanalyses - https://www.esrl.noaa.gov/csd/groups/csd8/sswcompendium/majorevents.html

Since 1958 there have been 5 with 1981 perhaps most well known - winter 1981/2 was famously cold for the UK.

FWIW this forecast event is very similar to 1998.

edit: pipped to the post, lol

Would I be correct in stating this would also be a Canadian Warming? I.e. anomalies in early winter in the Canadian sector are Canadian Warmings, but only some of these also classify as a full-SSW?

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2 hours ago, ArHu3 said:

That was a really sucky winter, as were 1960, 68, 77, 88,  and 2004 (winters with december or early to mid January warmings) 

Has the state of the tropospheric vortex at time of Canadian warming event taking place been considered?

For instance this was from December 1998, looks far more organise than it does now

NOAA_2_1998121518_1.png

Edited by Weather-history
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21 minutes ago, Weather-history said:

Has the state of the tropospheric vortex at time of Canadian warming event taking place been considered?

For instance this was from December 1998, looks far more organise than it does now

NOAA_2_1998121518_1.png

Nope, this was just looking at major warmings and hellmann number (in De Bilt but that location seems to be a reasonable reference here on this forum) 

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npst30.png npst30.png npst30.png
npst30.png npst30.png npst30.png

The 30 hPa sequence from the GFS 12z. Great consistency with previous runs, and the kick-off moving closer in time rather than being put back to stay at the same range each day.

The scale of vortex displacement and stretching depicted looks sufficient to my eyes for encouraging a tropospheric reverse zonal flow response (after approx. 14-20 day lag) across N. Eurasia, likely including much or all of the UK.

We can easily see, however, the risk that exists should the event not reach this magnitude; the reverse zonality line ends up drawn NW of the UK, much as was the case during the middle part of the week just gone but for a longer period, and we're stuck with unsettled conditions and temps between near average and very mild depending on the trough orientation.

So my interpretation is "high risk, high reward" when going along this route.

Has EPS been suggesting (or at least hinting at) anything like this magnitude and configuration of warming and height rises?

ecmwf50f240.gif ecmwf30f240.gif

I can see something in the works on the ECM day 10, although that was based on yesterday's 12z and I imagine the 00z produced something more pronounced based on the tropospheric charts? TIA

 

Edited by Singularity
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1 hour ago, Singularity said:

npst30.png npst30.png npst30.png
npst30.png npst30.png npst30.png

The 30 hPa sequence from the GFS 12z. Great consistency with previous runs, and the kick-off moving closer in time rather than being put back to stay at the same range each day.

The scale of vortex displacement and stretching depicted looks sufficient to my eyes for encouraging a tropospheric reverse zonal flow response (after approx. 14-20 day lag) across N. Eurasia, likely including much or all of the UK.

We can easily see, however, the risk that exists should the event not reach this magnitude; the reverse zonality line ends up drawn NW of the UK, much as was the case during the middle part of the week just gone but for a longer period, and we're stuck with unsettled conditions and temps between near average and very mild depending on the trough orientation.

So my interpretation is "high risk, high reward" when going along this route.

Has EPS been suggesting (or at least hinting at) anything like this magnitude and configuration of warming and height rises?

 

GFS 12z seems to be a bit extreme, some more images shown below, but GFS ensemble also has a very strong signal with a majority of the members now going for a reversal at 10 hPa 60N.

umedel60.thumb.png.c037a7376bc150069daaa2df1446c576.png28.thumb.png.fdd7cccf0d0b6227e303bba29a134c5f.pngu10serie.thumb.png.ac1900b847df2ca614f2c0f5ccef55b4.png

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