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Stratosphere and Polar Vortex Watch


Paul

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On 11/03/2020 at 16:32, mb018538 said:

To dig him out out on a forum that he can't see? 

Nah, his tweets are high quality, but splits in particular depend on fairly specific tropospheric patterns which are typically modeled wrongly at the end of a 16-day forecast. Of course it's more than reasonable to highlight the possibilities, but time and again when people make these forecasts in this thread they're invariably incorrect, Maybe because splits are seen as a bit of a holy grail by cold lovers, it's certainly not popular when it is suggested that it is an unlikely outcome!

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3 hours ago, knocker said:

The ecm at 10 & 50mb

ecmwf-deterministic-nhemi-t10_anom-4921600.thumb.png.14f9f81da1e034815d15416befdbf20f.pngecmwf-deterministic-nhemi-t50_anom-4921600.thumb.png.2b468c4a8f22a2788245f1568580356f.png

The action has been higher up, this chart shows GFS 1mb zonal wind from 8/3 when the forecast splits occurred, to 13/3 and actually wave 1 displacement has been indicated. For a number of days wind reversal stuck around the 240+ hr uncertainty range, but today's 00z and 06z brought it down to 231 and 201 hours respectfully -

1103247666_1mb8-13_3_20.thumb.png.d5d03379c150d14346ae31d428114cab.png

Doesn't look like having large effect at 10mb or below at the moment.

edit: Incidentally, does anybody else find those temperature charts slightly distracting with the multiple colour scales and repeated whites?

Edited by Interitus
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Posted
  • Location: st albans
  • Location: st albans

2020 finally loses its grip on the records at 10 hpa .....unlikely to return aswell ..... a drier and calmer period awaits nw Europe though whether that can be directly linked to a quickly declining upper spv isn’t proven .......

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Posted
  • Location: st albans
  • Location: st albans
6 hours ago, knocker said:

The 50mb is not dissimilar to the 500mb analysis

ecmwf-deterministic-nhemi-z50_anom-5008000.thumb.png.c70185a13bfb0147f15175406589e34d.png

10mb is a west Siberian high so I guess the answer is that the predicted strat drop off in intensity will be reflected low down 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

GFS has this now at T186:

image.thumb.jpg.dd800c817da2bf71c8722b5fff0e0262.jpg

I doubt for a stratospheric forecast, it is going to be wrong at this range.  Then the question becomes what is the trop response, when this vortex finally blows itself to bits just over a week from now?

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

Getting closer, GFS 12z at T162:

image.thumb.jpg.90acd6b0e4e0b42d2fb7982ff5375bf1.jpg

Looks to me like the last rites on the strat vortex for 2020.  What this means for us down here remains to be seen, but personally I would have preferred a slower transition to easterly winds in the strat, simply because it would probably impact the start of summer less. As it is, well.  Just a small part of the apocalypse, I guess.

Edited by Mike Poole
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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
11 hours ago, Mike Poole said:

Getting closer, GFS 12z at T162:

image.thumb.jpg.90acd6b0e4e0b42d2fb7982ff5375bf1.jpg

Looks to me like the last rites on the strat vortex for 2020.  What this means for us down here remains to be seen, but personally I would have preferred a slower transition to easterly winds in the strat, simply because it would probably impact the start of summer less. As it is, well.  Just a small part of the apocalypse, I guess.

I'm not so sure just yet...

image.thumb.png.f97ae4198e3e804b1e2b464b4e44d224.pngimage.thumb.png.b9db6c08b23373ae6e047644c25a37cb.pngimage.thumb.png.18aa836d048d6a8357f02b3b17d86798.png

Warming might be there, but it doesn't look like squashing it. All of the data today is still above average right into April.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

Yep... big warmth doesn’t necessarily equate to above-normal heights, when the vortex has organised the pressure gradients so strongly as it has this past month.

Going to take a lot to bring it down this spring, especially with the record-low ozone content within the vortex circulation. It’s that which warms majorly in response to UV radiation, helping to weaken the vortex.

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Posted
  • Location: Coniston, Cumbria 90m ASL
  • Weather Preferences: wintry
  • Location: Coniston, Cumbria 90m ASL
2 hours ago, Singularity said:

Yep... big warmth doesn’t necessarily equate to above-normal heights, when the vortex has organised the pressure gradients so strongly as it has this past month.

Going to take a lot to bring it down this spring, especially with the record-low ozone content within the vortex circulation. It’s that which warms majorly in response to UV radiation, helping to weaken the vortex.

Is that an impact of the low solar output, reduced ozone?

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
10 hours ago, JeffC said:

Is that an impact of the low solar output, reduced ozone?

Good question. Short answer no, longer answer:

Its a consequence of an exceptionally strong polar vortex walling off the air within its core so efficiently that the temperature of that air has dropped to unusually low levels for early springtime.

Ozone destruction occurs when temps are sufficiently low and the sun is above the horizon. It’s part of the formation process of polar stratospheric clouds (PSCs).

Usually, strat temps above the Arctic have risen too high by the time the sun returns to the Arctic stratosphere after the many months-long polar night - but this year they’ve still been cold enough.

So it is that the Arctic polar vortex has developed within it an ozone hole akin to - but still smaller and weaker than - the one that seasonally develops over the Antarctic each austral winter. An extraordinary event that last happened in 2011 but not to such a large extent.

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Posted
  • Location: Coniston, Cumbria 90m ASL
  • Weather Preferences: wintry
  • Location: Coniston, Cumbria 90m ASL
14 hours ago, Singularity said:

Good question. Short answer no, longer answer:

Its a consequence of an exceptionally strong polar vortex walling off the air within its core so efficiently that the temperature of that air has dropped to unusually low levels for early springtime.

Ozone destruction occurs when temps are sufficiently low and the sun is above the horizon. It’s part of the formation process of polar stratospheric clouds (PSCs).

Usually, strat temps above the Arctic have risen too high by the time the sun returns to the Arctic stratosphere after the many months-long polar night - but this year they’ve still been cold enough.

So it is that the Arctic polar vortex has developed within it an ozone hole akin to - but still smaller and weaker than - the one that seasonally develops over the Antarctic each austral winter. An extraordinary event that last happened in 2011 but not to such a large extent.

Thanks...is it just me or is everything weird at the moment?!

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On 16/03/2020 at 20:11, Singularity said:

Yep... big warmth doesn’t necessarily equate to above-normal heights, when the vortex has organised the pressure gradients so strongly as it has this past month.

Going to take a lot to bring it down this spring, especially with the record-low ozone content within the vortex circulation. It’s that which warms majorly in response to UV radiation, helping to weaken the vortex.

Mentioned this before, basically the strength of the vortex is related to the temperature gradient between the pole and the mid-latitudes, so simply put, pole colder than mid-lats = stronger vortex and vice versa. But interestingly, the 10mb zonal wind is more sensitive to temperature gradient at lower levels than at 10mb itself. Using the difference between the 80 and 50°N temperatures from MERRA reanalysis, over all days since 1979 the zonal wind correlation to 10mb temperature is 0.80, but with 30mb temperature it is 0.97 and 50mb it's 0.96. So while seeing a warming appearing at 10mb may hint at an SSW, a wind reversal at 10mb is unlikely if the warming doesn't progress to the 30mb level or below and reversing the temperature gradient there.

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

latest_cfs_u10.png

The end of the PV/final warming is currently progged for the 21st April at the moment. This has moved forward a few days from the 25th April in the last week. So after a brief recovery next week, it's down we go until we are back at easterlies around the 21st April.

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  • 2 weeks later...
Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
2 hours ago, knocker said:

Warming gently?

ecmwf-deterministic-nhemi-z10_anom-6044800.thumb.png.b87df55d30fbd5016861473b88944b08.pngecmwf-deterministic-nhemi-z50_anom-6044800.thumb.png.2199677be0fe8e9454cd5dea7c9541de.pngpolargmo.thumb.JPG.41efd48ead5b5ad411dd914e67f54592.JPG

Better news for warm summer lovers with a gentle warming leading to less chance of northern blocking establishing later in the spring/early summer?

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

I had kind of hoped for a benign Final Warming myself!

I could do with a long hot Summer ahead (plus plenty of evening/night Storms?) lockdown or no!

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Posted
  • Location: Netherlands
  • Location: Netherlands

We speculated about this back in October: another QBO disruption. EOF analysis of NCEP/NCAR 10-100hPa equatorial zonal winds shows no QBO progress since January. It will be fascinating to see where it goes from here.

 

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