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Stratosphere and Polar Vortex Watch

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4 hours ago, Kirkcaldy Weather said:

 

If you look at the NAM index tweeted & compare it with the tweet from simon lee you can see that the GFS was a massive outlier against the GEFS mean - so that means the above chart will only represent the operational viewpoint.

There is no chart constructed for the NAM for the GEFS mean -

There are the elliptical diagnostics that will show each member - which would probably be a better indicator....

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Following on from the Simon Lee tweet, here is the GFS vs GEFS 12z ZMZW. Spot the GFS -

gfsvsgefs19112112.thumb.png.533019f5f4c81b0641e6b5bcd31c6195.png

And the 18z -

gfsvsgefs19112118.thumb.png.055a9314f43b09c0b9125144014d3a01.png

GFS not quite as strong towards the end but the ensembles shifting en masse towards the op.

Notable that under the suggested SPARC/SNAP criteria for assessing NWP skill, the GFS forecast wouldn't even register as a weak vortex -

snap.thumb.png.507b25855e467eadc6711ff5bc40e744.png

courtesy A. Charlton-Perez

 

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Following on from @interitus above, the 00z gefs have min mean flow around 15m/s 

certainly weaker than average but certainly not the drop most were anticipating ..... my thoughts revert back to Andrej’s comments a few days ago that the actual charts are more informative than the mean graphical representation???

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A quick glance at the 100, 50 and 30mb gph charts with the gfs at t192 suggests to my untutored eye, significant warming at 30mb, a tight vortex at 50mb and a reflection of the trop 500mb level at 100mb

2019112100_f192_30.nonenonehghtnonenone_nhem.gfs003.thumb.gif.15fd858440bad17f5478bad0c1963bfb.gif2019112100_f192_50.nonenonehghtnonenone_nhem.gfs003.thumb.gif.d015f77cfbc336af31b65fb6e941e118.gif2019112100_f192_100.nonenonehghtnonenone_nhem.gfs003.thumb.gif.4e14e6bb542c2503017b5b8bee57e015.gif

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Yep, a bit of a reversal (or not as the case may be) from a couple of days back.

Monday

u_60N_10hpa_gefs.thumb.png.9c1be5c2e76a1cdb10891d4347e05ea1.png

 

Today

u_60N_10hpa_gefs.thumb.png.ad22f31c8a419c5492fe1764f5587f46.png

 

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5 minutes ago, knocker said:

A quick glance at the 100, 50 and 30mb gph charts with the gfs at t192 suggests to my untutored eye, significant warming at 30mb, a tight vortex at 50mb and a reflection of the trop 500mb level at 100mb

2019112100_f192_30.nonenonehghtnonenone_nhem.gfs003.thumb.gif.15fd858440bad17f5478bad0c1963bfb.gif2019112100_f192_50.nonenonehghtnonenone_nhem.gfs003.thumb.gif.d015f77cfbc336af31b65fb6e941e118.gif2019112100_f192_100.nonenonehghtnonenone_nhem.gfs003.thumb.gif.4e14e6bb542c2503017b5b8bee57e015.gif

For ease of viewing they've halved the isopleths for the 30mb chart by doubling the contour interval so a misleading comparison.

The take-out from those charts may be how closely co-located the vortex centres are - little vortex tilt/baroclinicity and warming at that time.

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2 minutes ago, Interitus said:

For ease of viewing they've halved the isopleths for the 30mb chart by doubling the contour interval so a misleading comparison.

The take-out from those charts may be how closely co-located the vortex centres are - little vortex tilt/baroclinicity and warming at that time.

Yes I should have mentioned that.

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2 minutes ago, Interitus said:

And I perhaps should have called them isohypse 🙂

Funny you should mention that as my finger was just poised 😉

Edited by knocker

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There appears to be a pretty close relationship between max wave1 in November and NAO in December

https://publish.twitter.com/?query=https%3A%2F%2Ftwitter.com%2Fantmasiello%2Fstatus%2F1197347865481404417&widget=Tweet

Knipsel.thumb.PNG.8f3dd5a66a0ef4fd24c64f9962c99d19.PNG

Maximum wave 1 this November off the chart:

Knipsel3.thumb.PNG.414c37a80c5df7a298faf4350f77403e.PNG

Seeing some real continuation of the wave1 pattern in the upper layers of the stratosphere as new Eddy heat flux is generated over Russia.

Knipsel2.thumb.PNG.984272c1968a9b680c8c61a2dc48c402.PNG

Also because of the favorable conditions of the troposphere for blocking because of the solar minimum, we may expect a siginificant blocking signal next month over the Atlantic.

I am wondering if the displacement of the SPV will be enough for an official SSW, later next month. 

 

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2 hours ago, Paul123 said:

 

I am wondering if the displacement of the SPV will be enough for an official SSW, later next month. 

 

Got a feeling it will, it looks vulnerable to further attacks, certainly relative to the usual looking vortex in early December.

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GFS/GEFS zonal wind difference continues on 06z, though the ensembles have some support from the 00z GEOS

gfsvsgefs19112106.thumb.png.e7ce0d76bcb8746c36956a1610a374a9.png

Edited by Interitus

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17 minutes ago, Interitus said:

GFS/GEFS zonal wind difference continues on 06z, though the ensembles have some support from the 00z GEOS

gfsvsgefs19112106.thumb.png.e7ce0d76bcb8746c36956a1610a374a9.png

What is the x-axis scale on that chart? I initially assumed hours, but that can't be right. Is each tick 6 hours?

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6 hours ago, s4lancia said:

Yep, a bit of a reversal (or not as the case may be) from a couple of days back.

Monday

u_60N_10hpa_gefs.thumb.png.9c1be5c2e76a1cdb10891d4347e05ea1.png

 

Today

u_60N_10hpa_gefs.thumb.png.ad22f31c8a419c5492fe1764f5587f46.png

 

GEFS always overshoots the decrease a lot at the end of a run, it also overshoots the increases at the end of the run but not that much. In previous years in reality the speeds always oscillate up or down 

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1 hour ago, Yarmy said:

What is the x-axis scale on that chart? I initially assumed hours, but that can't be right. Is each tick 6 hours?

Yes, 6-hourly forecast times, just an unformatted rough and ready plot!

Edited by Interitus

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19 minutes ago, Kirkcaldy Weather said:

 

No SSW in any of those Decembers. Admittedly they occurred in early Jan 1970 and 1977 (end of February for 1983/4) but this and another tweet are emphasising cold Decembers i.e. prior to SSW.

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4 minutes ago, mushymanrob said:

i didnt think decembers of 69, 76, or 83 were particuarly cold...

They might have been in America though.

EDIT : who knows anyway, he might be referring to cold ENSO episodes or something else.

Edited by feb1991blizzard

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