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something stirring in the strat. was pretty confident of a Canadian warming event this season. although less confidence now. so now its a race to get enough disruption to the polar vort

I've split posts from late September onwards into this thread, to make a fresh one for this year.   

Now showing up on the gfs op 

Posted Images

Noticed they have added a bias correction to the CFS runs on weather is cool

u10serie.thumb.png.e14c393969ad18f624d221d621778f25.png

I don't want that top one to happen. We don't want "POLAR VORTEX OF DOOM PART 2"

Notice how it also ramps up in the most convenient place too, as soon as December begins

Are they onto something again or is this a response to the last 2 winters when the vortex got its act together as soon as winter arrived

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On 22/09/2020 at 08:56, Daniel* said:

It’s quite interesting ECM 00z almost splits the vortex having a bit of a hard time so far.

0CC3C2C7-BEB9-424C-B5F1-31CFC21095B8.thumb.png.333f1b4e156ab8abe8bba4c0e3156fe2.png

We want the vortex split in winter, not now as it has plenty of time to get its act together again before winter

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1 hour ago, SqueakheartLW said:

Noticed they have added a bias correction to the CFS runs on weather is cool

u10serie.thumb.png.e14c393969ad18f624d221d621778f25.png

I don't want that top one to happen. We don't want "POLAR VORTEX OF DOOM PART 2"

Notice how it also ramps up in the most convenient place too, as soon as December begins

Are they onto something again or is this a response to the last 2 winters when the vortex got its act together as soon as winter

Even most of the bias corrected members are below average into December 🙂

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Recent years I think have brought a rather weak ragged vortex in November only for it to ramp into full gear come December, last year did this. We've had quite a few Novembers with spells of calm anticyclonic cold weather at times, 2013, 2016, 2017, 2019.

 

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2 hours ago, damianslaw said:

Recent years I think have brought a rather weak ragged vortex in November only for it to ramp into full gear come December, last year did this. We've had quite a few Novembers with spells of calm anticyclonic cold weather at times, 2013, 2016, 2017, 2019.

 

I think you mean slack cyclonic. Didn’t surpass 1020mb here until the 29th and the average SLP for the month was lower than all 3 winter months. Classic southerly jet stream.

Shame the PV suddenly blew up in December and sucked everything north again.

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13 hours ago, MR EXTREMES said:

jma showing some slight warming will this build further.

expecting some stratospheric action this year.

JN240-5.thumb.gif.1de5ac842dac9b56327d0f614e059a34.gif

'Ave Iiiit!!!

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Todays stratospheric zonal wind sets a date record for the weakest ever for 27/09 at 7.9M/S

Sadly the correlation between these date records & the strength of the subsequent DJF zonal wind is very low.

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18 hours ago, Steve Murr said:

Todays stratospheric zonal wind sets a date record for the weakest ever for 27/09 at 7.9M/S

Sadly the correlation between these date records & the strength of the subsequent DJF zonal wind is very low.

absolutely no surprise with the dominate heights in the northern hemisphere so far.

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On 26/09/2020 at 09:17, MR EXTREMES said:

jma showing some slight warming will this build further.

expecting some stratospheric action this year.

JN240-5.thumb.gif.1de5ac842dac9b56327d0f614e059a34.gif

Please not lets see endless T+384 strat charts again this year, it's a completely futile exercise. (Not aimed at you mate, there's a few that did it all the way through last winter, and it's completely pointless at that range).

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On 27/09/2020 at 11:59, Steve Murr said:

Todays stratospheric zonal wind sets a date record for the weakest ever for 27/09 at 7.9M/S

Sadly the correlation between these date records & the strength of the subsequent DJF zonal wind is very low.

Quite so Steve 7.9m/s in Mid December and we might be talking something interesting. Otherwise it means nothing at the moment.

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11 minutes ago, Broadmayne blizzard said:

Quite so Steve 7.9m/s in Mid December and we might be talking something interesting. Otherwise it means nothing at the moment.

Yes it's notable how quickly things can change in late Autumn. 

There has been plenty of recent October's with northern blocking but by late November the PV usually becomes dominant. 

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3 hours ago, phil nw. said:

Yes it's notable how quickly things can change in late Autumn. 

There has been plenty of recent October's with northern blocking but by late November the PV usually becomes dominant. 

In recent years we haven't quite achieved HP in the correct places to promote trop led blocking feedbacks. That has allowed the strat to dominate the trop as it strengthened.

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4 hours ago, CreweCold said:

In recent years we haven't quite achieved HP in the correct places to promote trop led blocking feedbacks. That has allowed the strat to dominate the trop as it strengthened.

Suspect the PV was weak throughout Autumns of 08, 09 and 10, lots of northern blocking in those years, also 12, any coincidence all four autumns were followed by cold or very cold winters, with all Decembers featuring some degree of cold, not so potent in 08 and 12 but it occurred in both years early on and later in 08, 09 notable cold second half, and 10 significant until the near end.

Recent Autumns, have featured relatively weak PV states, but as said not quite accompanied by the feedback needed to give it a proper bashing come start of the winter. End product has been lots of mid lattitude heights, or heights directly overhead especially in November or weaker heights to the north and cyclonic conditions overhead as happened last year. 

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1 hour ago, sebastiaan1973 said:

September 2020 7.95

https://psl.noaa.gov/data/correlation/qbo.data

We see the strengthening of the polar vortex.

ecmwfzm_u_f240.png

We also see the strengthening of the WQBO too to a moderate WQBO now. Guess that probably rules us out of an average weak WQBO for autumn 2020 then which is bad news for a colder winter unless the east based La Nina and low solar activity can override the WQBO signal

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3 minutes ago, SqueakheartLW said:

We also see the strengthening of the WQBO too to a moderate WQBO now. Guess that probably rules us out of an average weak WQBO for autumn 2020 then which is bad news for a colder winter unless the east based La Nina and low solar activity can override the WQBO signal

So many conflicting signals for the winter ahead!

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5 minutes ago, Don said:

So many conflicting signals for the winter ahead!

That's why I never pay 'signs' much attention, Don! Though, having said that, I did get a tad carried-away with the high expectations for winter 2018-19!:oldsad:

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