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At 30mb, where the temperature has been low to very low all month, a very similar minimum temp profile to that level with Dec'90 which averaged -82.7 up against December'13 which averaged -83.3.

 

Not sure that the 30mb minimum temperature is a good long term predictor of SSW. With regards to 1990 in particular yes the average minimum is quite close to December 2013 but the trend is actually not very similar with a correlation of 0.209.

Comparing 30 day periods by the sum of the square of daily differences to give a value where the smaller total = greater the similarity, the closest matching December to 2013 was 2004 followed by 1980 - this is reflected also in correlations of 0.890 and 0.790 respectively. These two winters are also QBO westerly and without full SSW but with minor warmings in February and reversals in March.

However, looking at the 100 closest 30-day winter periods to each month and then the following 30-day 60°N 10mb minimum zonal wind shows that only 7% of those closest to December 1990 were followed by an SSW within 30 days, compared to 16% for Dec 2004 and 23% for Dec 1980 so being more similar to these months may not necessarily be bad.

SSW followed in 15% of the time spans most similar to Dec 2013 and the closest single 30-day period up was 30/1/2007 which averaged only 0.05°C difference at a correlation of 0.880 and was followed by an SSW a little over three weeks later on 22/02

 

Briefly, though wave fluxes are heading in the right direction, applying the same method to the zonal wind data, it is noticeable that for those periods closest to December 2013 for the 50, 30 and 10mb levels, only between 2-3% were followed by an SSW within 30 days - possibly suggesting that it could be into February for any major warming.

Edited by Interitus
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I guess no ones going to answer my question how reliable are these models at such far out time periods? Can anyone answer?

 

I somehow missed your post yesterday. Posted Image

 

I already answered that question in the topic from last season. Posted Image

But to give you a summary: The GFS 300-384 mid-upper stratosphere forecasts, are generally as "reliable" as 500mb forecasts in the 6-8 day range. But since the stratosphere has its features on a much larger scale compared to the troposphere, the skill scores can automatically be a bit higher due to the verification process. 

Edited by Recretos
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good evening

northern hemisphere ( 50 mb => ~20000 m )
loop

Posted Image

===

sorry my off topic question

no like here my posting ?

I have posted several link here ( no good ? )

or is the problem my english ? Posted Image

 

kind regards

gino

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for recretos

what you think ( your great models ) for next few days

for region mediterranean sea ( sicily ) ... my original home

buccheri ( siracusa ) ... thanks !
 

 

as I said already if you need any specific day-to-day

or month-to-month comparisons from 1000mb to 1mb ( and some to 0.1mb)

just say so. I can plot it and I'm sure it would be interesting for others too

 

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I somehow missed your post yesterday. Posted Image

 

I already answered that question in the topic from last season. Posted Image

But to give you a summary: The GFS 300-384 mid-upper stratosphere forecasts, are generally as "reliable" as 500mb forecasts in the 6-8 day range. But since the stratosphere has its features on a much larger scale compared to the troposphere, the skill scores can automatically be a bit higher due to the verification process. 

Cheers that sounds pretty impressive to be honest.

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This strat vortex is proving be rather tougher than fi gfs envisaged. Berlin this morning looks ok at day 10 and similar to gfs at that timescale re the shape. According to gfs , the vortex will regroup somewhat and then we require another set of wave breaking to begin the process whereby the split will occur. (In line with ed's thoughts? )

What has become apparent over the past few days is the way that the reduction in zonal winds at the top of the strat pushes down into the middle strat thus zonal winds in this part of the atmosphere remain quite high. They are not increasing - fairly consistent. the problem comes even further down in the trop. Up till now, we have seen the middle and upper strat zonal winds flying along whilst way down in the trop above 70N, flow has been negligible and even reversed. it now looks as though the pressure from the warming at the top of the strat, is flushing the zonal wind momentum further down and subsequently, removing this negative polar profile in the trop. Extrapolating this would mean we lose our neg -AO and maybe see a more traditional zonality, further north than we've become used to, for a period with MLB possible.

Not sure this fits in with a lot of mid range forecasting but wouldn't it be ironic if the very process which we looked to in order to bring us wintry conditions, removes the neg -AO which presented us with possibilities for the middle part of January. Of course that may just be a lost battle in the winning of the war but all that lies in the future and we have our polar high NOW!

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The positive anomaly begins already at the 1mb level. just noting the warming has begun to an extent :-)

I see, thanks.

 

I was away for a few days and what I notice now is that the warming at the 30hpa level has been downgraded especially over the North Atlantic/south Greenland area and the vortex continues to rule.

 

Karyo

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Disappointing strat runs this morning especially from the GFS considering what we were

looking at just 3 days ago.

post-10506-0-24532600-1388828234_thumb.g  post-10506-0-73853700-1388828414_thumb.g

Rather than the vortex being to strong and harder to break down I think that the

forecasted warming is now far weaker than first projected with the stronger wave 2

on our side of the pole very much diminished from what was originally forecast. 

The stratosphere forecasts on the Berlin site show the same with a stronger warming on

the Siberian side and very little on our side.

This may be linked to the MJO which has died since entering phase 5.

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hi to all

 

MJO ( Madden Julian Oscillation )

current MJO forecast ( 2014 )

 

Posted Image

 

Posted Image

 

Posted Image

 

Posted Image

 

Posted Image

 

note: all cpc websites fron noaa ncep are offline ( no open => www )

why ?

Edited by aginob
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Disappointing strat runs this morning especially from the GFS considering what we were

looking at just 3 days ago.

Posted Image1mb 01.01.14.gif  Posted Image10mb 384 01.01.14 w.gif

Rather than the vortex being to strong and harder to break down I think that the

forecasted warming is now far weaker than first projected with the stronger wave 2

on our side of the pole very much diminished from what was originally forecast. 

The stratosphere forecasts on the Berlin site show the same with a stronger warming on

the Siberian side and very little on our side.

This may be linked to the MJO which has died since entering phase 5.

Our hopes for a cold second half of January are fast diminishing now.

 

Karyo

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Our hopes for a cold second half of January are fast diminishing now.

 

Karyo

 

really karyo? why so ?  the strat vortex will be weakened and likely no longer strong enough to be considered to be prohibitive of HLB in the trop. 

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really karyo? why so ?  the strat vortex will be weakened and likely no longer strong enough to be considered to be prohibitive of HLB in the trop. 

Because the warming doesn't seem to reduce the vortex strength significantly! If the warming was still looking as good as in the 6z GFS of 1st Jan then I would be much more positive. I mention that GFS stratospheric run because it was the last one I saw until last night. The downgrade is significant I'm afraid and if you look at today's 6z you will see that if anything the vortex is gaining strength by the end of the run.

 

Karyo

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Mean zonal winds forecast do show a slowdown at the very top but no real effect further down in the 10 day period.

post-2026-0-98615600-1388844246_thumb.gi

 

just a very slight easing at 10 and 30hPa.

 

Still plenty of wave breaking showing around the periphery squeezing the upper core but as yet not disrupting it.

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=ta1&lng=eng

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=ta2&lng=eng

 

Just a few images of the different levels from the GFS T240hrs.output showing the vortex seeing some continuing squeeze either side but the centre still very much intact.

post-2026-0-14337400-1388844849_thumb.gipost-2026-0-03322400-1388844856_thumb.gipost-2026-0-11315700-1388844865_thumb.gi

 

Unfortunately we have had an extremely cold Stratosphere over the pole and looking at the 30hPa 10day forecast it's still showing a very cold centre

 post-2026-0-59510300-1388845327_thumb.gipost-2026-0-38209700-1388845123_thumb.gi

 

so like a boxer-an analogy i have used before i know-he's started out much stronger than some previous years and will need more punches from wave breaking to get him to topple.

Edited by phil nw.
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I see, thanks.

I was away for a few days and what I notice now is that the warming at the 30hpa level has been downgraded especially over the North Atlantic/south Greenland area and the vortex continues to rule.

Because the warming doesn't seem to reduce the vortex strength significantly! If the warming was still looking as good as in the 6z GFS of 1st Jan then I would be much more positive. I mention that GFS stratospheric run because it was the last one I saw until last night. The downgrade is significant I'm afraid and if you look at today's 6z you will see that if anything the vortex is gaining strength by the end of the run.

Karyo

I agree. The double-sided (Asian and Atlantic) warmings we saw a while back are no longer as potent in recent runs. The attacks/warmings appear unable to penetrate the vortex (and get stranded in the surf-zone) and instead either subdue or circle around the vortex (conform the last two GFS runs; ofc. FI). Overall we can expect a reduction in mean zonal winds (except perhaps in the lower strat/trop at 70°NB, mentioned above), but I am less enthusiastic about our chances on a split/SSW within 14 days than I was at New Years Eve. Let's hope for January that the reduction in zonal wind is sufficient for some ML/HL blocking supported by the lower strat.

Posted Image

Edited by Ruben Amsterdam
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That GFS6h run was extreme. Perhaps some false expectations? Seemed to me (reading all interesting stuff over here) it would be a long term to knock the 'boxer' down (a muhammad ali stratosphere)

 

December 2013 achieved around 150 solar flux.

 

Since Christmas the solar flux rises again and yesterday around 180!

post-10577-0-29979600-1388848959_thumb.p

Edited by sebastiaan1973
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I agree. The double-sided (Asian and Atlantic) warmings we saw a while back are no longer as potent as in recent runs. The attacks/warmings appear unable to penetrate the vortex (and get stranded in the surf-zone) and instead either subdue or circle around the vortex (conform the last two GFS runs; ofc. FI). Overall we can expect a reduction in mean zonal winds (except perhaps in the lower strat/trop at 70°NB, mentioned above), but I am less enthusiastic about our chances on a split/SSW within 14 days than I was at New Years Eve. Let's hope for janaury that the reduction in zonal wind is sufficient for some ML/HL blocking supported by the lower strat.  

 

 

 

What are the chances of the Vortex revving back up again?

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That GFS6h run was extreme. Perhaps some false expectations? Seemed to me (reading all interesting stuff over here) it would be a long term to knock the 'boxer' down (a muhammad ali stratosphere)

 

Let's hope for a knock-out in the third round ;)

 

December 2013 achieved around 150 solar flux.

 

Since Christmas the solar flux rises again and yesterday around 180!

 

According to NOAA, solar flux will increase the coming days (185-190). 

 

Penticton 10.7 cm FluxObserved 03 Jan 182Predicted 04 Jan-06 Jan 185/185/19090 Day Mean 03 Jan 146

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