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From what I have seen normally the geopotential height (GPH) is related to the strength of the

warming seen in the stratosphere but this seem to me to be out of sinc on the GFS 12z run.

As you can see from the charts below, the GPH charts show almost a split vortex at the 10mb,

30mb and even 100mb level where as the warming is mediocre to say the least.

post-10506-0-42398800-1388857935_thumb.g post-10506-0-29354500-1388857972_thumb.g

post-10506-0-88551400-1388858047_thumb.g

 

It may well be as Bluearmy says, that with a stretched and weakened vortex the warming and

forcing need not be that strong for HLB's to form.

Personaly I think the warming shown on the instant weather maps is wrong and should be

stronger or the GPH charts are wrong.

I also agree with other posters in that the talk of big pattern change etc and my forecasts of

another Feb 91 were very premature although there may be enough amplitude from the

warming forcast for a colder and hopefully wintrier pattern to take hold.

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From what I have seen normally the geopotential height (GPH) is related to the strength of the

warming seen in the stratosphere but this seem to me to be out of sinc on the GFS 12z run.

 

It may well be as Bluearmy says, that with a stretched and weakened vortex the warming and

forcing need not be that strong for HLB's to form.

Personaly I think the warming shown on the instant weather maps is wrong and should be

stronger or the GPH charts are wrong..

 

Don't forget that the GPH is proportional to the summation of the (virtual) temperature from the ground to that pressure so depends on the various thicknesses to that height. So a warming between 20mb and 10mb will raise the 10mb height but then so would a warming and increase in thickness between 1000mb and 500mb for example. There might be a challenge for Recretos to create some thickness charts from the stratosphere NWP forecast data Posted Image

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Hi to all (my first message on the forum, read you all long time and decided to post here)

 

Question: Can we compare this winter stratosphere to the one we had in 1983 first 2 months? (vortex position and zonal wind)

 

Welcome to the forum Agreste.Posted Image 

 

A great reanalysis site here where you can create composites for years gone by.

 

Daily Climate Composites

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There might be a challenge for Recretos to create some thickness charts from the stratosphere NWP forecast data Posted Image

 

What thickness exactly are we talking about here? What levels? :)

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

 

Well, it's a bit of a status quo. According to GFS, the vortex remains under wave-2 pressure at least the coming 240hrs. Chances are that it is allowed to breathe a bit more easily after this, and will ramp up temporarily in wind speed, gph, and temperature, like Chionomaniac said. I doubt it will ramp up to berserk-mode like we've seen last December. 

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A much better 12z GFS, looks like another split again.

 

Posted Image

 

 

It is.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2014010512&var=HGT&lev=10mb&hour=336

 

 

From right up top.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2014010512&var=HGT&lev=1mb&hour=384

 

The reformed vortex at 30mb is split again.

 

Posted Image

Edited by feb1991blizzard
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The latest GFS12z run strengthens the warming compared to recent runs with a renewed

warming over the pole at the end of the run.

Below.

Taking the 30mb level of the stratosphere as an example you can clearly see the difference

in temperature profile at present to what is forcast at the end of the run. It is often at this level

on down that can have big implications on our tropospheric weather.

Again this is just a forecast and a long way out.

post-10506-0-53142100-1388942730_thumb.g   post-10506-0-56342300-1388942752_thumb.g

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Sebastiaan, you recently asked (I can't find the exact post) what underlies the connection between EQBO/solar minimum vs. WQBO/solar maximum and the chances of Major Warmings under these conditions. With solar flux peaking over 200 today -and likely to stay high/increase over the coming days- I found this a very relevant question. Does anyone here know the exact mechanism? Sunspot number  (#) is currently at 178. Similar years in terms of QBO and january sunspot number, ie. 57/58 (#203) and 78/79 (#167), featured major warmings in february.

 

Labitzke ends the 2005 summary paper with the following conclusion:

 

" The result of this paper is the introduction of the constructed annual mean of the solar cycle–QBO relationship. The differences of the solar signal in the two phases of the QBO are large and it is therefore necessary to stratify the data according to the phase of the QBO, in order to find the mechanism which transfers the direct solar signal from the upper stratosphere down to the lower stratosphere and to the troposphere. This new approach of an analysis of the solar signal may be useful for the interpretation of future model results."

 

 

Before doing any extensive digging in the literature, is anyone familiar with more recent papers adressing the same question?

 

Cheers,

 

Ruben

 

ps.: GFS12z indeed looks better. In the strat, at least. 

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A USLM (Upper Strat/lower Meso) disturbance looks to be developing. From studies, this would indicate there is a 33% chance of major SSW within 14 days +/- 2  from this point. 

 

Posted Image

 

To read more about USLMs, check out this study. 

 

http://www.academia.edu/4056817/A_climatology_of_polar_winter_stratopause_warmings_and_associated_planetary_wave_breaking

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A USLM (Upper Strat/lower Meso) disturbance looks to be developing. From studies, this would indicate there is a 33% chance of major SSW within 14 days +/- 2  from this point. 

 

To read more about USLMs, check out this study. 

 

http://www.academia.edu/4056817/A_climatology_of_polar_winter_stratopause_warmings_and_associated_planetary_wave_breaking

 

Are you sure the conditions are all met?

 

"This regionally conï¬ned temperature enhancement near 2 hPa in Figure 1 is part of an upper stratosphere and lower mesosphere disturbance that includes an unusually low-altitude stratopause near 42 km (2 hPa), a stratopause temperature in excess of 290 K (50 K above nominal conditions), a ~40 K cooling in the mesosphere near 75 km, and an undisturbed lower stratosphere [e.g.,Labitzke, 1972; von Zahn et al., 1998; Meriwether and Gerrard, 2004; Thayer and Livingston, 2008]. This thermal structure has been observed over the years and termed a “stratopause warming â€[ Duck et al., 2000; Braesicke and Langematz, 2000], "

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Yes, this is mainly the difference in the QBO between these two years. Posted Image Nonetheless, looking at the 20.12-30.12 periods, the 2013 was still a bit stronger than 2008. 

 

Thanks recretos for the reply and for displaying the comparison is such a clear manner. I thought I'd wait for the official qbo December figure to come in before replying, and u are indeed correct - December 2013 came in higher than both November 2013 and December 2008. In fact our strongest December qbo value since the NOAA records start in 1948.

Let's hope labitzke and her solar flux are correct :)

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Sebastiaan, you recently asked (I can't find the exact post) what underlies the connection between EQBO/solar minimum vs. WQBO/solar maximum and the chances of Major Warmings under these conditions. With solar flux peaking over 200 today -and likely to stay high/increase over the coming days- I found this a very relevant question. Does anyone here know the exact mechanism? Sunspot number  (#) is currently at 178. Similar years in terms of QBO and january sunspot number, ie. 57/58 (#203) and 78/79 (#167), featured major warmings in february.

 

 

Thanks Ruben for repeating this question. I really wonder what the underlying mechanism is. Seems to me important, with the high solar flux.

 

 

Thanks recretos for the reply and for displaying the comparison is such a clear manner. I thought I'd wait for the official qbo December figure to come in before replying, and u are indeed correct - December 2013 came in higher than both November 2013 and December 2008. In fact our strongest December qbo value since the NOAA records start in 1948.

Let's hope labitzke and her solar flux are correct Posted Image

Fingers crossed! Right now a solar flux around 220! average for this month (I know just 5 days) 187!

Edited by sebastiaan1973
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Are you sure the conditions are all met? "This regionally conï¬ned temperature enhancement near 2 hPa in Figure 1 is part of an upper stratosphere and lower mesosphere disturbance that includes an unusually low-altitude stratopause near 42 km (2 hPa), a stratopause temperature in excess of 290 K (50 K above nominal conditions), a ~40 K cooling in the mesosphere near 75 km, and an undisturbed lower stratosphere [e.g.,Labitzke, 1972; von Zahn et al., 1998; Meriwether and Gerrard, 2004; Thayer and Livingston, 2008]. This thermal structure has been observed over the years and termed a “stratopause warming â€[ Duck et al., 2000; Braesicke and Langematz, 2000], "

Yes in the study I linked shows a 15 K above normal. section 2.2 paragraph [10]
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I think it's fair to say we won't see an SSW from this current wave breaking, GFS has backed off completely. Zonal winds have weakened as a result of this event though, and this should make the vortex more vulnerable to splitting when we get the next wave breaking event.

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Twitter is a hoot just now as US media coverage of the polar vortex goes into overdrive. Read a post yesterday where the news had run with a story - What to do if you are caught in one???
 
 

 

 

Hahaha! I apologise for the off topic start to this post but that is absolutely brilliant. I'm starting to think we should collate all the ridiculous media overhype and mis-use of terminology they clearly don't understand and form some sort of weather stand up comedy tour.

 

Posted Image

 

E-P Flux forecast direction still looking better going forward but with the sharp decrease in overall flux as wave activity starts to wane in 10 days time we now await to see where the next stage of wave activity comes from. Given repeated tropospheric projections of a Scandinavian ridge my guess would be that we won't be too far away from seeing another bout of strong wave 2 activity later in January which could land the killer blow.

 

SK

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