Jump to content
Holidays
Local
Radar
Snow?
Sign in to follow this  
Paul

Stratosphere temperature watch - 2016/17

Recommended Posts

2 hours ago, Weather-history said:

What are the conditions for nacreous clouds to be seen from the UK? Any chances soon?

Not till next week Kevin (and I suggest we need clear skies !)

Share this post


Link to post
Share on other sites
On 1/15/2017 at 23:14, summer blizzard said:

Which other winters saw the double weakening?

Not as easy to answer as it might seem, depends on criteria for a weakening, whether the events are truly separate, is it a final warming etc. The Canadian warming in November wasn't a full SSW, minimum wind speed 7.6 m/s - there aren't any 10mb wind reversals in November in the MERRA data dating back to 1979. So if considering winters with a weakening <10m/s as a minor warming, and a full SSW, and ignoring March for possible final warmings (and probably too late to be of much interest) then there's -

1979/80, 2000/1 and 2009/10 with minor warmings followed by major

1981/2 and 2002/3 with major warming followed by minor.

Winters with two major warmings are rare but it occurred in 1998/9, whilst 2001/2 also had two SSW, and a fairly distinct minor warming sandwiched in between.

 

 

Share this post


Link to post
Share on other sites

Can anyone point me towards a historical site where I can view  strat height charts (10hpa to 50hpa).   (Want to see the upper strat charts evolution where we have seen a quick trop response to a SSW)

 

 

Share this post


Link to post
Share on other sites
5 hours ago, bluearmy said:

Not till next week Kevin (and I suggest we need clear skies !)

Yes, that will be the imortant thing! - the temperature conditions at 30mb look OK with -80C overhead from around the 24th - even colder in the north by the 27th going on latest ECM run. This does not dig as far south as last year so I wonder if opportunities will be as good over all the BI.

ecm0125_nat_gh30_t30_2017011700_240.png

3 minutes ago, bluearmy said:

Can anyone point me towards a historical site where I can view  strat height charts (10hpa to 50hpa).   (Want to see the upper strat charts evolution where we have seen a quick trop response to a SSW)

 

 

There's geopotential heights data on this site - back to 1958. Levels not as you asked but does 30mb, 100mb, 500mb and SLP. Available as 5 or 10 day segments, monthly and seasonal.

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/clisys/figures/db_hist_pen_tcc.html

 

 

Share this post


Link to post
Share on other sites
46 minutes ago, chionomaniac said:

or try here http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

The strat u mean wind and anomalies show right down to the troposphere

am trying to view the upper/mid strat height charts  when a quick trop response results and seeing if they display any particular pattern. we may see something at day 16 in the upper trop on the op and be able to deduce if would show anything lower down a few days later.   (assuming an ssw is going to verify which currently isn't certain)

Share this post


Link to post
Share on other sites
14 minutes ago, Summer Sun said:

 

Any timeframe for that Summer Sun? I presume end of the month?

Share this post


Link to post
Share on other sites
58 minutes ago, mountain shadow said:

Any timeframe for that Summer Sun? I presume end of the month?

Both charts are Feb 1st

Share this post


Link to post
Share on other sites

What would the time lag be anyone?

Sorry I mean for changes to work their way through to the trop.

And is there different time lags for different warming or the cause of warnings? 

Thanks.

Share this post


Link to post
Share on other sites

If one reads the rest of the tweets you get an idea of the answer to some of these question. For example regarding impacts on W; Europe Dr, Ventrice:

. "displacement events have been found to be less impactful for Eur.... You want a split"

Share this post


Link to post
Share on other sites

Been following the 1st of Feb for a few days now. Firstly the displacement of the strato pv had been more and more pronounced as we've ticked each run. Secondly  it's rapidly turning from a displacement to a complete destruction. As we go into Feb gfs is hinting at continual warming. 

If you then follow the 500 charts for that timeframe we very quickly see a noticeable change in buckling and out spilling of arctic air. Whether this is a coincidence or consequence it's too early to say. 

IMG_0719.PNG

Share this post


Link to post
Share on other sites

I think a more classic wave 1 displacement is more this. The pv remains intact but certainly still exists. 

IMG_0720.PNG

Share this post


Link to post
Share on other sites
6 minutes ago, Iceberg said:

Been following the 1st of Feb for a few days now. Firstly the displacement of the strato pv had been more and more pronounced as we've ticked each run. Secondly  it's rapidly turning from a displacement to a complete destruction. As we go into Feb gfs is hinting at continual warming. 

If you then follow the 500 charts for that timeframe we very quickly see a noticeable change in buckling and out spilling of arctic air. Whether this is a coincidence or consequence it's too early to say. 

IMG_0719.PNG

I think co incidence at this point - looking at the heights for the corresponding period and the vortex at 30 and 50 hpa not so displaced as at 10hpa 

doesnt look like a quick response downwelling if the strat heights are anything to judge this by (which is why I was asking where I could view historic height charts)

Share this post


Link to post
Share on other sites
11 minutes ago, Iceberg said:

I think a more classic wave 1 displacement is more this. The pv remains intact but certainly still exists. 

IMG_0720.PNG

The PV is still very much alive and kicking if you look at the geopotential heights chart and it is very much a displacement forecast. 

tempresult_fvy1.gif      g8KNV95.gif

I'm sure I read somewhere that an early CW can lead to a similar pattern in late winter. Is that what we might be seeing here?

Edited by Gael_Force

Share this post


Link to post
Share on other sites

It's a rise in dam though of about 45 from even a few days previous to that chart. From memory Those actual dam figures are very high for a winter pv centre at 10 hpa. 

Ie a pv with a lower dam centre is far stronger than a pv with a higher dam centre. 

Share this post


Link to post
Share on other sites

Here's the 100mb charts. The change in 100mb flow is evident. Higher dam figures. 

At the end of the run signs of a split pv at that level and a strong diving 100mb jet over the states, as opposed to the flat jet. 

All of this could change on the next run obviously but I would expect the 100mb layer to pick up soonest from the 10hpa. It could be a response to the earlier wave 1 activity. In which case as we move through Feb we see more and more response as the wave 1 activity increased through the second half of jan. ?

hand on heart I've not seen such a wave 1 enduced ssw in jan over the last 10 years so I honestly don't think anyone has much of a clue as to speed of propergation down and likely tropo response. 

IMG_0721.GIF

IMG_0722.GIF

Share this post


Link to post
Share on other sites
9 hours ago, Interitus said:

 

1979/80, 2000/1 and 2009/10 with minor warmings followed by major

1981/2 and 2002/3 with major warming followed by minor.

Winters with two major warmings are rare but it occurred in 1998/9, whilst 2001/2 also had two SSW, and a fairly distinct minor warming sandwiched in between.

 

 

Two major Sudden Stratospheric Warmings in both Winter 1998-99 and Winter 2001-02; neither of which were cold winters (Dec 2001 did, I recall, have some cold weather but it was certainly nothing apocalyptic, Jan and Feb 2002 were both mild and wet!). Winter 2002/03 was also milder than usual overall; though there were cold snaps in January and February 2003 these were hardly exceptional. It seems that you need more than Sudden Stratospheric Warmings to guarantee really severe winter weather in Britain.

For starters, the SSW needs to occur at high latitudes rather than over mid-latitudes in order to promote blocking in the right places to encourage cold-air advection over Britain; for instance SSW's over southern Canada are too far south and west to promote a high that would cause frequent Arctic incursions over the UK. There's been a good deal of high-pressure affecting Britain so far this winter, but clearly it is often in the wrong location to encourage cold: Currently where I live in the North Pennines it is mild (7C) with hill-fog at times. Other factors such as sea-surface temperature anomalies (and where these are) and Arctic pack-ice extent are also quite important as these will dictate where the jet-stream is with relation to the United Kingdom: If high-pressure often forms to the south or south-west and the polar-front jet is well to the north of the UK this hardly encourages the flow of Arctic or Siberian air-masses towards Britain.

Is has to be said that much of the activity that would seek to weaken the Stratospheric Polar Vortex seems to be little more than nibbling around the periphery. This will, of course, lead to high-pressure systems centred over 40 to 50N at times which can bring dry conditions to the UK but it won't deliver severe cold. If we are to have a Stratospheric disruption capable of delivering extreme cold to mid-latitude temperate margins (like in December 2010) it needs a big upper-level warm "explosion" working out  from the centre (i.e. over the Central Arctic). I cannot see that happening this winter because other factors, such as the extreme Westerly Phase of the Quasi-Biennial Oscillation and the relative warmth of the far North Atlantic encouraging a strong Polar Vortex well north of Britain along with the subtropical jet-stream remaining just a bit too high up and too far north to get severely retarded by the Himalayas/Pamirs (removing so much troublesome Westerly AAM), are all likely to prevent anything on that scale occurring high up over the central Arctic. 

Share this post


Link to post
Share on other sites

One has to remember that SSW's are currently defined by reversal of mean zonal mean winds at 10hPa and 60ºN. With displacement events then this can occur by a warming that 'knocks' the polar vortex off it's home but the vortex still maintains enough strength to recover quickly and regain pole position. Other displacement events if they are strong enough can complete destroy the vortex and leave a temporary complete reversal of mean zonal winds before the vortex recovers. It is the latter that will have a far greater chance of propagating downwards and have longer lasting trop effects.

I don't understand the notion of SSW's being a mid latitude or high latitude event, because by definition it occurs by reversal of the mean zonal winds at 60ºN - not by the positioning of stratospheric blocks.

@bluearmy have you looked at Martineau's site - it may be not quite what you want but you can analyse each event. http://p-martineau.com/ssw-animations/

Share this post


Link to post
Share on other sites
30 minutes ago, chionomaniac said:

I don't understand the notion of SSW's being a mid latitude or high latitude event, because by definition it occurs by reversal of the mean zonal winds at 60ºN - not by the positioning of stratospheric blocks.

@bluearmy have you looked at Martineau's site - it may be not quite what you want but you can analyse each event. http://p-martineau.com/ssw-animations/

I think wires have become crossed somewhere. The NOAA SSW compendium might also be a place to look @bluearmy

https://esrl.noaa.gov/csd/groups/csd8/sswcompendium/

@iapennell SSW event are so varied they have never been a sure thing for a cold UK. The ones you refer to did produce some severe cold in other parts of the world.

the feb 99 one.  SSWC_tsfcAnom30_JRA55_19990226.png

the feb 01 one. SSWC_tsfcAnom45_JRA55_20010211.png

 

 

Share this post


Link to post
Share on other sites

Well, the warming with this proposed event looks mighty impressive on the TWO format charts so I'll show the sequence because, well, it looks nice :laugh:

06_144_arctic10.png?cb=624 06_192_arctic10.png?cb=624

First warming kicks off days 5-6 and peaks days 7-8 having made good inroads toward the pole. Alone this would just be a sizable irritation to the vortex.

06_204_arctic10.png?cb=624 06_216_arctic10.png?cb=624 06_240_arctic10.png?cb=624

Second warming explodes into the 10 hPa level around day 9 (the left and middle charts are just 12 hours apart) with above-zero temps achieved by day 10 (may be a little overcooked given this is the 06z GFS - but the 00z was very similar, just 12 hours or so slower). Wrap-around of the vortex gets underway in earnest.

06_312_arctic10.png?cb=624 06_384_arctic10.png?cb=624

Vortex becomes severely displaced and stretched and I can see from the way the warm anomalies move that an anticyclone develops close to Alaska., at least for a time. Worth noting that down at 30 hPa the vortex spends the entire period days 4-16 locked into place near Siberia. This seems unusual, and as the elongation toward Canada is squeezed out by the warming, it seems the tropospheric N. Atlantic westerlies should find themselves lacking much support from above - but that may be too simplistic an interpretation.

npst30.pngnpst30.pngnpst30.png

 

Now, who's got access to 10 hPa geopotential height charts to help assess the true magnitude of this event being shown by GFS? TIA :good:

Share this post


Link to post
Share on other sites
15 minutes ago, Singularity said:

Well, the warming with this proposed event looks mighty impressive on the TWO format charts so I'll show the sequence because, well, it looks nice :laugh:

06_144_arctic10.png?cb=624 06_192_arctic10.png?cb=624

First warming kicks off days 5-6 and peaks days 7-8 having made good inroads toward the pole. Alone this would just be a sizable irritation to the vortex.

06_204_arctic10.png?cb=624 06_216_arctic10.png?cb=624 06_240_arctic10.png?cb=624

Second warming explodes into the 10 hPa level around day 9 (the left and middle charts are just 12 hours apart) with above-zero temps achieved by day 10 (may be a little overcooked given this is the 06z GFS - but the 00z was very similar, just 12 hours or so slower). Wrap-around of the vortex gets underway in earnest.

06_312_arctic10.png?cb=624 06_384_arctic10.png?cb=624

Vortex becomes severely displaced and stretched and I can see from the way the warm anomalies move that an anticyclone develops close to Alaska., at least for a time. Worth noting that down at 30 hPa the vortex spends the entire period days 4-16 locked into place near Siberia. This seems unusual, and as the elongation toward Canada is squeezed out by the warming, it seems the tropospheric N. Atlantic westerlies should find themselves lacking much support from above - but that may be too simplistic an interpretation.

npst30.pngnpst30.pngnpst30.png

 

Now, who's got access to 10 hPa geopotential height charts to help assess the true magnitude of this event being shown by GFS? TIA :good:

Instantweathermaps.com

doubt will be too impressive - just checked and vortex displaced to nw scandi as per Steve m's initial ens vista 

 

Edited by bluearmy

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...