Storm Australian Severe Weather Forum
Severe Weather Discussion => General Weather - all topics not current severe weather. => Topic started by: phix on 12 September 2008, 10:24:24 AM
-
maybe someone is interested ...
i would like to discuss the formation and passage of a pronounced sqall line over eastern Austria in June 2007.....
21 June 2007 was a hot summer day in Austria, with temperatures in the mid 30`s during the afternoon.
the synoptic situation shows a pronounced trough over the eastern Atlantic resulting in a pronounced warm southwesterly flow over the eastern alps. a weak cold front was approaching from the west and supposed to pass the region during the evening.
(http://www.phix.cc/pics/post_gew/gfs.gif)
The Vienna sounding showed very promising conditions for the development of severe convection
(http://www.phix.cc/pics/post_gew/sounding.gif)
Around 10 UTC convection was triggered along the weak cold front in Bavaria
(i`m sorry for the arrows, but the pictures were taken from a discussion paper for stormchasers)
(http://www.phix.cc/pics/post_gew/01_radar.png)
(http://www.phix.cc/pics/post_gew/02_radar.png)
about an hour later there was a fully developed line echo
(http://www.phix.cc/pics/post_gew/03_radar.png)
..turning rapidly into a pronounced bow echo (.. white pixels eqal a reflectivity of 60 dBz and more)
(http://www.phix.cc/pics/post_gew/04_radar.png)
(http://www.phix.cc/pics/post_gew/05_radar.png)
Later , the system started to weaken, but the outflow triggered another storm ahead of the line ..
(http://www.phix.cc/pics/post_gew/06_radar.png)
(http://www.phix.cc/pics/post_gew/07_radar.png)
.. which again rapidly turned into a bow echo
(http://www.phix.cc/pics/post_gew/08_radar.png)
(http://www.phix.cc/pics/post_gew/09_radar.png)
now the systems changes more into a line echo wave pattern, the southernmost cell develops some supercell-like features (sharp gradient ..)
(http://www.phix.cc/pics/post_gew/10_radar.png)
(http://www.phix.cc/pics/post_gew/11_radar.png)
(http://www.phix.cc/pics/post_gew/12_radar.png)
on the northern edge of the southernmost system a bookend vortex develops
(http://www.phix.cc/pics/post_gew/13_radar.png)
The LEWP caused damage because of large hail up to 6cm in diameter, especially on the southern edge, damaging winds up to 150 km/h as well as flooding. Unfortunately 3 people lost their lives in Vienna, due to windthrown trees and a destroyed crane.
The fully developed system caused a very pronounced pressure wave leading to gale force gusts.
(http://www.phix.cc/pics/post_gew/data02.png)
Also satellite imagery gives a good overlook on this impressive system:
(http://www.phix.cc/pics/post_gew/sat01.png)
(http://www.phix.cc/pics/post_gew/sat01.png)
(http://www.phix.cc/pics/post_gew/sat02.png)
(http://www.phix.cc/pics/post_gew/sat03.png)
(http://www.phix.cc/pics/post_gew/sat04.png)
(http://www.phix.cc/pics/post_gew/sat05.png)
Overshooting tops
(http://www.phix.cc/pics/post_gew/sat06.png)
(http://www.phix.cc/pics/post_gew/sat07.png)
and here is some footage by myself, as i was lucky enough to have my camera with me as the storm passed the place where i used to work.
(approach - gusts - rain - hail -- and more hail)
http://www.phix.cc/gew.html (http://www.phix.cc/gew.html)
regards, Manfred