On the 21.09.2014, numerous severe thunderstorm ocurred over Austria. Chasers from both Skywarn Austria and Stormhunters Austria chased and reported the storms.

In all of W Europe, 18,941 lightnings were registered. Below is a map by lightningmaps.org, showing the lightnings registered on the 21.09.2014.

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The initiating factor to overcome the convective inhibition was a cold front which moved through Austria in the afternoon.

Below is an analysis by the DWD (German weather service), which shows the situation (and ground station recordings) at 12UTC on Sunday, 21.09.2014.

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By the evening at 18UTC, the cold front had reached Austria.

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And in the night, by 00UTC, the cold front began to weaken along the north side of the Alps.

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By the next morning, a ew low pressure area had formed and moved towards the SE.

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The GFS model forecast run of 00UTC predicted the most severe thunderstorms for the evening at 18UTC. The forecast favored SE Carynthia, SW Styria, NE Styria and W Burgenland.

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Due to few clouds, the sun was able to shine very intensly on the eastern and southern regions of Austria. This enabled the temperatures to, reach high values compared to the usual temperatures for that time of year. 27°C was measured in Kleinzicken and Neusiedl am See, both located in Burgenland.

The temperatures at 17:00 local time can be seen below:

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The dewpoint was very high, especially in SE Austria.

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The arrival of the cold front can be clearly seen in the pressure tendency readings. In the map below, which shows the values of 17MEST (local time), the cold front has already reached the far W of Austria.

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More will be posted as a comment.

When the cold front passed, it was accompanied by severe thunderstorms. The highest gust that was not measured on a mountain was 76km/h in Kremsmünster.

During the passage of the front, also significant amounts of precipitation fell. 21l/m² were registered in Kremsmünster, Feuerkogel and at the Airport of Graz. These locations were followed by Ried (im Innkreis) with 16l/m².


ESWD (European Severe Weather Database) only received two reports about severe weather in Austria. Both were hail reports from Styria (Fernitz and Feldkirchen bei Graz). There, hail of up to 2cm in Diameter was reported. The hail shower in Feldkirchen bei Graz lasted 15 minutes, which is a relatively long time.

The UWZ (Unwetter Warn Zentrale) of Ubimet for Austria received more reports.
The first report of a thunderstorm came from Randegg (lower Austria) at 00UTC, 02MEST. It was reported that there was very strong rain accompanied by thunder.
The next report came from St. Roman (Upper Austria), nearly 8 hours later at 09:51MEST. A thunderstorm was reported with rain that suddenly started. 2 People confirmed the event.
At 10:28 local time, 5 people reported a thunderstorm moving towards Wels (Upper Austria). It was reported as a "black wall" that was moving towards the town.
At 10:29 a thunderstorm with sudden intense rain was reported from Gunskirchen (Upper Austria) - 3 people confirmed the event.
At 10:37 a light thunderstorm war reported from Buchkirchen, Upper Austria. Based on the reports the UWZ received, the thunderstorms seemed to be very fast moving.
At 10:44 thunderstorm clouds were reported W of Traun (Upper Austria), thunder was already being heard. 3 People confirmed the report.
At 10:54 a thunderstorm with rain of different intensities was reported in Marchtrenk (Upper Austria). The event wasn't confirmed.
At 10:56 the Stormhunters Austria reported a thunderstorm with strong rain and lightning activity from Marchtrenk (Upper Austria). 3 people confirmed the report.
At 11:08 a thunderstorm with strong rain was reported from Linz. 1 Person confirmed the report.
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At 12:48 A thunderstorm with strong rain was reported ("again", as was written) from Wels (Upper Austria). 2 People confirmed the report.
At 14:06 A thunderstorm was reported moving towards Spannberg (Lower Austria). The photo below was sent with the report. 1 Person confirmed the report.


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At 14:11 A thunderstorm with gusts and strong rain was reported from Groß-Schweinbarth (Lower Austria). 1 Person confirmed the report.
At 14:17 A thunderstorm with storm gusts and strong rain was reported from Seebenstein (Lower Austria). 3 People confirmed the report.
At 14:40 A thunderstorm with hail and strong rain was reported moving over Sieggraben (Burgenland). 1 Person confirmed the report.
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At 15:45 A thunderstorm with strong rain was reported from Bregenz (Vorarlberg). 1 Person confirmed the report.
At 15:59 A thunderstorm was reported to have passed Fohnsdorf (Styria). It was reported that there was hail. The thunderstorm was reported to have been 10 to 15 minutes long.
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At 16:02 a thunderstorm with small hail and strong rain was reported from Zeltweg (Styria). 1 Person confirmed the report. Below is a photo that was sent with the report.


At 16:10 a thunderstorm (probably the same as in Zeltweg) was reported from Buch Maria-Feistritz (Styria). It was reported with hail 0.5 to 1cm in diameter. The photo below was sent with the report. 3 People confirmed the report.


At 16:16 a thunderstorm with strong lightning activity was reported from Pichl bei Wels (Upper Austria). 1 Person confirmed the report.


Will be continued later.

At 16:22 A thunderstorm was reported to begin in Hartberg (Styria). The report was not confirmed.
At 16:36 A thunderstorm was reported with strong gusts moving through Seeham (Salzburg). The report was confirmed by 2 people. The photo below was sent with the report.


At 16.36 a thunderstorm with strong rain and light hail was reported in Hartberg (Styria). The report was confirmed by 1 person.
At 16:40 a thunderstorm with strong rain, storm gusts and hail was reported from Kleinlobming (Styria). The report was confirmed by 1 person. The photo below was sent with the report.


At 16:41 a thunderstorm was (again, as was reported) reported in Traun (Upper Austria). The report was confirmed by 1 person.
At 16:42 a thunderstorm was reported from Schalchen (Upper Austria). The report was reported by 2 people.
At 16:43 another thunderstorm report was received from Schalchen (Upper Austria). In this report a short event of strong rainfall was reported. This report was confirmed by one person.
At 16:54 a thunderstorm was reported from Köflach (Styria). Strong rain and storm gusts were reported. The report was confirmed by 1 person.

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At 17:03 a thunderstorm with storm and severe rainfall was reported from Voitsberg (Styria). The report was confirmed by 2 people.
At 17:14 a thunderstorm with strong rain and light wind was reported from Graz (Styria). The report was confirmed by 6 people.
At 17:32 a thunderstorm with storm and hail was reported from Attendorf (Styria). The report was confirmed by 2 people.
At 17:39 a thunderstorm was reported to begin with wind gusts in Grambach (Styria). The report was not confirmed. The photo below was sent with the report.


At 17:46 a rotating thunderstorm was reported from St. Marein bei Graz (Styria), looking towards Graz. The report was not confirmed. The photo below was sent with the report.


At 17:49 a thunderstorm with light rain was reported from Eberau (Burgenland). The report was not confirmed.
At 17:52 a thunderstorm with strong rain was reported from Gramberg (Styria). The report was not confirmed.
At 17:56 a thunderstorm was reported moving towards Fohnsdorf (Styria) from the N. The report was confirmed by 1 person. The photo below was sent with the report.


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At 18:01 a thunderstorm was reported from Schwarzau im Schwarzautal (Styria). The report was confirmed by 1 person. The photo below was sent with the report.


At 18:03 a thunderstorm was reported from Attendorf (Styria). It was reported as a thunderstorm of the highest intensity. The report was confirmed by 3 people.
At 18:19 a thunderstorm was reported from Kalsdorf bei Graz (Styria). It was reported that the thunderstorm was accompanied by strong rain, hail and storm. The report was confirmed by 1 person.
At 18:23 a thudnerstorm was reported from Kalsdorf be Graz (Styria). It was reported that the thunderstorm was in the highest warning category. The report was confirmed by 1 person.
At 18:24 a thunderstorm with strong rain was reported from Fohnsdorf (Styria). The report was confirmed by 1 person.
At 18:25 strong rain was reported from Pöls (Styria). It is not noted if the rain is thunderstorm-related or not, but it is likely. Local flooding is reported, as well as an amount of 14.5 l/m² within 1 hour. The report was confirmed by 1 person. The photo below was sent with the report.



Continuement will follow.

At 18:36 a thunderstorm was reported from Gnas (Styria). The report was confirmed by 1 person.
At 18:38 a thunderstorm with hail was reported moving towards Feldbach (Styria). The report was by 2 people.
At 18:46 a thunderstorm with light rain was reported from Kapfenstein (Styria). The report was confirmed by 1 person. The photo below was sent with the report.


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At 19:06 a thunderstorm was reported from Fürstenfeld (Styria). The report was confirmed by 3 people.
At 19:45 a thunderstorm with strong rain was reported from Grambach (Styria). The report was confirmed by 1 person.
At 19:54 a thunderstorm with rain was reported approaching Hartberg (Styria). The report was confirmed by 1 person.
At 19:58 strong rain was reported from Ragnitz (Styria). Based on the report, it is not clear if the event was thunderstorm-related or not. The report was confirmed by 1 person.

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At 20:06 a thunderstorm with hail and flooding was reported from Fernitz (Styria). The report was confirmed by 6 people.
At 20:09 a thunderstorm with moderate lightning activity and rain was reported from St. Martim im Sulmtal (Styria). The report was not confirmed.
At 20:18 a thunderstorm with high lightning activity and little rain was reported from Preding (Styria). The report was not confirmed.
At 20:39 a strong thunderstorm with rain was reported from Güssing (Styria). The report was confirmed by 3 people.

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At 21:02 a thunderstorm was reported from Fernitz (Styria) with flooding and a hail layer on the ground. The report was not confirmed. The photos below was sent with the report:

Skywarn Austria had chasers in following regions:

Graz
SE Austria
Fernitz
Voitsberg
Feldbach

Stormhunters Austriahad chasers in following regions:

Fernitz
Kalsdorf
Mühldorf
Seiersberg
Althofen

And here comes the bibliography for the above:

Works Cited
Web. 4 Jan. 2015. <http://www.stormhutners-austria.com>;.
"ALDIS." ALDIS. Web. 4 Jan. 2015. <http://www.aldis.at>;.
"Das Kompetenzzentrum Für Unwetter." (Österreich. Web. 4 Jan. 2015. <http://www.uwz.at>;.
"European Severe Weather Database." European Severe Weather Database. Web. 4 Jan. 2015. <http://www.eswd.eu>;.
"LightningMaps.org." Real-Time Lightning Map ::. Web. 4 Jan. 2015. <http://www.lightningmaps.org>;.
"Startseite - SKYWARN AUSTRIA | Unwetterwarnungen & Meldungen, Gemeinnütziger Verein Und Wetterplattform." Startseite - SKYWARN AUSTRIA | Unwetterwarnungen &amp; Meldungen, Gemeinnütziger Verein Und Wetterplattform. Web. 4 Jan. 2015. <http://www.skywarn.at>;.
"Wetter : Wetterzentrale." Wetter : Wetterzentrale. Web. 4 Jan. 2015. <http://www.wetterzentrale.de>;.
"Wetter Aktuell, Wettervorhersage Und Wetterbericht - WetterOnline." WetterOnline. Web. 4 Jan. 2015. <http://www.wetteronline.de>;.
"Wetter3- Aktuelle Wetterkarten." Wetter3- Aktuelle Wetterkarten. Web. 4 Jan. 2015. <http://www.wetter3.de>;.
"Zentralanstalt Für Meteorologie Und Geodynamik — ZAMG." Zentralanstalt Für Meteorologie Und Geodynamik — ZAMG. Web. 4 Jan. 2015. <http://www.zamg.ac.at>;.


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