Should My Chambelanes Wear Tuxedo

country in the region of convection over Lake Zurich

Today a view to neighboring Vorarlberg, my "original" homeland:

Unbelievable as it has tonight and poured in the morning on the eastern shore of Lake Constance. In Bregenz, it was within 12 hours about 130 mm of which fell about 70 mm in just 2 hours (see the second highest figure)! The extreme rainfall event was relatively small scale, but it has caused major damage.

way it looks has once again called the "Lake Effect" means, at least for a gain of precipitation, and this is the second time within a few days. How it works as follows: Rather cool and unstable stratified air flows over the relatively warm lake surface. It "sucks" the air with water vapor and fully above the lake to form showers and thunderstorms. These pledges have been raised on a slope, which resulted in an additional gain of Precipitation added.

wind direction and strength at different heights
using the wind profiler in Schaffhausen (source: MeteoSwiss)

Today, the wind direction was perfect (see picture above). With the NW to WNW-wind in the lower layers, the air brought up the Lake almost completely longitudinally crossed before on the other bank ausregnete. The wind speeds at 2,000 meters were constant at about 35 km / h.

The result of this continued moisture supply curve as the sum of precipitation of the weather station Bregenz Altreuteweg:

precipitation and intensity of the weather station
Bregenz-Altreuteweg. Source: Vorarlberg / Water

The temporal and spatial sequence of the precipitation event can be followed on the best means of radar images. Although the radar of MeteoSwiss in the Albis almost 100 km away from the scene, is the precipitate was very well captured:

12-hour rainfall (27 July 2010, approximately 0h to 12h)
basis the radar data. Due to the large distance to the radar site
the totals are a bit too deep (source: MeteoSwiss).

radar film in 5min increments of 27 July 2010,
about 5h to 11h in the morning. The black symbols are
lightning location (source: MeteoSwiss)

such events occur in the summer time and again - mostly, of course, not just in this form. On 6 August 2006, settled in Alberschwende a similarly intense thunderstorms. At that time fell in a few hours 140 mm of rain, so during a very similar weather conditions as today.

Here are some links to reports, damage reports, photos and footage:
Vorarlberg online
ORF Vorarlberg Studio

Bubble Inside Lower Lip

in the formation of these clouds sausage tonight just 20 clock probably two effects were involved: A wind convergence, and a relatively unstable stratification of the surface air with lower temperature and high water temperature. At the right edge of the cloud from the national SW wind is "sanded" addition.

At a water temperature of 23 ° C, an air temperature of about 15 ° C and a vertical temperature gradient from 0.8 to 0.9 ° C/100m near the ground, it takes only a very weak convergence to the convection in motion to bring.

After some time, is pulled from the northwest rain showers, and the wind picked up considerably. It was the convergence and thus disturbed convection - the cloud has disappeared rapidly.

If the weather is the observed evening convection over the valley and basins way, known as so-called "thermal inversion" downslope winds from the surrounding edges help to create convergence, and finally the detachment and rise of the warmer air from the valley floor. This form only in rare cases, cumulus clouds, because the air is much drier.