Mesoscale Discussion
Valid: Wed 11 Jun 2014 17:00 to Wed 11 Jun 2014 20:00 UTC
Issued: Wed 11 Jun 2014 16:48
Forecaster: PISTOTNIK

... Czech Republic, N Austria ...

Latest surface observations indicate that a mesoscale low pressure area has formed over the Southern Czech Republic, where the low-level winds are strongly converging. In particular, a pronounced outflow front, which originated from the MCS over Eastern Germany some hours ago, continues to move southeastward and pushes the mesolow further into the bordering area with Austria and Slovakia.
12z soundings indicated CAPE on the order of 1000 J/kg (Vienna, Prostejov) to 2700 J/kg (Prague) under rather weak vertical wind shear and relatively high dewpoint spreads. Numerous storms are initiating and will likely merge into a large, messy cluster that continues to propagate East and South. Excessive precipitation, large hail and localized downbursts may occur.

... W Poland ...

While the Southern Polish storms are currently decaying, a new convective line has formed further North along the German/Polish border. The 12z Lindenberg sounding, launched ahead of the activity, and latest surface observations indicate CAPE around 1500 J/kg. Despite rather weak vertical wind shear, Easterly surface winds ahead of the line may suffice to sustain its longeivity. Severe wind gusts and large hail are the main risks along is leading edge, possibly followed by a period of heavy rain afterwards.