Valid: Tue 11 Jun 2019 19:00 to Tue 11 Jun 2019 21:00 UTC
Issued: Tue 11 Jun 2019 19:33
A Mesoscale Discussion was issued for parts of NE Germany.
A growing cluster of strong to severe thunderstorms affects parts of Saxony to Brandenburg. Thunderstorms show temporal rotation signatures in radar data admits effective 35-40 kn DLS (taken 5-10 kn northerly surface winds into account). 18Z sounding of Lindenberg indicates a volatile thermodynamic environment with MLCAPE in excess of 3000 J/kg due to Tds around 20 C and steep mid-level lapse rates including PWATs of near 40 mm.
An increase of the 0-3 km flow was noted which results in better curved lower hodograph structures. Despite those favorable trends, latest radar appearance shows rather chaotic storm motions with numerous splits and complex cell to cell interaction. With weak low-tropospheric confulent flow ahead of current convection, conditions seem supportive for further upscale grwoth into a large thunderstorm complex over NE Germany during the following hours.
Initiating cells pose a large to isolated very large hail threat including a low-end tornado risk (low LCLs, deviating storms and enhanced 0-3 km flow). Effective warm rain process and temporal back-building also indicates an excessive rainfall threat. This also includes Berlin, although LL convergence zone is currently displaced just to the SW of town.
With missing synoptic-scale support and moist LL, confidence in cold-pool driven activity with swaths of severe wind gusts is not high right now, but wet downbursts with severe wind speeds are well possible in strongest storms.