Bericht van: Thom (Ens, Noordoostpolder)
, 25-06-2015 23:12
A level 1 was issued for Belgium and W-Germany mainly for an isolated tornado risk.
... Belgium, Luxembourg and W-Germany ...
During the evening/overnight hours, diffluent upper flow regime affects Benelux/W-Germany. Of interest is a wave in 800-600 hPa, crossing W-Germany during the night from W to E. Influx of rather rich BL moisture ahead of that feature is forecast with mixed-layer mixing ratios in excess of 10 g/kg. Forecast soundings indicate an interesting setup with strongly looped hodographs and SRH 1/3 km in excess of 200 m^2/s^2 with 15 m/s LL shear. Forecast soundings show a good chance for mainly elevated thunderstorm activity. However, not much BL modification is needed for thunderstorms to become near surface based. This would increase the chance for an isolated tornado event over W-Germany mainly between 00-06Z and beyond our forecast period. Despite still ongoing uncertainties regarding final nature of thunderstorms (elevated or surface based), we decided to issue a level 1 for an isolated severe wind gust/tornado threat.