Hallo zusammen, ab Samstag steht eine neue Gewitterlage an, die uns wohl das Wochenende über begleiten wird. Der Thread wird später sicher noch ergänzt, zum Start schon mal der Extended Forecast für Samstag bis Sonntagmorgen:
Valid: Sat 24 Jul 2021 06:00 to Sun 25 Jul 2021 06:00 UTC
Issued: Thu 22 Jul 2021 20:07
A level 1 was issued across Benelux and parts of W-Germany mainly for excessive rain and isolated hail.
A level 1 was issued for far E France to Switzerland into S/CNTRL Germany mainly for hail, severe wind gusts and heavy rain. An isolated tornado is possible.
Blockish pattern persists as an upper trough with an embedded distinct vortex approaches England/Belgium until 06Z. Downstream positive 500 hPa geopotential height field with gradually lowering anomalies betimes covers E-Europe into S-Scandinavia but both features remain progressive during this forecast (hence no real blocking event).
Another trough is parked over SE Europe (Turkey) with no real net motion in any direction while the S-Mediterranean remains hot and dry.
ICON/GFS/IFS show stable solutions with a good intra-run consistency. Subtle differences exist with weak short waves, but this uncertainty hopefully subsides in the future runs.
Complex pattern of MSLP geometry over W-/CNTRL Europe yields a dominant/eastward propagating despression over the Normandy and an eastward arching channel of lower surface pressure towards Benelux, bending SE to Germany. Geometry with this channel/strength differs, although all models agree in the overall configuration.
The general pattern is favorable for an active thunderstorm day over CNTRL Europe. Diffluent steering flow turns more divergent during the day with improving jet configuration in a weakly/moderately capped air mass. (Sub)tropical history features TPWs in the 30-40 mm range with slack mid-level lapse rates. Squeezed height field between the French/English vortex and a NE-ward expanding subtropical ridge over Algeria causes a strong SW-erly wind field, pushing kinematics in the range supportive for better organized updrafts from E-France/Switzerland into Germany/W-Austria (0-6 km 15-20 m/s and 0-3 km 10-15 m/s, decreasing towards Benelux).