Valid: Mon 04 Jun 2018 14:00 to Mon 04 Jun 2018 18:00 UTC
Issued: Mon 04 Jun 2018 13:30
A MD was issued across parts of Switzland, far SW-Germany and far E-France mainly for excessive rain.
A subtle mid-level impulse starts to affect the western Alps as it approaches from NW-Italy. Latest increase in mountainous thunderstorm activity emphasizes that (beside scoring the convective temperature). 12Z soundings from Stuttgart and Payerne both show similar lapse rates, which, albeit poor, are still adequate for 500 - 1000 J/kg MLCAPE build-up given available BL moisture (increasing towards Switzerland with surface dewpoints in the mid tens). A couple more hours of sunshine should help to increase CAPE to locally more than 1000 J/kg especially near BL convergence zones. This amount of CAPE assists in robust updraft strength with isolated large hail. Weak shear (DLS less than 10 m/s) and deep moist profiles however point to rapid clustering and slow moving convection, which crosses the MD from E to W. A few CAMS indicate augmented excessive rain chances with that activity mainly along mesoscale convergence zones. Water loaded downdrafts may also produce strong to isolated severe gusts.