Summary:

Category 1 was issued primarily for  excessive precipitation  (loc. > 50 mm) and possibly flash flood, secondary for hail (diam. ~1-2 cm) besides an isolated non-mesocyclonic funnel cloud or tornadoe is not ruled out. Western Europe’s weather is  determined by a wide trough and an accompanying elongated weakening frontalzone from south to north. Ahead of this waving front relatively wet and unstable airmass is persisted over Balkan peninsula and Central-Europe. However in wake of a weak cold front sligthly drier and more stable air is streaming over west part of our country mainly in the morning hours.  Considerable wind shear is not presented today therefore mainly monocellular or possibly slight-organised multicellular convection is expected along low level convergence zones due to diurnal heating as we could see also yesterday.

We issue Category 1 because we expect multicellular thunderstorms and the propagation of cells in these clusters compensates their slow motion (driven by the mean wind) in such a way that they reach their own mature stage above the very same area exposing it to flash-flood hazard. Furthermore permanent convergence with large horizontal wind shear along creates widely favourable conditions for non-mesocyclonic funnel clouds, possibly tornados, too.