Abstract
We compared May and August 2010 precipitation events that produced catastrophic flooding; in May, large rivers (Vistula, Oder) were affected, while smaller rivers (e.g. Lausitzer Neisse) were affected in August.
Similarities in precipitation characteristics (duration of several days, daily total maximum of approximately 180 mm) can be explained by similarities in the meso-alfa scale (thermo-dynamic indicia connected with a cyclonic system of the Mediterranean origin). These indicia were more significant in May (extreme and deep vertical wind speed, extreme northerly flux of moisture) than in August (strong but non-extreme northerly flux of moisture) when conditional instability was additionally detected.
Obviously more intensive orographic enhancement in the first case and the strong effect of convection in the latter case produced differences in the return periods of precipitation totals (longer return periods in August). Subsequently, the hydrological response was rapid and particularly strong in smaller streams in August.