Monitoring of mesoscale precipitation systems in the Alps and the northern alpine foreland by radar and rain gauges

Mesoscale convective precipitation systems in the Alpine region are studied by analyzing radar and rain gauge data. The data from weather radars in Austria, France, Germany, and Switzerland are combined into a composite. Availability of radar data restricts the study mainly to the northern part of the Alpine region. Mesoscale convective systems (MCS) occur often in this region and are comparable to large systems observed in the USA. Seven precipitation events lasting one to six days from the years 1992-1996 are examined in detail. They all moved west to east and showed no diurnal preference in formation or dissipation. They reach sizes of 2-6 . 10(4) km(2). MCS with leading-line trailing-stratiform structure tended to be larger and more intense. A 25-year set of rain gauge data indicates that a giant MCS (covering more than 4 . 10(4) km(2) with more than 30 mm/day) occurs every 6 years in the northern Alpine region. MCS occur more frequently in the southern Alpine region.