Radar observations and numerical modeling of a mesoscale convective system over northeastern Italy on 4 October during MAP

During MAP, " Project P1 - Orographic precipitation mechanisms " was aimed at addressing the basic mechanisms of creation or enhancement of precipitation by special configurations of topography in complex terrain. On 4 October 1999, the US National Center for Atmopsheric Research Electra and the National Oceanic and Atmospheric Administration P3 aircraft carrying meteorological Doppler radars and other instruments have been used to investigate the dynamic, thermodynamic and microphysical properties of a convective system that occured near the border between Italy and Slovenia, in a transition region between the flat Adriatic coast and the Julian Alps. The Italian operational Doppler radar at Fossalon di Grado provided complementary observations. This precipitating system started on the Italian side as a 100 km long and 10-20 km wide line of very intense convective cells at 0730 UTC and it propagated southeastwards. After 0900 UTC, a region of stratiform precipitation developed on its northern side and the system dissipated by about 1200 UTC as it moved toward Croatia. In both convective and stratiform regions, the radar, microphysical and flight level measurements suggested strong influence of the underlying topography. Preliminary analyses of these data will be discussed at the 9th Conference on Mountain Meteorology.