Precipitation, kinematic and thermodynamic structure of a flash-flood producing system over Lago Maggiore region on 19–20 September 1999 during MAP

During the Intensive Observation Period 2b of MAP (18 - 21 September 1999), a frontal system with embedded convective elements swept across northern Italy in association with a trough over northern Europe which rapidly moved eastward. This caused a heavy rain event over the Lago Maggiore region on 19-20 September. During this period, observations have been conducted with the French Ronsard radar located near Novara, the Swiss SMA operational radar at Monte-Lema and the US Doppler and Polarimetric S-POL near Vergiate in order to investigate the mechanisms of orographically induced heavy precipitation events with special emphasis on their dynamics and microphysics. The results about radar-derived wind and precipitation fields clearly show the influence of orography on the modulation of precipitation with a enhancement – attenuation cycle. Different analysis techniques are used to retrieve the precipitation, kinematic and thermodynamic characteristics at meso – and small scale over both the Pô valley and the steep mountains north of Lago Maggiore.