Comparison of Orographic Precipitation in Map and Improve Ii

The Mesoscale Alpine Programme (MAP) was conducted over the European Alps in September-November 1999. During autumn, heavy rains and floods can occur when baroclinic troughs move over the region, and moist air flows from the Mediterranean Sea toward the southern Alps. Dual-polarimetric Doppler and vertically pointing radar data collected during MAP on the Mediterranean side of the Alps provided a unique opportunity to examine orographic precipitation processes. They show that both coalescence and riming occurring at low altitudes in high Froude number flow over the foothills of the Alps are important contributors to the orographic precipitation enhancement in this region (Houze et al. 2001; Medina and Houze 2002).