Extreme Precipitation along the Himalayan Slope - Main Processes and Long Term Trends

The precipitation climatology for the Himalayan slope is heavily influenced by the main topographic features of the region. The precipitation variability is strongly connected to variability in the large scale Indian monsoon. In Nepal the average annual precipitation ranges from a few hundred to over 5000 mm and has been shown to be strongly linked to orography.Based on daily measurements of precipitation we calculate a climatology and long term trends for 270 meteorological stations. Especially, extreme precipitation is of increasing interest due to social impacts. Therefore, we further investigate extreme events for each measurement station. Since precipitation is influenced by large scale weather situations we relate the appearance of typical synoptical patterns to corresponding occurances of extreme precipitation events. In order to form groups with similar characteristics in precipitation we performe a cluster analysis on the stations and synoptical situations revealing typical weather patterns responsible for extreme precipitation events.