A seven-year synoptic climatology of heavy winter orographic precipitation events over the subtropical Andes (30º-37ºS)

VIALE, M.; NORTE, F. A.; NUÑEZ, M. N.

Valdivia, Chile

Simposio; II International Symposium "Reconstructing Climate Variations in South America and the Antarctic Peninsula over the last 2000 years"; 2010

Centro de Ingineria de la Inovacion y Universidad Austral de Chile

This study investigates the synoptic conditions during the 46 heaviest winter (Apr-Sep) orographic precipitation events from 1970 to 1976 over the Central Andes (30º-37ºS). Four to five heavy winter events account for most (~70%) of the winter total precipitation, which in turn represents more than 90% of the total annual precipitation. Consequently, heavy orographic precipitation events play a crucial role in the regional water cycle on central Chile and central-western Argentina, supplying water and generating in some cases floods, avalanches and road blockings. Based on the ERA-40 reanalysis and rawinsonde data, the dominant and key pattern for these events was a long (>2000km) and narrow (