Moisture sources for extreme rainfall events over the Mackenzie River Basin

Abstract

Extreme summer rainfall events (rainfall exceeding 100 mm) have a marked impact on the hydrologic budget over the Mackenzie River Basin (MRB). In this study we test the hypothesis that the atmospheric moisture feeding these rainstorms can be traced back to the Gulf of Mexico. Three-dimensional parcel trajectories were identified that originated near the Gulf of Mexico and terminated over the southern MRB. The transport time ranged from 6 to 10 days. Our study indicates that rapid lee cyclogenesis over Alberta (associated with a 500-hPa cutoff low) and the Great Plains Low Level Jet can act in unison to produce this moisture transport. © 2008 Springer-Verlag Berlin Heidelberg.