The formation of a secondary mid-level atmospheric river that contributed to the Reno floods of 1997 and 2005

This thesis investigates how the moisture is transported across the Pacific to the Sierra Nevada, which fueled the flooding events to the lee of the Sierra Nevada on January 01, 1997 and December 31, 2005. Current theory suggests moisture transport is restricted to the lower troposphere from the tropics by the low level jet of a single synoptic wave. However, from the synoptic and mesoscale analyses of observations and numerical simulations, it was discovered that moisture is transported from the tropics by a succession of several synoptic waves (3-5) into the midlatitudes. The moisture is then lifted into the middle troposphere prior to reaching the Pacific coast of North America creating a secondary midlevel atmospheric river that supplied a significant amount of the moisture that contributed to the spill-over precipitation events to the lee of the Sierra Nevada.