Yosemite Falls 2011 Merced River Flood

Peak flooding generated by snowpack depends on the amount of area covered by snow, temperature, and lateness of melt (sun angle). Heavy snow years, like 2011, can result in spring floods. The year 2010 also had a high snowpack; a cool May helped maintain extensive snow cover into June followed by rapid warming that produced a 5-year flood on the Merced River. Heavy snow years have generated similar magnitude floods in the past. Larger spring floods occurred in 1983–-the largest snowpack year on record-–and when rain occurs on a rapidly melting snowpack, such as in 1996 and 2005.