.There's a Moderate risk of excessive rainfall along coastal southernCalifornia today......Heavy Snow likely over Sierra Nevada and Shasta Siskiyous inCalifornia......Warming trend expected to expand across the Great Plains throughmidweek...A potent upper-level low will continue directing subtropical moisture overmuch of California today. Heavy coastal and low elevation rain,thunderstorms, heavy mountain snow and high winds are all expected fromthis Atmospheric River event. Excessive Rainfall...