.Heavy rain and heavy mountain snow in California are expected to becomeless intense......A moderate risk of excessive rainfall remains in effect along portionsof coastal southern California into tonight......Warming trend expected to expand across the Great Plains and into theGreat Lakes through midweek...The West Coast continues to be in the midst of an active weather patternas the core of an energetic large-scale low pressure system pushes onshoretoday.  Under this weather pattern, California remains under the impact ofheavy precipitation.  The northern portion of California will be one areaof concern where additional heavy rainfall will lead to a slight risk offlash flooding into Tuesday.  Another area of concern will be alongportions of coastal southern California where more focused heavy rainfallforced by local terrain will keep a moderate risk of flash flooding inplace through tonight.  Meanwhile, heavy snow can be expected over thehigher elevations.  By Tuesday, the low pressure system is forecast toweaken.  This will allow the coverage and intensity of the rain/snow toprogressively decrease with time.  Nevertheless, additional residualenergy arriving from the Pacific will result in more rounds of light tomoderate elevation-dependent rain/snow into Wednesday.  Meanwhile,moisture from the weakening low pressure system will continue to push wellinto the Intermountain West, bringing additional rounds of rain/snowacross the Great Basin and into the northern Rockies over the next coupleof days before reaching into the central Rockies and toward the FourCorners by Wednesday.Meanwhile, much of the eastern two-thirds of the country will remain drythrough the next couple of days under a slow-to-evolve weather pattern.  Awarming trend is expected to expand across the Great Plains throughmidweek where an upper ridge is forecast to build.  High temperatures willbe between 15-25 degrees above average by Wednesday over much of thecentral U.S.  Dry conditions will extend into portions of the Four Corners region as well.  By later on Wednesday, much of the energy associatedwith the upper-level trough moving through the western U.S. will begin tomove into the central Plains where a new low pressure system is forecastto develop.