Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 405 AM EDT Mon Apr 06 2015 Valid 12Z Mon Apr 06 2015 - 12Z Wed Apr 08 2015 ...A wet period in store for the Western U.S. including much of California... ...Large temperature departures from normal expected across the Central/Eastern U.S... ...Wintry precipitation likely from the Upper Midwest to New England... An upper trough currently spinning off the Oregon coast is expected to split in two with the initial feature quickly moving toward the Upper Intermountain West. Meanwhile, a much stronger closed low will evolve from this circulation with the system working its way toward Northern California by late Monday night. A pronounced cold front should work its way inland spreading an abundance of precipitation to much of California. The best moisture feed and strongest upslope flow seems to be across the Shasta and Central/Northern Sierra Nevada range where the heaviest rain and snow are expected. The current WPC winter weather forecast indicates 1 to 2 feet of snow will be possible across these mountain ranges. As the closed low works its way inland, moisture will diminish which should decrease the intensity of precipitation. During the next couple of days, expect roughly 4 to 6 inches of snow to fall across the Ruby Mountains of northeastern Nevada as well as over the Tetons and Bitterroots. While the weather will be quite active along the West Coast, likewise can be said for the evolving pattern over the Central/Eastern U.S. The focus for unsettled conditions will be in response to a meandering west-to-east oriented frontal zone. Temperature forecasts suggest a gradient of 40 to 50 degrees along this front which leads to quite impressive anomalies. For instance, high temperatures on Tuesday being in the low to mid 80s across the Southern Plains translates to readings 15 to 20 degrees above normal. Meanwhile, north of the meandering boundary, highs should only reach the 40s over the Northern Plains and Upper Midwest which suggests anomalies in the 5 to 10 degree range below climatology. As persistent southerly flow from the Gulf of Mexico overrides this boundary, a broad area of overrunning precipitation is expected north of the front. This supports some sort of mixture of wintry precipitation types with 2 to 4 inches of snow possible from Central Minnesota eastward across the Northern Great Lakes and into the northern section of New England. Similarly, a light area of freezing rain is likely along this axis of snowfall which could compromise travel over these regions. The other aspect of this pattern is the showers and thunderstorms which will break out in the expansive warm sector. The drivers of this convection will be a combination of energy shearing from the Western U.S. trough working with instability that builds from daytime heating. Much of the activity should be rather disorganized with heavy downpours possible within some of the stronger convective elements. Given recent issues with flash flooding along the Ohio River, a threat for additional excessive rainfall is possible given the chances for heavy rainfall during the next couple of days. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php