Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 305 PM EST Sat Feb 28 2015 Valid 00Z Sun Mar 01 2015 - 00Z Tue Mar 03 2015 ...Snow and ice event setting up from the Middle Mississippi Valley to the Mid-Atlantic region... ...Unsettled weather will continue across California and the Four Corners states... ...Heavy rain and thunderstorms expected for the Lower Mississippi Valley... Widespread precipitation is expected to develop over much of eastern half of the Nation the next few days as a disturbance crosses the northern tier and moisture surges northward out of the Gulf of Mexico. An Arctic airmass initially in place will keep temperatures low enough to support a wide axis of light to moderate snow accumulations from the Middle Mississippi Valley to the northern Mid-Atlantic states. The warm Gulf of Mexico air moving in over slow-to-erode Arctic air will set up a zone of sleet and freezing rain...especially just east of central and even southern Appalachians. Unsettled weather will continue across California and the Four Corners states this weekend and into early next week as an upper low closes off over the southwestern U.S.. Pacific moisture streaming inland...impulses of energy embedded within the flow aloft...and orographic effects will all help produce some hefty precipitation totals along the favored slopes of the terrain. Conditions will be cold enough for accumulating snow across much of Sierra Nevada ranges...the Great Basin...and the central to southern Rockies...with over a foot of snow expected in the San Juan ranges of southwestern Colorado. Precipitation will begin to focus along a frontal boundary strengthening in the southern tier of the Nation on Monday. Plenty of moisture lifting north out of the Gulf of Mexico will fuel moderate to heavy rains and thunderstorms over the Lower Mississippi Valley. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php