Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 225 AM EST Sun Jan 08 2017 Valid 12Z Sun Jan 08 2017 - 12Z Tue Jan 10 2017 ...Extended period of heavy rain and snow expected to continue for much of the western U.S... ...Frigid air mass remains in place today for areas from the Southeast to the Appalachians and Mid-Atlantic... Rain and snow will remain widespread across much of the western U.S. through the next few days as onshore flow persists and a series of Pacific frontal systems affect the region. Snow levels will rise across the West Coast and the Great Basin today as warmer air temporarily moves inland. Rain is expected to fall across most much of central and northern California, with snow confined to only the highest peaks of the Sierras. Cold air will linger at the lower elevations close to the coast in Oregon and Washington this morning, and across portions of the interior valleys into this evening, keeping freezing rain a possibility for some areas. Farther inland across much of the central and northern Rockies, snow will continue to fall, with only the valleys seeing potential for rain and/or freezing rain. A cold front will move onshore on Monday, gradually lowering snow levels as it moves inland. Rain will change back to snow across the Sierras, and across the Great Basin late Monday. The pattern will continue into Tuesday as onshore flow and widespread precipitation persists, and another frontal system begins to approach the coast. Due to the long duration of the event and the high moisture content of the air, originating in the tropical Pacific, both heavy rain and snow are possible through the next few days. Heavy rain may cause flooding or flash flooding for some areas, and heavy snow is possible at the higher terrain and across much of the interior West. Additionally, strong and gusty winds can be expected at times, particularly along the coast and at the higher elevations. On Monday and Tuesday upper-level energy will move from the Rockies into the plains, with a low pressure system developing across the central plains by Tuesday night. Snow is expected to gradually develop Monday across portions of the northern plains and Upper Midwest, which will then spread east into the Great Lakes Monday night and Tuesday morning. Farther south, rain and areas of freezing rain are possible from the Ohio valley to the central Appalachians and portions of the Mid-Atlantic by Tuesday morning. Very cold temperatures are expected once again across much of the eastern U.S. today. High temperatures are expected to be 15 to 30 degrees below average from portions of the Southeast to the Appalachians and Mid-Atlantic. Temperatures across these areas will slowly moderate on Monday, but will remain below average. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php