Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 255 PM EST Fri Jan 20 2017 Valid 00Z Sat Jan 21 2017 - 00Z Mon Jan 23 2017 ...Severe thunderstorms possible through the weekend across portions of the Gulf Coast and Southeast... ...Heavy snow possible from the higher elevations of California to the central and southern Rockies... Periods of scattered to numerous showers and thunderstorms are expected through much of the weekend from portions of the Gulf Coast and lower Mississippi valley to the Southeast, as a series of upper-level disturbances move overhead. One round of showers and thunderstorms is expected by this evening along much of the Gulf Coast, spreading across portions of the Southeast overnight into Saturday morning. On Saturday, a warm front will develop across the region, which will once again focus numerous showers and thunderstorms through the day and into the overnight hours. A low pressure system forecast to take shape across the southern plains on Saturday will move east into the lower Mississippi valley by Sunday morning. This system will bring yet another day of widespread showers and thunderstorms from the lower Mississippi valley and Gulf Coast to the Southeast. Severe thunderstorms are possible through the weekend in association with each of these rounds of showers and storms. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. Rain will also spread north into the Mid-Atlantic region by Sunday. The weather pattern will also be an active one across the western U.S. through the weekend, as a series of Pacific storms move onshore. The first of these storm systems is moving into the West Coast states today, and will bring rain and thunderstorms to areas along the coast as well as in the Desert Southwest tonight and Saturday. Heavy snow is possible across portions of the Sierras as well as the Mogollon Rim and the central/southern Rockies tonight into Saturday. The West Coast should see a very brief lull in precipitation during the day on Saturday before another more powerful Pacific storm system begins to approach late in the day. This second system will spread rain and mountain snow along nearly the entire West Coast Saturday night into Sunday. Snow will also spread across much of the interior West on Sunday. Heavy snow will be possible in association with this system once again across the mountains of California, as well as across portions of the Great Basin through Sunday. Heavy rain is also expected at lower elevations of California. Lastly, the northern plains and Upper Midwest will also see the potential for some relatively light precipitation tonight through the weekend as a slow-moving upper-level disturbance remains in the vicinity. A mix of rain, snow, sleet, and freezing rain is possible tonight through Saturday from the northern plains to the Upper Great Lakes. Scattered lighter precipitation will linger across the Upper Midwest into Sunday, with a wintry mix still possible. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php