Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 222 PM EDT Fri Mar 18 2016 Valid 00Z Sat Mar 19 2016 - 00Z Mon Mar 21 2016 ...Severe thunderstorms possible through tonight across portions of the southern plains and lower Mississippi valley... ...Locally heavy rain possible across portions of the Southeast... ...Snow expected for portions of the Mid-Atlantic and Northeast Saturday and Sunday... A stationary frontal boundary will linger across the Gulf Coast states before moving north tonight as a warm front across the Southeast. At the same time, a cold front, the leading edge of a polar air mass, will move across the southern plains, Tennessee valley, and the Mid-Atlantic. Ahead of the cold front, a moist and unstable air mass will result in scattered to numerous showers and thunderstorms tonight from the southern plains to the Southeast. The Storm Prediction Center is forecasting a slight risk of severe thunderstorms through tonight across portions of this area, from the southern plains to the lower Mississippi valley. Locally heavy rain is also possible. Showers and thunderstorms will continue through Saturday across the southeaster U.S. as a wave of low pressure develops along the front. Rainfall amounts of 1 to 2 inches, with locally higher amounts, are possible through Saturday night across portions of the Southeast. The surface low forecast to develop across the Southeast on Saturday will move northeastward, and is forecast to be located off the Mid-Atlantic coast by Sunday morning. Rain will spread into the Mid-Atlantic during the day on Saturday, with a rain/snow mix possible for many areas by Saturday afternoon. A mix of rain and snow, with all snow west of the I-95 corridor, is forecast by Sunday morning. Snow is also forecast to spread into much of the Northeast on Sunday, with heavy snow possible for some areas. A Pacific low pressure system will approach the northwestern U.S. early Sunday morning, with rain spreading into much of the region during the day. Snow levels will be relatively high through Sunday, with snow expected only at the highest elevations of the Cascades and the Sierras, as well as the northern Intermountain region. Colder temperatures will move into much of the central and eastern U.S. in the wake of the cold front Saturday and Sunday. High temperatures on Saturday and Sunday are forecast to be 10 to 20 degrees below average for much of the central and eastern U.S. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php