Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 338 AM EST Mon Nov 16 2015 Valid 12Z Mon Nov 16 2015 - 12Z Wed Nov 18 2015 ...Severe thunderstorms possible from portions of the southern and central plains to the lower Mississippi valley... ...Flash flooding possible possible from portions of the southern plains to the lower and middle Mississippi valley... ...Heavy snow possible from portions of the central Rockies to the central High Plains... A powerful and dynamic storm system is taking shape across the Rockies early this morning which will bring a variety of significant weather to the central U.S. over the next couple days. An upper-level trough will quickly amplify over the Four Corners region today before closing off into an upper-level low. A surface frontal system will move across the Rockies today before beginning to exit into the plains by tonight. Southerly flow across the plains ahead of the storm system will transport moist and unstable air northward. As a result, showers and thunderstorms will be possible across much of the central U.S. today. The best mid and upper-level dynamics will be in place across the southern plains, where some of the thunderstorms may become severe. The Storm Prediction Center is forecasting a slight to enhanced risk of severe thunderstorms across that area today. The system will move east on Tuesday, with showers and thunderstorms possible across the entire length of the Mississippi valley. Severe thunderstorms will again be possible on the southern end of the system, across the lower Mississippi valley. In addition to the threat of severe weather, flash flooding is possible across the southern plains today and across portions of the lower and middle Mississippi valley on Tuesday. By Wednesday morning, showers and thunderstorms will spread east into the Ohio valley and the southeastern U.S. On the north side of the storm system, snow will fall across much of the Rockies today. Heavy snow is possible, with snowfall amounts in excess of one foot possible at the highest elevations. As the surface low deepens and moves into the central High Plains tonight, colder air will be pulled into the north side of the system, causing rain to mix with or change to snow north and west of the surface low across the central plains. Heavy snowfall amounts of 3 to 7 inches are possible in this area, along with winds that may become gusty as the surface low strengthens. There will be little break between systems, as another Pacific storm system is forecast to approach the Northwest later today with lower elevation rains and high elevation snows. More heavy snow will be possible in the Cascades of Washington, with snowfall amounts exceeding one foot in some areas. Precipitation will spread inland across the northern Intermountain states Tuesday into Tuesday night, with mountain snow and valley rain. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php