Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 348 PM EDT Sat May 18 2013 Valid 00Z Sun May 19 2013 - 00Z Tue May 21 2013 ...There is a slight risk of severe thunderstorms from parts of the Northern Plains to North-Central Texas, with an embedded area of moderate risk of severe thunderstorms from West-Central Oklahoma to Southwestern Nebraska... ...Heavy rain is possible over parts of the Upper Midwest and Central Carolinas... A deep upper-level trough over the Rockies will develop into a closes upper-level low over the Northern/Central Plains by Monday. A much weaker upper-level low over Western Ohio will drift eastward to the Southern Mid-Atlantic by Monday. The energy will trigger showers and thunderstorms over parts of the Southeast, Tennessee Valley, and the Mid-Atlantic. Rain will also develop over parts of the Ohio Valley to parts of the Northeast/Mid-Atlantic through Monday. Overnight Sunday, upper-level energy over Southeastern Canada will move over Maine producing an area of light to moderate rain on Monday morning. Another area of upper-level energy over the Pacific Northwest will enter into the deep upper-level trough over the Rockies, that will aid in developing the upper-level closed. As the disturbance moves inland, showers and thunderstorms will develop over parts of the Northern/Central Rockies and the Northern/Central High Plains on Saturday evening, becoming rain overnight Saturday, remaining mostly rain through Monday over the Northern/Central Rockies. Additionally, onshore flow will produce rain over parts of the Pacific Northwest through late Saturday night. Under the developing upper-level low, showers and thunderstorms, some with moderate rain, will develop over parts of the Plains Saturday into Sunday, moving into parts of the Upper/Middle Mississippi Valley by Sunday evening. The showers and thunderstorms, with moderate rain, will be confined mostly to the Northern Plains by Monday morning. Some scattered showers and thunderstorms will develop over parts of the Lower/Middle Mississippi Valley, also by Monday. In addition, areas of light to moderate rain will develop over parts of the Northern High Plains and the Upper Great Lakes overnight Sunday into Monday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php