Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 345 AM EDT Sun Jul 21 2013 Valid 12Z Sun Jul 21 2013 - 12Z Tue Jul 23 2013 ...There is a slight risk of severe thunderstorms for parts of the Northern/Central Plains... A front extending from the Mid-Atlantic westward to the Central Plain then northwestward to the Northern High Plains will have a wave of low pressure develop over the Northern High Plains that in turn will move northeastward to Central Ontario by Monday evening. The low will pull the boundary northward as a warm front starting over the Northern/Central Plains on Sunday morning, moving eastward to the Great Lakes and the Central Appalachians/Mid-Atlantic on Monday. The associated cold front will move from the Northern Plains to the Upper Great Lakes by Monday. Showers and thunderstorms will develop along and near the stationary front from the Middle Missouri Valley eastward to the Central Appalachians/Mid-Atlantic and extending as far south as the Tennessee Valley on Sunday. The showers and thunderstorms will continue from the Western Ohio Valley/Tennessee Valley to parts of the Mid-Atlantic/Southern New England on Monday. As the wave moves eastward, an area of showers and thunderstorms, with moderate rain, will develop over the Northern Plains moving eastward to the Upper Great Lakes by Monday morning. The showers and thunderstorms will expand southwestward along the cold front from the Upper Great Lakes to the Middle Missouri Valley by Monday evening. In addition, showers and thunderstorms will develop along the Southeast Coast through Monday. Showers and thunderstorms will also develop along parts of the Central Gulf Coast through Monday, too. Elsewhere, an upper-level low over Northwestern Mexico will trigger showers and thunderstorms over parts of the Southwest and Southern California on Sunday into Monday. Additionally, diurnal heating and monsoonal moisture will produce showers and thunderstorms over parts of the Southwest/Southern Rockies on Sunday. The showers and thunderstorm will also develop over parts of the Lower Rio Grande Valley Sunday and Monday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php