Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 416 AM EDT Tue Apr 30 2013 Valid 12Z Tue Apr 30 2013 - 12Z Thu May 02 2013 ...There is a slight risk of severe thunderstorms from parts of the Middle Mississippi Valley to parts of the Upper Great Lakes... ...A strip of snow is possible from parts of the Central Plains to the Upper Great Lakes... ...Heavy rain possible over parts of the Central Plain to parts of the Upper Mississippi Valley and the Central Gulf Coast... A strong cold front extending from the Upper Mississippi Valley southwestward to the Central High Plains will move slowly eastward to the Upper Great Lakes to the Southern Plains by Wednesday evening. Rain and a little snow along the U.S./Canadian border, across the Upper Midwest, will move northward into Canada by Tuesday evening. An area of showers and thunderstorms over the Middle Mississippi Valley/Upper Great Lakes will also move into Canada by late Tuesday evening. Additional upper-level energy will drop southeastward from the Pacific Northwest to the Central Rockies by Wednesday evening. The energy will aid in producing snow over parts of the Northern/Central Rockies by Tuesday evening, becoming heavy snow over parts of the Central Rockies/Central High Plains by Wednesday morning. The snow will become lighter over the area by Wednesday evening. In addition, moisture from the Gulf of Mexico will overrun the front producing showers and thunderstorms over parts of the Central Plains to the Upper Mississippi Valley on Tuesday evening. By Wednesday Morning, moderate to heavy rain will develop over the Central Plains into parts of the Upper Mississippi Valley, weakening slightly to light to moderate rain by Wednesday evening. Showers and thunderstorms will develop over parts of the Southern Plains by Wednesday evening. Furthermore, snow will develop over parts of the northwest side of the precipitation shield from parts of the Central High Plains to parts of the Upper Great Lakes also by Wednesday evening. Meanwhile, an upper-level disturbance just off the Southern Mid-Atlantic/Carolina coast will trigger mainly light rain over the area through Wednesday evening. Additionally, a developing upper-level low along the Central Gulf Coast will aid in developing showers and thunderstorms over the Western Gulf Coast, migrating to the Central Gulf Coast by Tuesday evening and continuing through to Wednesday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php