Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 440 AM EDT Mon May 20 2013 Valid 12Z Mon May 20 2013 - 12Z Wed May 22 2013 ...Moderate risk of severe weather for eastern Oklahoma and the southern Ozarks through Tuesday morning... ...Slight risk of severe weather for the Midwest and upper half of the Mississippi Valley today and tonight... ...Heavy rainfall possible for the Upper Missouri and Mississippi Valleys... ...Slow-moving Pacific system to bring rainfall...windy conditions and cooler weather to the Pacific Northwest and northern Rockies... Deep...slow-moving trough of low pressure in the north central Plains and broad fetch of moist...southerly flow off the Gulf of Mexico is expected to produce widespread showers...thunderstorms and locally heavy rainfall over a large portion of the Plains...Midwest and central Great Lakes today and Tuesday. Along with the threat of heavy rainfall...there is a moderate risk of severe storms for the southern Plains and Ozarks and a slight risk of severe weather for the upper half of the Mississippi Valley. Please refer to the Storm Prediction Center for the latest information and updates concerning the potential severe weather threat through Tuesday morning. Out West...low pressure in the Gulf of Alaska will slowly move across the Pacific Northwest and northern Rockies. Inland...low pressure is expected to intensify over southwest Canada with an increase in southerly flow and threat for mountain showers and thunderstorms. By Tuesday morning...a strong cold front and windy conditions surges across the Cascades and spreads cooler and wetter weather into the northern Rockies and produces scattered showers and a few thunderstorms into western sections of Washington and Oregon. In the East...scattered showers will continue across Maine and portions of northern New England through this evening...as a slow-moving Canadian cold front sweeps into the north Atlantic. For Monday night and Tuesday...a broad warm front and more humid conditions will work their way up the East Coast...with the threat of showers and a few thunderstorms for the mid-Atlantic states...Appalachians and Northeast...including the upper Ohio valley and Eastern Great Lakes. Vojtesak Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php