Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 304 AM EDT Mon May 01 2017 Valid 12Z Mon May 01 2017 - 12Z Wed May 03 2017 ...Severe thunderstorms possible today across much of the eastern U.S... ...Heavy snow possible today across portions of the Upper Midwest... An expansive low pressure system will move northeastward across the Upper Midwest today. Ahead of the surface low, a cold front will bring widespread showers and thunderstorms to much of the eastern U.S. Some of these thunderstorms could be severe. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. The cold front will sweep off the East Coast Monday night into Tuesday morning, bringing and end to the showers and thunderstorms as it does so. Meanwhile, in the cold air on the northwestern side of the low pressure system, wintry precipitation is possible across portions of the Upper Midwest. A mix of rain and snow is expected, with heavy snow possible for some areas. Rain and snow showers may linger across portions of the Upper Midwest and Upper Great Lakes into Tuesday morning as the low pressure system moves northeastward into Canada. In the wake of this low pressure system, cooler air will move into much of the plains, Midwest, and the Great Lakes, where high temperatures on Tuesday are forecast to be 10 to 20 degrees below average. Elsewhere across the country, a weakening Pacific cold front will move from the Rockies into the northern plains today before washing out across the plains this evening. The front will produce scattered rain and mountain snow showers from the northern and central Rockies east into the High Plains. A few thunderstorms are also possible across the northern High Plains. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php