Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Fri May 10 2013 Valid 00Z Sat May 11 2013 - 00Z Mon May 13 2013 ...Changeable weather pattern to continue with severe weather/heavy rain over the lower Mississippi and Ohio valleys, eastern U.S. and Gulf Coast followed by another shot of much cooler air from the Northern Plains south and eastward... A slow moving frontal boundary currently extending from the Great Lakes back into the southern plains will continue to push slowly east, spawning showers and thunderstorms eastward across the Gulf Coast, lower Mississippi and Ohio valleys through this evening. Some of these storms may produce severe weather and heavy rains. As low pressure lifts northeastward across the eastern Great Lakes into southern Ontario and then Quebec on Saturday, showers and some heavy thunderstorms will spread eastward across East Coast, especially the Northeast and northern mid Atlantic states. By early Sunday, the cold front will span much of the East and Gulf Coasts leaving behind cooler, drier weather. Even in the wake of the front, showers and thunderstorms are expected to continue through the evening and into tomorrow across portions of south Texas and the southern and central Rockies as moisture from the Gulf of Mexico streams westward, interacting with a number of upper level disturbances. A more significant cool air outbreak is expected to follow behind the initial front and begin to cross the northern plains by later Friday. Colder air will once again push southward across the northern plains into the central plains/Midwest by Saturday morning, reaching the northern Gulf Coast and East Coasts by Sunday morning. Temperatures will likely fall well below normal again with rain and snow showers returning to the Great Lakes. Unlike the initial front, this front has little moisture support and only some scattered showers, with maybe a thunderstorm, will accompany its passage south and eastward. Out west, an approaching frontal system will bring clouds and rain showers across western Washington late Saturday into Sunday. Very warm conditions will increase across the West ahead of the advancing front. Pereira Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php