Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EDT Fri May 10 2013 Valid 12Z Fri May 10 2013 - 12Z Sun May 12 2013 ...Changeable weather pattern to continue with severe weather/heavy rain over the Mississippi and Ohio Valleys followed by another shot of much cooler air from the Northern Plains south and eastward... A slow moving frontal boundary with one or more waves of low pressure will move eastward spawning showers and thunderstorms from the Southwest and Southern Plains eastward across the Gulf Coast/Lower and Mid Mississippi Valleys and Midwest through Friday. As low pressure moves northeastward across the eastern Great Lakes into Quebec on Saturday...showers and some heavy thunderstorms will spread eastward across East Coast...and especially the Northeast. By late on Saturday...the cold front will span much of the East and Gulf Coasts with cooler air behind. 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 penetrate southward across the Northern Plains into the Central Plains/Midwest by Saturday morning and reach 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 first front, this front has little moisture support and only some scattered showers and maybe a thunderstorm will accompany its passage south and eastward. Out west...scattered convection will occur across the Rockies under late day heating on Friday and Saturday...while much of the West Coast remains warm. By late Saturday into Sunday...an approaching frontal system will bring clouds and rain showers across the Washington coast. Very warm conditions will increase across the West ahead of the advancing front. Kocin Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php