Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Fri Jun 30 2017 Valid 12Z Fri Jun 30 2017 - 12Z Sun Jul 02 2017 ...Showers and thunderstorms will generally shift eastward into the eastern U.S. for the next couple of days... ...Strongest thunderstorms are expected to be in the central Plains where flash flooding is possible... A broad upper-level trough over the northern and central U.S. is forecast to generally migrate eastward into the eastern U.S. as we head into the weekend. Multiple smaller-scale disturbances and surface fronts associated with this complex system will gradually consolidate into a better-defined cold front as it approaches the Appalachian later on Saturday. This means that there will be a broad but scattered areas of showers and thunderstorms slowly progressing eastward across much of the East Coast through Saturday before the front moves off the coast on Sunday, with the return of drier and slightly cooler weather. Meanwhile, the trailing portion of the cold front will become nearly stationary over the central Plains and will remain the focus for formation of heavy showers and thunderstorms. Since the front is expected to remain slow-moving, heavy rain that forms in the vicinity could move across the same areas, leading to the possibility of flash flooding today and into the weekend. Farther south, typical summer heat and humidity along with scattered thunderstorms can be expected in the Deep South down into the Gulf Coast. Generally quiet weather can be expected over the western U.S. as we head into the weekend with temperatures slight above normal. Mostly sunny conditions can also be expected before the next upper-level trough arrives on Saturday, triggering some thunderstorms over the northern Rockies and the Great Basin on Sunday. Meanwhile, replenishing cool air from Canada should begin to move into the northern Plains on Sunday. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php