Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 459 PM EDT Thu Jul 25 2013 Valid 00Z Fri Jul 26 2013 - 00Z Sun Jul 28 2013 ...A developing low pressure system is expected to bring moderate to heavy rain over parts of Maine on Friday... ...A cold front preceded with showers and thunderstorms is expected to bring a reinforcing shot of cool air into much of the eastern two-thirds of the country... Following the passage of a cold front, much of the eastern two-thirds of the country is under the influence of a cool air mass. In fact, some areas in upstate New York was quite chilly this morning as temperatures approached the freezing mark! As the cool air pushes off into the Atlantic, a low pressure center is forming on the frontal boundary just off Cape Hatteras. The low is expected to intensify and move northward towards Maine on Friday. A period of moderate to heavy rain can be expected to move across Maine, especially eastern Maine, during the daytime and evening hours. Rain should begin tapering off by Saturday morning as the low moves into the Canadian Maritimes. Meanwhile, a reinforcing shot of cool air from Canada is moving into the Northern Plains. The leading edge of the cool air is expected to push gradually eastward across the Plains, reaching the Ohio and Tennessee Valleys by Saturday. Showers and thunderstorms are expected to develop ahead of the cold front, and some of the showers can be heavy. The cool air will once again drop temperatures to well below normal levels for late July in the Northern Plains. By Saturday, fine weather will return to much of the Plains as scattered thunderstorms are shoved into the Deep South. However, widely scattered thunderstorms could form in the Central Plains ahead of a stationary front across the Rockies. Elsewhere, monsoonal moisture and diurnal heating will trigger showers and thunderstorms over portions of the Southwest and the Southern/Central Rockies for the rest of the week. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php