Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 PM EDT Fri Sep 11 2015 Valid 00Z Sat Sep 12 2015 - 00Z Mon Sep 14 2015 ...Heavy rain possible over parts of the Lower Great Lakes and Northeast... ...Well above average temperatures will continue for much of the western U.S... A relatively strong cold front characteristic of early autumn will move across the eastern U.S. tonight into Saturday. Scattered to numerous showers and thunderstorms are expected along the front tonight from the Lower Great Lakes to portions of the Ohio valley and Appalachians. A wave of low pressure is forecast to develop along the frontal boundary on Saturday across the Mid-Atlantic region, which will enhance coverage of showers and thunderstorms from the Mid-Atlantic region northward into the Northeast as the low moves northeastward. The front will move off the Mid-Atlantic coast, bringing an end to precipitation for most of the Mid-Atlantic by Sunday. Rain and thunderstorms will continue into Sunday for the Northeast, however, as the surface low and an occluded front cross the region. Rainfall totals may be heavy in some areas of the Lower Great Lakes and the Northeast, with 2 to 3 inches of rain possible. The trailing end of the same cold front will bring scattered showers and thunderstorms from the southern plains to the Southeast tonight into Saturday. Behind the cold front, a cool, dry, fall-like air mass will overspread much of the eastern U.S. Afternoon high temperatures on Saturday will be 10 to 20 degrees below average across much of the Ohio and Tennessee valleys, and these below average temperatures will begin to spread toward the East Coast by Sunday. In stark contrast to the East, temperatures in the West will remain well above average on Saturday. Afternoon high temperatures across interior portions of the Northwest may approach 20 degrees above average in some areas, with many areas exceeding 10 degrees above average. A cold front will move into the northwestern U.S. on Sunday. The system will be relatively starved for moisture. A few showers are possible Sunday across coastal portions of Washington State, but dry conditions are expected to persist through Sunday for most areas. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php