Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 338 AM EDT Fri May 13 2016 Valid 12Z Fri May 13 2016 - 12Z Sun May 15 2016 ...Flash flooding possible across portions of the Ohio and Tennessee valleys and central Appalachians... ...Strong to severe thunderstorms possible across the Midwest and MI-Atlantic... ...Below average temperatures on the way for much of the central and eastern U.S... Showers and thunderstorms are forecast from the Great Lakes region to the Northeast, along most of the East Coast and into the Gulf Coast through today and into early Saturday morning as a cold front pushes through. A secondary front will swing through the the most of the same areas, bringing additional showers, possibly some snow showers mixed in, across the Midwest, Ohio valley, Mid-Atlantic and Northeast this weekend. Periods of heavy rainfall may lead to flash flooding for portions of the Ohio and Tennessee valleys, as well as, portions of the central Appalachians early this morning. Some of the thunderstorms that develop in the Mid-Atlantic region may turn severe today. The Storm Prediction Center has highlighted areas of slight risk across portions of the Midwest and across eastern North Carolina and Virginia. Showers and thunderstorms associated with this secondary will be the leading edge of a much cooler air mass that will plunge through the Great Plains. High temperatures will be 10 to 20 degrees below average across the northern plains and Upper Midwest today; these cooler temperatures will spread into the southern plains and Ohio valley by Saturday. Much of the western states will have dry conditions today, but convection will become more prevalent by Saturday as the upper low moves further inland. Showers and thunderstorms will move inland from the Pacific Northwest to the Intermountain West. Mountain snows may be possible at the high lest elevations this weekend, especially for the Central Idaho and western Wyoming. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php