Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 AM EDT Wed May 16 2018 Valid 12Z Wed May 16 2018 - 12Z Fri May 18 2018 ...A wet and stormy pattern will continue over much of the eastern U.S., with flash flooding and strong thunderstorms possible over southern New England and the northern Mid-Atlantic states... ...An active pattern is expected over the northwestern quarter of the Nation the next few days... ...Shower and thunderstorm activity will be possible for portions of the Great Plains, with severe thunderstorms possible Thursday and Friday... Much of the eastern U.S. will stay in a persistent, wet and stormy pattern over the next few days as a wavy frontal boundary sags southward into a moist and unstable airmass. The most favorable region for excessive rainfall will be along the eastern stretch of the Ohio River to the Chesapeake Bay and along the Central Appalachians. Additionally, a weak disturbance is forecast to lift out of the eastern Gulf of Mexico which could lead to localized areas of heavy rainfall within widespread convection developing across the Southeast and Carolinas today. Scattered to widespread showers and thunderstorms will likely develop over the central/northern High Plains, with favorable conditions to become severe. The greatest chance for storms should shift farther north to a frontal boundary setting up over North Dakota and Minnesota. The Storm Prediction Center has a slight risk covering this area Thursday and Friday. Also, heavy rainfall will also be likely within this area of convection. WPC has broad area of marginal risk across the Plains with slight risks focusing over southern North Dakota and western Nebraska. An active pattern is expected over the northwestern quarter of the Nation the next few days as a weakening upper low lifts northeastward of the central Great Basin and an upstream upper low begins to edge inland over California. Campbell/Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php