Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 347 AM EDT Wed Apr 20 2016 Valid 12Z Wed Apr 20 2016 - 12Z Fri Apr 22 2016 ...Flash flooding possible for portions of the southern plains, western Gulf Coast and Lower Mississippi Valley... ...Severe thunderstorms possible today across the Texas panhandle... ...Well above average temperatures expected for the northwestern U.S... The system that brought widespread heavy precipitation flooding to portions of the southern and central plains will slowly track to the east through the end of the week. Showers and thunderstorms will persist for much of the southern/central plains and portions of the western Gulf Coast today before expanding into the Midwest and Upper Midwest by tonight into the Ohio and Tennessee Valleys on Thursday. Some of the storms that develop in northern Texas could become severe. The Storm Prediction Center has issued a slight risk for portions of the Texas today. Locally heavy rain will be also possible, which may result in flash flooding for some areas. An excessive rainfall outlook have been issued for portions of the southern plains and the Lower Mississippi Valley today. Warm conditions will continue for most of the Northeast and Mid-Atlantic states. Showers and thunderstorms will begin to spread into the region by Thursday afternoon/evening ahead of the advancing system. Most of eastern third of the CONUS will have widespread precipitation by Friday morning. A vast portion of the West will also remain relatively dry with well-above normal temperatures. High pressure at the mid and upper-levels of the atmosphere will help to keep coverage of precipitation scattered, and will also keep high temperatures 10 to 25 degrees above average today and Thursday. More widespread showers are forecast to begin spreading into the coastal Northwest by late Thursday as a Pacific frontal boundary approaches. Snow is forecast for Sierras - highest elevations could have snow accumulations near 10 inches. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php