Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 342 AM EDT Thu May 19 2016 Valid 12Z Thu May 19 2016 - 12Z Sat May 21 2016 ...Heavy rain and severe thunderstorms possible over portions of Texas and Louisiana... ...Potential heavy rain expected across the Southeast, Tennessee Valley, and Mid-Atlantic... ...Rain expected for the Pacific Northwest and Great Basin... Southerly flow will transport a fairly deep layer of Gulf Moisture into the southern Plains, lower Mississippi Valley and the Southeast through the weekend. Precipitable water values of 1 to 2 inches will span from Texas to Florida, with intermittent pockets of 2+ inches along the Texas Coast. Numerous showers and thunderstorms will develop along a quasi-stationary front drape across the western and central Gulf Coast through at least Friday. Some of these storms may become strong to severe across South Texas and the western Gulf Coast today, and will likely dump a lot of rain. As waves move eastward across the stationary front, the rainfall bulls-eye will also shift from the Big Bend region toward the southeast Texas coast by this evening and into Friday morning- which is an area that is still recovering from previous extreme rainfall events. Flash flooding will be possible from West Texas to the southeast Texas coast through Friday; therefore, an excessive rainfall outlook has been issued. The area of slight risk for severe storms on Friday will shift toward the central Gulf Coast. As the waves continue to move toward the eastern Gulf Coast along the quasi-stationary front, showers and thunderstorm will redevelop across the Southeast today, then spread into the Mid-Atlantic as the front begins to lift northward into the Tennessee valley and Mid-Atlantic region. With Gulf of Mexico moisture continuing to pumping into the region, the potential for heavy rainfall and flash flooding will increase. A closed upper-level low will dig from the Pacific Northwest to the Desert Southwest today into the weekend. A surface cold front will slowly move through the Great Basin and Intermountain West over the next few days. Showers and thunderstorms will be possible across much of the West, with snow in the favored highest elevations of the Cascades, Sawtooths and Northern Rockies. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php