Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Thu May 19 2016 Valid 00Z Fri May 20 2016 - 00Z Sun May 22 2016 ...Heavy rain and severe thunderstorms possible over the western Gulf Coast... ...Potential heavy rain expected across the Southeast, Tennessee Valley, and Mid-Atlantic... ...Unsettled weather expected for the Pacific Northwest and Great Basin... A quasi-stationary front will continue to be draped along the Gulf Coast and Southeast over the short term period which will prolong rounds of convection across these regions. In addition, there is also strong southerly flow pulling a deep layer of moisture from the Gulf of Mexico across the southern U.S., which creates the prime ingredients for focusing convection across the Texas and into Louisiana on Thursday and into Friday. This is also creating a recipe for strong thunderstorms along with potential for flash flooding. In fact, a line of strong thunderstorms is moving across Deep South Texas and the southeast Texas coast, and will move into the Gulf by tonight. This area of convection will skirt the Louisiana and Mississippi coast through Thursday night and into Friday morning, bringing with it potential for flash flooding. The front will begin lifting across the Tennessee Valley and eastward into the Southeast during the day Friday, which will advance precipitation eastward toward the Mid-Atlantic and East Coast. By Saturday afternoon, most of the showers and thunderstorms will exit the coast--except for some lingering showers across the Mid-Atlantic. Deep South Texas will also continue to see showers and thunderstorms on Friday and Saturday, albeit not as intense as they are experiencing on Thursday. The stationary front lingers along the Rio Grande Valley during Friday and into the weekend and will remain the focus for igniting convection. A large closed upper level low will drop southward across the Pacific Northwest and Great Basin through tonight and into Friday. At the surface, a cold front will slowly move across the Great Basin with showers and thunderstorms along the front and behind it. Because the upper level will move slowly toward the Desert Southwest through Saturday, the front will also advance very slowly and will even stall across the Great Basin. Consequently, expect scattered showers and thunderstorms across the Pacific Northwest and Great Basin with heavier amounts of rain in the higher terrain. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php