Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 407 PM EDT Wed May 18 2016 Valid 00Z Thu May 19 2016 - 00Z 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... A very wet pattern will ensue over the southern Plains and into parts of the lower Mississippi Valley during the next few days. A quasi-stationary front will drape across the western and central Gulf Coast through at least Friday; this will act as a focal point for convection as deep southerly flow from the Gulf of Mexico provides ample amount of moisture across the southern Plains. As waves move eastward across the stationary front, the rainfall bullseye will also shift from the Big Bend region toward the southeast Texas coast by Thursday evening and into Friday morning--which is an area that is still recovering from previous extreme rainfall events. Thus, there is a risk of flash flooding from West Texas to the southeast Texas coast on both Thursday and Friday. In addition, the risk of severe thunderstorms lingers across Big Bend through Thursday morning and will shift toward the western Gulf Coast from Thursday and into Friday morning. By the end of Wednesday, most of the heavy rain across Florida and the Southeast will dissipate. However, by Thursday, the amount of rainfall will begin to ramp up as waves along the stationary front move toward the eastern Gulf Coast. By Friday, expect the front to begin lifting northward across the Tennessee Valley and Mid-Atlantic. This will also lift Gulf moisture across these regions. Once again, the front will act as a focal point for convection and thus may give way to the potential for heavy rainfall and flash flooding. A closed upper level low will dig across the Pacific Northwest throughout Wednesday and Thursday and move toward the Desert Southwest on Friday. At the surface, a cold front will push toward the northern Rockies and Great Basin which will give way to precipitation across these regions. On Thursday, expect precipitation to linger across the Pacific Northwest while spreading across the Great Basin and northern Plains--in addition to the central and southern Rockies. Rain will continue to fall across the Cascades Sierra Nevada, and Rockies on Friday as the surface front moves very slowly across the western U.S. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php