Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 221 PM EDT Sun May 21 2017 Valid 00Z Mon May 22 2017 - 00Z Wed May 24 2017 ...Severe thunderstorms possible across the southern plains... ...Flash flooding possible across the southern and central Appalachians and foothills, and across the Gulf Coast states... ...Well above average temperatures expected along the West Coast Monday and Tuesday... A deepening upper-level trough across the central and eastern U.S. through the short range will result in a period of wet conditions, especially from the Gulf Coast to the Eastern Seaboard. A frontal boundary will move from the Ohio valley toward the Mid-Atlantic and Northeast tonight into Monday morning, bringing widespread showers and thunderstorms to those regions. Farther south, the trailing end of the front is expected to become stationary along the Gulf Coast, bringing numerous showers and thunderstorms to southern Texas tonight, and spreading east along the Gulf Coast on Monday. Some thunderstorms could be severe across the southern plains tonight and Monday; please refer to products issued by the Storm Prediction Center for more details. Additionally, heavy rainfall may lead to flash flooding for some areas. Flash flooding will be possible across portions of the central and southern Appalachians and adjacent foothills through tonight, and from southern Texas to the central Gulf Coast through Monday. By late Monday into Tuesday, a wave of low pressure is expected to develop across the southeastern U.S. along the front, which will bring another round of rain and thunderstorms, including potentially heavy rain to areas from the Southeast to the southern Mid-Atlantic. Meanwhile, a secondary cold front will bring scattered showers and thunderstorms from portions of the central/northern plains to the Midwest Monday and Tuesday. High pressure aloft will strengthen along the West Coast through Monday, resulting in dry conditions with rising temperatures. High temperatures will rise well into the 90s for interior areas of the Pacific Northwest on Monday and Tuesday, with temperatures nearing 100 across the Central Valley in California. High temperatures may approach or surpass daily records in a few locations. A strong cold front is expected to move into the Northwest late Tuesday, which will usher a cooler air mass of Pacific origin into the region for the middle of the week. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php