Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 348 PM EDT Fri Aug 09 2019 Valid 00Z Sat Aug 10 2019 - 00Z Mon Aug 12 2019 ...Severe weather and flash flooding possible across portions of the Northwest through Saturday... ...Heavy rain and flash flood potential for portions of the Southwest into the Great Plains... ...Heat and humidity over Texas into the Lower Mississippi Valley to spread north this weekend... An anomalous upper level low will move ashore across northern California into Oregon tonight, bringing increased Pacific moisture into the West and the potential for severe thunderstorms. Above average moisture is already in place across portions of Washington, Oregon into Idaho and Montana. As favorable jet level flow aloft combines with the heating of the day, thunderstorm coverage is expected to increase later this afternoon across Oregon where the Storm Prediction Center has a Slight Risk for severe storms. The severe threat shifts northeastward into Idaho and western Montana for Saturday where thunderstorm coverage is expected to be greatest, with storms containing the potential for damaging winds and hail. Flash flooding from intense rainfall from any of these thunderstorms will also pose a flash flood risk across many of these same locations across the Northwest. The entire system will advance eastward for Sunday with heavy rain and severe thunderstorm risks extending from eastern Montana into portions of the Central Plains, while temperatures cool off significantly in the wake of the system's cold front. Across the South, Heat Advisories are currently in affect for much of central and eastern Texas, through Louisiana and portions of the Gulf Coast States. Temperatures in the mid-upper 90s and even lower 100s will combine with high humidity to generate heat Index values in the 105-110 degree range during the afternoon, located south of a weakening stationary front. As the stationary front across southern Oklahoma dissipates early Saturday, heat and humidity will spread north into Kansas and Missouri, with a warming trend expected through the Mid-Mississippi Valley through early next week. Heat Index values could reach 105 degrees on Sunday from southern Kansas into western Tennessee with values approaching 110 degrees from Texas and Oklahoma into the Lower Mississippi Valley. Across the Southwest, upper level impulses riding around a slow moving ridge centered over Texas will combine with anomalous moisture to produce numerous thunderstorms during the afternoon and evening hours. There is a Slight Risk for flash flooding across portions of Arizona into New Mexico through Saturday given rainfall potential of 1-3 inches through Saturday night. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php