Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 405 PM EDT Wed Aug 15 2018 Valid 00Z Thu Aug 16 2018 - 00Z Sat Aug 18 2018 ...A slight risk of severe thunderstorms and flash flooding over parts of Nebraska and South Dakota... ...A frontal boundary will be the epicenter for excessive rainfall and strong storms stretching from the Southern Plains into the Ohio Valley today through Thursday... ...Dry thunderstorms possible across the western U.S.... An deep upper level wave is currently moving across the northern plains, resulting in complex of showers and thunderstorms across South Dakota and northern Nebraska. As this area of heavy rain and strong thunderstorms is expected to continue, the Storm Prediction Center has issued a slight risk for severe thunderstorms through tonight. The Weather Prediction Center has also outlined this area as having a marginal to slight risk for excessive rainfall and flash flooding. This upper level wave will continue to shift southeast, putting southeast Nebraska, much of eastern Kansas, and far northwest Missouri in a slight risk for severe storms on Thursday. A frontal system is currently stretching from the Southern Plains northeast towards the Great Lakes and across the Northeast. Warm, moist air is being pumped northward from the Gulf of Mexico towards this frontal boundary, especially across the Southern Plains and Low/Middle Mississippi Valley. This is resulting in an unstable atmosphere capable of producing strong storms and excessive rainfall. The Weather Prediction Center have outlined two areas as being in a slight risk for excessive rainfall and flash flooding through tonight. The first encompasses the northwest portion of the Southern Plains (including the Oklahoma and Texas panhandles), and the second stretches from far eastern Oklahoma into southern Indiana and along the Ohio River of Kentucky. Furthermore, a portion of West-Central Arkansas and far East-Central Oklahoma is in a moderate risk for flash flooding. Flash flood watches and warnings are ongoing across this moderate risk region, stretching northward into the Southern Missouri. The Storm Prediction Center has also placed these same regions in a moderate risk of severe weather development. As the frontal boundary slowly shifts eastward over the coming days, so too with the risk for excessive rainfall and strong storms. Meanwhile the western U.S. is still being impacted by fire weather concerns. Monsoonal moisture is currently making its way into the Southwest. However, as this moisture surges northward across the western U.S., a very dry near-surface layer will likely prevent any rainfall from hitting the ground. Furthermore it will likely result in dry thunderstorms, with lightning potentially sparking new wildfires. Red Flag warnings are in effect across central Oregon, northeast California, western Nevada, and southwest Wyoming through this evening. Air Quality Alerts are also encompassing large portions of the western U.S. as ongoing wildfires continue to infuse the air with copious amounts of smoke. Much of Washington, Oregon, northern Idaho, and western Montana, as well as a portion of Central California are included in an Air Quality Alert. An Air Quality Alert for blowing dust has also been issued near and around Phoenix, Arizona through Thursday. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php