Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 411 PM EDT Thu Aug 16 2018 Valid 00Z Fri Aug 17 2018 - 00Z Sun Aug 19 2018 ...Slight risk of severe thunderstorms and flash flooding over parts of the Central/Southern Plains and the Middle/Lower Mississippi Valley... ...Monsoonal rains bring flash flooding concerns to the Southwest... ...Fire Weather Concerns continue across the western U.S.... A quasi-stationary front currently extends from coastal New England southwestward through the Great Lakes, Middle Mississippi Valley and into the Southern Plains. Warm moist unstable air from the Gulf of Mexico is flowing northward towards this frontal boundary, allowing for scattered to numerous showers and thunderstorms along and ahead of the front. This boundary is expected to slowly shift eastward heading into the weekend, as will the best shower and thunderstorm potential. The Storm Prediction Center has outlined a region encompassing northeast Oklahoma, southeast Nebraska, southwest Missouri, and far northwest Arkansas as being in a slight risk for seeing severe thunderstorms today through tonight. The Weather Prediction Center has also outlined an area along the frontal boundary from the Southern Plains to the Tennessee Valley as being in a slight risk of seeing excessive rainfall and flash flooding through tonight. This slight risk of excessive rainfall will shift eastward into Kentucky and southern Indiana for Friday. Flash flood watches and warnings are currently in effect for portions of Oklahoma. Flash Flood watches are also in effect across north-central Kentucky and south-central Indiana ahead of the approaching system. Given the strong pull of warm air into the region, Heat Advisories are also in effect for portions of the Southern Plains and the Lower Mississippi Valley. Meanwhile, monsoonal moisture is making its way into the Southwest. Excessive rainfall is likely here through tonight, as is outlined by the Weather Prediction Center's slight risk forecast which encompasses much of the region. Flash Flood Watches and Warnings are also ongoing here. This same airmass will cause widespread fire weather concerns across other portions of the West. Scattered thunderstorms are expected across much of the western U.S., however a very dry near-surface layer will prevent most of the moisture from making it to the ground. Any lightning that occurs out of these storms could easily induce new wildfires, plus thunderstorm winds could cause them to quickly spread. Red Flag Warnings and Fire Weather Watches are currently in effect across much of Oregon, Idaho, southeast Washington and western Montana as a result. Furthermore, ongoing wildfires continue to pollute the air with extensive amounts of smoke. Air Quality Alerts remain in effect across central California, as well as much of Oregon, Washington, Idaho, and northwest Montana. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php