Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 351 PM EDT Sun Aug 19 2018 Valid 00Z Mon Aug 20 2018 - 00Z Wed Aug 22 2018 ...Heavy rainfall and strong thunderstorms expected to impact parts of the Plains, Midwest and Mississippi Valley over the coming days... ...Air quality will remain a concern across portions of the Western U.S. and the Upper Midwest... A strengthening low pressure system is currently located across the Central Plains, with a cold front extending south into the Southern Plains, and a warm front extending eastward into the Lower/Mid Mississippi Valley and Ohio Valley. This system will continue to push eastward as it strengthens during the first part of the work week. A strong influx of warm and moist air from the Gulf of Mexico is aiding in heavy rain production and strong to severe storms near this system. Meanwhile, another cold front originating from Canada will continue to quickly dive southward, bringing with it a much cooler airmass. These two systems are currently in fairly close proximity to one another, and will continue to interact with one another in the coming days, exasperating the storm and heavy rain potential. The Weather Prediction Center has issued a slight risk for excessive rainfall through tonight across a large north-to-south oriented region stretching from the Northern Plains and Upper Midwest southward into the Lower Mississippi Valley. This slight risk region will shift eastward with the low pressure and frontal systems for Monday and Tuesday. On Monday it will encompass portions of the Mid/Northern Mississippi, Ohio, and western Tennessee Valleys. On Tuesday the slight risk region will encompass an area from the Lower Great Lakes to the central Appalachians. Meanwhile, a flash flood watch is currently in effect through Monday morning for eastern Nebraska and southwest Iowa. Preemptive flash flood watches are also in effect across portions of southeast Wisconsin and southern Louisiana. The Storm Prediction Center also has a slight risk for severe storms through tonight for an area including northwest Arkansas and southwest Missouri. This slight risk area will also shift eastward over the next couple of days, encompassing many of the same areas as was outlined by the Weather Prediction Centers risk for excessive rainfall. Fire weather remains a concern across the western U.S. The combination of high winds and low humidities may contribute to igniting wildfires as we head into the work week. Several fire weather watches are currently in effect, including portions of Utah, Washington, and Montana. Due to the smoke pollution from ongoing wildfires, Air Quality Alerts remain in place for large portions of Oregon, Washington, Idaho, and all of Montana. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php