Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 413 AM EDT Fri Aug 24 2018 Valid 12Z Fri Aug 24 2018 - 12Z Sun Aug 26 2018 ...Severe storms and excessive rainfall possible across portions of the Upper and Middle Mississippi Valleys today... ...Shower and thunderstorm chances for the Southwest and coastal Southeast... ...Fire concerns persist across the western U.S.... A frontal system will continue to evolve across the Plains today and move eastward towards the Mississippi Valley. The low pressure center associated with this system will move from the Northern Plains to the Upper Great Lakes during the course of the day. A surge of moisture northward from the Gulf of Mexico will lead to showers and thunderstorms along the leading edge of this system, with best coverage along and just ahead of the center of low pressure. The Storm Prediction Center has outlined a portion of the Middle and Upper Mississippi River Valley as having a slight chance for severe storms throughout the day today. The Weather Prediction Center has also issued a slight risk for excessive rainfall and flash flooding across the same general area. In general, Missouri and Iowa may have the best shot for storm development today. This system will continue to shift eastward through the day Saturday, while losing considerable strength. However, heavy rain may persist during the day, leading the Weather Prediction Center to continue the slight risk of excessive rainfall for much of central and southern Wisconsin, as well as far northern Illinois on Saturday. Another frontal system across Florida and off the Atlantic Coast will remain stalled over the next couple of days, leading to scattered to numerous showers and thunderstorms across Florida and coastal regions across the Southeast. Monsoonal moisture will bring scattered showers and thunderstorms across the Southwest over the next few days as well, mainly during the afternoon and evening. The Weather Prediction Center has issued a marginal risk of excessive rainfall and flash flooding across portions of Arizona and New Mexico for the weekend, expanding northward into southern Colorado on Sunday. Meanwhile, fire weather concerns continue across the western U.S.. A Red Flag Warning is in effect through this evening for much of eastern Idaho due to high winds and low relative humidities, especially during the afternoon. Fire Weather Watches are also in effect for the Sierras and Western Nevada and much of western and central Wyoming. Ongoing wildfires continue to lead to large amounts of smoke in the air and resulting air quality concerns. Air Quality Alerts remain in effect for much of Oregon, Washington, Idaho, and northwest Montana. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php