Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Sun Aug 26 2018 Valid 12Z Sun Aug 26 2018 - 12Z Tue Aug 28 2018 ...Heavy rain expected for the north-central U.S.... and building heat across the eastern states... An upper level trough is expected across the northwestern U.S. and the Dakotas through the beginning of the week while an upper level ridge builds across the eastern third of the nation. An active frontal zone will stretch from the Central Great Basin, northeast through the Northern Plains and across the Upper Misssippi Valley today, with multiple low pressure centers expected to develop along the boundary. This boundary is then expected to slowly straighten out as it pushes southeast over the coming days. Showers and thunderstorms are expected along the frontal boundary, especially near any low pressure centers. The strongest area of low perssure will be found across the northern Plains today, with the Storm Prediction Center outlining a large area stretching from the Dakotas eastward across Wisconsin as being in a slight risk for severe thunderstorm development today. The Weather Prediction Center has also outlined a portion of this region as being in a slight risk for excessive rainfall and flash flooding. As the front progresses slowly eastward on Monday, the slight risk area for severe thunderstorms and excessive rainfall will focus iteself across the Upper Midwest and Upper Great Lakes region. Meanwhile, across much of the eastern U.S., a strong ridge of high pressure will be in place. This will couple with strong southerly flow heading towards the above mentioned frontal system, leading to hot and humid conditions over the coming days. The heat is expected to continue until after the cold front has passed through, which could mean persistant above normal temperatures for much of the east and southeat through most of the week. Several heat advisories have been posted for today, including near the Kansas City and St. Louis metropolitan areas, as well as much of eastern Oklahoma, and northeast Arkansas where heat indices will likely top out in the tripple digits. For the western U.S., fire weather concerns rage on. High winds and low humidity have led to Red Flag Warnings today across across much of the Central Great Basin (Central and Northern Nevada as well as western Utah), and across much of Wyoming, western Nebraska, and southwest South Dakota. Ongoing wildfires continue to contaminate the air with smoke, continuing Air Quality alerts across the region. Areas affected by Air Quality Alerts today include central California, southern Oregon, much of Washington, Southeast and northern Idaho, and northwest Montana. Finally, lingering monsoonal moisture will lead to scattered showers and thunderstorms stretching from the Southwest and into the Southern and Central Rockies today. A marginal risk of excessive rainfall remain in place across a portion of Arizona and New Mexico today. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php