Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 457 AM EDT Fri Sep 04 2015 Valid 12Z Fri Sep 04 2015 - 12Z Sun Sep 06 2015 ...Severe thunderstorms possible Today across portions of the northern plains and Upper Midwest... ...Excessive rain possible for portions of Montana and the Upper Midwest on Saturday... ...Above average temperatures expected for the eastern two-thirds of the U.S. through Saturday... The upper-level pattern through Sunday will be a trough over the West and a ridge over the eastern two-thirds of the U.S. The ridge will keep much of the country rather warm and dry. Numerous locations are expecting temperatures that are above average for early September - afternoon highs of 5 to 10 degrees above will be common, with isolated 10 to 15 degrees possible for the Midwest. A nearly stationary thermal boundary just south of the Great Lakes region will generate scattered showers and thunderstorms through Saturday. The eastern flank of the boundary will drop south as a cold front into the Mid-Atlantic states. Scattered showers and thunderstorms will be possible for the Southeastern states through the weekend. The trough over the west is relatively strong for this early in Autumn. The cold front associated with this feature extends from the Hudson Bay, through the Northern Plains and into the northern Intermountain West. Multiple waves will pass through the flow through Saturday which will allow scattered to numerous showers and thunderstorms to fire up across the Northern Plains to portions of the Upper Midwest. Some of the storms may turn severe -- as highlighted by a slight risk of severe thunderstorms in the Day 1 Convective Outlook from the Storm Prediction Center. Additional showers and thunderstorms are expected over portions of the Four Corners, Great Basin and Central Rockies through Sunday as the front stalls over the area and monsoonal moisture continues to advect in. With strong upper-level jet support, a nearly stationary front and a persistent feed of Gulf moisture in the lower atmosphere, the Northern Plains and the Upper Midwest will be primed for higher rainfall amounts and intensity. Excessive rainfall, with possible flash flooding, will be possible for Montana, the Dakotas and Minnesota on Saturday; Iowa, Minnesota and Wisconsin on Sunday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php