Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 454 AM EDT Sat Sep 05 2015 Valid 12Z Sat Sep 05 2015 - 12Z Mon Sep 07 2015 ...Heavy rainfall possible for portions of the Northern Plains and Upper Midwest Sunday and Monday... ...Severe thunderstorms possible for Minnesota and extreme northwest Wisconsin on Sunday... The main system to impact the US over the next couple of days is a cold front that extends from Manitoba/Ontario/Hudson Bay area through the Dakotas and southwest into Idaho and Nevada. An eastward progression will be minimal until Sunday when the associated low pressure center of this system deepens. A series of weak waves of low pressure will traverse through the flow, allowing widespread rain and thunderstorms to initiate and persist from the Intermountain West to the Upper Midwest. Temperatures in the mid-levels will be just cold enough with this trough for the higher elevations of Montana, Idaho and Wyoming to have a rain and snow mix. The slow movement of the frontal system combined with the duration of the rain and thunderstorm activity raises concern of flash flooding given that heavy rainfall will be possible. Some areas may receive 2-4 inches of rain through Sunday- Minnesota will be the main area of focus. The Storm Prediction Center has highlighted most of the state, in addition to a narrow swath of Wisconsin along the state line, as having a slight risk for severe thunderstorms to develop on Sunday. The cold front will track into the Central Plains and Central Rockies by Monday. Monsoonal moisture will remain in place across the southwestern U.S., with scattered showers and thunderstorms expected during the afternoon and evening through the weekend across the Four Corners region. Slightly cooler temperatures will makes its way into the Mid-Atlantic region as a weakening cold front moves southward through the area. Many locations will observe temperatures this holiday weekend that are a few degrees below the seasonal average. Scattered shower and thunderstorms will be possible ahead of the leading edge of the front, near the Ohio Valley, all the way to the Southeast states. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php