Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 327 AM EDT Wed Aug 3 2016 Valid 12Z Wed Aug 3 2016 - 12Z Fri Aug 5 2016 ...Cooler air will move across much of the northern U.S. while summer heat continues for the rest of the country... ...Heavy rain and flash flooding possible for the southern Rockies... A potent upper level disturbance tracking eastward along the U.S./Canadian border will support the development of a well-defined surface low across the Dakotas and eventually lifting northward into Canada. Severe thunderstorms are expected to develop ahead of the trailing cold front across the Upper Midwest, followed by a cooler and drier air mass from the northwest. Pleasantly cool temperatures are also expected over much of the Pacific Northwest and northern Rockies through the middle of the week. The area of the country with the greatest potential for heavy rain and flash flooding will be the 4-corners region, especially the higher terrain of Arizona and New Mexico. An enhanced monsoonal flow over this region south of the cold front will result in the development of numerous showers and thunderstorms each afternoon and evening, and some areas may receive in excess of 2 inches of rainfall by Thursday evening. Parts of the Southeast U.S. are also expected to get copious rainfall in the vicinity of a stalled frontal boundary. The heat and humidity are forecast to continue unabated across much of the central and southern U.S. Heat advisories are in effect from eastern Texas to Mississippi where heat indices could easily be in the 100 to 110 degree range, perhaps even higher at times. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php