Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 306 PM EDT Fri Aug 22 2014 Valid 00Z Sat Aug 23 2014 - 00Z Mon Aug 25 2014 ...Heavy rainfall is expected over portions of the Northern Rockies into the Northern and Central Plains with much cooler temperatures... ...Some snow is possible at the higher elevations of the Northern Rockies... ...Heat and humidity to continue over the Southern Plains, lower Mississippi Valley into the Southeast... ...Sun and clouds and a few showers while mild temperatures prevail across the Northeast and Middle Atlantic states... A deepening upper level trough over the northwestern US is expected to bring a prolonged period of showers and thundershowers, followed by cooler temperatures and moderate to heavy rainfall across the northern Rockies into parts of the Northern and Central Plains. Heaviest rains are expected to fall across Montana into the Dakotas, where several inches are likely through the weekend into Monday. Low pressure is expected to consolidate into a pretty significant storm system that will move across the Northern Plains over the weekend before heading northeastward into south central Canada. Cooler temperatures are expected across the entire region as Canadian air is drawn southward behind the developing low. There is even the possibility of some snow in the higher elevations of the Rockies in Montana and Wyoming as well. Hot and humid conditions responsible for heat advisories across parts of the southern and central Plains, the mid Mississippi Valley and into parts of the Southeast will continue for the next few days with temperatures mostly in the 90s and a few readings may top 100 degrees with high humidity. The heat is not expected to spread eastward, however, as a back door cold front along the Middle Atlantic coast subsides southward with cooling easterly flow easing the heat along the Southeast coast later Saturday into Sunday. Kocin Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php