Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 1225 AM EDT Sat Apr 28 2018 Valid 12Z Sat Apr 28 2018 - 12Z Mon Apr 30 2018 ...Rain and cooler conditions expected with a new storm system coming into the western U.S. this weekend... ...Record lows possible across the Midwest and Lower Ohio Valley Sunday morning... ...The severe weather risk increases in the High Plains Sunday into Monday... A gradual cooling trend is expected across the western U.S. this weekend as an expansive upper low edges inland from the Pacific. This system will bring light to moderate rain and mountain snow in the highest elevations to the favored terrain of the Pacific Northwest, northern California, and the northern Rockies. Moisture returning ahead of the system moving slowly through the West will increase the chance for showers and thunderstorms across the southern Rockies and adjacent High Plains from Saturday into Monday. The Storm Prediction Center indicates a marginal risk of severe weather in the High Plains on Sunday elevates further on Monday across the central Plains near and east of a dryline. Daytime temperatures should reach as much as 10 to 20 degrees above normal across portions of the central to northern Plains Saturday and Sunday as an upper ridge shifts eastward from the Rockies to Great Plains. Light to moderate precipitation, with some snow in the higher elevations, is expected across New England into Monday morning. Behind this system, a surge of cooler air and scattered precipitation will accompany a cold front pressing eastward out of the Great Lakes on Saturday. The surge of cooler air could result in some record low temperatures and snow showers across portions of the Ohio Valley and Great Lakes region Sunday morning. Roth/Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php