Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 346 AM EDT Sat Mar 18 2017 Valid 12Z Sat Mar 18 2017 - 12Z Mon Mar 20 2017 ...Record warmth expected over much of the western U.S. as heavy snow moves across the northern Cascades... ...Cold and wintry precipitation expected to spread from the Great Lakes into the Northeast during the weekend... Much of the central and eastern U.S. will be cooler than seasonal average over the next few days as an upper-level trough is forecast digs southeastward across the Great Lakes and the mid-Atlantic. A couple of associated surface cold fronts will track eastward allowing Arctic air to overspread the region and generating a swath of a wintry mix of precipitation from the Upper Great Lakes to the Mid-Atlantic/Northeast. Once the system has pushed offshore late tonight the central low pressure is forecast to deepen on Sunday a couple of hundred miles from Cape Cod -- keeping gusty winds and snow... possibly heavy at times along the coast from Maine to southern Virginia. Prior to the frontal passage rain will be the primary precipitation type from mid-Atlantic southwestward through the mid and lower Mississippi Valley. Some scattered thunderstorms will be possible. A strong cold front combined with moist onshore flow will keep lower elevation rain and mountain snow possibly across portions of the Pacific Northwest... Great Basin and Intermountain West. A few thunderstorms will be possible today across portions of Idaho and Montana. Heavy snow may be possible for the northern Cascades. The northern portion of the front will progress across the Northern Plains and Upper Midwest while the southern flank stalls in the Intermountain West. Prior to the cold front temperatures across the Desert Southwest and Rockies may reach or exceed daily records today-- and for the Central Plains on Sunday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php