Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Fri Mar 17 2017 Valid 00Z Sat Mar 18 2017 - 00Z 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... An upper-level trough is forecast to deepen and dig southeastward across the Great Lakes and the mid-Atlantic states before moving off the coast on Sunday. Unseasonably cold air will once again overspread much of the northern and northeastern portions of the country along with a swath of wintry precipitation. A surface low pressure system is forecast to deepen rapidly as it moves off the mid-Atlantic coast Saturday night and should pass about a couple hundred miles off Cape Cod on Sunday. Much of the wintry precipitation in the Northeast should be tapering off on Sunday with the exception of Cape Cod where the storm could be close enough to produce a period of heavier snow along with strong gusty winds. Ahead of the trailing cold front, rain will be the primary precipitation type from mid-Atlantic southwestward through the mid and lower Mississippi Valley where some scattered thunderstorms are possible. Out West, a progressive upper-level trough will usher in a strong cold front across the Pacific Northwest into the northern Rockies during the weekend. Temperatures ahead of the cold front are expected to reach record levels from the Desert Southwest through much of the Rockies on Saturday, spreading into the central Plains on Sunday. Behind the front, snow is expected to be heavy in the northern Cascades before tapering off later on Sunday. The front is forecast to become nearly stationary across the Intermountain West on Sunday with coastal/valley rains and higher elevation snows. Meanwhile, the northern portion of the front should continue to move steadily eastward into the northern Plains on Sunday with rain in the upper Midwest and possibly thunderstorms farther south in the Midwest. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php