Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 414 PM EDT Sat Mar 18 2017 Valid 00Z Sun Mar 19 2017 - 00Z Tue Mar 21 2017 ...Record warmth over much of the western U.S. expected to spread into the northern and southern Plains... ...Cold and wintry precipitation expected to spread from the Great Lakes into the Northeast through the weekend... A deepening upper-level trough in association with another push of unseasonably cold air from central Canada is moving across the Great Lakes and is expected to trigger the development of a low pressure system off the mid-Atlantic coast on Sunday. Snow is forecast to spread across much of upstate New York, Pennsylvania and into New England tonight. A mix of rain and snow can also be expected in interior mid-Atlantic into the western slopes of the central Appalachians through Sunday morning. The system is expected to move offshore and deepen rapidly a couple of hundred miles from Cape Cod. Much of the northeastern U.S. will see precipitation tapering off on Sunday. The exception will be along eastern New England coast down to Cape Cod where the storm will be close enough to bring snow, possibly heavy at times, before tapering off Sunday night. Cold air behind the low will drop temperatures well below normal through the Southeast, even down into Florida on Monday before a moderating trend begins on Tuesday. Out West, a strong cold front will bring lower elevation rain and mountain snow across the Pacific Northwest during the weekend. The front is expected to become stationary, keeping the rain and snow across northern California, much of Oregon, the Great Basin, Intermountain West, and northern Rockies on Sunday. The northern portion of the front will race eastward into the northern Plains on Sunday before sinking southward into the central Plains on Monday. Showers and thunderstorms ahead of the front are expected to form in the Midwest on Sunday, spreading into the mid-Mississippi and Tennessee Valleys as well as the Appalachians on Monday. In addition, some of the valleys in the northern Appalachians and northern New England could see wintry precipitation on Monday. Meanwhile, rain is expected to become more widespread along the West Coast as the next Pacific low approaches. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php