Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 336 AM EDT Fri Mar 17 2017 Valid 12Z Fri Mar 17 2017 - 12Z Sun Mar 19 2017 ...Heavy snow possible over the Northern Cascades... ...Snow possible from the Upper Mississippi valley to parts of the Northern Mid-Atlantic and Northeast... Snow... possibly with pockets of mixed precipitation... is forecast from the Upper Mississippi valley/Great Lakes region to the Mid-Atlantic/Northeast as a surface low pressure system tracks across the central U.S this weekend. Moisture from the Gulf of Mexico will stream into the Southern Plains and pool along the advancing front. Showers and thunderstorms are expected to develop along and ahead of the boundary as it passes through the Midwest/Mississippi valley into the Ohio/Tennessee valley/Appalachians. High pressure will slide into the Northern and Central Plains as the system continues to track toward the East Coast. An upper-level trough will move inland over the Pacific Northwest today ushering in a plume of moisture to the Pacific Northwest. Coastal/valley rain and higher elevation snow over parts of the Pacific Northwest and eastward into parts of the Northern Rockies will continue over the next few days. Portions of the Cascades may observe heavy snowfall this weekend. Numerous flood watches and warnings are in effect across portions of the Great Basin and the Intermountain West. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php