Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Sun Apr 15 2018 Valid 00Z Mon Apr 16 2018 - 00Z Wed Apr 18 2018 ...There is a slight risk of severe thunderstorms from the parts of Southeast to the Southern Mid-Atlantic... ...Heavy snow possible over the Upper Great Lakes, Cascades, Sierras, and Northern Rockies... ...Rain/freezing rain possible over parts of the Northeast... ...Heavy rain possible from parts of the Central Appalachians/Northern Mid-Atlantic to parts of New England... A strong storm over the Great Lakes/Ohio Valley will slowly move northeastward into Southeastern Ontario into Northern New England by Tuesday. The system will produce snow, heavy at times, over the Upper Great Lakes into Upper/Middle Mississippi Valley that will move into parts of the Ohio Valley/Central Appalachians by Monday morning. The snow will end over the Middle/Upper Mississippi Valley by Monday evening with snow moving into parts of the Northern Mid-Atlantic/Lower Great Lakes by Tuesday morning. Areas of rain/freezing rain will develop over parts of the Northeast through Tuesday morning. In addition, showers and thunderstorms will develop along and ahead of the associated front over parts of the Southern Mid-Atlantic into the Southeast that will move off the Southeast Coast by Monday morning. Additionally, rain will develop over parts of Great Lakes to the Tennessee Valley into the Northern Mid-Atlantic that will move northeastward into parts of the Lower Great Lakes to parts of New England by Tuesday morning. Meanwhile, a deep upper-level trough and associated front will move inland over the West Coast to the Northern Rockies to the Great Basin/Southwest/Southern California by Tuesday. The storm will produce rain over the Pacific Northwest and Northern/Central California into the Northern Rockies with some snow over the highest elevations of Northern California on Sunday evening. As the trough and associated front moves onshore, snow levels will lower across the West Coast into the Northern Rockies/Great Basin. Overnight Sunday as the snow levels lower, snow will develop over the higher elevations of the Northwest into California and the Northern Rockies. Rain and higher elevation snow will move into the Northern High Plains overnight Monday into Tuesday. The coastal rain and higher elevation snow will end over most of California overnight Monday, too. Coastal rain and higher elevation snow will continue over the Pacific Northwest into Tuesday. Snow will also continue over parts of the Northern Rockies/Great Basin into Tuesday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php