Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 321 PM EST Thu Dec 15 2016 Valid 00Z Fri Dec 16 2016 - 00Z Sun Dec 18 2016 ...Heavy snow for parts of the Upper Mississippi Valley and Upper Great Lakes... ...Rain and freezing rain possible for parts of the Ohio Valley to the Northeast and Mid-Atlantic... ...Heavy snow for parts of the Sierras and Central Rockies... ...Temperatures will be 20 to 40 degrees below average for parts of the Northern Rockies and Northern High Plains... A strong storm over the Great Basin will move eastward to the Middle Mississippi Valley/Western Ohio Valley by Saturday. The system will produce snow over the Northern Rockies into parts of the Northern Plains and Central Rockies by Thursday evening that will expand into the Upper Great Lakes and into parts of the Great Basin by Friday evening. The snow will move into Lower Great Lakes/Northeast and into the Southern Rockies by Saturday morning. The snow will end over the Northern Rockies and Western Great Basin by Saturday morning as well. A narrow band of sleet and rain/freezing rain will develop in between the snow and rain over parts of the Middle Mississippi Valley into Western Ohio Valley on Friday afternoon into Saturday morning. In addition, a narrow band of sleet and rain/freezing rain will develop a long the rain/snow line over the Eastern Ohio Valley into the Mid-Atlantic late Friday night into Saturday morning. Additionally, rain will develop with the storm over California into the Great Basin Thursday evening that will expand into parts of the Southwest/Southern Rockies by Friday morning. Snow will also develop over the higher elevations of the Sierras. The rain and snow will end over California and Western Great Basin by Friday morning. As the storm moves onto the Plains, showers and thunderstorms will develop over parts of the Western/Central Gulf Coast Friday afternoon into evening expanding into parts of the Tennessee Valley and Lower Mississippi Valley by Saturday morning. Rain will begin to develop over parts of the Middle Mississippi Valley on Friday evening that will expand into parts of the Southern Ohio Valley overnight Friday. Likewise, rain will develop and expand over parts of the Southern Mid-Atlantic and the Northern Mid-Atlantic overnight Friday into Saturday morning. Meanwhile, upper-level energy and cold air flowing over the Great Lakes will aid in producing lake effect snow downwind from the Great Lakes and into parts of the Northeast through Friday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php