Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EST Sun Jan 21 2018 Valid 12Z Sun Jan 21 2018 - 12Z Tue Jan 23 2018 ...Heavy snow and freezing rain possible from the Central Plains to the Upper Midwest, Great Lakes and New England... ...Heavy snow possible over the Cascades and the Rockies... ...Heavy rain possible over parts of the Pacific Northwest and Northern California... A front passing through the Central and Southern Rockies today will quickly develop into a robust winter storm system tonight/early Monday as it moves out into the Central and Southern Plains. Warm, Gulf moisture drawn northward into this system will help produce widespread snow from the Northern/Central Rockies to the Upper Mississippi Valley and east to the Great Lakes region and New England by Tuesday. Snow will likely be heavy at times, especially along a swath from Nebraska to Wisconsin. Along and near the front itself, a relatively narrow band of freezing rain is expected to develop. Both types of precipitation will likely have a significant impact to transportation through at least Tuesday. Much of Wyoming, Colorado, northwest Kansas, Nebraska, southern South Dakota, Iowa, southern Minnesota and northern Wisconsin have Winter Weather Advisories, Winter Storm Warnings or Winter Storm Watches in effect. Showers and thunderstorms are expected along and ahead of the trailing cold front as it moves eastward through the central U.S. Periods of heavy rain will be possible across the South, especially near the Ozarks of Arkansas and Missouri. The risk for flash flooding may become elevated in that region through Monday morning. Rain will spread to the eastern Tennessee and Ohio Valleys and the Mid-Atlantic Monday and Tuesday. The Pacific Northwest and northern California will remain in an increasingly wet pattern over the next few days as upper-level energy moves inland. Rain and higher elevation snow will spread from much of the Pacific Northwest and northern California to the Northern Rockies today- expanding into parts of the Great Basin by Monday. Heavy snow is forecast for the Cascades, as well as, portions of the Northern and Central Rockies. Winter Storm Warnings and Winter Weather Advisories are in effect from north-central Washington to northern California. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php