Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 427 PM EDT Wed Mar 24 2021 Valid 00Z Thu Mar 25 2021 - 00Z Sun Mar 28 2021 ...Pacific Northwest to the Northern and Central Rockies and Great Basin... Days 1-3... An amplifying shortwave trough diving south through the northwestern U.S. into the Great Basin will spread mountain snows south and east from the Northwest into the northern and central Rockies and Great Basin from late Wednesday into Friday. While some areas, including portions of the northern Cascades and Rockies will likely see storm total amounts of 8-inches or more, widespread heavy accumulations are not expected. ...Southwest to the Southern Rockies... Days 2... Beginning overnight, drier weather is expected as the current shortwave impacting the region lifts out through the Plains. Dry weather will continue into late Thursday when another shortwave trough is expected to dive into the Southwest. This will bring high elevation snow back into Utah and Arizona, with some potential for locally heavy accumulations late Thursday into Friday. A greater threat for heavy accumulations is farther east, where a period of southwesterly inflow ahead of the approaching trough is expected to support heavy snows developing across the San Juan Mountains. ...Great Lakes to Northern New England... Day 2 -3... A shortwave trough lifting out of the southern Plains on Thursday is expected to assume a negative tilt, with a compact closed low developing as it tracks from the mid Mississippi Valley toward the Great Lakes Thursday night. A wintry mix, including snow, sleet and freezing rain, resulting in light snow and ice accumulations, is expected across portions of northern Illinois, southern Wisconsin and Lower Michigan Thursday night and Friday morning. Probabilities for ice accumulations of 0.25-inch or more and snow accumulations of 4-inches or more are both less than 10 percent. As the system moves east from the Great Lakes into the Northeast, rain changing to snow is expected across northern Maine on Friday, with a greater threat for significant accumulations. Pereira