Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 430 AM EST Tue Feb 18 2020 Valid 12Z Tue Feb 18 2020 - 12Z Fri Feb 21 2020 Day 1... ...Northeast... Strong warm air advection ahead of a low lifting across northern Michigan into eastern Canada will support widespread precipitation moving east across the Northeast on Tuesday - with wintry precipitation changing over to rain across much of Upstate NY early in the period. However, models continue to show cold air hanging in longer across the Tug Hill Region and Adirondacks, where strong orographic accent in the face of strong southerly winds, followed by a brief period of lake enhancement, may bolster amounts. Farther east, a weak wave developing along the northern New England coast Tuesday evening is expected to enhance inflow into New Hampshire and Maine -- raising the potential for locally heavy amounts, with several inches possible along the White Mountains from northern New Hampshire into western Maine. Day 2... ...Central Plains and Rockies... Deepening moisture along a low-to-mid level frontal band associated with an upper trough moving southeast from the northern Rockies into the central Plains is expected to support a stripe of mainly light amounts from Nebraska into Kansas on Wednesday. Meanwhile a low level wave developing and moving south through eastern Colorado is expected to support upslope flow/low level convergence -- supporting at least some light snows across the plains into the eastern mountains on Wednesday. Day 3... ...Southern Appalachians and Southern Mid Atlantic... Positively-tilted upper trough extending from the Great Lakes into the central Plains will continue to move east, drawing subtropical stream moisture and energy across the Southeast Thursday into early Friday. Low confidence forecast, especially late in the period, with some of the overnight models developing a stronger surface wave along the Southeast coast and in turn directing deeper moisture back into the colder air across North Carolina and southern Virginia. Lacking strong ensemble support, the heavier amounts of the NAM and GFS were less preferred across this area. For Days 1-3, significant icing (amounts of 0.25-inch or more) is not expected. Pereira