Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 337 AM EST Tue Mar 08 2022 Valid 12Z Tue Mar 08 2022 - 12Z Fri Mar 11 2022 ...Western U.S.... Days 1-3... A series of shortwaves diving south through western Canada will amplify the upper pattern over the Northwest beginning with a wave dropping into the region later this morning. This will be followed a more defined shortwave digging into the Northwest Tuesday night. Favorable forcing aloft will support snow developing along a strong surface-to-low level baroclinic zone as it pushes south through the Northwest and northern Rockies on Tuesday. As the upper shortwave continues to amplify and dig southeast, the front is expected to push into the Great Basin and central Rockies on Wednesday, and eventually through the Southwest and southern Rockies on Thursday. Mountain snows of 4-8 inches will likely be common, with locally heavier amounts expected, from the Washington and Oregon Cascades southeastward to the central Rockies. WPC probabilities show the greater potential for locally heavier amounts of a foot or more centering across the Tetons and Wasatch into the western Colorado ranges. Models show the front lingering across the region ahead of the approaching shortwave, with ample moisture and upper forcing helping to support heavy accumulations. ...Central Rockies to Mid Mississippi Valley... Days 2-3... Upslope flow behind the front pushing south trough the Rockies and High Plains will support snow developing and spreading south along the central and eastern Wyoming ranges on Tuesday. The better potential for organized heavier snow is expected to settle into southern Wyoming overnight. A low level wave dropping southeast across the state is expected to enhance the upslope flow into the southeastern Wyoming ranges, raising the potential heavy amounts along the Laramie, Medicine Bow, and Sierra Madre mountains. Meanwhile as the low level wave drops through the High Plains this is expected to increase theta-e advection into the boundary over the Plains. This along with increasing upper divergence afforded by a coupled upper jet is expected to support snow spreading east across southern Nebraska and northern Kansas. The overnight model consensus has shifted south, but still shows a good signal for at least light to moderate snows developing across the region. Latest WPC probabilities indicate that accumulations of 4 inches or more are likely from far northeastern Colorado across southwestern Nebraska and northwestern Kansas, with a significant threat for accumulations of 8 inches or more over northwestern Kansas. As the upper trough begins to move east of the Rockies, snow is expected to spread farther east ahead of a low level wave tracking northeast from northern Oklahoma through southeastern Kansas Thursday. This is expected to bring at least light to moderate snows from northeastern Kansas and southeastern Nebraska through northern Missouri and southern Iowa. ...Northeast & Mid Atlantic... Days 1-2... A well-defined shortwave moving across the southern Rockies this morning is forecast to move steadily northeast, reaching the Northeast by late tomorrow. Consensus of the overnight guidance has trended wetter across portions of the northern Mid Atlantic into southern New England. Meanwhile, thermal profiles appear sufficient for snow at least at the onset as precipitation spreads northeast from the central Appalachians and interior Mid Atlantic into the Northeast on Wednesday. With the overnight trends, probabilities for at least a couple of inches of snow have increased from West Virginia into northern Pennsylvania along the Allegheny Mountains and eastward into the Poconos and Catskills. Probabilities have also increased farther east along the Berkshires and Worcester Hills. Pereira