A significant winter storm has begun to spread a mix of rain, freezing rain, and heavy snow across portions of the Central Plains and into the Midwest today and into tomorrow. This system will eventually moving into the Mid Atlantic and the Northeast. The heaviest snow is likely to develop across Kansas and spread through Missouri, Iowa, and Illinois where places could see 8-12" of snow accumulation with isolated higher amounts over a foot. Snowfall rates of 1-2" an hour are possible which could cause reduced visibility in intense snow squalls. A mesoscale discussion for heavy snow and snowfall rates of 1-2" was issued for places across Kansas and southern Nebraska this morning. Freezing rain is also likely, with the greatest potential of freezing rain to stretch across parts of northern Missouri through central Illinois into Indiana and western Ohio. Freezing rain accumulations of a few hundredths of an inch likely with possible accumulations of a tenth of an inch. Freezing rain also possible across parts of the Appalachian Mountains in West Virginia, Virginia, and southern Pennsylvania where places could see up to a quarter of an inch of ice accumulation. The threat for severe thunderstorms continues today with a marginal threat for severe weather across parts of the Lower Mississippi Valley region, the Southeast, and into the Tennessee Valley Region. Damaging winds and some hail will be the primary threat.
A deep upper-level trough and a potent shortwave will move northeastward today while taking on a negative tilt across the Plains. Behind this mid and upper-level trough and shortwave, CAA and a pool of cold air will allow for snow across parts of the southwestern US to the Great Lakes region. This will combine with a strengthening jet streak and mid-level frontogenesis maxima will produce enhanced ascent across the region. As the low deepens and moves eastward, guidance has a good agreement that a band of heavy snow is likely to begin to fall early to across northern Kansas on the NW side of the low-level circulation, and then track northeast in tandem with the deep moisture and lift along the track of the 700 mb low/deformation zone/theta-e advection across southeast Nebraska and southern Iowa. The deformation band is likely to combine with strong upper divergence and occasional slightly negative equivalent potential vorticity from 700-600 mb to cause heavy snow rates, which may reach 2"/hr. A few additional inches of snow are likely from northeast Illinois to eastern Wisconsin on Tuesday due to some lake enhanced snowfall.
WPC probabilities for 6" peak near 100 percent in these areas, with maxima of 12" expected in parts of southeast Nebraska to southern Iowa.
Day 1 Winter Storm Severity Index
Moderate to Major impacts today across the Central Plains into the Midwest due to heavy snowfall across the region.
Northeast and Mid Atlantic
As this system tracks into the northeast cooler temperatures along with moisture transport and ascent will allow for some snowfall across the deformation zone across portions of central Pennsylvania and New York. WPC probabilities for 4 inches are moderate across central Pennsylvania and into southern New York. The weakening low-mid level convergence and ascent move into eastern New England on Wednesday, where forecast accumulations will be just an inch or two. Then a trailing wave will progress across the Ohio Valley and Tennesse Valley and across into the southern Appalachians on Wednesday. With this an area of low pressure will form in the lee areas of the Carolinas before moving offshore. As the wave crosses the mountains near the TN/NC border and Southwest Virginia, a period of snow is expected, with accumulations of a few inches likely.
WPC probabilities for 0.25" of freezing rain are as high as 40% in northern Missouri and central Illinois. Across much of the rest of the Ohio Valley across parts of Indiana and Ohio expect ice accumulations of a few hundredths of an inch to a tenth of an inch across this region. Further to the east in the Appalachian mountain region across parts of southern Pennsylvania and into parts of West Virginia and Virginia expect ice accumulations of a quarter of an inch.
72 Hour Snowfall
Central Plains/Midwest 72 Hour Snowfall
Northwest/Mid Atlantic 72 Hour Snowfall
Southwest/California 72 Hour Snowfalll
A marginal severe threat is expected today from parts of the Arklatex east-northeastward into parts of Kentucky and Tennessee, and tonight over parts of the Deep South.
Heavy Rainfall across the Tennessee and Ohio Valley Today.