Tax Day storm northeast with snowfall inland

“This late-season snowfall will likely be quite heavy and wet, and could have significant impacts,” the National Weather Service wrote. “This includes possibly downed trees, power outages and difficult shoveling. Hazardous travel conditions may develop due to slush covered roads.

Snowfall totals will be highly dependent on elevation, with mountain peaks showing the greatest amounts.

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The same global storm system can bring isolated severe weather to the Outer Banks of the Carolinas in its “warm sector,” with a brief tornado or two possible.

A center of low pressure moved through central Tennessee during Monday morning, with a counterclockwise swirl of clouds visible in satellite imagery. Light snow was falling to the north over parts of the Great Lakes with rain to the east.

This low, fueled by an upper disturbance arriving from the west, will transfer its energy to a new low developing near the North Carolina coast Monday evening. On Monday evening, it will move up the Mid-Atlantic coast and reach southern New England on Tuesday morning.

Lows spin counterclockwise in the Northern Hemisphere, so extreme eastern North Carolina, essentially the Outer Banks, will eventually let a trickle of mild air flow north ahead of a cold front. A change in wind speed and/or direction with height, known as wind shear, could promote some rotation in some thunderstorms. A level 1 in 5 “marginal risk” of severe thunderstorms was raised along the immediate coast of Charleston, South Carolina at Cape Hatteras.

Behind the western low if the track of the system, northerly winds will carry frigid air southward from Canada. Moisture straddling near-freezing conditions will deposit a band of snow inland from the West Virginia-Virginia border into Quebec and Ontario.

Schedule of storms and predicted snowfall totals

Rain arrived in the nation’s southwest capital before noon Monday, mixing with a bit of sleet, but snow was developing in parts of Blue Ridge and the Allegheny Range. The snow could be moderate to heavy for a short time during the afternoon before easing around 5 or 6 p.m. south of the Mason-Dixon line. About 2 to 4 inches of snow could fall in the mountains of western Maryland and northeastern West Virginia as well as the Blue Ridge in Virginia. Locally higher amounts are even possible near mountain peaks.

Many areas of western and west-central Pennsylvania will also see snow accumulation, especially on higher ground. Up to 3 to 6 inches are possible there on Monday afternoons and evenings

Southeast Pennsylvania will see mostly rain between Monday morning and Monday evening, but snow is likely in the Poconos in the northeastern part of the state, which is under a winter storm warning until 4 a.m. at 8 inches until Tuesday morning.

In New York, rain will develop Monday evening and last until just before sunrise, totaling nearly an inch. Boston will see its heaviest rain from midnight to around 8 a.m. Tuesday, with maybe a thunderclap or two southeast over Cape Cod.

Heavy snowfall is also expected in interior portions of New York State, particularly near and just east of Interstate 81. Winter storm warnings are in effect there, with the weather service warning that heavy snowfall could impact the morning commute on Tuesday. A general 4 to 8 inches is likely, with isolated amounts of nearly a foot, mostly above 2000 feet elevation.

“Snowfall rates can reach 1 to 2 inches per hour at times, with isolated areas approaching 3 inches per hour,” the weather service wrote. Regardless of total accumulation, snowfall at this level is extremely difficult or impossible for road crews to track. A few thunderstorms are also possible.

Up to a few inches of snow is also likely in Vermont, though the coastal storm could draw enough warm air into the state to turn precipitation to ice and rain and reduce some accumulations. Even so, the Burling Weather Service wrote that “rapidly accumulating snowfall will impact the morning commute and may result in isolated to scattered power outages.”

After a period of several days of abnormally cold and wintery weather, the high pressure will move off the east coast by mid-week. This will strengthen the southerly winds and allow balmy air to spread northward.

Washington DC will be in the mid 70s on Friday before hitting 80 on Saturday and possibly mid 80s on Sunday. Friday will be in the upper 60s near 70s in New York, although the weekend may be cooler as a blocked frontal border persists in the region.

Relatively mild, near-seasonal temperatures will help eat away at the snowpack that will build up over the next 48 hours.