Travelers returning from the Thanksgiving holiday and commuters alike will soon be thwarted by nasty weather. The same storm system responsible for bringing blizzard conditions and over a foot of snow to parts of the Midwest this weekend will soon be responsible for heavy snowfall over parts of the interior Northeast while returning flooding woes to the I-95 corridor.

Rain already overspread most of the Northeast throughout the day Monday. The low’s track across the Great Lakes has allowed warm air to surge northward such that precipitation has only begun as snow in New York’s Adirondacks and in Northern New England. The rain won’t last long across much of the inland Northeast, however. A secondary low pressure system has already begun to develop over the New Jersey coast and will help draw cold air southeastwards as it tracks northeastwards. The cold air will arrive too late for the coastal plain and for southern New England, but further north and west a complete changeover to heavy snow is expected overnight Monday into Tuesday.


Rain was already beginning to intensify as of this writing over portions of eastern Pennsylvania, southeastern New York, and New Jersey in the warm sector. The rain will continue to intensify as the low over the northern Mid-Atlantic coast intensifies and treks toward New England. Powerful winds just above the surface are serving as a conveyor belt transporting moisture all the way from the southern Gulf of Mexico. The transport of this warm, immensely wet air mass and its collision into the cold antecedent air mass will provide for heavy precipitation rates across the Northeast.

Flash flooding will be a strong possibility in eastern Pennsylvania, the northern two-thirds of New Jersey, and southeastern New York, where 2-4″ of rain have already fallen over the weekend and an additional 1-1.5″ of rain is expected through Monday evening. Moderate flooding is already ongoing in this region, especially along the Delaware, Passaic, and Hudson Rivers, with other nearby rivers in minor flood stage. This additional rain will likely further exasperate flooding woes.

The timing of the rain will only make matters worst. The heaviest of the rain is expected to fall during the evening rush. Traffic will likely come to a crawl in major metropolitan centers like Philadelphia, Scranton, New York City, and Poughkeepsie. Major arteries connecting New Jersey to New York City and Philadelphia are especially susceptible to rush hour woes, given the high concentration of creeks and rivers at flood stage here. The heavy rain will hold off in New England’s major metro centers until later Monday evening. Flooding will be a possibility here too, but New England escaped the worst of this weekend’s rain, so the risk is not as significant.


Winds will become an additional concern Monday evening into Tuesday, especially on Long Island and southeastern New England, where winds could gust as high as 55 mph during the overnight hours. Winds may gust as high as 40 mph elsewhere in the region. Winds could be strong enough to down trees and cancel or delay flights for those returning from the Thanksgiving holiday.

Further north and west, rain will changeover to snow from northwest to southeast in western Pennsylvania, Upstate New York, and Northern New England Monday night. The heaviest snow will fall north and west of I-88 in New York and New England. Lake Effect enhancement from Lake Erie will provide for up to a foot and a half of snow from northeastern Ohio to southwestern New York including the cities of Erie and Buffalo. Otherwise the heaviest precipitation will focus over northern and eastern portions of the Northeast. The Adirondack mountains, Green Mountains, White Mountains, and northern Maine will likely pick up a hefty 12-24″ of snow with heavier snow likely in the highest peaks. The foothills of these mountains will encounter lower snowfall ratios, so the totals here will more likely fall within the 6-12″ range.


The more populous, lower elevation regions of Upstate New York and Northern New England including the cities of Syracuse, Utica, Montpelier, and Concord can expect 3-6″ of snow to accumulate after the changeover, with the lowest valley locations like Burlington only receiving 2-4″.  Further south and west, only 1-3″ of snow is expected in northern and western Pennsylvania, New York’s southern tier, and southern Maine. The snow should clear the further south and east areas by Tuesday morning, but it will persist longer elsewhere.

Ski resorts should rejoice. The main batch of snow will likely persist into Tuesday morning in New York and Pennsylvania and Tuesday evening in Northern New England, but enhancement from Lake Erie and Ontario will keep the precipitation from falling well into the work week. After a brief lull, snow will continue through Thursday morning across most of this area due to orographic lift up mountain slopes and from lake effect snow. Several feet of additional snow are likely to fall within the higher elevations of Upstate New York and Northern New England as well as near the vicinity of Lake Erie. Up to a foot of additional snow may fall downwind of Lake Ontario, mainly on the Tug Hill Plateau.

The unsettled weather pattern will continue through the weekend, when two additional systems bring December to a wet start. The more significant of the two systems is poised to cross the Ohio Valley Friday and Saturday, bringing unsettled conditions to the Northeast late Saturday and Sunday.

 


Author

Josh is a lifelong nature and weather enthusiast as well as the Head Meteorologist at WeatherOptics. He began regularly forecasting for New Jersey, Long Island and New York City in 2014 on social media, contributing to community pages such as SBU Weather. He holds degrees in Physics and in Atmospheric and Oceanic Sciences from Stony Brook University, from which he graduated in 2018. In the Fall of 2018 Josh will start graduate school for his M.S. in Marine and Atmospheric Sciences at Stony Brook, continuing his research on approaches to non-convective wind gust forecasting.

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