Storm to wallop East with ‘extreme weather’ on Christmas Eve

Upcoming storm is predicted to unleash rain that will eat away at the existing snow cover in New England and the coastal mid-Atlantic. The rainfall can add a tremendous amount of weight to areas that were recently buried by up to 3-4 feet of snow in parts of New York state and northern Pennsylvania.

AccuWeather Global Weather Center – December 23, 2020 –  Those hoping for a white Christmas in much of New England and the mid-Atlantic are likely to have their hopes dashed at the last minute even after a major storm dumped over a foot of snow in some locations just a week ago. Forecasters are also warning of more serious weather threats, including flooding rain and high winds, with an upcoming storm that will press into the East on Christmas Eve and Christmas Day.

Unlike the storm last week, which had a fresh supply of Arctic air to tap, strong southerly winds will draw in warmer air from the south ahead of the system set to arrive in the East late this week. The upcoming storm is predicted to unleash rain that will eat away at the existing snow cover in New England and the coastal mid-Atlantic. The rainfall can add a tremendous amount of weight to areas that were recently buried by up to 3-4 feet of snow in parts of New York state and northern Pennsylvania.

The storm will unleash “extreme weather Christmas Eve” in the East, AccuWeather Chief On-Air Meteorologist Bernie Rayno said, “Make sure you’re ready for that,” he warned.

“The rapidly melting snow, which contains approximately 1-3 inches of water will combine with an anticipated 1-3 inches of rain and locally higher amounts from the storm from Christmas Eve to early Christmas Day,” AccuWeather Senior Meteorologist Brett Anderson said.

In some cases, 3-6 inches of water can be released on the landscape in a matter of several hours.

The anticipated rainfall, even without the added liquid from melting snow cover, would be heavy enough to trigger flooding in urban and poor drainage areas. The combination of rain and melting snow is expected to cause small streams to rise rapidly and major street flooding due to storm drains that are clogged with piles of snow. A somewhat delayed rise is likely on water levels of the major rivers as well, which could put low-lying areas that are not protected by levees at risk for flooding into this weekend.

A man walks past City Hall during a snowstorm, Thursday, Dec. 17, 2020, in Lawrence, Mass. (AP Photo/Elise Amendola)

But, according to AccuWeather meteorologists, not all of the snow will melt everywhere.

There is the danger of roof collapses, especially in parts of northern Pennsylvania and the southern tier of New York state, or anywhere in the Northeast, where last week’s storm dropped from 30 to 44 inches of snow. In these snowbound locations, temperatures may rise only to several degrees above freezing. The snow will tend to act like a sponge and absorb the rainfall. The added weight of the snow and rain could push some weak, flat roofs to the point of failure. One square foot of 6 inches of water weighs about 31.2 pounds.

Adding to the misery created by the excessive rainfall will be high winds along with the storm’s arrival.

“Winds are forecast to gust between 50 and 60 mph over a broad area from eastern North Carolina to Maine,” AccuWeather Meteorologist Alex DeSilva said.

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