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Flooding threat, brief warmup to proceed Arctic blast in Northeast next week

Alex Sosnowski

As the holidays approach and many may find themselves dreaming of a white Christmas, Mother Nature has a different idea up her sleeves. The weather pattern will soon be reversed in the northeastern United States, allowing wintry landscapes to transform into a sloppy, muddy mess instead.

Forecasters are closely watching a storm system that is expected to take shape and track toward the Great Lakes late Sunday. As yet another wave of cold and snow pushes into the Midwest, warm and moist conditions will surge ahead of the storm into the Northeast.

Temperatures are expected to rebound to the 30s over the northern tier to near 50 F in parts of Virginia as a southerly breeze develops on Sunday.

On Monday, temperatures are forecast to surge into the 40s across the northern tier and the 50s and 60s across part of the mid-Atlantic region.

The warm air combined with rain will dissolve the deep snow over part of the Northeast, potentially leading to flooding issues for some communities. Recent storms have buried parts of New York state and central and northern New England under as much as 1-3 feet of snow in the last couple of weeks.

A car makes its way through a snowy landscape in Highland Falls, N.J., Tuesday, Dec. 3, 2019. The last of the snow is falling over parts of New Jersey after leaving behind power outages in the northwest part of the state. (AP Photo/Seth Wenig)

That snowcover contains a significant amount of locked-up moisture, called the snow-water equivalent.

Within the existing snow on the ground, there is between 1 and 4 inches of water as of early Saturday, Dec. 7.

Many areas, including those places where deep snow is on the ground, may stay well above freezing Sunday night, which can allow the snow to soften up.

Some of the deep snow may harmlessly melt from Sunday to early Monday before the storm and its soaking rain arrives, but there is a risk that surging temperatures, moist air and drenching rain may cause a rapid meltdown of the existing snowcover from later Monday into Tuesday.

Instead of releasing the 1-4 inches of water by itself, another 1-2 inches of water may be added in depending on the intensity of the rainfall that occurs.

"Since the ground is not frozen, some of the melting snow and rain will be absorbed by the soil and should avoid disastrous stream and river flooding," Dale Mohler, AccuWeather senior meteorologist, said.

However, some quick rises on small streams are likely with minor flooding possible in low-lying areas that are prone to flooding during heavy rain or spring thaw events. Some of the rivers may surge to bank full as well.

"Even if only part of the snow melts and only a light amount of rain falls, piles of snow along streets and highways that are blocking storm drains can lead to urban flooding," Brett Anderson, AccuWeather senior meteorologist, said.

Anderson said that property owners should make sure that runoff has easy access to storm drains ahead of the system's arrival to reduce the risk of flooding as a precaution.

"Even in some of the major cities along the Interstate 95 corridor from Washington, D.C., to Philadelphia and New York City where there is no appreciable snow on the ground, enough rain can fall to cause travel delays and ponding on roads that drain poorly," Dave Bowers, AccuWeather meteorologist, said.

Ski resorts in the region that have gotten off to their earliest start in recent years will take a hit from the storm. Those seeking ideal ski conditions are encouraged to hit the slopes into Sunday, before the rainstorm arrives.

As the storm pushes off the coast, forecasters predict Arctic air will unleash in its wake later Tuesday and Wednesday.

After a high in the mid-60s on Tuesday in the D.C. area, the mercury will dip way down into the lower 30s by Wednesday afternoon.

Remaining areas of slush and standing water can freeze as temperatures plummet across the northeastern U.S.

Residents in the interior Northeast would be faced with AccuWeather RealFeel® temperatures in the single digits.

There is a chance that the cold air may catch up with the back end of the rain and cause a period of snow at the tail end of the storm at midweek.

This would be especially true if a secondary storm were to develop along in the Carolinas late on Tuesday in wake of the weaker storm Monday into Tuesday.

The exact track of the secondary storm would help to pull the cold air down faster and increase the chance for snow, perhaps even for the I-95 corridor from the mid-Atlantic to New England.

According to AccuWeather Chief Broadcast Meteorologist Bernie Rayno, no indications are currently pointing to a big snowstorm developing and rather it could be more of a nuisance snowfall.

If a weaker secondary storm develops, then it will likely push out to sea. If a secondary storm forms and it strengthens enough, it may bring snow to the Northeast.

However, this type of weather pattern has yielded major snowstorms in the past, and meteorologists will have to keep a watchful eye on how all of the weather players come together, Rayno added.

AccuWeather meteorologists are also tracking the potential for yet another significant storm toward the middle of the month, warning that it could be disruptive to the eastern U.S.

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