Nor’easter, Winter Storm To Deliver Heavy Snow, Wind To Northeast – The Washington Post

Less than two days remain before a major winter storm rocks the Northeast and coastal Mid-Atlantic, and yet snowfall forecasts continue to fluctuate wildly amid a dissonant ensemble of bickering weather models. Disagreeing simulations are playing a tug-of-war with projected snow jackpots, but the propensity for a major winter storm — and possibly a blizzard — on Saturday remains.

What’s almost certain is that somebody in the Northeast will see a foot or more of snow. That’s most likely in coastal Maine or in eastern Massachusetts, particularly from Boston to Cape Cod. Totals topping 16 inches with blizzard conditions can’t be ruled out there.

Farther south, cities like Hartford, Conn., New York and even Salisbury, Md., and Virginia Beach could be in for a hefty plowable snowfall, with a sneaky plastering set to back in off the ocean.

Winter storm watches, affecting more than 35 million people, stretch from coastal North Carolina and the Virginia Tidewater all the way northeast to the Massachusetts-New Hampshire border. They will probably be extended north into Maine later Thursday. The watches include Virginia Beach; Richmond; Ocean City, Md.; Dover, Del.; Philadelphia; New York; Hartford; Providence, R.I.; Boston and Worcester, Mass.

In addition to heavy snow, some residents of Rhode Island, southeastern Massachusetts and coastal Maine and New Hampshire will see a 1- to 3-foot ocean surge as the storm pushes water toward the coastline. The surge, combined with high astronomical tides, could spur flooding and beach erosion. Strong to damaging winds are possible, too, with gusts topping 60 mph on the Cape and Islands.

The town of Scituate, Mass., is calling for voluntary evacuations of residents occupying vulnerable beachside homes.

“Travel could be very difficult to impossible,” wrote the National Weather Service office in Boston. “Strong winds could cause tree damage.”

A pair of “shortwaves,” or high-altitude lobes of cold air, low pressure and spin nestled within dips in the jet stream, were rolling southeast across North America on Thursday morning. The first was over Montana, and the second was slipping through northern Alberta. Both will overlap and “phase” on Friday.

That approaching upper-air kicker will energize a zone of low pressure offshore of the Carolinas beginning Friday afternoon. As that low treks northeast, it will undergo “bombogenesis,” or explosive intensification. In fact, it will more than meet the requisite breakneck pace to qualify as a “bomb cyclone,” its minimum central air pressure set to plummet.

That will enhance the storm’s winds and precipitation as the counterclockwise-swirling low tosses snow back at the coast. Near the waters, a heavier, wetter snow is likely, but temperatures in the teens and 20s inland should favor a lighter snow with a greater fluff factor.

For a storm barely 48 hours away, a bombardment of conflicting information has led to a highly uncertain forecast along the Acela corridor, the most densely populated stretch of the country. Forecasters are still unsure about two key factors in the storm’s development that will have huge implications on the distribution of snow amounts:

• When the system gets going. In other words, meteorologists are not sure whether “phasing” will occur earlier, and allow low pressure to develop closer to the coast, or if it will be delayed. An earlier phasing would deposit moderate to heavy snows in southeast Virginia, the Delmarva Peninsula and in coastal New Jersey.
• Where the storm tracks. The American (GFS) model as been consistent in allowing the storm to slip more out to sea, which would reduce or eliminate snow for most except those inside of Interstate 495 in southeastern New England. The European model, farther west in its simulations, projects heavy snow in the Big Apple.

The maps below from the National Weather Service, projecting the probability of warning criteria snow and the magnitude of storm impacts, are a useful guide as to where the storm will be most serious:

Plymouth and Bristol counties in Massachusetts, as well as the Cape and the Islands, could see some of the heaviest snowfall totals. A general 12 to 16 inches is possible there, with an outside shot at 18 or 20 inches. Thundersnow can’t be ruled out, too, during the height of the storm Saturday afternoon.

Light snow will overspread Connecticut, Rhode Island and areas south of the Mass Pike during the predawn hours Saturday, becoming moderate to heavy by sunrise. There may be some mixing with sleet on the outer Cape and Nantucket initially.

Snow may fall at a rate of 1 to 2 inches per hour briefly in the heaviest band far southeast near the storm’s center, while moderate snows expand through most of New Hampshire and Maine during the late-morning to noontime hours. Damaging winds around 60 to 70 mph on Cape Cod and 40 to 50 mph elsewhere within a county or two of the cast could make for blizzard conditions with reduced visibilities and result in scattered power outages.

There’s also a risk of coastal flooding, particularly during the Saturday evening high tide. Typically prone locations such as the Sandwich Boardwalk, Buzzards Bay, Barnstable Harbor, Narragansett Bay and Scituate Harbor ought to be closely watched.

Snow will taper down southwest to northeast Sunday morning.

Here are predicted amounts in eastern New England, which may still require fine tuning as the storm track comes into focus:

Providence: 8 to 14 inches

Worcester: 6 to 12 inches

Manchester, N.H. 8 to 14 inches

Portland, Maine: 8 to 14 inches

In New York City, the odds of a plowable snowfall have increased, but the system doesn’t look to be a blockbuster. The forecast is dependent on how far west a potentially heavy band of snow extends

Whether New York City ends up under that band is the million-dollar question. For now, the Big Apple should plan for flurries or light snow Friday afternoon becoming moderate around 9 or 10 p.m. and lasting intermittently through Saturday evening. That’s assuming a far enough west track. The snow could end considerably earlier if the system trends farther out to sea.

Philadelphia should expect a similar timeline but shifted up about two or three hours. Like their neighbors to the north, amounts may very substantially from west (less) to east (more) across the metro.

New York City: 5 to 10 inches

Philadelphia: 4 to 7 inches

Atlantic City, N.J.: 6 to 12 inches

If the storm tracks on the east side of forecasts, these amounts will probably be lower.

If the system develops on the earlier end of its range of possibilities, it could easily produce substantial snowfall on the eastern shores of the Chesapeake Bay, the Delmarva Peninsula and toward the Virginia Tidewater.

Light snow breaks out around or just after lunchtime Friday, including in the D.C.-to-Baltimore stretch, and lingers through evening before increasing in areal coverage and intensity to the east during the evening. The Delmarva Peninsula could see it last through Saturday.

Even northeastern North Carolina could wind up with a healthy snowfall. Here are some initial snowfall projections that could be high or low depending on the storm track:

Washington, D.C.: Coating to 2 inches

Virginia Beach: 2 to 5 inches

Salisbury, Md.: 4 to 7 inches

Ocean City, Md.: 4 to 7 inches

Dover, Del.: 4 to 7 inches

Raleigh, N.C.: Coating to 2 inches