The East Coast of the United States hasn’t experienced a hurricane this year, but forecasters have warned that a storm taking shape this week could bring hurricane-force winds and heavy rain as it moves through the region.
Forming on Wednesday in the western Atlantic, off the coast of North Carolina and Virginia, the storm is forecast to intensify as it moves north in the coming days. The biggest impacts are expected from Friday into the weekend, especially along the New England coast.
But on Tuesday, there was still a lot of uncertainty about the storm’s exact path and how strong it will become, which will determine which areas could experience the greatest impacts.
The setup
The storm is technically a nor’easter, a type of storm that more commonly stirs visions of heavy snow and plunging temperatures.
But the term applies broadly to storms that move along the Eastern Seaboard with winds that blow from the northeast. These types of storms typically occur between November and March. A nor’easter in September would be relatively early, but not unheard of.
That much forecasters were certain of on Tuesday. But as with many of those classic wintertime nor’easters, there is considerable uncertainty about what this storm will do over the next few days and where it will do it.
The scenarios
In the days before a storm actually forms, weather forecasters use computer prediction models to help them understand where it might go. The nearer those models are to the date of the storm, the more accurate they tend to be. And sometimes, as with this one, the models can disagree about a storm’s most likely path, which becomes clearer only as the days advance.
If this storm becomes more organized just a bit later or earlier, or if it shifts a little to the east or to the west as it moves north, there are significant differences in where the strongest winds and rain would occur. Some models on Tuesday showed the storm staying farther offshore, and others brought it closer to the Northeast coast.
Bob Oravec, a meteorologist at the Weather Prediction Center, an arm of the National Weather Service, said this storm could be notably strong, with the potential for multiple days of strong winds, coastal flooding, high surf, rip currents and possible beach erosion.
“Especially from Cape Cod northward to coastal Massachusetts, maybe into Boston, coastal New Hampshire, coastal Maine,” he said early Tuesday. “Really anywhere along the New England coast could be stormy.”
Depending on the storm’s exact track, rain and strong winds could also reach areas farther inland across parts of the Northeast and Mid-Atlantic, Mr. Oravec said.
The impacts
Emergency agencies and local weather offices along the East Coast were already preparing for the storm, even as the path was uncertain.
In North Carolina, gale watches were upgraded to warnings on Tuesday, because forecasters said strong winds from the storm were expected to arrive sooner. A coastal watch was also issued for Hatteras and Ocracoke Islands, a part of the state where dozens of beachfront houses have been swept away by powerful waves in recent years.
Forecasters said the strongest winds and greatest risk of coastal impacts there were expected Thursday into Friday, particularly across the Outer Banks as the storm coincides with the peak lunar tides of the month.
Seas and surf could become increasingly dangerous through the weekend, even far from the storm’s center. From North Carolina to Boston, and most points in between, local Weather Service offices expected seas to be 10 feet or more above normal by Thursday.
On Tuesday, as the models and meteorologists were fine-tuning their forecasts, there remained considerable uncertainty over how much rain would fall. A path closer to land could deliver more rain to cities like New York and Boston. But if the storm remains farther out to sea, there is far less likelihood of wind and rainfall effects in the major cities.
Still, forecasters were warning that heavy rain was likely in portions of New England and North Carolina.
“We have some heavy rainfall amounts along the New England coast,” Mr. Oravec said. “We’re forecasting over five inches of rain right along across Eastern Massachusetts, including Boston, Cape Cod.”
Nowhere was the difference between a little rain and a lot of rain more clear than the Outer Banks: The area could get only a half-inch if the storm forms farther from the coast, but six inches or more could fall if it happens closer.
Is El Niño to blame?
Indirectly.
You might have heard about the powerful El Niño that has been brewing this year. El Niño is a natural weather pattern that peaks in the winter, but it doesn’t, by itself, cause one storm to grow strong or a heat wave to settle in.
As the seasons change and El Niño becomes the dominant global weather pattern, it has a tendency in winter to create patterns that push storms like this across the Southern United States and up the East Coast. Coastal towns between New York and Georgia routinely shatter high-tide flood records during El Niño years, not only during severe winter storms, but also on sunny days with no storm in sight.
Judson Jones contributed reporting.
The post How a Brewing Storm Could Slam the East Coast This Week (or Not) appeared first on New York Times.
