A powerful storm that is expected to move up the East Coast this weekend was still organizing itself off the Carolinas on Wednesday afternoon. While the storm is expected intensify between Thursday and Friday, forecasters warned that there was still significant uncertainty about its path and potential impacts.
“The knowns are that there’s going to be a strong storm off the New England northeast coast,” said Bob Oravec, a senior meteorologist with the National Weather Service. “The only unknowns are the exact details of the track.”
And that’s a big unknown: if the storm tracks to the west, more rain will fall on the towns and cities between North Carolina and New England. If it tracks to the east, away from land, many of those cities will remain relatively dry. It was far too early on Wednesday for forecasters like Mr. Oravec to say with accuracy what would happen by the weekend, but the picture was beginning to come into focus.
Here’s what to know
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Coastal flooding and erosion are the most certain threats, as the storm is developing during some of the highest tides of the month.
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Rainfall totals will depend largely on the storm’s precise path, with coastal New England the most likely area to experience what meteorologists call “excessive” rain this weekend.
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High winds will persist across areas at the coast through the end of the week.
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More storms may follow: This is likely the first of several East Coast storms to follow this path over the next few months, driven by a developing El Niño weather pattern.
The Scenarios
“At the moment, our forecast is still emphasizing eastern New England for the heaviest rain,” Mr. Oravec said on Wednesday. “The heaviest rains will definitely be on the coast.”
As the storm strengthens and moves north this week, the primary impacts are expected across eastern New England, particularly eastern Massachusetts, including Cape Cod, Rhode Island and coastal Maine. Heavy rain is expected to concentrate along the coast, with lighter precipitation extending farther west into southern New England.
Cape Cod and the islands offshore could receive five to seven inches of rain, and lower amounts are expected farther inland. Mr. Oravec cautioned that these totals could shift in the coming days depending on the storm’s exact track.
Farther south, coastal cities including New York City are expected to see some rain and wind, but nothing severe.
“They’re going to have windy conditions on Saturday and Sunday, but the worst conditions are definitely going to be east of them,” Mr. Oravec said.
As things stood on Wednesday, New York City was likely to receive very little rainfall — around an inch over a seven-day period — resulting in a prolonged, unpleasant spell of light rain and wind rather than a major weather event.
How far west the storm tracks as it heads north will determine the extent of the effects. Some of the computer forecast models that meteorologists use to understand the breadth of possibilities indicated that the storm could loop back toward the west.
If that happens, inland areas that were mostly dry initially could end up with more rain and longer-lasting effects. One outlier prediction even suggested stronger effects on New York City. Other scenarios keep the storm far enough offshore that significantly less rain would fall.
Regardless of its path, the storm is expected to weaken gradually on Sunday and Monday. Because it is moving so slowly, however, weather in eastern New England could remain unsettled well into next week.
“Even though the storm weakens Sunday and Monday, it’s slow to move out,” Mr. Oravec said, adding that residents in eastern New England might not see the sun again until Tuesday.
Coastal Flooding
Some alerts were already in effect along coastal portions of the Eastern Seaboard, with more expected as the system moves north.
“In the short term, the biggest impacts from tidal flooding are along the Mid-Atlantic coast,” Mr. Oravec said. “As the storm starts cranking up, the winds are going to be blowing offshore along the Mid-Atlantic coast, but they’ll be blowing onshore across coastal New England.”
Seas will also build significantly. Mr. Oravec said offshore wave heights could exceed 15 feet, while waves along the immediate coast could reach six to 10 feet.
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.
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