Hurricane Makes Landfall in North Carolina

A storm is born: When a low-pressure system that was dithering over the tropical Atlantic last week posed a threat to Puerto Rico and the island of Hispaniola, the center designated it Potential Tropical Cyclone Nine and started issuing forecasts and warnings. The system formed into Isaias, but it was far from clear yet what its future held.

Isaias weakened while passing over the mountainous Dominican Republic, as storms generally do, but it strengthened more quickly than expected afterward, and by the time it reached the Bahamas on Friday it was a Category 1 hurricane.

At that point, the forecast track threatened nearly the whole Eastern Seaboard of the United States, from South Florida to Maine. The storm could have affected almost anywhere, everywhere or nowhere along that track, as far as we could tell.

A near miss: Florida, the closest potential target, braced for a hurricane, but as the weekend progressed, it gradually became clear that the storm would only graze the state as a ragged tropical storm that seemed likely to stay that way until landfall in the Carolinas.

But Isaias reorganized yet again, reaching hurricane strength again on Monday night before making landfall in North Carolina.

A helping hand: At the same time, the wind shear that used to look as though it would diminish the storm may now sustain it. The hurricane center noted for the first time on Monday morning that “an unusually strong winter-type Jetstream” would produce “strong baroclinic forcing” — meteorologist-speak for what drives nontropical storms like nor’easters — and would “produce very strong wind gusts along the Mid-Atlantic states.”

That is why, a day before Isaias is expected to reach New York City, we now have a forecast for hurricane-strength gusts in the area, with the potential for widespread power outages and other problems that were not on the radar, literally or figuratively, until today.