CALERA, Ala. — It had been a sleepy Sunday morning in the National Weather Service’s office outside of Birmingham. The hot temperatures in the forecast were not out of the ordinary for the waning days of summer. There was a faraway tropical storm that the office was keeping an eye on — one with the name of Dorian — but with each passing day, it seemed more likely to veer in a different direction.

Then, out of nowhere, there came a flurry.

It was incoming phone calls from Alabamians energized about Hurricane Dorian, suddenly confused and worried about whether they were in the path of the giant Caribbean storm. At one point, the few people on duty were all answering calls at the same time.

In response to the alarm, one employee dashed off a short message to the office’s 50,000 Twitter followers that reaffirmed what the latest models were saying: Alabama had little to worry about.

A far more alarmist forecast had gone out 20 minutes before on an account with a much, much larger reach. Alabama and other states, @realDonaldTrump had warned, would likely be hit “harder than anticipated.”