It advanced slowly. Eight miles an hour, maybe ten. It moved west and slightly north and covered about two hundred miles a day, roiling the seas and erecting an electric wall of clouds visible to ships far outside its arc of influence. The first formal sighting occurred Monday, August 27. The captain of a ship at latitude 19 N, longitude 48 W, in the open sea below the Tropic of Cancer halfway between Cape Verde and the Antilles, noted in his log signs of unsettled weather. He recorded from the east-northeast at Force 4, a "moderate breeze." Thirteen to eighteen miles an hour. His barometer showed 30.3 inches.
He dismissed the storm as a distant squall.
Excerpted from ISAAC'S STORM. Copyright © 1999 by Erik Larson.