Hurricane Alma (1966) - Meteorological History

Meteorological History

During June 1966, low atmospheric pressure stretched across the western Caribbean Sea and Gulf of Mexico—a pattern that is conducive for tropical cyclogenesis. During the first few days of the month, a dissipating trough extended from the southeastern United States into the western Caribbean. A mid-level circulation developed along the trough near Cabo Gracias a Dios on June 3. By the next day, the circulation had reached the surface, which marked the development of a tropical depression over eastern Nicaragua. On June 5, the depression crossed Honduras and emerged into the western Caribbean, moving north-northeastward through an area of warm sea surface temperatures. It had a good cyclonic circulation, convection, and moisture content, but most significantly, a passing trough to the north provided the depression with favorable outflow. On June 6, the depression rapidly intensified into Tropical Storm and later Hurricane Alma. This made it the earliest hurricane in the basin since Hurricane Able in 1951.

After attaining hurricane status, Alma continued moving slowly to the north-northeast, although its intensification rate slowed. While over the western Caribbean, Alma was a large hurricane with gale force winds covering about 200,000 sq mi (520,000 km2). The hurricane accelerated on June 8, quickly moving across Isla de la Juventud and later mainland Cuba with winds of around 100 mph (160 km/h). Alma did not weaken over land and entered the Gulf of Mexico, where it turned northwestward and passed between Key West and the Dry Tortugas. Late on June 8, a station in the Dry Tortugas reported winds of 125 mph (201 km/h); this would be Alma's peak intensity. The hurricane began weakening as it paralleled the west coast of Florida, at which point a developing upper-level low over the northern Gulf of Mexico began to influence its motion. While the hurricane moved northward through the Gulf of Mexico, it had a large, ragged eye that reached 75 mi (121 km) in diameter. Initially, forecasters anticipated Alma would cross central Florida, although the hurricane turned to the north-northwest. Cool water temperatures contributed to weakening, and Alma made landfall near Apalachee Bay with winds of 90 mph (140 km/h). This marked the earliest United States hurricane landfall since a hurricane in May and June of 1825.

While turning northeastward over northern Florida, Alma quickly weakened to a tropical storm. It moved across Georgia and emerged into the Atlantic near Savannah late on June 10. Its circulation remained near the coast, although by late on June 11, Alma had moved far enough offshore that it was able to re-intensify into a hurricane. It developed a large eye and maintained hurricane intensity for about 18 hours. Afterward, Alma turned to the north into an area of drier air and colder waters, and again weakened to a tropical storm on June 12. The next day, Alma transitioned into an extratropical cyclone to the east of Maryland. The remnants continued to the northeast and dissipated on June 14 over Massachusetts.