Hurricane Betsy (1956) - Meteorological History

Meteorological History

Before Betsy's formation, the northeastward shift of the Azores High allowed for an increase in atmospheric instability across the tropical Atlantic, which made conditions for tropical cyclogenesis more favorable in early August. A tropical wave exited the west coast of Africa on August 4. On August 9, a ship reported rough seas and winds of force 10 on the Beaufort scale. On that basis, it is estimated that Tropical Storm Betsy developed that day about 835 mi (1345 km) east of Barbados. The next day, a Hurricane Hunters flight observed winds of 120 mph (190 km/h), which indicated that Betsy had intensified significantly overnight. The flight reported how small the hurricane was, including a 10 mi (16 km) wide eye. After maintaining that intensity for about 24 hours, Betsy began weakening, moving directly over Marie-Galante and southern Guadeloupe. It entered the eastern Caribbean with winds of 90 mph (150 km/h) before it began a track to the west-northwest.

On August 12, Hurricane Betsy passed about 30 mi (48 km) south of Saint Croix before striking southeastern Puerto Rico. This made Betsy the first hurricane to strike the island since the 1932 San Ciprian hurricane. It crossed the central portion of the island, and the structure deteriorated and the eye became difficult to locate as Betsy crossed the highest mountains. On two occasions the eye dropped slightly to the south because of the mountains. The eye became well-defined as it approached the coast, and Betsy emerged on the northwest coast near Camuy at a similar intensity as when it moved ashore. The hurricane re-intensified as it moved toward the Bahamas, reaching winds of 110 mph (180 km/h) on August 13. That day, the eye passed near Grand Turk Island and San Salvador Island. By that time, the storm had increased in size; the Hurricane Hunters reported that the gale force winds extended 125 mi (201 km) to its north. The eye reformed on August 14, becoming well-organized and attaining a minimum barometric pressure of 960 mbar (28 inHg). The next day, Betsy turned to the northeast due to an approaching trough. Despite beginning a weakening trend, the pressure dropped further to 954 mbar (28.2 inHg) on August 17. The eye became increasingly poorly-defined, and Betsy weakened to a tropical storm on August 18 to the south of Nova Scotia. Turning to the east, it became extratropical later that day, eventually dissipating on August 20.