Hurricane Agnes - Meteorological History

Meteorological History

In early-mid June 1972, atmospheric conditions favor tropical cyclogenesis in the Caribbean Sea. Banded convection developed in the northwestern Caribbean Sea by June 11, though the system did not significantly organize. After an upper trough moved east, wind shear decreased, causing lower atmospheric pressures observations in Cozumel, Quintana Roo, Mexico. It is estimated that a tropical depression developed by 1200 UTC on June 14, while centered over the Yucatán Peninsula, about 78 miles (126 km) southeast of Mérida, Yucatán. The depression tracked eastward and entered the western Caribbean Sea on June 15. Operationally, the National Hurricane Center did not initiate advisories on the depression until 1500 UTC on June 15. Early on June 16 at 0000 UTC, the depression strengthened into Tropical Storm Agnes. However, the depression was not operationally upgraded until sixteen hours later.

After becoming a tropical storm on June 16, Agnes slowly curved northward and approached the Yucatán Channel. Late on June 17, it was noted that projected path indicated the possibly of landfall in western Cuba. However, the storm remained offshore, though it closely brushed the western tip of Cuba. At 1200 UTC on June 18, Agnes intensified into a hurricane while in the southeastern Gulf of Mexico. Prematurely, the National Hurricane Center operationally upgraded Agnes to a hurricane at 0200 UTC on that day. Upon becoming a hurricane, Agnes attained its maximum sustained winds of 85 mph (140 km/h), though it had not reached its minimum atmospheric pressure. Due to unfavorable conditions, Agnes leveled-off slightly in intensify and weakened to a minimal hurricane while approaching the Gulf Coast of the United States. Shortly before 2200 UTC on June 19, Agnes made landfall near Cape San Blas, Florida with winds of 75 mph (120 km/h).

At 0000 UTC on June 20, only a few hours after moving inland, Agnes weakened to a tropical storm. After crossing the Florida/Alabama/Georgia stateline, Agnes rapidly weakened to a tropical depression. While over Georgia, the depression curved northeastward and eventually to the east-northeast after entering South Carolina. Though the storm had not dissipated, the National Hurricane Center issued its final bulletin on Agnes at 1600 UTC on June 20. By early on June 21, a large extratropical trough spawned a low pressure area, which resulted in baroclinic activity. As a result, Agnes restrengthened into a tropical storm at 1800 UTC on June 21, while centered over eastern North Carolina. Three hours later, the National Hurricane Center noted decreasing atmospheric pressures, and indicated that winds had reached gale force winds and once again upgraded Agnes to a tropical storm. By early on June 22, Agnes emerged into the northwestern Atlantic Ocean, where it continued to re-intensify. At 1200 UTC, Agnes reached its minimum atmospheric pressure of 977 mbar (28.9 inHg), as reported by a reconnaissance aircraft. However, maximum sustained winds were at only 70 mph (110 km/h). Late on June 22, Agnes made its final landfall on Long Island, New York, near New York City with winds of 65 mph (100 km/h). Shortly after moving inland, the storm was absorbed by the low pressure area that previously caused baroclinic activity at 0000 UTC on June 23.