Hurricane Diana - Meteorological History

Meteorological History

The origins of Hurricane Diana were from a tropical wave that emerged into the Atlantic from the west coast of Africa on July 27. Conditions were unfavorable for development of a tropical cyclone, and the tropical wave remained disorganized until reaching the eastern Caribbean Sea. The system entered the Caribbean Sea through the southern Windward Islands, where falling barometric pressures were observed, decreasing by 3.5 mbar (hPa; 0.1 inHg) in 24 hours. Upper-level air data from the Lesser Antilles indicated that the tropical wave was associated with an upper-level anticyclone. With increasing convection, the first Air Force reconnaissance plane flight indicated no low-level circulation, but a relatively large amount of thunderstorm activity. The system continued to have a large amount of associated convection while passing over the Netherlands Antilles, as indicated by satellite images and surface observations. Cyclonic rotation was observed in the low-level convection by satellite images, and the fifth tropical depression of the season had developed at 0000 UTC on August 4, situated in the southwestern Caribbean Sea. However, this was based on surface observations, and it was not confirmed that tropical cyclone formation occurred until later that day.

The new tropical depression moved to the northwest under the influence of a mid-level trough, and rapidly intensified to a tropical storm the following day offshore of eastern Honduras; the National Hurricane Center assigned the system to the name Diana. Becoming a tropical storm, Diana further intensified, and winds reached 65 mph (105 km/h) before landfall in Felipe Carrillo Puerto in Quintana Roo occurred. The storm initially rapidly weakened over land, although it retained winds of 50 mph (80 km/h) until moving over open waters. When Diana entered the southern Gulf of Mexico, the trough of low pressure in that vicinity weakened and steering currents caused the storm to head westward. Conditions became more favorable in the Gulf of Mexico, and Diana quickly intensified, becoming a hurricane late on August 7. Hurricane Diana rapidly intensified, and briefly reached category 2 hurricane status, attaining peak intensity with winds of 100 mph (165 km/h) and a minimum barometric pressure of 980 mbar (hPa; 28.94 inHg). Only two hours after attaining peak intensity on August 7, Hurricane Diana made landfall near Tampico, Tamaulipas at the same intensity.

Moving inland, Diana rapidly weakened over the high terrain of Mexico, quickly deteriorating from a low-end category 2 hurricane immediately to a strong tropical storm just four hours later. Diana continued westward over Mexico, and weakened to a tropical depression on August 8, while centered near Mexico City. The weakening tropical depression turned west-northwestward over central Mexico, and emerged into the Pacific Ocean on August 9, before dissipating in the Gulf of California. The remnants of Hurricane Diana curved northward and tracked trough the Gulf of California, and eventually came ashore in northwestern Sonora. Crossing northwestern Mexico, the remnants of Diana entered Arizona and quickly dissipated.