User:12george1/Meteorological history of Hurricane Irene (1999)

The meteorological history of Hurricane Irene spanned six days from October 13 to October 19, 1999.

Formation and Cuba landfall
Between October 8 and October 10, a low pressure area situated over the western Caribbean Sea initially had minimal deep convection. By October 11, a tropical wave reached the area and caused the overall system to begin developing into a tropical cyclone. A United States Air Force Reserve reconnaissance plane flight on October 12 indicated a low-level circulation within a 1006 mbar low pressure area. However, the disorganization of the circulation deemed it too weak to classify. Later on October 12 and early on October 13, convection began increasing, while banding features and upper-level outflow began to become well-defined. Based on surface and upper-air data from Grand Cayman and T-number obtained using Dvorak technique, it is estimated that Tropical Depression Thirteen formed at 0600 UTC on October 13, while located about 160 mi north of Cabo Gracias a Dios.

The depression quickly strengthened and by 1200 UTC on October 13, it became Tropical Storm Irene. Operationally, the National Hurricane Center did not initiate advisories on Irene until three hours after it reached tropical storm intensity. The initial predictions stated that Irene would reach hurricane status within 36 hours, as well-defined outflow and several computer models indicated that significant further strengthening was very likely. Additionally, the storm was approaching an area of increasing sea surface temperatures. Despite the outflow, Irene was overall a poorly organized tropical cyclone, with the strongest winds located in a convective band to the northeast of the center. After tracking north to north-northwestward and approaching Cuba on October 14, Irene decelerated while strengthening and improving satellite appearance. Although conditions were favorable at the time, upper-level southwesterly winds were expected to halt intensification in about 48 hours.

Prematurely, the National Hurricane Center operationally upgraded Irene to a hurricane at 0900 UTC on October 14, possible due to radar estimations, as a hurricane hunter aircraft was forbidden to enter Cuban airspace. By 1200 UTC on October 14, Irene made landfall on the western side of Isla de la Juventud with winds of 70 mph (115 km/h). Although a hurricane hunter aircraft could not reach the storm, a National Oceanic and Atmospheric Administration P3 plane was able to examine the wind structure associated with Irene. After briefly re-emerging into the northwestern Caribbean Sea, Irene made another landfall near Batabanó, Cuba, with winds of 70 mph (115 km/h) at 1900 UTC on Ocotber 14. Despite the mountainous terrain of Cuba, the storm did not weaken inland.

Straits of Florida and Florida landfall
Early on October 15, Irene emerged into the Straits of Florida and immediately resumed intensification. At the time, computer models were widespread and inaccurate, with many indicating a landfall in West Central Florida, while a few predicted that Irene would track as far west as southeastern Louisiana. As the storm was emerging into the Straits of Florida near Havana, radar imagery from Key West indicated that an eye was developing. Post-analysis indicates that Irene actually became a hurricane at 0600 UTC on October 15, almost 24 hours after the National Hurricane Center operationally upgraded the storm. Early on October 15, data from a WSD-88D radar from Key West and United States Air Force Hurricane Hunter aircraft indicated the the center of Irene reformed further to the east. Due to wind shear, the eye weakened slightly, while further intensification of the storm halted.

At 1300 UTC on October 15, Irene made landfall on Key West, Florida, with winds of 75 mph (120 km/h). Although further intensification was expected because landfall, due to improved satellite depictions, very cold clouds tops, and re-development of outflow to the southwest, though rapid deepening seemed unlikely because of poor organization of the inner core. After minimal further strengthening, Irene made another landfall in Cape Sable, Florida, with winds of 80 mph (130 km/h). Once inland, the National Hurricane Center predicted significant weakening, followed by another landfall in South Carolina by October 17. However, by early on October 16, the National Hurricane Center revised their forecast and stated Irene would likely maintain hurricane status while crossing Florida. Nonetheless, Irene emerged into the Atlantic Ocean as a minimal Category 1 hurricane near Jupiter, Florida at around 0600 UTC on October 16.

Intensification and extratropical transition
Although upper-level winds were not favorable for strengthening, the National Hurricane Center noted that Irene would track across the warm sea surface temperatures of the Gulf Stream, allowing for potential intensification.