Hurricane Hilary (2011)

Hurricane Hilary

Category 4 major hurricane (SSHWS/NWS)
Hurricane Hilary at peak intensity on September 23
Formed	September 21, 2011
Dissipated	October 3, 2011
(Remnant low after September 30)
Highest winds	1-minute sustained: 145 mph (230 km/h)
Lowest pressure	942 mbar (hPa); 27.82 inHg
Fatalities	None
Damage	Minimal
Areas affected	Southwestern Mexico
Part of the 2011 Pacific hurricane season

Hurricane Hilary was a powerful tropical cyclone that developed during the 2011 Pacific hurricane season. The fourth Category 4 and major hurricane, seventh hurricane, and eighth tropical storm of the season, Hilary developed from an area of low pressure off the Pacific coast of Central America in mid-September. Organizing quickly, the system became a tropical depression on September 21, after gaining enough organization to be declared as such. While moving towards the west-northwest, the depression continued to gather strength, and was subsequently upgraded to a tropical storm just several hours later. On September 21, Hilary was declared as a Category 1 hurricane, while located close to the Mexican coastline, where the storm brought heavy rainfall and flooding. Undergoing rapid intensification, Hilary strengthened into a Category 4 hurricane on September 22, recognized with a distinct eye feature. Beginning to enter cooler Ocean temperatures, Hilary began to weaken by September 25, but briefly restrengthened into a Category 4 the following day. Atmospheric conditions became increasingly unfavorable late on September 26, and the system began to weaken. During the afternoon hours of September 30, Hilary became a remnant low, while located several hundred miles away from any landmasses.

On September 7, a tropical wave moved off the coast of Africa. During the nighttime hours of September 18, an area of showers and thunderstorms associated with a broad area of low pressure was observed a couple of hundred miles south-southeast of the Gulf of Tehuantepec as it moved westward. The following day, the area of disturbed weather began to become better organized, and the National Hurricane Center (NHC) upgraded its chances of tropical cyclone development to the "Medium" category. Moving towards the west-northwest, the area of disturbed weather was upgraded into a tropical depression during the morning hours of September 21, after radar data showed that the low pressure area had gained enough structure to be declared as such. Due to a favorable upper regime characterized by low wind shear and a moist environment, the National Hurricane Center predicted intensification into a hurricane within two days. Later on September 21, despite the fact that rainbands on the western semicircle of the depression became less defined, the depression acquired gale-force winds, and was subsequently upgraded into a tropical storm, earning the name Hilary. That afternoon, the Government of Mexico issued a tropical storm watch for parts of the Mexican coastline, indicating that rainfall totals of 3–5 inches, with isolated 10 inch amounts, were possible.