Hilary (2011)

A tropical wave that left the eastern Atlantic on 7 September moved across Central America and organized in the eastern North Pacific, becoming a tropical depression about 0600 UTC 21 September roughly 310 nautical miles southeast of Acapulco, Mexico. The system strengthened to a tropical storm six hours later and moved generally west-northwest and then westward. Hilary underwent a prolonged period of rapid strengthening from 21–23 September, reached peak intensity late on 23 September to early 24 September, then slowly moved westward and weakened over cooler waters and increasing wind shear before degenerating to a remnant low on 30 September and dissipating by 3 October.

Hilary did not make a direct landfall on the Mexican mainland. It passed close to the coast near Acapulco on 23 September but remained offshore; tropical storm warnings and watches were issued along parts of the southern Mexican coast and later discontinued as the center moved away. No official landfall location is given in the best track; the cyclone’s closest approach produced only minimal reported effects onshore.

Maximum intensity was estimated at 125 knots (about 144 mph) with a minimum central pressure of 942 mb, making Hilary a Category 4 hurricane at its peak on 23–24 September. The cyclone was fairly small at peak strength, with tropical-storm-force winds extending only about 75 nautical miles from the center.

Storm surge and rainfall impacts were limited. There were media reports of downed trees in Acapulco after the close approach on 23 September; no specific storm surge heights are reported in the report, and no coastal stations in Mexico recorded sustained tropical-storm-force winds. Peak gusts reported on nearby islands included 44 kt at Isla Clarion (26 September) and 41 kt at Isla Socorro (25 September). The report does not list large rainfall totals at named cities, implying major rainfall records were not observed or documented in the official data.

Three direct fatalities were confirmed: three fishermen drowned when their boat sank off the town of Marquelia (Marguelia), Mexico. Damage on land was reported as likely minor overall, with no monetary estimate provided. Forecasts captured Hilary’s genesis well, and official track and intensity forecasts performed at or better than recent averages for many lead times, though several models showed an eastward bias late in the storm’s life.