Eugene (2011)

A tropical depression formed about 380 nautical miles south of Acapulco, Mexico around 0600 UTC on 31 July 2011 and became Tropical Storm Eugene six hours later. The storm moved generally west‑northwest, strengthening into a hurricane by about 1800 UTC 1 August. Eugene intensified rapidly during 2–3 August while well offshore, reached peak strength on 3 August, then moved over progressively cooler water and weakened to a tropical storm on 5 August. Deep convection ceased and Eugene became a non‑convective post‑tropical low by 1200 UTC 6 August; the remnant low dissipated by 10 August east of Hawaii.

Eugene remained entirely offshore of the Mexican coast; there were no landfalls associated with the system.

The hurricane reached a peak intensity of 120 knots (about 138 mph) with a minimum central pressure of 942 mb on 3 August, making it a Category 4 hurricane at peak. The peak intensity is based on a blend of satellite analysis methods (Dvorak estimates and the Advanced Dvorak Technique).

No storm surge heights or significant rainfall totals associated with Eugene were reported in the operational record; there were no ship reports of tropical‑storm‑force winds and no watches or warnings were issued. Because Eugene remained far offshore, coastal surge and heavy rainfall impacts on named cities or counties were not recorded in the NHC report.

There were no reported casualties or damage attributed to Eugene. Noteworthy aspects include the storm’s rapid intensification to a major Category 4 hurricane well offshore and the difficulty forecasters had predicting its formation (genesis was not well anticipated) and the later track at long lead times; overall, official NHC intensity forecasts performed reasonably well early in the event while some dynamical models (notably HWRF and GFDL) had large track and intensity errors.