Calvin (2011)

A tropical depression formed about 150 nautical miles southwest of Acapulco, Mexico, at 1200 UTC on 7 July 2011. The system moved generally west‑northwest parallel to the Mexican coast, became a tropical storm at 0000 UTC 8 July, and then rapidly intensified into a hurricane by 1800 UTC 8 July. Calvin reached peak strength early on 9 July and then weakened quickly as it moved over cooler water, degenerating into a remnant low by 0600 UTC 10 July about 355 nmi south‑southwest of Cabo San Lucas. The remnant low drifted over the open Pacific and dissipated by 0600 UTC 14 July about 675 nmi west‑southwest of Cabo San Lucas.

Calvin remained well offshore of the Mexican mainland for its entire life; there were no tropical‑cyclone landfalls recorded. The cyclone’s center stayed over open water, and no watches or warnings were issued for coastal areas.

The storm’s maximum sustained winds reached 70 knots (80 mph) and its minimum central pressure was 984 mb at peak, making Calvin a Category 1 hurricane at its strongest (0000 UTC 9 July). Winds had dropped to tropical‑storm strength within about 12 hours after the peak and to a remnant low by 10 July.

Storm surge observations were not reported for the Mexican coast in association with Calvin. Rainfall and coastal flooding impacts were not documented in the report. On Clarion Island, which the remnant low passed near on 10 July, a peak wind gust of 39 knots was observed at 1415 UTC and a 10‑minute average wind of 32 knots with a gust to 37 knots was measured later that day; no surge or rainfall totals of note were reported for named cities or counties.

There were no reported deaths, injuries, or damage attributable to Calvin. Noteworthy items include the storm’s rapid intensification from tropical storm to hurricane over about 18 hours and its equally rapid weakening afterward. The National Hurricane Center’s track forecasts were generally comparable to recent averages through 36 hours but larger than average at 48 hours, while the official intensity forecasts performed relatively well compared with guidance for this system.