Cosme (2013)

A broad low pressure area formed from a tropical wave on 21 June 2013 several hundred miles south of Acapulco, Mexico. The system organized into a tropical depression by 1200 UTC 23 June about 435 nautical miles south of Manzanillo and became Tropical Storm Cosme 12 hours later. Cosme moved little at first, then turned northwest on 24 June and accelerated to the west-northwest as a ridge over Mexico steered it. The cyclone strengthened to hurricane status early on 25 June, reached peak intensity around 0000 UTC 26 June, weakened as it moved over cooler waters, and lost its deep convection by 1200 UTC 27 June about 600 nautical miles west-southwest of Cabo San Lucas. Its remnants continued westward and eventually opened into a trough well east-southeast of Hawaii.

Cosme remained well offshore of mainland Mexico and did not produce any recorded landfalls on the Mexican coast or nearby islands. It brought tropical-storm-force conditions to Socorro and Clarion Islands while staying at sea; no watches or warnings were issued for the mainland.

The hurricane’s maximum sustained winds peaked at 75 knots (85 mph) about 0000 UTC 26 June, with a minimum central pressure estimated at 980 mb. At its peak Cosme was a Category 1 hurricane on the Saffir–Simpson scale.

Reported storm surge and rainfall impacts were minimal. Socorro Island reported a wind gust of about 40 knots on 25 June. Clarion Island recorded a minimum pressure observation of 982.4 mb on 26 June (which may be 5–7 mb too low based on other data). The NHC report did not list specific storm surge heights or rainfall totals for Mexican cities or counties associated with Cosme.

There were no reports of damage or casualties—no deaths, injuries, or structural impacts—associated with Cosme. The storm’s effects were limited to maritime and island observations, and it did not affect populated coastal areas.

Noteworthy items include that Cosme’s formation was well forecast (a high chance of genesis was issued about 36 hours before formation) and NHC track and intensity forecasts for Cosme were substantially more accurate than typical five-year averages. No watches or warnings were required.