Hurricane Calvin 2011
© UnknownCalvin has become the third hurricane of 2011
Hurricane Calvin, the third hurricane of the 2011 eastern Pacific hurricane season, continued to pick up strength as it neared the west coast of Mexico late on Friday.

At 4 p.m. GMT, Calvin's maximum sustained winds had already grown to 70 mph, just 4 mph under hurricane strength. By 9.30 p.m maximum sustained winds had reached 75 mph (120 kph).

The National Hurricane Centre confirmed at 9 p.m. GMT that Calvin had achieved the minimum strength to be classified a Category One hurricane on the Saffir-Simpson Scale. However, the system is expected to weaken during Saturday. Calvin is then forecast to weaken further as it passes over slightly cooler water and dissipate to a remnant low on Monday, July 11, 2011.

The centre of Hurricane Calvin is located about 210 miles southwest of Manzanillo, Mexico, and is moving toward the west near 14 mph.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite provided a look under the hood of Calvin this evening, shortly before it reached Hurricane Status, and noticed the heavy rainfall at the centre of its heat engine. The TRMM satellite can measure rainfall from space, and rainfall rates can be a gauge for the strengthening or weakening of a tropical cyclone.