Hurricane forms off Mexican coast

A tropical storm which formed off the west coast of Mexico has gained strength and become a hurricane.

Hurricane Hernan was detected 1,390km (865 miles) off the coast and was expected was keep moving out to sea.

It is the fifth named hurricane of this year's Pacific hurricane season, which runs from August to November.

Meteorologists warned on Thursday that an above-average number of storms and hurricanes were expected to hit the Pacific in 2008.

American's National Hurricane Center (NHC) said Hurricane Hernan had reached maximum sustained wind speeds of nearly 75mph (120km/h).

HOW HURRICANES FORM Sea surface temperatures above 26.5C (79.7F) A pre-existing weather disturbance Moisture in the atmosphere Favourable conditions, such as light winds or weak wind shear Animated guide: Hurricanes

On Friday, hurricane force winds extended up to 35km (25 miles) from the storm's centre.

NHC forecasters predict that the hurricane may strengthen slightly over the next two days before weakening as it moves over cooler waters.

On Thursday, America's National Oceanic and Atmospheric Administration (NOAA) reported that the 2008 Pacific storm season is likely to be more active that previously predicted, with up to ten hurricanes expected.