Hainan, China's southernmost island province, is bracing for weekend gales brought by tropical storm Pakhar, the first to hit the country this year, provincial weather forecast authorities warned Thursday.

NASA's TRMM satellite measured rainfall rates in Tropical Storm Pakhar on March 29 at 1123 UTC (7:23 a.m. EDT). Light to moderate rainfall is depicted in blue and green, falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour. Heavy rainfall is seen in red, and is falling at 2 inches/50 mm per hour.?[NASA]?

The tropical storm formed on the surface of the southwestern part of the South China Sea Thursday morning, the meteorological bureau of Hainan reported.

The storm, packing winds moving 18 meters per second, is expected to gain strength and move northwest in the next 48 hours.

Strong winds will start to buffet Hainan and surrounding areas of the South China Sea late Friday night, the bureau said, warning fishing boats in the region to take precautions.

It is not immediately clear if the tropical storm will affect the annual Boao Forum for Asia, an economic forum usually attended by senior officials, economists and businesspeople of the region, that is expected to be held in Hainan's coastal resort town of Boao from April 1 to 3.