UPDATE 4-Nicaragua braces for Tropical Storm Ida

(Updates with Colombia discontinuing islands warning, quote)

By Ivan Castro

MANAGUA, Nov 4 (Reuters) - Tropical Storm Ida strengthened off the coast of Nicaragua on Wednesday as heavy rains forced a Caribbean island to evacuate and the Central American nation, fearing devastating mudslides, was put on hurricane watch.

Ida, the ninth named storm of the Atlantic hurricane season, dumped rain on northern Nicaragua and around 300 people fled the popular tourist spot Corn Island to wait out the storm in government-run shelters.

Dark clouds and rains menaced Managua, Nicaragua's capital, and the U.S. National Hurricane Center said a hurricane watch was in effect for the eastern coast from the town of Bluefields up to the border with Honduras.

"A hurricane watch means that hurricane conditions are possible within the watch area, generally within 36 hours," the hurricane center said.

The storm, which is set to hit land early Thursday, had maximum sustained winds of nearly 65 miles per hour (100 km/hr) and could dump up to 25 inches (64 cms) of rain on Nicaragua and eastern Honduras.

"These rains could produce life-threatening flash floods and mudslides," the NHC's forecast said.

"A storm surge could raise water levels by as much as 3 feet above ground level along the east coast of Nicaragua, with large and dangerous battering waves."