UPDATE 4-Storm Ida revives, churns toward Gulf of Mexico

* Storm Ida regains strength after hitting Nicaragua

* Mexico issues hurricane watch for parts of Yucatan

* Ida seen entering energy-rich Gulf of Mexico Sunday (Updates storm position, adds comment from Pemex)

MEXICO CITY, Nov 7 (Reuters) - Tropical Storm Ida regained strength off Mexico's Yucatan Peninsula on Saturday and spun north toward the Gulf of Mexico, where it could again become a hurricane.

The U.S. National Hurricane Center said Ida, which had weakened to a depression on Thursday, now carried maximum sustained winds of nearly 70 mph (110 kph) and was located about 200 miles (325 km) southwest of Cozumel, Mexico.

The center said Ida could become a hurricane later on Saturday or overnight but forecasters expected the storm to weaken as it moves into the Gulf of Mexico.

Skies were sunny and clear on Saturday in the Mexican resort of Cancun, and Ida is expected to pass east of the city on Sunday afternoon.

Mexico issued a hurricane watch for the Yucatan peninsula from the resort of Tulum to Cabo Catoche, north of Cancun.

A tropical storm warning was in effect for Grand Cayman Island and for the western Cuban province of Pinar del Rio, the Miami-based NHC said.