MIAMI, Florida (CNN) -- Omar strengthen to a hurricane Tuesday night as it churned in Caribbean waters near Puerto Rico, the National Hurricane Center said.
At 8 p.m., Omar was 335 miles south-southwest of Puerto Rico.
Omar formed Tuesday in the eastern Caribbean and dumped heavy rain on the islands of Aruba, Bonaire and Curacao off the coast of Venezuela. At 11 p.m. ET, its center was about 315 miles (505 km) south-southwest of San Juan, Puerto Rico.
The storm was moving northeast near 6 mph (9 kph).
Omar's maximum sustained winds were 75 mph (120 kph), making it a minimal Category 1 hurricane. Hurricane force winds extended outward up to 15 miles (30 km) from Omar's center. Tropical storm-force winds extend 90 miles (145 km) from Omar's center, forecasters said.
"Omar would move through the northern Leeward Islands Wednesday night," the hurricane center said
A hurricane watch and a tropical storm warning were in effect Tuesday night for Puerto Rico. Hurricane warning were in effect for many other islands in the area.
The storm is generally expected to dump up to 8 inches of rain over some areas, with 12 inches possible in some areas, the hurricane center said.
Some portions of Puerto Rico could get up to 20 inches of rain and the storm could produce life-threatening flash floods and mudslides, according to the forecast.
Also, the storm could produce large swells affecting the west- and south-facing coasts of the Lesser Antilles, of which the Leeward Islands are a part. The swells could cause beach erosion and damage coastal structures, the hurricane center said..
Omar is the 15th named storm of the Atlantic hurricane season, which began June 1 and ends Nov. 30.
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