SAN JUAN, Puerto Rico Tropical Storm Olga knocked out power and caused widespread flooding in Puerto Rico on Tuesday and hit the Caribbean island of Hispaniola with torrential downpours, threatening to unleash mudslides.
Olga's maximum winds strengthened from 45 mph (75 kph) to about 60 mph (96 kph) but forecasters at the U.S. National Hurricane Center predicted strong winds in the upper atmosphere would start to tug it apart on Wednesday.
Olga was born as a subtropical storm on Monday but forecasters said it had gained tropical storm characteristics on Tuesday. Both types of storms are cyclones but subtropical storms have a cooler core, which can slow development.
The hurricane center said Olga's greatest threat was its torrential rains.
"These rains have already produced life-threatening flash floods and mudslides in Puerto Rico," the forecasters said in an advisory.
Tropical storm warnings and watches were in effect for parts of Haiti and the Dominican Republic, which share the island of Hispaniola, and for the Turks and Caicos islands and the southeastern Bahamas.
At 7 p.m. EST (0000 GMT), the storm's center was moving over the Dominican Republic about 30 miles north-northeast of the capital of Santo Domingo.
Olga was moving west at nearly 13 mph (21 kph) and was expected to dump up to 10 inches of rain on the island.
Authorities evacuated scores of families in vulnerable areas of the Dominican Republic, where at least 89 people died in devastating floods from Tropical Storm Noel in October.
Olga pounded Puerto Rico with rain on Monday. Central mountain towns like Orocovis and Jayuya had received 8 inches
by midday Tuesday, the National Weather Service said.
The storm knocked out electricity to 80,000 customers, the Puerto Rico Electric Power Authority said. The Aqueduct and Sewer Authority said 144,000 clients were without water because the storm disabled 11 of 33 filtration plants.
Children were evacuated from a school in Aguada, on the west coast, after the Culebrinas River flooded, officials said. Six other rivers flooded and a dozen major roadways were closed due to flooding and fallen trees, they said.
Most forecasting models showed the storm moving westward across the Caribbean toward Central America, keeping it well away from U.S. oil and gas facilities in the Gulf of Mexico.
One had it crossing Cuba into the southern Gulf of Mexico and then veering across Florida toward the Atlantic Ocean.
The 15th storm of the year, Olga formed over the Virgin Islands 10 days after the official end of the six-month Atlantic-Caribbean hurricane season.
Tropical storms draw strength from warm seas, so December storms are unusual. Olga was the 17th named storm to form in the region in the month of December since record-keeping began in 1851, the hurricane center forecasters said.
(Additional reporting by Manuel Jimenez in Santo Domingo and Jane Sutton in Miami, editing by Eric Walsh)