Tropical Storm Ernesto expected to become hurricane anytime now

Tropical Storm Ernesto was churning through the Caribbean early Wednesday, just days after Debby finished its trek along the U.S. East Coast. Ernesto was expected to become a hurricane sometime Wednesday morning as it passed north of Puerto Rico, the National Hurricane Center said, adding that it could become a major hurricane "in a couple of days."

President Biden approved an emergency declaration for Puerto Rico Tuesday night.

As of 5 a.m. EDT, forecasters said Ernesto had maximum sustained winds of 70 mph, just shy of the 74 mph needed for it to be classified as a hurricane, and was moving northwest at 16 mph. It was centered about 85 miles north-northwest of San Juan, Puerto Rico, the hurricane center said.

A storm needs to have winds of 111 mph to be considered a major hurricane.

"On the forecast track," the Miami-based hurricane center said, "the center of Ernesto will pass to the north of Puerto Rico through today. Ernesto should then move over the western Atlantic later in the week and be nearing Bermuda on Saturday."

A hurricane watch was in effect for the British Virgin Islands. A tropical storm warning was posted for the U.S. and British Virgin Islands, Puerto Rico, Vieques and Culebra.

CBS News senior weather producer David Parkinson said "rain will be a far bigger player than wind" when it comes to Ernesto.

The hurricane center said the storm is expected to produce between 4 and 6 inches of rain over the U.S. and British Virgin Islands and up to 10 inches across southeastern Puerto Rico.

"Minor coastal flooding remains possible in areas of onshore winds along the eastern coast of Puerto Rico, including the islands of Culebra and Vieques, and in the U.S. Virgin Islands, including St. Thomas, St. John, and St. Croix," the center added.

Parkinson said, "The U.S. remains outside of the risk zone for direct impacts, but rip currents and larger waves will be a concern along the eastern seaboard."

Ernesto marks the fifth named storm so far of the Atlantic hurricane season, which has already proven to be historic after Beryl reached record strength at the beginning of the season in above-average temperatures of the Gulf of Mexico. NOAA has predicted an above-normal season, with 17-25 named storms, eight to 13 hurricanes, and four to seven major hurricanes.

The fifth-named storm typically doesn't form until Aug. 22 , according to NOAA.