Beta, the 23rd named storm of the Atlantic hurricane season, formed in the Bay of Campeche, about 280 miles (450 km) southeast of the Rio Grande River, with 40 miles (64 km) per hour winds.

It was only the second time in history forecasters have taken to using the Greek alphabet for storm names, having exhausted names selected before the season began. The first year storms exceeded given names was 2005, when there were a record 27 named storms.

Beta, which forecasters predicted could become a hurricane next week, is the third named storm in the U.S. Gulf of Mexico in less than a month, following Laura and Sally. Hurricane Sally swept through the eastern Gulf and struck Alabama on Wednesday with winds of up to 105 miles per hour.

Beta will approach the western coast of the U.S. Gulf of Mexico over the next three days, moving northwest toward the south Texas coast then turning northeast, the U.S. National Hurricane Center said at 4 p.m. CDT (2100 GMT).

Its winds could strengthen to 75 mph by Monday morning, a category one hurricane on the five step Saffir-Simpson Wind Scale, the NHC said.

The storm took shape Friday as energy producers had nearly completed flying crews back to oil production platforms on the opposite end of the Gulf of Mexico.

Energy firms reported 37 platforms remained unstaffed on Friday out of the 149 that initially had been evacuated for Hurricane Sally. That was down from 70 platforms unoccupied a day earlier.

Oil output in the U.S. offshore remained down 21% of normal, or 396,554 barrels-per-day (bpd), at midday, offshore regulator Bureau of Safety and Environmental Enforcement (BSEE) said.

Natural gas output from the offshore U.S. Gulf also was down 16%, or 435 million cubic feet per day (mmcfd), BSEE said. Production in Gulf was shut because of the threat from Hurricane Sally.

U.S. Gulf of Mexico offshore oil production accounts for 17% of total U.S. crude oil production and 5% of U.S. dry natural gas production.

By Erwin Seba