MIAMI, Florida (AP) -- Tropical Storm Beta formed Thursday in the southwestern Caribbean Sea, extending this year's record of named storms in the Atlantic hurricane season. Beta is the season's 23rd tropical storm, the most since record keeping began in 1851. The disturbance formed Wednesday night, but forecasters said it was not expected to threaten the United States. Richard Knapp, hurricane specialist at the National Hurricane Center, said it was not unusual to get storm activity toward the end of hurricane season, which ends November 30. "It may not be over with Beta, but let's hope so," he said. At 5 a.m. EDT, it was about 75 miles south of San Andres Island and about 140 miles east-southeast of Bluefields, Nicaragua. A hurricane watch and a tropical storm warning has been issued for the islands of San Andres and Providencia. Heavy rain and strong winds were expected there Thursday. A tropical storm warning has been issued for the entire Caribbean coast of Nicaragua and adjacent islands. Hurricane conditions are possible in the next several days, forecasters said. Its maximum sustained winds were near 40 mph and was moving northwest near 5 mph. Tropical storm force winds extend outward up to 35 mph. Beta is expected to produce 10 to 15 inches of rain across western Panama, Costa Rica and Nicaragua, forecasters said. Last week Tropical Storm Alpha formed, which was the first time a letter from the Greek alphabet has been used because the list of storm names was exhausted. The previous record of 21 storms stood since 1933. Reprinted from cnn.com