Miami ? A subtropical depression formed Saturday in the open Atlantic, prompting Bermuda to issue a tropical storm watch.

The system could strengthen into Tropical Storm Vince, according to the National Hurricane Center in Miami. Vince would be the 20th named storm in one of the busiest hurricane seasons on record.

Long-term forecasts showed the system either reaching the United States mainland in about five days, or curving farther out to sea after passing Bermuda. But hurricane specialist Jack Beven said it appears the system might not survive if it gets closer to the U.S. because of other weather in the area.

“It’s really too early to say just how much of a threat this will pose to the U.S.,” he said.

The depression’s strongest winds are far from its center, but if they start closing in on its core it could strengthen into a storm, said Robbie Berg, a hurricane center meteorologist.