A tropical storm watch is in effect for Bermuda after Tropical Storm Sean formed between the British territory and the Bahamas.

The National Hurricane Center in Miami said in an advisory Tuesday that the weather system was located 685 kilometers southwest of Bermuda with 75 kilometer-per-hour winds. Forecasters expect the nearly stationary system to begin moving toward the northwest and possibly increase in strength in the coming days.

The forecasters also warn that tropical storm conditions on Bermuda are possible late Thursday and that swells generated by the storm are expected to affect portions of the southeastern United States, causing life-threatening surf and rip currents.

The Atlantic hurricane system began June 1 and runs through November 30.