MIAMI — Tropical Storms Karina and Lowell formed Thursday in the Pacific Ocean, both of which were expected to become hurricanes in the next few days, the National Hurricane Center said.

Tropical Storm Dolly formed in the central Atlantic Thursday morning, but increasingly hostile atmospheric conditions will leave the season's fourth-named storm with only a brief window to strengthen.

The National Hurricane Center issued its first advisory on Tropical Storm Dolly at 11 a.m. Aug. 27, warning residents of the Leeward Islands to monitor the system.