(Reuters) - Weather system Kilo weakened into a depression by early Saturday but is expected to form a hurricane as it travels across the central Pacific towards the Hawaiian islands over the next several days, the National Weather Service said.
Kilo, with sustained winds of up to 35 miles per hour (56 km per hour), was centered roughly 450 miles (725 km) southwest of Hawaii's Hilo Island by 11 p.m. (0500 ET) on Friday, moving west at about 16 mph.
Kilo is expected to strengthen and slow over the weekend, as it begins to turn northwest. Because it is tracking over warm water, south of the islands, it will likely avoid a wind shear that weakened two hurricanes earlier this month.
Forecasters say Kilo will not make a direct hit on any of the islands, but Kauai appears to be the most vulnerable.
Flash-flood warnings are in effect for Maui and Hawaii's Big Island through Monday.
Meanwhile, Hurricane Danny was churning over the Atlantic with slightly less force by early Saturday.
Danny, the first of the 2015 Atlantic season, has strengthened into a potentially destructive Category 3 storm. However, it weakened slightly overnight, registering winds measured at up to 100 mph (160 kph) by Saturday morning, down from 115 mph (185 kph) the evening before.
Danny was expected to weaken back into a tropical storm as it reaches the outer Caribbean islands early next week.
Hurricanes can bring high winds, torrential rains and exceptionally big waves, causing what forecasters call a "triple threat," bringing possible large-scale destruction, the National Weather Service said.
(Reporting by Laila Kearney; Editing by Fiona Ortiz and Robin Pomeroy)