UPDATE 5 p.m.
Deep moisture associated with the remnants of Barbara is expected to move over Hawaii island as early as Sunday night and spread over the state on Monday.
The National Weather Service said this deep moisture will bring the potential for heavy rainfall, especially over windward areas. Windy conditions are possible on Monday, especially on the Big Island.
Drier and more typical tradewind weather will return Tuesday and continue for the remainder of the week.
A small craft advisory is in effect for waters off Hawaii island through late Monday.
The National Weather Service said east to northeast winds will increase to 20 to 30 knots tonight and possibly 25 to 35 knots on Monday. Seas will build to 9 to 13 feet Monday. Inexperienced mariners, especially those operating smaller vessels, should avoid navigating in these conditions.
A gale watch has been issued for the Alenuihaha Channel from Monday morning through Monday evening. Northeast winds will increase to 20 to 30 knots tonight and possibly 25 to 35 knots on Monday. Seas will build to 9 to 13 feet Monday.
Tropical Storm Cosme continues to churn behind a weakened Barbara in the Eastern Pacific and is located 635 miles southwest of the southern tip of Baja California.
Cosme, with maximum sustained winds near 50 mph, is moving toward the west-northwest near 12 mph. A turn toward the northwest and a reduction in forward speed is expected on Sunday and Monday.
Gradual weakening should begin Sunday night and Cosme is forecast to become a remnant low by Monday night or Tuesday.
UPDATE 12 p.m.
Tropical Storm Cosme continues to churn behind a weakened Barbara in the Eastern Pacific west-northwestward at near 13 mph just southwest of Mexico.
Cosme was located about 620 miles southwest of the southern tip of Baja California.
The National Hurricane Center in Miami said Cosme is forecasted to continue on the general path today followed by a turn to the northwest Sunday.
Cosme’s maximum sustained winds remain near 50 mph with higher gusts. Forecasters said there will be little change in the storm’s strength this weekend followed by a slow decrease in speed anticipated Monday.
Tropical storm-force winds extend outward up to 160 miles from the eye.
Tropical Storm Barbara, once a powerful Category 4 hurricane, has degenerated into a post-tropical cyclone as it enters the Central Pacific.
The National Hurricane Center in Miami said Barbara was located about 1,040 miles east of Hilo with maximum sustained winds of near 40 mph with higher gusts and moving toward the west near 17 mph at 5 a.m. today.
“Additional weakening is indicated, and the system should dissipate in a couple of days while it moves toward the west steered by the low-level trade winds,” forecasters said.
Tropical storm-force winds extend outward up to 115 miles from the storm’s center.
The National Weather Service in Honolulu said Barbara should become a post-tropical low this morning, then dissipate as a surface low before reaching the Hawaiian Islands.
Barbara is forecasted to bring wind and rain to Hawaii. Light winds will gradually strengthen today into Sunday with breezy trade winds. Although winds will be on the lighter side today, isolated showers are likely to develop in the interior and leeward areas this afternoon. Trade winds will send a few brief showers to the windward areas through Sunday.
“Deep moisture associated with the remnant of Barbara is expected to move over the islands from the east, reaching the Big Island as early as Sunday night, and spreading over the other islands on Monday,” forecasters said. “This deep moisture will bring the potential for locally heavy rainfall, especially windward.”
Happy #FullDiskFriday 🎉 NOAA's #GOESWest watches as Tropical Storm Barbara churns across the eastern Pacific. A disturbance just southwest of Mexico has joined #Barbara and could become a tropical cyclone this weekend. More imagery: https://t.co/z6KgATrhKB pic.twitter.com/ZY68AIFnFo
— NOAA Satellites (@NOAASatellites) July 5, 2019
Drier and more typical trade wind weather is expected to return Tuesday and Wednesday and the latter part of next week.
Barbara will also generate a large east swell spreading across the islands this weekend.
The NWS issued a high-surf advisory for the east-facing shores of the Oahu, Hawaii island, Kauai, Maui and Molokai along with a high-surf advisory for the south-facing shores of all islands.
Surf is expected to increase to 5 to 8 feet today on the east shores, then build to 6 to 10 feet Sunday. Surf on all south shores of the islands is expected to reach 5 to 8 feet this weekend.
The high-surf advisory expires Sunday night.