Photo Credit: Braden Jarvis

West Kaua’i

Rest Of Today: Mostly cloudy. Scattered showers in the morning, then showers likely in the afternoon. Highs around 82 near the shore to around 68 above 3000 feet. Southwest winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 64 near the shore to around 53 above 3000 feet. West winds up to 15 mph shifting to the north after midnight. Chance of rain 70 percent.

Thursday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 79 near the shore to around 64 above 3000 feet. North winds 10 to 15 mph. Chance of rain 40 percent.

South Kaua’i

Rest Of Today: Partly sunny. Breezy. Scattered showers in the morning, then showers likely in the afternoon. Highs around 80. West winds 10 to 20 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 62. West winds up to 15 mph shifting to the north after midnight. Chance of rain 60 percent.

Thursday: Partly sunny with scattered showers. Highs 75 to 80. North winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Rest Of Today: Partly sunny. Scattered showers in the morning, then showers likely in the afternoon. Highs 74 to 80 in the valleys to around 63 above 4000 feet. Southwest winds up to 15 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 55 to 61 in the valleys to around 51 above 4000 feet. West winds up to 15 mph shifting to the northwest after midnight. Chance of rain 70 percent.

Thursday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 68 to 74 in the valleys to around 58 above 4000 feet. North winds 10 to 20 mph. Chance of rain 60 percent.

North Kaua’i

Rest Of Today: Partly sunny with scattered showers. Highs 71 to 81. East winds up to 15 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 56 to 64. Northwest winds up to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 68 to 78. North winds 10 to 15 mph. Chance of rain 60 percent.

East Kaua’i

Rest Of Today: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 82. Southwest winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 57 to 67. West winds up to 15 mph shifting to the north after midnight. Chance of rain 70 percent.

Thursday: Partly sunny with scattered showers. Highs 68 to 79. North winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Winds will strengthen out of the southwest today as a front approaches from the northwest, then passes over the island chain tonight through Friday morning. Expect increased clouds and showers as the front passes by. North winds will fill in behind the front, then become northeasterly trade winds through the weekend.

Discussion

Troughing to our northwest has pushed a weakened subtropical ridge across the islands this morning, keeping our winds light. Cloud cover across the islands decreased from last evening, but has begun to increase again early this morning across Kauai and Oahu as light southwesterlies develop ahead of an approaching front. Expect continued strengthening of these southwesterlies statewide today. Rainfall was minimal overnight, reflecting a rather dry and stable prefrontal airmass. Latest soundings showed less than in inch of PW with positive lifted index values.
Models show the front approaching from the northwest will reach Kauai tonight, then move down the island chain afterwards through Friday morning. Expect a limited period of wet weather for each island as frontal clouds and showers pass by. The front will have little upper level support, so we are not expecting heavy rain or thunderstorms along the boundary. High pressure will build in behind the front, producing cooler temperatures along with breezy north to northeast winds. Passing windward and mountain showers will continue through early next week as the high shifts eastward north of the main Hawaiian Islands this weekend.

Aviation

A cold front approaching the islands from the northwest will produce southwesterly winds spreading across the state today. A few showers will develop along south and west facing slopes of each island today and tonight. This cold front will reach Kauai later tonight and Oahu by early Thursday morning, producing periods of MVFR conditions as the front marches eastward down the island chain.
No AIRMETs are in effect and none are expected through this afternoon. AIRMETs for mountain obscuration will be needed as the front passes through each island.

Marine

An approaching cold front from the northwest will strengthen south to southwest winds to more moderate magnitudes, with locally stronger winds reaching Small Craft Advisory (SCA) thresholds around Kauai, later today. The front will move down the state from tonight through late Thursday as fresh northerly winds fill in behind the front. Winds will gradually veer to the northeast Friday and likely strengthen to SCA magnitudes as surface high pressure moves into the central North Pacific. This high will pass far north of the state on Sunday, maintaining fresh to locally strong trade winds.
Surf along north and west-facing shores will remain small through today with as background, short period northwest energy fades out. A significant, XL northwest (320 degree) swell will arrive late tonight and rapidly build down the island chain Thursday. This swell will lift surf to well above High Surf Warning levels along most north and west-facing shores. The passing of this swell within moderate to locally strong northeast winds will result in rough sea conditions and warrant an SCA for most local nearshore waters. A swell of this size will adversely impact coastal areas, especially during periods of high tide both Thursday and Friday evenings. Preparations should be made for the threat of coastal flooding as ocean water runs up and inundates beaches and potentially affects coastal properties and roadways. The northwest swell will slowly decline Friday and Saturday with a large, medium period north swell (350 degree) following on its heels Saturday and Sunday. This swell will maintain solid High Surf Advisory level surf along most northern exposures and keep seas at SCA heights. Surf along east-facing shores will experience a rapid increase this weekend due to a combination of rough, short period trade wind swell and large north swell. Seasonal small surf will occur along south shores.

HFO Watches/Warnings/Advisories

High Surf Warning from midnight tonight to 6 PM HST Friday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Kauai East, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
Small Craft Advisory from midnight tonight to 6 AM HST Saturday for all Hawaiian waters except Maalaea Bay,

Data Courtesy of NOAA.gov