Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Windy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs around 81 near the shore to around 70 above 3000 feet. East winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 71 near the shore to around 54 above 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Mostly sunny with isolated showers. Highs around 80 near the shore to around 69 above 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Windy. Partly sunny with scattered showers. Highs around 78. Northeast winds 20 to 30 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 61 to 70. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 77. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 69 to 75 in the valleys to around 61 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 53 to 61 in the valleys to around 49 above 4000 feet. East winds 10 to 25 mph. Chance of rain 80 percent.

Friday: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 68 to 74 in the valleys to around 60 above 4000 feet. East winds 10 to 20 mph. Chance of rain 80 percent.

North Kaua’i

Today: Partly sunny. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 71 to 81. East winds 10 to 20 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 58 to 69. East winds 10 to 20 mph. Gusts up to 40 mph in the evening. Chance of rain 70 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs 70 to 80. East winds 10 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 70 to 80. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 54 to 72. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 69 to 79. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Strong and gusty easterly trade winds are expected into Friday as high pressure strengthens north of the state. Showers will favor windward and mountain areas with some reaching the leeward areas. Drier and more stable conditions will return over the weekend, with the easterly trades easing into the moderate to breezy range. Rainfall chances could trend up again early next week as an upper disturbance moves through and trade winds increase.

Discussion

Guidance remains in good agreement and shows the pressure gradient steadily tightening across the region today as high pressure builds to the north. The easterly trades are responding and will become strong and gusty today through tonight as they peak. This has prompted a Wind Advisory for the typically windier areas of Maui County and the Big Island. In addition to the winds, spotty windward shower coverage is expected, especially overnight through the morning periods due to a sufficient amount of low- level moisture and a weak upper trough in the area. These showers will be brief with minimal accumulations anticipated.
Drier and more stable conditions will briefly return over the weekend as upper heights rise and PWs dip to around an inch. Trade winds are expected to ease into the moderate range due to a weakness forming in the ridge as a front passes to the north.
A return of breezy to strong trades is anticipated through the first half of next week as high pressure builds north of the state (near 1050 mb). Model differences still remain with the GFS being stronger with the winds, while the ECMWF has a more moderate solution. Regardless of these differences, both depict an upper trough digging southward over the region creating an increased chance of heavier trade wind showers Monday through midweek.

Aviation

Surface high pressure due N of the islands will support locally strong trade winds through Friday. Although the island atmosphere will be capped by a subsidence inversion based near 8 kft, showery low clouds will produce periods of MVFR VIS/CIG, mainly over windward slopes and coasts. Spatial and temporal coverage is not expected to be sufficiently significant to warrant an AIRMET for mountain obscuration, but AIRMET Tango for tempo moderate turbulence lee of the island terrain will remain in effect.

Marine

Trade winds will increase into the strong to gale force range through the rest of the work week. A Gale Warning remains in effect from 6 AM this morning through 6 AM Friday morning for the Alenuihaha and Pailolo Channels. A Small Craft Advisory (SCA) remains in effect through tonight for all remaining coastal waters. Next week, another high pressure building in from the northwest is expected to continue the breezy trend across the coastal waters.
Strong trades will create rough and choppy surf along east facing shores into next week. A small medium period swell from the north-northwest (330 degree) will arrive this morning, keeping surf elevated but far below advisory level across north and west facing shores. A series of small medium to long period northwest swells are expected through early next week. Mainly background surf will continue for south facing shores through the weekend with some long period energy arriving early next week.

HFO Watches/Warnings/Advisories

Wind Advisory from 6 AM this morning to 6 AM HST Friday for Lanai Mauka, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, South Haleakala, Big Island Southeast, Big Island North.
Small Craft Advisory from 6 AM this morning to 6 AM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST Friday for Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 AM HST early this morning for Pailolo Channel, Alenuihaha Channel.
Gale Warning from 6 AM this morning to 6 AM HST Friday for Pailolo Channel, Alenuihaha Channel.

Data Courtesy of NOAA.gov