West Kaua’i

Tonight: Mostly clear. Lows around 74 near the shore to around 64 above 3000 feet. East winds up to 15 mph.

Thursday: Sunny. Highs 87 to 93 near the shore to around 79 above 3000 feet. East winds up to 15 mph.

Thursday Night: Partly cloudy with isolated showers. Lows around 75 near the shore to around 64 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Breezy. Partly cloudy with isolated showers. Lows 71 to 77. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs 80 to 91. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy with scattered showers. Lows 71 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70 in the valleys to around 62 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 76 to 84 in the valleys to around 69 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 67 to 72 in the valleys to around 62 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Partly cloudy with scattered showers. Lows 66 to 76. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 73 to 89. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 66 to 76. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 68 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 87. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 67 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will remain moderate to breezy through the weekend before potentially weakening by the middle of nextweek. Showers will remain limited under relatively dry conditions before slightly increasing by this weekend.

Discussion

Current satellite and radar imagery shows limited shower activity and drier conditions prevail statewide. Windward and mauka areas as well as Kona slopes of Big Island continue to be the primary areas of cloud cover and occasional light showers. Drier air is allowing dewpoints to sit between mid 60s to lower 70s, allowing some relief from previous muggy weather.
A stagnant and strong high pressure system far north of the state will continue to drive moderate to breezy trade winds through the weekend. Winds could potentially weaken by the middle of next week due to a weak surface trough that approaches the state from the east. A trade wind inversion resides between 5,500 and 6,500, but is expected to lift slightly by this weekend, and is expected to modestly increase showers. By the middle of next week, global models depict a weak low level trough moving through from the east. Details regarding timing have been inconsistent between the models, so for now we can expect a slight enhancement of windward and mountain showers.
NHC continues to monitor several disturbances in the eastern and central Pacific that have potential to develop in the next several days to a week. These potential systems play a role in the long range forecast, but it is too early to know if the state will be impacted. We will continue to monitor the tropics, especially the area between 130W and 140W.

Aviation

Moderate trades expected through the period. Low cigs locally below 2000 ft MSL in SHRA over windward and mauka slopes, best chance through tonight. MVFR conds in heavier SHRA, otherwise VFR prevails.
AIRMET Tango is in effect for mod low-level turb lee of terrain and may be needed for a few days.

Marine

Moderate to locally strong trades will persist as a broad high pressure remains far north of the state. A Small Craft Advisory for the typically windier waters around Maui County and the Big Island has been extended through Thursday.
A small, long period south swell will continue to fill in overnight and peak Thursday afternoon into Friday. This swell could push surf towards advisory thresholds before slowly fading over the weekend.
Surf along east facing shores will remain rough and choppy due to persistent trade wind swell. A small, medium period east swell from Tropical Storm Iselle may fill in Friday, peak Saturday before slowly fading into early next week.
Surf along north facing shores will remain tiny to flat.

Fire weather

A dry airmass has settled in today, which has dropped humidities to the upper 40s to low 50s across leeward areas. Fire weather concerns will remain at moderate levels through the weekend. A slight increase in moisture this weekend could marginally improve conditions.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov