West Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 70 near the shore to around 60 above 3000 feet. Light winds becoming northeast up to 10 mph after midnight. Chance of rain 40 percent.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 82 to 88 near the shore to around 74 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Thursday Night: Mostly clear. Lows 68 to 73 near the shore to around 61 above 3000 feet. East winds up to 15 mph.

South Kaua’i

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70. Northeast winds up to 10 mph increasing to 10 to 15 mph after midnight. Chance of rain 40 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 87. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

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

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows 61 to 69 in the valleys to around 58 above 4000 feet. Light winds becoming east up to 10 mph after midnight. Chance of rain 50 percent.

Thursday: Partly sunny with isolated showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 74 to 80 in the valleys to around 65 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy with scattered showers. Lows 61 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 63 to 71. Southeast winds up to 10 mph. Chance of rain 40 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs 75 to 85. East winds up to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy. Isolated showers in the evening. Lows 64 to 71. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 64 to 74. Northeast winds up to 10 mph. Chance of rain 40 percent.

Thursday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 73 to 84. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Trade winds have developed across the state this afternoon, but remain light enough for some sea breeze clouds and showers over leeward and sheltered areas. Trade winds will strengthen to moderate to locally breezy by Friday and continue into early next week, with clouds and showers favoring windward and mauka areas.

Discussion

Light trade winds have developed across the state this afternoon as a weak surface trough north of Kauai continues to dissipate and surface high pressure builds far northeast of the islands. Radar and satellite imagery shows scattered clouds and showers over leeward and sheltered areas due to weak sea breezes. Some of these showers have been pushed offshore by the developing trades and the lingering showers should dissipate later this evening. Trades will continue to gradually strengthen across the islands tonight, with stable conditions developing as a mid-level ridge builds overhead. Moderate to locally breezy trades are expected to return Friday then hold through early next week as a pair of strong high pressure systems move north of the state. With the return of stable trade wind conditions expect clouds and showers to favor windward and mauka areas, particularly during the overnight and early morning hours.
Also, as trades become reestablished across the state expect vog to slowly shift away from the smaller islands.

Aviation

Limited showers this afternoon as returning trades prevented the sea breeze from establishing. What few interior/leeward showers exist will dissipate with the loss of diurnal heating this afternoon. Locally breezy trade winds then prevail focusing clouds and showers windward and mauka. VFR anticipated with nothing more than spotty MVFR within any heavier showers.
No AIRMETs in effect.

Marine

High pressure will build far north of the state through Friday then gradually move eastward over the weekend. Trade winds should steadily strengthen on Thursday with fresh to locally strong trades expected by Thursday afternoon for the typical windy areas around Maui County and the Big Island. Trade winds will likely strengthen a touch on Friday with widespread fresh to locally strong trade winds through the weekend. Small Craft Advisory (SCA) should return to the typical windy areas around Maui County and the Big Island on Thursday.
Starting tonight, a moderate to long period north-northwest swell is expected to arrive, producing surf above the seasonal average. Buoy 51001 northwest of Kauai is starting to show long-period forerunners this afternoon. This north- northwest swell should peak late Thursday then slowly decline over the weekend. A series of northwest to north swells are expected next week which should produce surf near or above the seasonal average (6 feet for the month of May).
A new long-period south-southwest swell will continue to fill in tonight and peak Thursday into Friday with surf heights above the summer average then slowly fade into the weekend. However, a mix of reinforcing south- southwest swell and new south-southeast swell energy will arrive this weekend and should help maintain surf near or above the summer average (5 feet). Surf will generally decline next week, but smaller swells from the south- southwest should maintain surf near the summer average through the middle of next week.
Weak upstream trade wind flow will keep surf on the small side for east facing shores. An increase is expected on Friday as the trade winds strengthen a notch. Rough and choppy surf is expected along east facing shores Friday through the weekend.

HFO Watches/Warnings/Advisories

None.

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