West Kaua’i

Tonight: Mostly clear. Lows 71 to 76 near the shore to around 63 above 3000 feet. East winds up to 15 mph.

Thursday: Mostly sunny with isolated showers. Highs 87 to 93 near the shore to around 80 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy. Lows around 74 near the shore to around 63 above 3000 feet. East winds 10 to 15 mph shifting to the northeast after midnight.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows around 75. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 83 to 91. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday Night: Partly cloudy with isolated showers. Lows around 74. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 66 to 71 in the valleys to around 60 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 77 to 87 in the valleys to around 68 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 66 to 71 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 75. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 78 to 89. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday Night: Partly cloudy with scattered showers. Lows 66 to 75. East winds 10 to 15 mph. Chance of rain 30 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 67 to 78. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Highs 76 to 88. 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 78. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will persist through at least the weekend as high pressure holds north of the islands. Typical stable summertime conditions will bring periods of mainly windward and mauka showers, while most leeward areas remain rather dry.

Discussion

A locally breezy and stable trade wind flow continues. The trades are being driven by broad surface high pressure far north and northeast of the state, while a mid-level ridge is maintaining stable conditions with an inversion based between 5,000 and 7.000 ft. A shallow band of moisture traveling within the stable trade wind flow moved across all islands except Kauai today, dropping up to a quarter of an inch of rainfall along windward slopes as well as a few hundredths on the burn area of the Kunia Camp Fire. Another batch of shallow moisture will move onto windward Big Island and Maui overnight, then pass over the western half of the island chain on Thursday. We are not expecting significant windward rainfall, and with the exception of afternoon showers across the Kona Districts of the Big Island, leeward areas should remain rather dry. In addition, thin high clouds will linger overhead into tonight, adding some color to the sunset.
Little change to the typical mid August weather pattern is expected through the weekend, followed by a possible slight decline in winds late Sunday into Tuesday. A persistent mid-level ridge will maintain stability, and little organized moisture is seen in the guidance until Tuesday. As a result, expect limited windward rainfall, and with the exception of the Kona slopes of the Big Island, most leeward areas will remain rather dry.

Aviation

Moderate to locally breezy trades will persist through the next several days, focusing low clouds and showers over windward and mountain areas, particularly overnight into the morning hours. MVFR conditions will be possible in showers, otherwise VFR will likely prevail.
No AIRMETs are currently in effect.

Marine

High pressure will maintain fresh to locally strong trade winds across Hawaiian coastal waters throughout the next several days. Based on the latest guidance, the Small Craft Advisory (SCA) that is in effect for the windier waters and channels of Maui County and the Big Island has been extended in time through Saturday.
A series of small, medium period south (170-190 degree) swells is expected throughout the rest of this week, with surf near the summertime average through around Saturday along south-facing shores. The largest of these south swells looks to arrive Thursday into Friday. Surf heights should decrease Sunday into early next week as these swells fade. Another small, long period south swell could arrive by the middle of next week.
Choppy conditions will continue for east-facing shores through the forecast period due to the persistent fresh trades. Surf along north facing shores will remain nearly flat through the next week.
Peak high tides associated with the lunar cycle will lead to minor coastal flooding along shorelines and low lying coastal areas during the afternoon high tides through Thursday afternoon. A Coastal Flood Statement remains in effect for minor coastal flooding.

Fire weather

Trade winds will remain in the moderate to locally breezy range into Sunday while a ridge aloft maintains an inversion between 5,500 to 7,000 ft. Under this rather typical August weather pattern, afternoon relative humidity should remain near summertime average on Thursday. Slightly drier conditions are possible Friday into the weekend. As a result, near critical fire weather conditions are expected, though we do not anticipate fire weather headlines at this time.

HFO Watches/Warnings/Advisories

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

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