West Kaua’i

Rest Of Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs 83 to 89 near the shore to around 75 above 3000 feet. East winds up to 15 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 61 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Rest Of Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 72. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs 77 to 87. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 69 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Rest Of Tonight: Mostly cloudy with numerous showers. Lows around 67 in the valleys to around 59 above 4000 feet. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 73 to 80 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows around 66 in the valleys to around 59 above 4000 feet. East winds up to 10 mph. Chance of rain 80 percent.

North Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 63 to 73. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 70 to 84. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 73. Southeast winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 66 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly cloudy with scattered showers. Highs 76 to 84. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 66 to 74. Northeast winds up to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trades will gradually weaken to moderate speeds Wednesday through the rest of the week, becoming relatively light this weekend. Isolated to scattered showers will continue to focus over windward and mauka areas through Wednesday. Thursday, lighter winds will support sea breezes each afternoon, increasing chances of clouds and showers over mauka and interior areas with land breezes clearing these clouds and decreasing chances of showers overnight and early morning.

Discussion

A high northeast of state will maintain breezy trades through Wednesday. A batch of low level clouds and showers will continue to generate isolated to scattered showers mainly along windward and mauka areas. Clouds and moderate showers have developed along the upslope of the kona coast of the Big Island this afternoon as seabreezes have kicked in. Expect clouds and showers to clear along shortly after sunset as land breezes develop along the kona slopes of the Big Island.
Near term model analysis shows the high northeast of the state gradually shifting further northeast tonight and Wednesday allowing winds to ease a notch compared to today. Continue to expect clouds and showers to focus mainly along the windward and mauka areas tonight and early Wednesday morning with drying trend starting Wednesday afternoon. This will be to a combination of weak lift from easing tradewinds and drier air filtering in from the east.
The high will begin to weaken Thursday through the weekend as a weak cold front approaches the state from the northwest. Breezy tradewinds will weaken to light to gentle speeds Friday and hold through the weekend in response to the lack of a pressure gradient across the state. The lighter winds will allow for seabreezes to develop each afternoon beginning Thursday that could slightly increase chances clouds and showers developing upslope of mountain terrain and over interior areas, however available moisture will be limited.
Late this weekend the surface high far northeast of the state will build back as the front dissipates to the north. Breezy northeast trades will gradually build back Sunday into early next week. A more typical breezy tradewind pattern will return next week as clouds and showers become more focused along windward and mauka areas.

Aviation

Breezy trades continue across the islands. Intermittent windward showers will make for brief periods of MVFR conditions, otherwise widespread VFR is expected through the period. Trades are then expected to gradually weaken through the rest of the week.
AIRMET Sierra is in effect for windward Maui and the Big Island due to intermittent shower activity causing mountain obscuration. Maui is expected to improve this evening, while the Big Island may see marginal conditions through at least the overnight hours tonight.
AIRMET Tango is in effect for turbulence downwind of mountains due to breezy trade winds, however this may be cancelled within the next 24 hours as winds trend downward.

Marine

A high pressure far northeast of the islands will shift further northeast tonight and Wednesday before gradually weakening through the weekend as a weak front passes far north of the state. A Small Craft Advisory for windier waters around Maui County and the Big Island has been cancelled as winds have weakened just below advisory levels and the winds. Moderate to locally fresh trades will hold through Wednesday before easing to light to moderate category by Friday and may hold into the weekend.
A series of southern hemisphere swells will continue through the week with the largest south swell due to arrive this weekend. Currently, a small, long- period south swell is overlapping a fading medium- period swell and is producing inconsistent near seasonal average surf along south facing shores. These swells will slowly decline Wednesday into Thursday. A smaller pulse of south- southwest swells will fill in late Thursday into Friday keeping surf elevated along south facing shores.
Long period energy from a storm that formed just east of New Zealand Tuesday is now filling in at the American Samoa buoy at 20 seconds. This swell is expected to gradually fill in locally late Friday into Saturday. Wave models have this swell peaking Sunday into Monday that could produce High Surf Warning conditions. This swell will coincide with the peak monthly tides and will likely lead to significant wave runup and impacts to coastal infrastructure during the first half of next week.
A small west-northwest swell will hold into Wednesday and fade Thursday. East shore surf will slowly decline below seasonal average Wednesday through the rest of the week as tradewinds locally and upstream ease.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov