West Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Lows around 74 near the shore to around 64 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Sunny. Highs 84 to 91 near the shore to around 77 above 3000 feet. East winds up to 10 mph.

Wednesday Night: Mostly clear. Lows around 74 near the shore to around 64 above 3000 feet. Northeast winds 10 to 15 mph decreasing to up to 15 mph after midnight.

South Kaua’i

Tonight: Partly cloudy. Isolated showers after midnight. Lows 69 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday: Sunny. Highs 79 to 90. Northeast winds 10 to 15 mph.

Wednesday Night: Partly cloudy. Isolated showers after midnight. Lows 70 to 77. Northeast winds around 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy with isolated showers. Lows around 68 in the valleys to around 61 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Sunny with isolated showers. Highs 77 to 83 in the valleys to around 70 above 4000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday Night: Breezy. Mostly clear in the evening, then mostly cloudy with scattered showers after midnight. Lows around 69 in the valleys to around 62 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

North Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 75. East winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Sunny. Highs 73 to 87. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Wednesday Night: Partly cloudy. Isolated showers after midnight. Lows 65 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 66 to 76. East winds around 10 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the morning. Highs 79 to 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Isolated showers after midnight. Lows 66 to 77. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trades will gradually build breezy levels tonight through Thursday as weak troughing around the state dissipates and a new surface high develops north of the state. Expect limited clouds and showers to focus along windward and mauka areas, particularly overnight and early morning hours. Slightly wetter tradewind showers will be possible late Friday into the weekend. A drier tradewind pattern may develop early next week.

Discussion

Limited clouds and showers can be seen mainly along windward and mauka areas, except for the Big Island where light to moderate showers are developing along the kona slopes. Starting tonight, upper level trough will have moved east of the state, while mid level ridging continues to limit clouds and showers to windward and mauka locations, especially overnight and early morning Wednesday. Rainfall totals are expected to be less than what was observed overnight Monday into Tuesday morning.
A surface high will develop and shift northwest of the state Wednesday allowing tradewinds to gradually strengthen to more typically breezy levels throughout the day and Thursday as the high settles north of the state. During the this time mid and upper level ridging will maintain dry and stable tradewind pattern while passing bands of low level clouds and showers embedded within the tradewind flow focuses light showers along windward and mauka areas.
An upper level trough will approach the state Friday just as an area of enhanced low level moisture moves from east to west across the state Friday afternoon into Saturday, increasing chances of showers for windward and mauka slopes. Cooling temperatures in the mid levels could make for some brief isolated heavy showers. Although there will be some lingering instability over the state for the rest of the weekend, there could be an over all drying trend as low level moisture becomes limited into early next week.

Aviation

Moderate trades will persist through Wednesday with mostly VFR conditions expected across the state. Brief MVFR ceilings will be possible with any passing shower, but overall mostly dry conditions are expected through Wednesday afternoon.
No AIRMET's are in effect.

Marine

Troughs to the west and east, coupled with the high to the far northeast with an accompanying ridge north of the islands will maintain gentle to moderate trade winds through tomorrow. As the troughs weaken, the pressure gradient will tighten, and trades will strengthen to moderate to locally fresh Thursday. Winds may strengthen to Small Craft Advisory (SCA) levels as early as Wednesday night in some of the typical windier waters near Maui and the Big Island. Winds are then expected to remain at SCA levels through the weekend.
The current long period northwest swell will linger into tomorrow, holding surf near seasonal average for north and west facing shores, before declining Wednesday night through Friday. By late Friday, a medium period north- northwest swell will build and once again help bring surf to near seasonal averages through the weekend.
The current long period south-southwest swell will keep surf along south facing shores elevated through tomorrow. Another long period south swell will help produce surf near seasonal average Thursday into early this weekend.
Surf along east facing shores will remain small through Thursday as small wind waves and tiny east swell persist. Choppy surf will increase slightly as trade winds strengthen across the region Friday into the weekend.

Fire weather

Moderate trade winds will gradually strengthen to typical breezy levels by Thursday. Dry air will keep RH levels near- critical values each afternoon for parts of the state for the next several days. RH values will increase towards the end of the week before another drying trends begins over the weekend into early next week. Inversion heights tonight will range from 5,000 to 6,000 ft.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov