Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Highs around 89 near the shore to around 77 above 3000 feet. Northeast winds up to 10 mph shifting to the west in the afternoon.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 71 to 76 near the shore to around 62 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Thursday: Mostly sunny with isolated showers. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Isolated showers in the morning. Highs around 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 69 to 75. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 86. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy. Numerous showers in the evening, then frequent showers after midnight. Lows 62 to 67 in the valleys to around 57 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Thursday: Mostly cloudy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 75. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 70 percent.

Thursday: Mostly cloudy with scattered showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with isolated showers. Highs 79 to 87. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 76. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 70 percent.

Thursday: Cloudy with numerous showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 79 to 87. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Trade winds will ease briefly later today through Thursday, then return to breezy levels Friday through the weekend. Showers will favor windward and mauka locations, particularly during the overnight and early morning periods as areas of moisture move through.

Discussion

Short-term guidance remains in decent agreement, depicting a mostly dry trade wind pattern prevailing today as surface high pressure remains centered north of the area. A broad surface trough (remnants of former TC Emilia), located just under 700 miles east of Hilo this morning, will move through the area from east to west tonight through Thursday night, likely weakening the local trades to moderate levels. This broad surface trough, combined with a mid-level trough and an increase in low-level moisture, could lead to better shower coverage, primarily for windward and mauka locations.
Breezy trade wind conditions are expected to return Friday through the weekend as the aforementioned trough begins to track away from the state and the deep-layer ridge strengthens. A modest increase in low-level moisture, accompanying another low- to mid- level trough passing to the south, could translate to increasing shower coverage Sunday through Monday, most likely over the eastern end of the state.

Aviation

Surface high pressure north of the area will help generate moderate to locally breezy trade winds across the area through the forecast period. Expect showers to stick mainly to windward locations this morning with a few showers spilling over to the leeward side. Some of the more robust showers may bring brief periods of MVFR cigs and visibilities. VFR conditions expected elsewhere. Shower activity is forecast to diminish by late this morning into the afternoon, before returning again tonight.
No AIRMETs are currently in effect.

Marine

Moderate to locally strong trade winds will continue through the weekend, with a brief easing expected late today through Thursday. A Small Craft Advisory (SCA) is now in effect through 6 pm this evening, with winds expected to hold below advisory levels tonight and Thursday. Winds will likely return to SCA levels Thursday night through the weekend.
Several small long-period swells from the south and southeast will produce some small surf along south facing shores through the work week. A more significant south swell will arrive late Sunday and Sunday night, peak above the summertime average Monday, then slowly lower through the middle of next week.
Seasonally flat to tiny surf is expected through early next week for north facing shores. Little change in east shore surf is expected during the next 7 days, with surf remaining near or slightly below normal levels.
The combination of the full moon and water levels running around 0.5 ft higher than normal should produce minor coastal flooding each afternoon along the shorelines across the state beginning 8/17 and likely continuing through 8/20. A Coastal Flood Statement will eventually be needed as we get closer to the event.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov