West Kaua’i

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 71 near the shore to around 61 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday: Sunny and breezy. Highs 83 to 89 near the shore to around 75 above 3000 feet. East winds up to 20 mph.

Friday Night: Mostly clear. Breezy. Lows around 71 near the shore to around 60 above 3000 feet. East winds up to 20 mph.

South Kaua’i

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 70 to 75. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 77 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Breezy. Isolated showers after midnight. Lows 69 to 74. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 68 in the valleys to around 57 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Friday: Mostly sunny with isolated showers. Highs 73 to 79 in the valleys to around 66 above 4000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Friday Night: Breezy. Partly cloudy with isolated showers. Lows around 65 in the valleys to around 56 above 4000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 61 to 73. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers. Highs 69 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Isolated showers after midnight. Lows 61 to 73. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 65 to 75. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 76 to 83. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 64 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trades deliver showers windward and mauka through the forecast period.

Discussion

Batch of moisture advancing through the island chain today has rather efficiently produced numerous showers windward and mauka, even during the unfavorable peak heating period and beneath building subsidence associated with 500mb height rises to 590+dm. Breezy trades will deliver some of the taller showers to leeward zones through late afternoon. Satellite trends suggest this activity will shift west of the area by late this evening. Very little change going forward as a seasonally stable and benign trade wind pattern persists well into next week.

Aviation

Moderate to breezy trade winds with embedded showers are expected through tomorrow. Showers are primarily affecting windward and mountain areas, but are capable of spilling over into leeward areas as well. Expect MVFR to isolated and brief IFR conditions within showers, and VFR elsewhere.
AIRMET Tango is in effect for moderate turbulence below 8kft for areas downwind of terrain due to breezy trade winds. Expect this to remain for the next couple of days, as the breezy trade winds remain steady.
AIRMET Sierra is in effect for mountain obscurations across windward and mountain areas from Kauai through Maui. Expect these conditions to generally prevail through tomorrow due to upstream and ongoing showers.

Marine

Fresh to strong easterly trades will prevail as high pressure remains anchored far northeast of the islands through the weekend. A Small Craft Advisory (SCA) for the typically windier channels and waters around Maui County and the Big Island remains in effect through Saturday and will likely be extended through at least Monday. Trades may ease slightly Tuesday as high pressure shifts away to the northeast.
A moderate to large south-southwest swell will maintain surf above the High Surf Advisory (HSA) threshold along south-facing shores through this evening before continuing to gradually decline, allowing surf heights to drop below HSA thresholds late tonight. Nearshore buoys continue to observe this swell around 4 to 5 feet, 15 seconds, and offshore buoy 51002 hasn't dropped much through the day, maintaining swell around 3 feet, 15 seconds. With these swells being held through the afternoon and surf cams still showing surf heights around 10 feet at the standout spots, decided to extend the HSA through midnight tonight. Overnight, surf is expected to fall to moderate levels and will continue to gradually fade through Sunday. A small long-period south-southwest swell is expected to arrive late Sunday and peak early next week.
Along north-facing shores, a small medium-period north swell will build tonight and is forecast to peak early Friday, then ease over the weekend. A tiny west-northwest swell is possible early next week. Surf along east-facing shores will gradually build to around seasonal average by Friday, though some areas exposed to wrapping north swell could be slightly larger Thursday night and Friday. Near average east shore surf will prevail this weekend into early next week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 12 AM HST tonight for south facing shores of all Hawaiian islands.
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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Data Courtesy of NOAA.gov