West Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Lows around 73 near the shore to around 63 above 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Sunny. Isolated showers in the afternoon. Highs 85 to 91 near the shore to around 77 above 3000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows around 73 near the shore to around 62 above 3000 feet. Light winds.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 71 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 79 to 90. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 70 to 76. Northeast winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 65 to 70 in the valleys to around 60 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Sunday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 69 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Sunday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 67 in the valleys to around 60 above 4000 feet. Northeast winds around 10 mph. Chance of rain 30 percent.

North Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Lows 63 to 75. Southeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Sunny. Highs 72 to 86. East winds up to 15 mph shifting to the northeast in the afternoon.

Sunday Night: Mostly clear. Isolated showers after midnight. Lows 63 to 74. East winds around 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 67 to 76. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 78 to 86. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 67 to 77. Northeast winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate east-southeasterly winds will persist this evening, then take on an east northeasterly component by Sunday. Despite the slight variation in wind direction, the light to moderate background flow will bring a combination of limited windward and mauka showers along with isolated sea breeze induced leeward and interior showers. Then easterly trade winds will strengthen to moderate to breezy levels by midweek with an uptick in windward and mauka showers expected.

Discussion

A low to the far north and its trailing series of interconnected fronts and troughs draped across the Central Pacific will continue to disrupt the local trade wind flow through Sunday. Light to moderate east-southeast winds will persist through this evening before the approach of the front/trough from the northwest causes the weak background flow to back out of the east-northeast on Sunday. Despite the slight variation in wind direction, this light to moderate background flow will bring a combination of windward and mauka showers along with isolated sea breeze-induced leeward and interior showers through the weekend. However, overall shower activity should remain limited as drier air filters in.
Heading into next week, the subtropical high to the far northeast will gradually regain control, allowing easterly trades to build to moderate to breezy speeds by Wednesday. A weak surface trough, currently seen on visible satellite imagery passing west of 143W near 20N, is projected to track across the island chain late Tuesday into Wednesday on the strengthening trade wind flow. At the same time, model guidance continues to show an upper-level low pinching off from a longwave trough to the far north. This upper low is expected to move toward the state from the northeast, passing westward just north of Kauai Wednesday night through Friday. The combination of low-level troughing, its associated moisture plume, and instability aloft from the upper low will bring an uptick in windward and mauka showers around midweek, as well as with any subsequent batches of moisture rolling through.

Aviation

A weak surface trough to our north will help keep wind speeds relatively light through Monday. In combination with a stable atmosphere, this will also limit showers and low clouds. Wind speeds will strengthen Tuesday. No AIRMETs are in effect.

Marine

Little change to the forecast this afternoon.
A ridge remains northeast of the islands, and a trough to the northwest. The trough is expected to move slowly to the east. This will maintain the light to moderate trade winds through the remainder of the weekend. As the trough moves east and dissipates on Monday, the trade winds will increase. The ridge will strengthen through the week, allowing trade winds to increase.
A small, medium-period south swell will continue to fade, with a new long-period south swell peaking overnight. The result surf along south and west-facing shores should begin to diminish Sunday. Additional medium to long period south and southeast swells are expected through the middle of next week, which will maintain surf heights near seasonal averages.
Tiny surf will prevail along north-facing shores through most of the coming week as limited short-period energy reaches the islands from the north and northwest. As the trade winds increase next week, expect the surf along east facing shores to trend upwards.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov