West Kaua’i

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 67 to 72 near the shore to around 60 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 83 to 88 near the shore to around 72 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday Night: Mostly clear. Isolated showers after midnight. Lows 67 to 72 near the shore to around 59 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Breezy. Occasional showers. Lows around 69. Northeast winds 15 to 20 mph. Chance of rain near 100 percent.

Wednesday: Breezy. Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 86. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

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

Kaua’i Mountains

Tonight: Breezy. Occasional showers. Lows 63 to 68 in the valleys to around 57 above 4000 feet. East winds up to 20 mph. Chance of rain near 100 percent.

Wednesday: Breezy. Occasional showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 72 to 82 in the valleys to around 62 above 4000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Wednesday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 68 in the valleys to around 57 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Occasional showers. Lows 64 to 71. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain near 100 percent.

Wednesday: Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 75 to 84. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Wednesday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 63 to 70. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Occasional showers. Lows 64 to 73. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Wednesday: Breezy. Mostly cloudy with occasional showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 72 to 84. Northeast winds 10 to 20 mph. Chance of rain 90 percent.

Wednesday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 73. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will persist into early next week as high pressure holds far north of the state. Rainfall will be focused over windward slopes, though showers will be slightly enhanced and will periodically pass over leeward areas during the next several days.

Discussion

Robust surface high pressure centered far northwest of Hawaii continues to drive locally breezy and gusty trade winds. A mid- level ridge is maintaining modest stability with an inversion, while broad and weak upper-level cyclonic flow is producing slight instability aloft. Under these conditions, showers have been somewhat active, with many windward slopes measuring up to a half of an inch of rainfall during the past 24 hours. The breezy trades have been carrying some brief rainfall over leeward areas from Kauai to Maui, and spotty active showers have been falling over the heated South Kona slopes in the afternoon and evening hours.
Breezy and somewhat wet trade wind weather will continue through into Friday, and slightly unstable conditions will persist, enhancing pockets of moisture traveling along the trade wind flow. The next such area of enhanced moisture will move in tonight and produce a boost in rainfall, especially over windward areas from Kauai to Maui. Expect brief, passing showers over leeward areas, except for South Kona, where spotty and briefly heavy showers will develop each afternoon.
A decrease in showers is expected during the weekend as a ridge builds aloft and brings increased stability. Modest showers will likely become confined to windward slopes, and trade wind strength will chance little as surface high pressure passes north of the state.

Aviation

Moderate to locally breezy trades will continue through the next couple of days. Expect increasing shower trends tonight through Wednesday morning with more frequent periods of MVFR and brief IFR due to moderate to locally heavy shower activity.
AIRMET Tango remains in effect for moderate low-level turbulence over and immediately SW through NW of all island mountains due to the locally breezy trade winds. This AIRMET will likely continue for the next few days.
In addition, mountain obscuration across north through east sections of the islands could become an issue tonight into early Wednesday as showers increase.

Marine

Fresh to strong easterly trades will persist through the weekend as the surface ridge remains anchored north of the islands. A Small Craft Advisory will persist each day for the typical windier waters and channels around Maui County and the Big Island.
Surf along exposed north and west-facing shores will continue to increase this afternoon and evening to near-average levels as a medium-period northwest swell builds down the island chain. This swell will linger into the second half of the week, gradually shifting out of the north.
Surf along south-facing shores will remain below average through Thursday as a background south swell fades. A fresh long-period south-southwest swell is expected to arrive over the weekend, bringing an upward trend with above-average surf. Forerunners should begin filling in Friday, with the swell peaking Saturday through Sunday. If it comes in larger than expected, surf could approach advisory levels this weekend.
Surf along east-facing shores will remain rough and choppy, with heights hovering around average (5 ft) each day.

HFO Watches/Warnings/Advisories

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

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.