West Kaua’i

Tonight: Mostly cloudy with isolated showers. Haze. Lows 67 to 72 near the shore to around 60 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Saturday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 80 to 86 near the shore to around 73 above 3000 feet. Southeast winds up to 10 mph shifting to the south around 10 mph in the afternoon. Chance of rain 50 percent.

Saturday Night: Partly cloudy. Scattered showers early in the evening. Haze through the night. Lows 66 to 71 near the shore to around 58 above 3000 feet. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers. Haze. Lows around 69. Light winds. Chance of rain 30 percent.

Saturday: Partly sunny with scattered showers. Haze. Highs 80 to 86. East winds around 10 mph shifting to the south in the afternoon. Chance of rain 40 percent.

Saturday Night: Partly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Haze through the night. Lows around 69. West winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Haze through the night. Lows 60 to 68 in the valleys to around 57 above 4000 feet. South winds up to 10 mph. Chance of rain 40 percent.

Saturday: Mostly cloudy. Isolated showers in the morning, then numerous showers in the afternoon. Haze through the day. Highs 74 to 80 in the valleys to around 65 above 4000 feet. Southeast winds up to 10 mph shifting to the south in the afternoon. Chance of rain 60 percent.

Saturday Night: Mostly cloudy with numerous showers early in the evening, then mostly cloudy in the late evening and overnight. Haze through the night. Lows 60 to 68 in the valleys to around 57 above 4000 feet. West winds up to 10 mph in the evening becoming light. Chance of rain 60 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Haze through the night. Lows 63 to 70. East winds up to 15 mph in the evening becoming light. Chance of rain 40 percent.

Saturday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 75 to 83. Southeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers early in the evening, then partly cloudy in the late evening and overnight. Haze through the night. Lows 62 to 69. West winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Haze. Lows 63 to 73. South winds up to 10 mph. Chance of rain 40 percent.

Saturday: Mostly cloudy with scattered showers. Haze. Highs 73 to 85. Light winds becoming southeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Saturday Night: Partly cloudy. Scattered showers early in the evening. Haze through the night. Lows 63 to 73. North winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Winds will weaken this weekend with land and sea breezes becoming dominant. A disturbance aloft could bring some unsettled weather and locally heavy rainfall to the islands early next week. A return to more typical trade wind weather featuring mainly windward and mauka showers may return during the latter part of next week.

Discussion

A 1012 mb surface low is centered 850 miles northwest of Kauai, while a 1029 mb high is centered around 1500 miles north northeast of Honolulu. Between these two features lies a band of thunderstorms along a trough of low pressure stemming from the low, which passes around 150 miles northwest of Kauai. Visible satellite shows thin cirrus clouds tracking across the main Hawaiian Islands. At the low levels, moderate southeast flow across the state are pushing a few clouds with isolated showers onto windward and southeast slopes, but overall mostly dry conditions expected through night. A slight chance of thunderstorms possible tonight for waters north and west of Kauai along the eastern fringes of the trough, but stability is expected to increase this weekend.
The surface low will shift eastward this weekend, then dampen into a trough over the islands early next week. This will ease the east-southeast flow allowing for daytime sea breezes and nighttime land breezes to become dominant across the state this weekend through the middle of next week. Low clouds and showers will favor leeward and interior sections in the afternoon and evening hours, and east and southeast facing slopes and coasts overnight and during the morning hours, with most showers over the coastal waters or near the immediate coast overnight. A disturbance aloft diving southward over the state could bring locally heavy rainfall to portions of the island chain Tuesday into Wednesday.
The trough will then fizzle out with a gradual return and strengthening of the trade winds across the state for the second half of next week featuring mainly windward and mauka showers.

Aviation

Light winds with a background southeasterly flow will continue to persist through Saturday. Winds will be light enough for localized land breezes to develop tonight and sea breezes during the day Saturday. Clouds and scattered showers may produce brief MVFR conditions tonight. A strong upper level jet passing just south of the state will produce a stream of high clouds and moderate upper level turbulence across the entire state through tonight and possibly into Saturday. AIRMET TANGO is in effect for moderate turbulence between FL280 and FL400.

Marine

Locally fresh southeast winds will gradually ease and become light and variable over the weekend as low pressure northwest of the Islands slowly weakens and shifts northward. Light flow will continue into Monday and Tuesday. Trade winds will eventually return midweek. A slight chance of thunderstorms remains northwest of Kauai through late tonight.
Existing small northwest swell will continue to fade, but a new slightly larger long-period northwest swell is forecast to build in overnight, peak Saturday night or Sunday, then fade through early next week. Surf along north and west facing shores is expected to remain small for the coming week.
Multiple small early season south swells will maintain small background southerly energy into the coming week. Weak upstream trade wind flow will keep surf along east facing shores near or below seasonal averages.

HFO Watches/Warnings/Advisories

None.

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