West Kaua’i

Tonight: Partly cloudy with isolated showers. Haze. Lows around 69 near the shore to around 59 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs around 84 near the shore to around 74 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows around 69 near the shore to around 59 above 3000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

South Kaua’i

Tonight: Partly cloudy. Haze. Lows around 69. Light winds becoming northeast around 10 mph after midnight.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs 79 to 86. Northeast winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Haze after midnight. Lows around 70. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy with isolated showers. Haze. Lows 61 to 67 in the valleys to around 56 above 4000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 74 to 81 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 61 to 67 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 62 to 70. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 76 to 84. South winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 63 to 70. South winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Haze. Lows 61 to 73. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs 73 to 84. South winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 62 to 73. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light southeast flow will continue through the weekend due to a ridge near Kauai and fronts weakening to the west. Stable air and relatively low inversion heights will help keep the state fairly dry through the weekend with daytime sea breezes and nighttime land breezes. A front will approach the area in the middle of next week, potentially bringing an increase in rainfall and humidity.

Discussion

A surface ridge is located near Kauai this afternoon with light southeast flow across the state. Soundings from 00Z show a 7000 foot inversion at Hilo and a very weak 5000 foot inversion at Lihue with a precipitable water value of 0.83 inches. Visible satellite and radar show dry conditions with some interior clouds across each island. Land breezes will dissipate the cloud cover tonight.
Southeast winds will strengthen a little bit Friday across the eastern half of the state, but overall dry pattern with interior cloud build ups in the afternoon and clear nights will be the story through the weekend as a front approaches, stalls and dissipates before reaching the islands. Daytime highs will be in the low to mid 80s, but feel a bit warmer with the light winds, while vog will continue to track up over the smaller islands at times due to the southeast flow.
Another front will approach from the west Monday and Tuesday and stall over or just to the west of Kauai on Wednesday, with the ECMWF bringing the front a bit further east than the GFS. Light southeast flow will continue, but will begin to draw in a bit more moisture and humidity over the state during the first half of next week. Overall looks like a little bit wetter next week, but with the long range models out of sync on the front, impacts a bit more uncertain.

Aviation

Light east-southwest winds remain in place over the state today, which has allowed for daytime sea breezes and some clouds developing over interior and leeward areas. However, stable conditions have limited shower development. Interior clouds will begin to dissipate after sunset as land breezes resume overnight. Light to moderate southeast background flow will continue into Friday, with daytime sea breezes once again developing over the islands. VFR flight conditions are expected to prevail over most locations into the weekend.
There are no AIRMETs in effect, and none are anticipated at this time.

Marine

Weak surface high pressure located northeast of the state will hold light to low end moderate east to southeast breezes through Friday. A cold front associated with a large hurricane force low moving across the Central Pacific will approach the far western islands early next week. Primarily gentle to moderate easterly winds will veer more southerly ahead of this slowing front that will eventually stall just west of Kauai Tuesday. The front may pass across Niihau and Kauai during the middle of next week. If this does occur, expect moderate to locally fresh northerly winds in the wake of the front. A very large northwest swell will pass around the islands from Saturday through Monday. This will increase seas to Small Craft Advisory heights (10 feet or higher) early next week.
A moderate size, long period northwest swell that peaked this morning has lifted surf to High Surf Advisory (HSA) heights along the north and west-facing shores of Niihau, Kauai, Oahu and Molokai and the north-facing shores of Maui. A quick hitting reinforcing northwest swell will arrive early Friday morning that will help maintain HSA level surf through Friday morning. North and west-facing shore surf should significantly drop Friday afternoon and evening.
The hurricane force Central Pacific low currently located 1,400 nm northwest of Kauai is generating a large fetch of seas. This fetch is being aimed straight down the northwest great circle route toward the islands. The resultant very large northwest swell will produce XL size surf along north and west-facing small island shores Saturday night through Monday morning. Long period forerunners will begin arriving Saturday afternoon, then surf will quickly ramp up Saturday evening. The peak of this event is forecast to be from late Saturday night through Sunday morning. There is a high potential for giant size surf (40 to 50 feet) along the north-facing shores of the smaller islands Saturday night into Sunday. A High Surf Warning for these shores will likely be in effect from Saturday night into Monday.
East-facing chop will remain small through the weekend due to weak winds. Select south-facing shores will likely experience westerly wrap from this weekend's large northwest swell passage.

Fire weather

Even though we will see relative humidity levels fall heading into the weekend, weak winds will preclude reaching critical fire weather conditions for the next few days. Temperature inversion heights near Big Island and Maui will range between 5000 to 7000 feet.

HFO Watches/Warnings/Advisories

High Surf Advisory until noon HST Friday for north and west facing shores of Niihau, Kauai, Oahu, Molokai, and north facing shores of Maui.

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