West Kaua’i

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 73 near the shore to around 61 above 3000 feet. Light winds. Chance of rain 70 percent.

Friday: Mostly sunny with isolated showers. Highs 85 to 91 near the shore to around 77 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Lows around 73 near the shore to around 62 above 3000 feet. Light winds.

South Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 73. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers. Highs 83 to 90. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows around 73. Northeast winds up to 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with numerous showers in the evening, then partly cloudy with scattered showers after midnight. Lows 64 to 70 in the valleys to around 59 above 4000 feet. Light winds. Chance of rain 70 percent.

Friday: Mostly sunny with isolated showers. Highs 77 to 84 in the valleys to around 69 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 64 to 71 in the valleys to around 60 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 66 to 73. Light winds. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers. Highs 78 to 88. South winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy. Lows 65 to 74. Light winds.

East Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 65 to 77. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers. Highs 77 to 88. South winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 65 to 77. Light winds becoming north up to 10 mph after midnight. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A surface trough will bring showers to Kauai through tonight. Light wind flow will allow a land and sea breezes pattern to dominate with possible light trades building this weekend. Winds shift out of the east southeast next week with a wet and unstable pattern setting up over the islands by midweek.

Discussion

A low pressure system north of Hawaii will bring a period of relatively light wind flow across the state into next week. A trough axis originating from the low is located over Kauai this afternoon and characterized as a band of showery clouds that has been stationary across the Garden Isle today. The rest of the state is in diurnal land and sea breeze pattern bringing clear nights and mornings and cloudy afternoons and evenings across island interiors.
Through Friday, the land and sea breeze pattern will persist until the surface trough axis slides to the north. The low to the north is forecast to weaken by remain a disturbance in this area. This feature will continue to block much of the trade wind flow, but guidance suggest gentle to moderate trade wind nosing in south of this system at times this weekend.
An upper low will dig southward and position itself just west of the state by the middle of next week. The upper low will induce a surface trough that will veer and strengthen winds out of the east southeast beginning Monday night and continuing over the next several days after that putting Hawaii is a relatively unstable and wet weather pattern. East southeast winds will focus clouds and scattered showers over windward and southeastern sides of the islands.

Aviation

Weak south to southeast winds will continue through tonight and into Friday for the western half of the state while strengthening slightly for the eastern half of the state. Expect land breezes to develop across the state this evening. Seabreezes will likely develop over the western half of the state and more sheltered areas for the eastern half of the state late Friday morning and afternoon. Enhanced showers near PHLI will persist through tonight due to decaying moist axis drifting north across Kauai. Most sites will see VFR conditions, but MVFR and isolated IFR in showers is to be expected through tonight around Kauai.
AIRMET SIERRA is in effect for IFR conditions due to low visibility/ceilings in heavier showers for SE thru SW sections of Kauai, elsewhere AIRMET Sierra is in effect due to mtn obsc. These AIRMETs may likely be cancelled as the moist axis further decays and shifts north of Kauai later tonight.

Marine

A surface trough near Kauai and Oahu will continue to drift northwest slowly through the end of the week. Light to gentle southeast to south flow with localized land and sea breezes over nearshore waters will transition to gentle to locally fresh easterly trade winds Friday through the weekend. Early next week, a surface trough could develop north of the waters and may disrupt the trade winds for another round of light to gentle east southeast winds. These east southeast winds could potentially become stronger by the middle of next week. Long range guidance depicts strengthening high pressure far to the northeast moving south and creating a stronger pressure gradient against the new surface trough.
A mix of a small, medium period northwest swell and a small, short period north northeast swell will maintain small surf for north facing shores through Saturday. Another small medium period northwest swell will fill in late Saturday followed by a moderate to possibly large medium to long period northwest swell that is expected to fill in Sunday and peak on Monday near or above High Surf Advisory criteria. Recent model guidance has exhibited a low bias, compared with observed nearshore buoy readings running higher than forecast guidance. As a result, surf heights may come in larger then currently indicated by the model output.
Surf along south facing shores will remain small through the weekend with a series of small medium to long period south and southwest swells. East facing shores will remain tiny to small through Friday except for select shorelines exposed to the current small north northeast swell. A slight uptick is expected this weekend as easterly trade winds return. In addition, a small, medium to long period easterly swell from Tropical Cyclone Priscilla in the East Pacific is forecast to arrive late Saturday into Sunday.
Peak high tides associated with the lunar cycle will lead to minor coastal flooding along shorelines and low lying coastal areas through early next week. Coastal flooding will coincide with the daily peak tide each morning. A Coastal Flood Statement remains in effect for all coastal areas through Friday, but will likely need to be extended into early next week.

Fire weather

Weak winds and continued isolated to scattered showers will help mitigate fire weather concerns for the next several days. Inversion heights across the state will range from as low as 5,000 to as high as 9,000 feet.

HFO Watches/Warnings/Advisories

None.

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