Hilo

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 66 to 72 near the shore to 53 to 59 at 4000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 87 near the shore to 68 to 73 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to 52 to 59 at 4000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Partly sunny. Isolated showers in the afternoon. Highs 84 to 89 near the shore to around 69 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 74 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy. Scattered showers in the evening. Lows 65 to 73 near the shore to 57 to 64 near 3000 feet. Light winds. Chance of rain 40 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 83 near the shore to 73 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with isolated showers. Lows 65 to 74 near the shore to 56 to 64 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy. Scattered showers in the evening. Lows 65 to 73 near the shore to 57 to 64 near 3000 feet. Light winds. Chance of rain 40 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 83 near the shore to 73 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with isolated showers. Lows 65 to 74 near the shore to 56 to 64 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 75 near the shore to around 56 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 75 near the shore to around 56 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 66 to 72 near the shore to 53 to 59 at 4000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 87 near the shore to 68 to 73 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy with scattered showers. Lows 66 to 72 near the shore to 52 to 59 at 4000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 75 near the shore to around 55 above 4000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to 66 to 74 above 4000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Lows around 75 near the shore to 52 to 57 above 4000 feet. Light winds.

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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Data Courtesy of NOAA.gov