West Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Lows 69 to 74 near the shore to around 61 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 84 to 91 near the shore to around 76 above 3000 feet. East winds up to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Saturday Night: Mostly clear. Lows 69 to 74 near the shore to around 61 above 3000 feet. Northeast winds up to 10 mph.

South Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Saturday: Mostly sunny. Isolated showers in the morning. Highs 82 to 89. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows around 67 in the valleys to around 58 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 84 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 64 to 69 in the valleys to around 58 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 65 to 74. East winds up to 10 mph. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers. Highs 77 to 86. East winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 65 to 73. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 64 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers. Highs 74 to 87. Northeast winds around 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 64 to 77. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trades will ease to gentle to moderate strength into the weekend in response to an approaching weak surface trough from the east, An increase in mainly windward and mauka rainfall is possible along this dissipating feature late Saturday into Monday. Trades will strengthen again around Tuesday or Wednesday.

Discussion

Trades will ease to gentle to moderate strength into the weekend in response to an approaching weak surface trough from the east. While this trough is progged to dissipate upon reaching the islands, the associated moisture escorted by the trough may be just enough to increase humidity levels and prompt a greater chance for windward showers across Big Island and possibly Maui County during the latter half of the weekend, and then further north into Oahu and Kauai by early next week. Otherwise, shower activity will be limited and primarily across windward and mauka areas, with exception to the South Kona slopes during the afternoon periods.
Latest model guidance continues to depict trades strengthening back to moderate to locally breezy by Tuesday or Wednesday of next week, however, with uncertainty persisting with regards to tropical development south of Hawaii, confidence of the forecast remains low. That said, the likeliness of breezy trades within drier conditions is high.

Aviation

Moderate trades will ease slightly to gentle to moderate trades Saturday and Sunday. A relatively stable and dry pattern will hold through in Saturday. Expect predominately VFR conditions across the Hawaiian Islands, however, brief periods of isolated showers across windward and mountain areas remain possible. A weakening trough moving from east to west may possibly increase chance of low level clouds and precipitation and thus MVFR conditions first for the windward areas the Big Island Saturday afternoon then for the rest of the state by Saturday night into Sunday.
There currently are no AIRMETs in effect.

Marine

High pressure north of the area has weakened today allowing for moderate to locally fresh trades. The high will further weaken this weekend, easing wind speeds to gentle to fresh. Moderate to strong trades then return next week as high pressure restrengthens and a tropical disturbance tracks south of the state.
Small background S swell keeps surf from going flat along S shores through early next week. A storm force low E of New Zealand is producing seas up to 40 feet per JSON satellite observations indicating undersimulation of winds by the model guidance. Confidence is therefore increased that this low will generate a moderate long period S swell that approaches or exceeds the High Surf Advisory threshold during its peak.
Choppy surf along E facing shores will trend down into the weekend as winds ease locally and upstream. Flat to tiny surf expected along N facing shores through the forecast period.
Peak afternoon high tides combined with elevated water levels are running about half a foot higher than predicted. This trend will continue through this afternoon and could lead to minor flooding along the shoreline and in low lying coastal areas of Maui County and the Big Island. Water levels then lower for the weekend.

Fire weather

Dry and stable conditions will persist through Saturday, and locally breezy trade winds will ease slightly. A shallow area of moisture moving in from the east should bring an increase in humidity late Saturday into Monday, further decreasing fire weather concerns. Trade winds are expected to restrengthen Tuesday or Wednesday, with developing dry conditions reestablishing, may result in elevated fire weather concerns

HFO Watches/Warnings/Advisories

None.

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