West Kaua’i

Rest Of Tonight: Partly cloudy. Lows around 70 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 89 near the shore to around 75 above 3000 feet. Northeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Lows around 70 near the shore to around 60 above 3000 feet. Light winds.

South Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers. Lows 68 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 76 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 68 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Rest Of Tonight: Mostly cloudy with scattered showers. Lows around 65 in the valleys to around 58 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny with scattered showers. Highs 74 to 80 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 65 in the valleys to around 58 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

North Kaua’i

Rest Of Tonight: Partly cloudy. Scattered showers early in the evening, then isolated showers after midnight. Lows 62 to 72. East winds up to 10 mph. Chance of rain 40 percent.

Saturday: Mostly sunny with isolated showers. Highs 70 to 83. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Lows 62 to 72. East winds up to 10 mph in the evening becoming light.

East Kaua’i

Rest Of Tonight: Mostly cloudy with scattered showers. Lows 65 to 73. Northeast winds around 10 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 84. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Saturday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 65 to 73. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trades will gradually weaken through the weekend as a low pressure system developing to the far north weakens the surface ridge over the islands. Clouds and showers will favor windward and mauka areas the rest of today, and to a lesser extent Saturday, before the focus shifts to sea breezes Sunday. Early next week, increasing moisture will move up the island chain from the southeast, increasing rain chances for the state Monday through Wednesday. Moderate to locally breezy trades are expected to return late Wednesday and stay with us through next weekend.

Discussion

Radar and satellite show isolated showers mainly windward and mauka this afternoon with mostly sunny skies elsewhere. Trade winds continue, averaging 10 to 15 mph with gusts 15 to 25 mph.
A surface high pressure centered north of the islands will weaken through Sunday and remain fairly weak into Monday. Trade winds will hold through tomorrow, then weaken significantly Sunday. this will allow sea-breezes to develop Sunday, bringing an above-normal amount of cloud cover and showers to leeward areas. Windward areas will still see their typical amount of summer showers.
An enhanced area of moisture will move northwest over the state Monday through Wednesday. This should bring additional showers as the surface ridge to the north strengthens. Trade winds will return Wednesday as the moisture is pushed west of the area.
The remainder of next week should see a return to typical trade winds with showers and clouds once again mainly over windward and mauka areas.

Aviation

Trade wind pattern continues with isolated showers in windward areas. Localized MVFR windward and mauka, but improving conditions during the day. VFR will prevail.
AIRMET Sierra may be needed tonight for mountain obscuration as low clouds again develop in windward locations.
And AIRMET Tango is in effect for moderate turbulence downwind of mountain areas which will continue today.

Marine

Developing low pressure centered over the Aleutian Islands today will drop south this weekend, eroding a broad ridge to the north of the Hawaiian Islands this weekend. This will translate to local trade winds easing into the light to moderate range, likely giving way to localized land and sea breezes near the coasts late this weekend through early next week. A return of moderate to fresh easterly trades is likely by midweek as the ridge strengthens.
An active pattern is in store for surf along south-facing shores as we head into June due to a series of recent gale- to storm- force lows passing through our swell window near New Zealand over the past week. Surf will continue to build tonight as a long- period south-southwest swell arrives and a medium-period south swell continues to fade out. A High Surf Advisory (HSA) has been issued for south-facing shores as the building swell brings surf heights to reach advisory level tonight. The swell becomes fully established by Saturday and surf heights are expected to hover near the advisory level through the weekend, keeping the HSA in effect through Sunday afternoon. As the swell gradually begins to ease early next week, long- period forerunners from the next south- southwest swell are expected to arrive. Heights may briefly dip below the advisory level on Monday, but as the next swell fills in, surf will likely return to the advisory level Tuesday through midweek as it peaks. A gradual downward trend is then expected through the second half of next week.
A combination of advisory-level surf this weekend and water levels hovering above predicted levels could lead to some wave runup issues, with water sweeping across areas of beaches that typically remain dry. Water levels will steadily lower each day early next week as the next large south swell arrives.
The current small northwest swell will slowly lower through Saturday before fading on Sunday. A small north swell will likely produce surf near seasonal averages along north-facing shores from late Tuesday or Wednesday into Thursday.
Expect surf along east-facing shores to remain near seasonal averages tonight, then gradually decline through early next week as trade winds ease. A slight increase is possible Tuesday and Wednesday due to a combination of rebuilding trade winds and a wrapping north swell.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Sunday for Big Island South, Big Island Southeast, East Honolulu, Ewa Plain, Honolulu Metro, Kahoolawe, Kauai South, Kauai Southwest, Kona, Lanai Leeward, Lanai South, Maui Central Valley South, Maui Leeward West, Molokai Leeward South, Niihau, South Haleakala, South Maui/Upcountry, Waianae Coast.

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Data Courtesy of NOAA.gov