West Kaua’i

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 69 to 74 near the shore to around 62 above 3000 feet. East winds up to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 85 to 90 near the shore to around 77 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 69 to 74 near the shore to around 61 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 70 to 75. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 88. Northeast winds 15 to 20 mph. Chance of rain 40 percent.

Tuesday Night: Breezy. Mostly cloudy with scattered showers. Lows 70 to 75. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows 64 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs 73 to 84 in the valleys to around 66 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 74. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 87. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 40 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 76. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 73 to 85. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 63 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy to windy trades will persist through tomorrow, with the strongest winds focused across Maui County and the Big Island. Dry weather conditions will combine with these strong gusty winds to produce elevated fire danger across the state through tomorrow. Winds will ease starting Wednesday, with a ridge aloft confining brief passing showers to mainly windward and mountain areas.

Discussion

Strong high pressure to the north of the state will maintain a tight pressure gradient across the island chain and help drive breezy to windy trades through tomorrow. At the same time, a mid level ridge will remain situated over the state, maintaining stable conditions with temperature inversions lowering through tomorrow, which may help to enhance downsloping winds across lower elevation leeward communities. As such, a Wind Advisory remains in effect for the typical windier portions of Maui County and the Big Island through 6 PM HST tomorrow. The summits of Mauna Kea and Mauna Loa have also been included in the Wind Advisory as a mid level easterly jet streak moves overhead this evening through tomorrow. This afternoon's radar and satellite imagery show clouds and showers moving into windward and mauka areas on the trades. Upstream moisture suggests that clouds and showers will focus over the eastern end of the state, with some drier air expected to filter over across the smaller islands tonight into tomorrow, helping to limit shower coverage across these areas.
The pattern will begin to change on Wednesday as the center of the strong surface high to the north of the state lifts to the northeast. This will help to ease the local pressure gradient, and combined with the weakening of the mid level ridge and lifting of the inversion, the trades are expected to weaken slightly through the rest of the week. Pockets of moisture will filter in on the trades, bringing periodic upticks in windward and mauka shower coverage.

Aviation

Strong stability favors VFR with scattered showers and the occasional MVFR condition windward and mauka. Strong trades continue through Tuesday.
AIRMET Tango for lee turb remains in effect.

Marine

High pressure will remain nearly stationary far north of the islands through Tuesday, which will support continued fresh to strong trades across the area. As a result, a Small Craft Advisory remains in effect for all Hawaiian coastal waters through 6 PM HST Tuesday. The surface high will move eastward and weaken slightly during the second half of the week, but winds are likely to remain breezy to locally strong in the windier channels and waters of Maui County and the Big Island. Therefore, the SCA will likely need to be extended for these areas. Additionally, seas may also approach 10 feet at times in the Alenuihaha Channel over the next couple of days.
South shore surf is expected to slowly decline as the current small south swell fades through early Tuesday. The next small, long-period south swell is expected to arrive Tuesday evening and peak on Wednesday. This swell may boost south-facing shore surf heights slightly from Tuesday night through Wednesday before gradually easing again through Friday. Guidance shows that another, smaller long-period reinforcement could arrive Friday night into the first half of the weekend.
Surf along east-facing shores will be rough and choppy for the next couple of days in response to the gusty easterly trade winds. As the trades ease a bit during the latter portion of the week, surf along east-facing shores will also trend down.

Fire weather

Breezy to windy trade winds with stable and relatively dry conditions will persist through tomorrow. Minimum relative humidity at lower leeward elevations will likely fall to around 45 percent each afternoon, and with the inversion dropping to as low as 5,000 feet, winds will become gusty over and downwind of island mountains. This will result in near critical fire weather conditions over dry leeward areas at times, though no headlines (watches or warnings) are due since the Keetch Byram Drought Index will remain below the 600 threshold at Honolulu.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST Tuesday for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Summits, Molokai, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST Tuesday for all Hawaiian waters,

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