West Kaua’i

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 74 near the shore to around 62 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers. Highs 84 to 90 near the shore to around 76 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy. Isolated showers in the evening. Lows around 71 near the shore to around 61 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows around 72. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs 79 to 87. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Breezy. Mostly cloudy with scattered showers. Lows around 72. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with showers likely. Lows 64 to 70 in the valleys to around 59 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tuesday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 73 to 83 in the valleys to around 65 above 4000 feet. Northeast winds around 15 mph. Chance of rain 70 percent.

Tuesday Night: Breezy. Mostly cloudy with scattered showers. Lows 63 to 69 in the valleys to around 59 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Mostly cloudy with showers likely. Lows 65 to 73. East winds up to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with scattered showers. Highs 75 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 65 to 73. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 76. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 73 to 85. Northeast winds around 15 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 64 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Strong trade winds will gradually weaken over the next several days, with moderate trades expected by the middle of the week. Passing showers will mainly impact windward and mauka areas with light rainfall amounts.

Discussion

High pressure far northeast of the state will maintain breezy to locally strong trade winds across the islands. Radar and satellite imagery show clouds and passing showers embedded in the trade wind flow impacting mainly windward and mauka areas. The one exception is the Kona Slopes of the Big Island where sea breezy clouds and showers have developed. Expect these showers to continue through this evening then wane overnight as the land breeze develops.
Trades will gradually weaken over the next day or two. A weak upper level trough will pass near the state tonight into Tuesday which could enhance the trade wind showers, particularly near Kauai where some weak instability could allow for periods of moderate rain. Elsewhere, shower activity is not expected to be as frequent with passing showers expected across windward and mauka areas.
Medium range guidance now shows the upper level trough lingering north of the state through the end of the week and into the upcoming weekend as upper level ridging develops to the east. Lingering instability could help to enhance showers at times across the islands, but no significant impacts are expected at this time. Otherwise, expect moderate to locally breezy trades with passing windward and mauka showers.

Aviation

High pressure sitting to the far northeast will bring breezy trades to the main Hawaiian Islands through this evening, focusing clouds and showers over windward and mountain areas. Winds will drop down a notch tomorrow as the high weakens slightly to our northeast, but will still remain locally breezy.
AIRMET Tango is in effect for moderate turbulence below 8000 feet downwind of island terrain. This AIRMET will likely be needed through at least tomorrow with the breezy trades.
AIRMET Sierra is in effect for mountain obscuration for windward portions of the Big Island this afternoon and may be needed overnight.

Marine

High pressure far northeast of the islands will drive breezy to locally strong trade winds through Tuesday before weakening during the remainder of the week. The Small Craft Advisory (SCA) is in effect for the windier waters and channels around Maui County and the Big Island through the day Tuesday. Winds are expected to drop below SCA thresholds by Tuesday night or on Wednesday.
Surf along south shores are showing a modest increase this afternoon as a new long-period south swell continues to gradually fill in. Offshore buoys continue to show a gradual increase and we should see this moderate, long-period south swell peak Tuesday into Tuesday night then gradually decrease through the rest of the week. This swell is expected to peak just below High Surf Advisory criteria on Tuesday.
Surf along east facing shores will remain rough and choppy through the week with a gradual decline expected as the trades weaken throughout the week. Surf along north facing shores will remain tiny with mainly background energy through the forecast period.
Peak high tides associated with the lunar cycle will lead to minor coastal flooding along shorelines and low lying coastal areas through Thursday. A Coastal Flood Statement has been issued for the daily peak tide each afternoon and may be exacerbated by the ongoing south swell as it peaks on Tuesday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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