West Kaua’i

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 69 near the shore to around 58 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 83 to 88 near the shore to around 72 above 3000 feet. Light winds. Chance of rain 20 percent.

Tuesday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 69 near the shore to around 58 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

South Kaua’i

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

Tuesday: Sunny. Highs 80 to 87. Northeast winds 10 to 15 mph.

Tuesday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 68. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 63 to 68 in the valleys to around 56 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 82 in the valleys to around 64 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Tuesday Night: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 62 to 67 in the valleys to around 56 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 80 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 63 to 71. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 76 to 84. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 70. Southeast winds up to 10 mph. Chance of rain 70 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 63 to 73. North winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 74 to 85. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 73. Northeast winds up to 10 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Gentle to moderate trade winds will prevail through Thursday as a weak surface ridge sits about 300 miles north of Kauai. Modest showers will remain focused over most windward slopes, though an upper-level disturbance may produce more rainfall on Kauai late Tuesday and Wednesday. The disturbance will also generate areas of high clouds over mainly the southern end of the island chain. Trades will strengthen and become more stable Friday and Saturday.

Discussion

Trade winds have eased as a weakened subtropical ridge has been displaced to about 300 miles north of Kauai. A weak upper-level trough is centered just north of Kauai, sending thin high clouds over the Big Island, and a mid-level ridge is maintaining stable conditions with an inversion based between 5000 and 6500 feet. Moisture within the trade wind flow is unimpressive and has resulted in low rainfall totals along windward slopes, mainly confined to portions of Big Island and Kauai where small pockets of showers moved through early in the morning. This afternoon, dry conditions dominate, with the exception of typical afternoon clouds and scattered showers over the South Kona slopes.
The subtropical ridge will remain roughly stationary through Thursday, keeping trades in the gentle to locally moderate range. A shallow low aloft will develop within the upper-level trough just north of Kauai on Tuesday. A narrow band of moisture will move onto the Garden Isle Tuesday night and Wednesday, and the modest instability provided by the low aloft will likely produce slightly active showers on windward slopes, while leeward Kauai could experience scattered afternoon showers. Across the rest of the state, shower activity should remain low and focused mainly over windward areas under continued stable conditions, while sheltered leeward terrain experiences clouds and maybe an isolated shower each afternoon. The low aloft will generate high clouds, mainly over Big Island and Maui.
Trade winds should strengthen a notch Friday and Saturday as surface high pressure rebuilds far northeast of the state. The low aloft will be pushed off to the east, and ridging aloft will move overhead and bring stable and somewhat dry conditions. Trade winds will become more easterly and may ease slightly Sunday due to a surface trough developing several hundred miles west of the islands.

Aviation

Regional satellite imagery this afternoon reveals very little upstream of the islands in the way of clouds and showers. Moderate east northeasterly trade winds will prevail throughout the next few days. VFR conditions are expected across much of the state through Tuesday, with only brief passing showers possible over windward locations throughout this period.
There are currently no AIRMETs in effect and none are anticipated through tonight.

Marine

High pressure to the far north-northwest will drift west and weaken over the next several days, with easterly trade winds gradually easing into the gentle to locally fresh range through the week.
Surf along south facing shores will remain small through Tuesday, with a tiny to small long-period reinforcement will expected late tonight. A long-period south-southwest swell is expected Wednesday into Thursday and will bring another boost to south shore surf.
East shore surf will gradually decline through mid-week as the trades weaken slightly. Surf along north facing shores will remain tiny for the next several days. Gale force winds associated with a surface low moving near the Aleutians this weekend are expected to send a small, medium-period north-northwest swell towards the islands for the latter half of the week.
Through Wednesday, higher than normal tides could lead to some coastal flooding during the peak of high tides in the early afternoon hours. However, since the elevated tides are generally expected between the peaks of the aforementioned south swells, this event should have minimal impacts.

HFO Watches/Warnings/Advisories

None.

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