West Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening. Lows around 70 near the shore to around 59 above 3000 feet. Light winds. Chance of rain 40 percent.

Tuesday: Mostly cloudy with isolated showers. Highs around 84 near the shore to around 70 above 3000 feet. Light winds. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy in the evening then becoming partly cloudy. Lows around 70 near the shore to around 59 above 3000 feet. Light winds.

South Kaua’i

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 67 to 72. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Isolated showers in the afternoon. Highs 78 to 84. Light winds. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 67 to 72. Light winds becoming northeast around 10 mph after midnight. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 69 in the valleys to around 58 above 4000 feet. Light winds. Chance of rain 50 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 73 to 82 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 69 in the valleys to around 58 above 4000 feet. Light winds. Chance of rain 40 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening. Lows 64 to 71. Light winds. Chance of rain 40 percent.

Tuesday: Mostly cloudy. Isolated showers in the morning. Highs 75 to 82. Light winds. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy in the evening then becoming partly cloudy. Lows 64 to 72. Light winds.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 73. Light winds. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 83. Light winds. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 64 to 73. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Lighter winds are expected Tuesday and Wednesday as a low passes north of the state. Along with the lighter winds, expect a few clouds and showers over the interior parts of the islands during the afternoon and evening hours. As the low moves to the northeast late Wednesday, a ridge will build in to the north of the islands. This will allow trade winds to build back into the region during the second half of the week. By the weekend, more typical trade wind showers will reach the islands on the trade wind flow.

Discussion

The shortwave trough that passed through the islands earlier today has moved to the east. Some thunderstorms formed over the Big Island slopes around midday, but have died off this afternoon. Another stray thunderstorm is possible through the evening hours.
A low pressure system north of the islands is helping to keep winds light, and that is expected to continue into Wednesday. The lighter winds will result in some localized land and sea breezes. This in turn will lead to some clearing overnight, with some afternoon clouds and showers forming over the interior of the islands.
The second half of the week should see the low move to the far northeast of the islands, and that will allow a new ridge to build north of the region. This will allow trade winds to build across the area during the latter part of the week. A ridge aloft will help to provide a stable airmass over the region with limited shower activity. Moisture upstream of the islands will be carried in on the returning trade wind flow and will likely reach the islands over the weekend, bringing a return to more typical trade wind shower activity by the end of the weekend.

Aviation

High clouds limited interior convection today, except for several tstorms over the Big Island, and suspect conuted high clouds will once again limit potential tomorrow. Onshore sea breezes will nonetheless bring interior clouds followed by overnight clearing with emerging offshore land breezes.
No AIRMETs in effect.

Marine

A series of lows and troughs northwest and north of the islands will act to keep weak to locally moderate east southeast flow in place across the local waters through early Wednesday. Light wind flow should allow for afternoon sea breeze development near the shores. By Late Wednesday through this weekend, surface high pressure building north of the area will bring a return of moderate to locally strong trades.
Forerunners from a small, medium- period, northwest swell are still on track to arrive late tonight, with this swell forecast to build Tuesday and peak on Wednesday. This should bring an uptick in surf along north facing shores.
A moderate, medium- period north- northeast swell arrives on Tuesday and peaks also on Wednesday, bringing moderate surf to north and northeast facing shores, before slowly declining through the end of the week. East facing shores will see an increase in surf with wrap from the aforementioned north-northeasterly swell despite below- seasonal average trades. Strengthening trades late this week will also give east facing shores a bump in surf.
Surf will continue to be small along south facing shores through the period.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov