West Kaua’i

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with numerous showers after midnight. Lows 61 to 68 near the shore to around 51 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to around 73 above 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 70 percent.

Thursday Night: Breezy. Mostly cloudy with scattered showers. Lows 61 to 68 near the shore to around 51 above 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then frequent showers after midnight. Lows 58 to 67. Northeast winds 15 to 25 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs around 82. Northeast winds 15 to 25 mph. Chance of rain 90 percent.

Thursday Night: Breezy. Mostly cloudy with numerous showers. Lows 58 to 67. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Kaua’i Mountains

Tonight: Cloudy and breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 50 to 58 in the valleys to around 46 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 90 percent.

Thursday: Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 72 to 77 in the valleys to around 65 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

Thursday Night: Breezy. Mostly cloudy with numerous showers. Lows 50 to 58 in the valleys to around 46 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 55 to 66. East winds 10 to 20 mph. Chance of rain 90 percent.

Thursday: Cloudy and breezy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 74 to 81. East winds 10 to 20 mph becoming up to 25 mph in the afternoon. Chance of rain 90 percent.

Thursday Night: Breezy. Mostly cloudy with numerous showers. Lows 55 to 66. East winds up to 20 mph. Chance of rain 70 percent.

East Kaua’i

Tonight: Cloudy and breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 51 to 69. Northeast winds 10 to 20 mph. Chance of rain 90 percent.

Thursday: Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 73 to 83. Northeast winds 10 to 20 mph. Chance of rain near 100 percent.

Thursday Night: Breezy. Mostly cloudy with numerous showers. Lows 51 to 69. East winds 10 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy trade winds will continue through the weekend, with clouds and showers favoring windward and mauka areas. Moisture from a remnant front will maintain periods of enhanced shower activity for portions of the state through Friday. Expect a more typical trade wind pattern to return Friday night through the weekend.

Discussion

A moisture band is set up upstream of the smaller islands this afternoon. Breezy trade winds from a 1032 mb high 1000 miles north of Hawaii will focus most of the incoming clouds and showers across windward sections reaching leeward sides at times. The high will strengthen to 1035 mb high as it slides eastward through the rest of the week, which will veer winds more easterly. Expect a wetter-than-average trade wind pattern to continue into Friday until the upstream moisture is moved to the west.
Rising upper heights and strengthening inversion should lead to a more stable and drier trade wind pattern Friday night into the weekend, with a more typical distribution of windward/mauka showers.

Aviation

Moderate to breezy trade winds continue for the next few days. This will focus clouds and showers over mainly windward and mauka areas, with an uptick in activity during the overnight and early morning hours. Lingering moisture from a remnant front will bring some enhanced showers through Thursday, with periods of MVFR likely.
AIRMET Sierra for tempo mountain obscuration remains in effect for northeast thru southeast sections of Oahu and Kauai. Expect these conditions to continue overnight due to upstream moisture.

Marine

Trade winds will build over the next 24 hours as strong high pressure passes far north of the island chain, with fresh to locally strong winds holding through at least Friday. Northeasterly trades will continue to ramp up tonight along and north of a band of clouds and showers that stretches across Oahu and Kauai. As this band falls apart on Thursday, stronger easterly trade winds will develop across the rest of the island chain. A Small Craft Advisory (SCA) is now in effect for most waters through Thursday night and will likely need to be extended through Friday afternoon in most areas. The pressure gradient and resulting trade winds will weaken over the islands late Saturday and Sunday, though SCA conditions may hang on across the typically windy waters around the Big Island and Maui.
A series of small northwest to north-northwest swells will produce surf below April average on northern shores this week. The current north-northwest swell is down to 3 feet at 12 seconds at the local PacIOOS buoys and will drop through Thursday as a similarly sized northwest swell fills in. This new swell will shift out of the north-northwest and hold on Friday, then decline through the weekend. A slightly larger northwest swell is expected early next week.
The current south-southwest swell will produce surf around summertime average through the evening, then gradually decline Thursday. A small reinforcing pulse is expected Thursday and Friday, falling back to summertime background levels during the weekend.
A belt of strong trade winds will produce an increase in rough surf along east facing shores tonight through through Friday, with the largest waves affecting Kauai and Oahu. During the peak of this wind swell Thursday afternoon into early Friday, surf could rise near the High Surf Advisory level on Kauai, and the elevated seas will contribute to the need for a SCA around Kauai and Oahu. Surf along eastern shores will be near April average statewide on Saturday and decline below average Sunday into early next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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