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. Chance of rain 20 percent.

Thursday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 83 to 89 near the shore to around 74 above 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 62 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 around 73. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 78 to 87. East winds 15 to 25 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows around 73. East winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Windy. Cloudy with numerous showers. Lows 64 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 30 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 81 in the valleys to around 64 above 4000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Thursday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 69 in the valleys to around 59 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows 65 to 73. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Gusts up to 40 mph. Chance of rain 70 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 75 to 86. East winds up to 20 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 65 to 73. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 65 to 76. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 71 to 83. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 76. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy to locally windy trade will continue to push deep tropical moisture over the state tonight. Moderate to locally heavy rain remains possible along windward and mauka areas of Maui County and the Big Island. Heavy rain chances diminish late tonight, but breezy and showery trades will persist through Thursday. Mid level drying will limit clouds and showers Friday into early next week. Easing trade winds over the weekend could allow for more of a hybrid land/sea breeze pattern over the weekend. Drier moderate trades should return Sunday.

Discussion

Satellite imagery continues to show thick mid and high clouds streaming over the eastern end of the state this afternoon. Radar imagery also shows scattered moderate showers over mainly windward and mauka areas of all islands, with locally heavy showers moving into windward areas of Molokai, Maui, and the Big Island. Rainfall totals the last 6 to 12 hours across these areas have ranged from 0.25 inches on the low end to over 2 inches at Kulaimano on the Big Island and West Wailuaiki on Maui. High resolution guidance continues to show this moisture band being pushed westward overnight by the trades. The main chance of locally heavy rainfall remains along windward and mauka areas of Maui County and the Big Island as PWATs remain close to 2 inches, with the threat diminishing overnight as the air mass starts to stabilize and dry out. Some of these showers may continue to produce some nuisance flooding tonight, but overall threat is minimal. As for the rest of the state, scattered light to moderate showers will remain focused along the windward and mauka areas under breezy trades.
The Big Island summits remained above freezing this afternoon, with minimal rain accumulations. However, guidance continues to show temperatures falling to near or below freezing tonight as the moist air mass lingers over the area. Therefore, any precipitation that fall across the summits tonight will be a wintry mix of rain and snow showers tonight, with a slight chance of light freezing rain possible. The current Winter Weather Advisory remains in effect until noon on Thursday. Conditions should quickly clear by late Thursday morning as temperatures climb above freezing.
The strong surface high passing north will maintain breezy trade winds into Thursday. Guidance continues to show a band of low level clouds and showers moving across the area on Thursday keeping a rather cloudy and wet trade wind pattern in place.
Trade winds are expected to ease Friday into the weekend as a front approaches the state from the far northwest. Mid level drying should limit clouds and showers. A few high clouds may remain as an upper level short wave trough passes north of the state Friday.
A hybrid trade wind and sea breeze pattern could develop Saturday as winds relax allowing for clouds and showers to develop along leeward and interior areas and low level moisture from the dissipating front moves over the state. However, cloud heights and showers will continue to be limited due to dry mid levels. The greatest chance of showers will be around Big Island where lingering moisture will be the deepest.
Drier and more stable conditions will fill in Sunday into early next week as mid to upper level ridging builds over the state and moderate trades return.

Aviation

Conditions improve early in the forecast period as the back edge of deeper moisture embedded within the trades advances quickly through the Big Island and Maui. AIRMET Sierra remains in place for now but can likely be dropped as the evening progresses. Elsewhere, a more typical trade wind pattern prevails with a typical distribution of lighter and less organized showers windward and mauka. Anticipate emerging VFR beneath a canopy of high clouds at all windward locales by the predawn hours Thursday.
AIRMET Tango in effect for lee turb.
AIRMET Sierra for mountain obscuration in effect for Windward Maui through Big Island.

Marine

Strong trade winds will continue through Thursday, then trend down through the weekend. A Small Craft Advisory (SCA) is out through Thursday for contributions from both winds and seas. With the swells and winds expected to taper off Thursday night and Friday, the SCA will likely be paired back during this period, and then dropping all together this weekend. East shore surf will decline as trades weaken over and upstream of the islands.
An overlapping north and northwest swell will bring advisory conditions to north and west facing shores today through midday Thursday. Most of the focus of the north swell will be directed towards Niihau and Kauai. A High Surf Advisory has been posted for Niihau, Kauai, Oahu and Molokai through noon Thursday with both swells falling through the afternoon. For south shores, tiny background south swell energy will persist. Another northwest swell will build north and west shores to advisory level surf Saturday.

Fire weather

Critical fire weather conditions not expected through the forecast period. Periods of locally heavy rain remain possible over Maui County and the Big Island through tonight. Breezy to locally windy trades continue into Thursday, then ease below critical thresholds heading into the weekend. Lingering moisture will keep relative humidity above critical thresholds.

HFO Watches/Warnings/Advisories

High Surf Advisory until noon HST Thursday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Kauai North, Molokai Windward, Molokai North, Molokai West.
Winter Weather Advisory until noon HST Thursday for Big Island Summits.
Small Craft Advisory until 6 PM HST Thursday for all Hawaiian waters,

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