West Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 69 to 74 near the shore to around 62 above 3000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers. Highs 85 to 90 near the shore to around 77 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy with isolated showers. Lows 69 to 74 near the shore to around 62 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 70 to 75. Northeast winds around 10 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 80 to 89. East winds 10 to 15 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 72. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

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

Friday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 84 in the valleys to around 66 above 4000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Friday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 70 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 with scattered showers. Lows 65 to 74. East winds up to 10 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 77 to 87. East winds up to 15 mph. Chance of rain 50 percent.

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

East Kaua’i

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

Friday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 86. Northeast winds up to 10 mph. Chance of rain 70 percent.

Friday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 76. Northeast winds around 10 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

High pressure far north and northeast of the state will maintain moderate to locally breezy trades through Friday, with winds starting to weaken over the weekend. Expect to see fairly typical summertime weather into next week as clouds and showers favor windward and mauka areas.

Discussion

A 1032 mb surface high remains well north and northeast of the Hawaiian Islands, with moderate to locally breezy trades blowing across the state this afternoon. Satellite imagery continues to show clouds moving into windward and mauka areas, with a band of moisture moving towards Maui County. Radar imagery shows some enhanced showers embedded in this moisture that is currently moving into Molokai. Expect this band of moisture to shift towards Oahu and Kauai tonight bringing a slight increase in clouds and showers. Otherwise, expect fairly typical summertime conditions tonight.
Guidance continues to show the high slowly drifting north over the weekend and into next week, with winds weakening a bit starting Saturday. It also shows no organized bands of moisture upstream of the islands, with a fairly typical dry and stable summertime air mass over the region. As such, expect clouds to favor windward and mauka areas, with passing showers moving in at times through the forecast period. Kona Slopes of the Big Island will also continue to see the typical summertime afternoon showers as the sea breeze develops across leeward Big Island.
The one wrinkle to the forecast will be the evolution of an upper level disturbance to the north of the islands. This disturbance could help to enhance instability over the western half of the state which could bring some enhanced showers this weekend and early next week.

Aviation

Fresh to locally strong winds will persist into the weekend. AIRMET Tango is posted for tempo moderate turbulence below 8000 feet leeward of mountains for all Hawaiian islands due to winds and the stable atmosphere.
A band of incoming low clouds and showers will impact Maui County late this afternoon and tonight, and spread to Oahu later tonight. AIRMET Sierra is posted for tempo mountain obscurations above 2500 feet along windward sides of Maui and Molokai. This AIRMET will likely be needed for windward Oahu later tonight, and possibly Kauai early Friday morning. Prevailing VFR conditions expected for Big Island.

Marine

High pressure far northeast of the Hawaiian waters will drive moderate to locally strong trade winds through Friday. As such, the Small Craft Advisory is in effect for the typical windy waters around Maui County and Big Island through Friday afternoon. Trades will ease slightly later this weekend into early next week as the high moves further away to the north.
The recent small, long period south swell will continue its decline through tomorrow. Two more small, long period south swells are scheduled to arrive Friday night into Saturday and Sunday night into Monday. The first of these swells will likely only lead to a minor bump in surf, while the second is expected to be a little more noticeable. However, south-facing shore surf will likely remain below the summer average through the next several days.
East-facing shore surf will remain rough and choppy as moderate to locally strong trades blow through Friday, then drop a notch as the trades ease slightly later this weekend into early next week. A very small northwest swell originating behind a front hanging up far northwest of the islands is expected to arrive early next week.

Fire weather

Moderate to locally breezy trades will continue through Friday, then weaken slightly over the weekend and into next week. Afternoon relative humidity remains near summertime normals, with fairly typical fire weather conditions expected.

HFO Watches/Warnings/Advisories

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