Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs around 84 near the shore to around 72 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to around 58 above 3000 feet. Northeast winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Thursday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84 near the shore to around 73 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 80 to 85. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Thursday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 85. Northeast winds around 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 71 to 77 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 64 in the valleys to around 54 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy with numerous showers. Highs 72 to 78 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 75 to 82. East winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 69. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 83. East winds 10 to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 72 to 82. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 60 to 71. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 82. East winds 10 to 15 mph. Chance of rain 90 percent.

Detailed Forecast

Synopsis

A ridge will remain north of the islands for several days, keeping trade winds blowing through the forecast period. The ridge will weaken today, then restrengthen later in the week into the weekend. This will bring trades up to windy levels by Sunday. A series of upper disturbances passing near the islands will enhance trade showers at times, mainly from tonight into the weekend, especially for windward Maui and the Big Island. Leeward areas will generally see the most sunshine and the least amount of rain through the period.

Discussion

Locally breezy trades persist this morning, thanks to a surface ridge a few hundred miles north of the islands. Moisture was scarce over and upstream of the islands, keeping rainfall quite limited overnight. Expect the bulk of clouds and showers to affect windward portions of Maui and the Big Island this morning before cloud cover increases farther to the west this afternoon.
Models show surface ridging remaining in place a few hundred miles north of the islands, weakening a bit Thursday, then restrengthening this weekend. Expect returning windy trades to peak Sunday before they ease a bit early next week. Shortwave upper troughs forecast to pass over and north of the islands will keep our airmass less stable and may help to enhance incoming trade wind showers, mostly for windward Maui and the Big Island. One shortwave may enhance showers tonight into Thursday morning, while another one Thursday night into Friday and Saturday does the same. This second feature will cut off into an upper low well east of the islands early next week. Associated heavy showers and thunderstorms should stay east of our area, but we will need to keep an eye on model trends over the next few days.

Aviation

High pressure far to the northwest will drive moderate trade winds across the state. Scattered light showers will favor windward slopes and coasts of all islands. Isolated moderate showers possible along leeward slopes of the Big Island in the afternoon and evening. Brief MVFR conditions are likely in showers, otherwise VFR conditions will prevail all areas.

Marine

A high pressure center far north of the region will weaken as it approaches the state today. Trade winds will remain in the moderate to fresh range through Friday. The ridge will strengthen over the weekend with increasing trade wind speeds ranging from fresh to strong breezes over most windier coastal waters and channels from late Saturday through Monday. Winds are expected to remain below Small Craft Advisory (SCA) thresholds for the next few days, however rising northwest swell energy will produce seas just below SCA thresholds for northern waters today. Trade wind speeds will bring additional SCA conditions some coastal waters zones by late Friday to early Saturday, and then continue into the first half of next week.
A northwest swell continues to fill in this morning and spread High Surf Advisory (HSA) conditions over north and west facing shores of most windward islands through this afternoon. The HSA was expanded this morning to include Maui County. This swell will be reinforced by a small northerly swell later tonight into Thursday. North and northwest swell energy will briefly trend downward into the weekend. The next small long period northwest swell arrives on Sunday bumping up surf heights along north and west facing shores into Monday.
Surf will remain small along east facing shores for the next couple of days as winds briefly taper off, except for east shores exposed to the north swell. Surf along east facing shores will build from Friday through the weekend as strong trades return. South shore surf will remain small through tonight, by Thursday a small southern hemisphere swell will bring a small bump in south shore surf for eastern islands of Maui and the Big Island, then expanding to all islands by Friday. This south swell energy will then fade quickly on Saturday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Koolau Windward, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.

Data Courtesy of NOAA.gov