Photo Credit: Braden Jarvis

West Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 20 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 71 near the shore to around 61 above 3000 feet. East winds 10 to 25 mph decreasing to up to 25 mph after midnight. Chance of rain 40 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs around 87 near the shore to around 73 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 79 to 87. Northeast winds 20 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 73. East winds 20 to 25 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 78 to 86. East winds 20 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 72 to 82 in the valleys to around 64 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows 63 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 30 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 71 to 82 in the valleys to around 63 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 75 to 88. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 72. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 74 to 86. East winds up to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 71 to 84. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 76. East winds 10 to 25 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 70 to 84. East winds 10 to 25 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Windy trade winds will persist into the weekend. Showers will focus along windward mauka exposures, reaching leeward sides of the smaller islands.

Discussion

A strong 1036 mb high north of the state is generating robust trade winds across the islands today. 12Z soundings at Hilo and Lihue show a strong 8-10 kft inversion in place across the area. Satellite and radar show a band of showery clouds over and just upstream of Maui County and the Big Island early this morning. Expect mostly light to moderate showers to quickly pass mainly for windward slopes of the island this morning, with some showers spilling over to leeward areas of the smaller islands with the elevated trade wind inversion. Expect a slightly drier trend later this afternoon. Trade wind showers are likely to increase again tonight into Thursday.
The high to the north will strengthen as a front weakens and is pushed southward. Trade wind speeds will begin to increase today. A wind advisory has been issued for select windy areas around Maui County and the Big Island through Thursday. This advisory will likely be extended and expanded for Friday and Saturday. Model guidance remains on track with winds continuing to strengthen and possibly peak Friday through Saturday near High Wind Warning speeds for select locations. A High Wind Watch may need to be issued later today as we get closer in time and confidence increases. The remnants of a dissipated front mentioned above may arrive late Friday into Saturday. This may translate to an increase in cloud cover and showers as this feature passes through for both windward and leeward sides of the islands. Wind speeds will slowly taper down Sunday into Monday (but still remain fairly breezy) with showers focusing along windward and mauka areas.

Aviation

Windy easterly trades will gradually strengthen today and towards the weekend. Clouds and showers will favor windward and mauka areas. Expect periods of MVFR CIGS/VSBYS within passing showers. Otherwise, VFR conditions will prevail, including at the TAF sites.
AIRMET Tango for moderate low-level turbulence will persist over and downwind of all island terrain.
AIRMET Sierra is in effect for mountain obscuration above 2500 feet across windward slopes due to low clouds and showers.

Marine

A strong high pressure system will build in north of the Hawaiian Islands over the next several days. Expect strong and gusty trade winds today and tonight, possibly reaching gale force levels in the windier channels from Thursday into the weekend. The Small Craft Advisory remains in effect for all coastal waters due to these strong trade winds and corresponding high seas. A Gale Watch may be needed for the second half of this week, for the windier waters and channels near Maui and the Big Island, in anticipation of even stronger wind speeds.
A large and long period northwest (320-330) swell started building into the Hawaiian region during the overnight hours and will reach advisory levels by early morning. This swell will rise quickly and peak well above advisory levels for exposed north and west facing shores later today, potentially nearing High Surf Warning thresholds by tonight, and then slowly decreasing, falling below advisory thresholds by Thursday night. A High Surf Advisory will start this morning at 6 AM HST, affecting north and west facing shores of Niihau, Kauai, Oahu, and Molokai, as well as north facing shores of Maui.
Rough and choppy surf along east facing shores will gradually become more elevated from Thursday onward, as trade winds strengthen. Surf heights along east facing shores is expected to build to advisory levels from Thursday into Friday, and then hold into the weekend.
Surf along south facing shores remains small through the period, except for a small bump later today.
Peak monthly tides are forecast from Nov 14th to 18th. These high tides will combine with elevated seas due to strong trades and slowly fading northwest/north swells to exacerbate coastal inundation impacts, particularly for vulnerable locations during early morning high tides.

Fire weather

Trade wind speeds are forecast to exceed sustained 20 mph at Honolulu airport Friday and Saturday, with higher speeds in more exposed areas around the state. It is also possible for winds to also reach 20 mph on Thursday while ramping up, and on Sunday while trending down. The limiting factor will be relative humidity, which is expected to stay in the upper 40s to lower 50s as around Honolulu. While a Fire Weather Watch or Red Flag Warning is not anticipated at this time, conditions may come close on Thursday or Friday afternoon. Will be monitoring for any changes in this forecast in the coming days.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Thursday for north and west facing shores of Niihau, Kauai, Oahu, Molokai and for north facing shores of Maui.
Wind Advisory from 8 AM this morning to 6 PM HST Thursday for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Molokai North, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Maui Central Valley South, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 AM HST Friday for all Hawaiian waters,

Data Courtesy of NOAA.gov