West Kaua’i

Tonight: Breezy. Partly cloudy with scattered showers. Lows 68 to 73 near the shore to around 60 above 3000 feet. Northeast winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 83 to 88 near the shore to around 73 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Thursday Night: Breezy. Partly cloudy with isolated showers. Lows 68 to 73 near the shore to around 60 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 72. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Thursday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 86. East winds 15 to 20 mph. Chance of rain 70 percent.

Thursday Night: Breezy. Mostly cloudy with scattered showers. Lows around 72. East winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then occasional showers after midnight. Lows 62 to 69 in the valleys to around 57 above 4000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 70 to 79 in the valleys to around 63 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 62 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 72. East winds 10 to 20 mph. Chance of rain 70 percent.

Thursday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 85. East winds 10 to 20 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 64 to 72. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 76. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 70 to 83. East winds 10 to 20 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 76. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

A broad high dominating much of the Central Pacific will maintain breezy to windy trades across the Hawaiian Islands through Thursday morning. Enhanced shower activity and cloud coverage will persist predominately over windward and mauka areas. Trades will begin to weaken to a more moderate regime by Friday in response to the high weakening and propagating northeastward away from the Hawaiian Islands.

Discussion

The latest surface analysis shows a broad 1035 mb area of high pressure far north of the Hawaiian Islands. This is keeping breezy to windy trades blowing across the islands so the current Wind Advisory for portions of Maui County and the Big Island remains in effect through 600 AM Thursday morning. Surface observations this afternoon show widespread wind speeds greater than 30 mph, with the strongest winds blowing across the Kohala District of the Big Island. Guidance continues to show the strongest winds continuing through tonight, with some of the models suggesting advisory winds may continue across portions of the Big Island through the day Thursday. Will need to monitor this trend through tonight and may need to extend the Wind Advisory for portions of the Big Island through Thursday evening. Otherwise, expect the winds to slowly weaken on Thursday and become moderate to breezy by Friday as the area of high pressure meanders northeastward away from the state.
Meanwhile, radar and satellite imagery continue to show enhanced showers moving into windward and mauka areas, with some of the more robust showers producing over 0.50 inches of rain over the last 6 to 12 hours. CIMSS MIMIC PWATs continue to show additional areas of moisture embedded in the trades upstream of the islands. This will keep windward and mauka showers going through the week, with a few showers likely spilling over into leeward areas during the overnight and early morning hours. Shower activity looks to gradually taper off over the weekend as a drier and more stable air mass briefly moves into the area.
Confidence in the forecast lowers as we head into next week. Some model guidance continues to show a surface trough producing southerly flow propagate over the islands, escorting an abundance of moisture from the tropics with it around Monday or Tuesday (Days 6 and 7) of next week. If the GFS solution pans out, we could see ample tropical moisture being pulled northward into the islands which could lead to a period of moderate to heavy rain next week. However, if the ECMWF solutions wins, most of the tropical moisture will remain south of the islands and the heavy rain threat would be lower. The one thing both models now have in common is the depiction of a cold front advancing south towards the islands early next week. Will need to monitor trends over the next several days to see how the synoptic pattern evolves before we can determine what, if any, threats there are for the Hawaiian Islands early next week.

Aviation

Breezy to windy trades are forecast to last into tomorrow. Lower clouds and showers assoicated with the stronger trades will cause MVFR and some isolated IFR conditions on windward and mountain areas. VFR will prevail elsewhere.
AIRMET Sierra will continue for mountain obscuration across all islands through at least tomorrow morning.
AIRMET Tango will continue for turbulence over and downwind of terrain below 10,000 feet. AIRMET Tango will also continue for 30 kt or greater sustained winds between Oahu and Big Island.

Marine

A strong surface high, centered roughly 950 nm north-northeast of the islands, is driving fresh to locally gale force trade winds across Hawaiian waters. The high will slowly drift slowly southeast through tonight and maintain the robust east- northeasterly flow. The strong trade winds, combined with both northeast and northwest swells, will also result in seas greater than 10 feet across the area. A Gale Warning remains in effect through Thursday morning for the Alenuihaha Channel, where flow funneling around the terrain of Maui and the Big Island will accelerate trades even more. Elsewhere, a Small Craft Advisory (SCA) remains in effect for a combination of winds and seas. The high pressure to our north will gradually drift eastward and weaken Friday into this weekend, allowing winds to weaken to moderate to locally strong speeds through this weekend.
The current short period northeasterly (030 to 050 degree) swell will maintain advisory level surf along east facing shores tonight into Thursday, where a High Surf Advisory remains in effect through 6 PM HST Thursday. This swell will then decline late Thursday through this weekend as local trade winds weaken. Meanwhile, a small to moderate long period northwest swell is peaking this afternoon into this evening. This swell energy is keeping keeping surf along north and some west facing shores elevated, but below advisory levels. This swell will then decline late tonight through Friday. Another small, long period, northwest swell is progged to enter the local waters this weekend, which will again bring a sub-advisory level bump to surf along north and west facing shores.
A small, long period, south swell that peaked earlier today and generated surf near or slightly above the November average is now fading. Therefore, expect surf along south facing shores to gradually decline through the remainder of the week.

Fire weather

Critical fire weather conditions are not expected through the forecast period. Breezy to windy trades will continue through Thursday morning, becoming moderate to breezy before the weekend. However, low-level moisture embedded in the trades should help to keep relative humidity from reaching critical thresholds.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Thursday for Olomana, Maui Windward West, Kauai East, East Honolulu, Koolau Windward, Molokai Windward, Molokai Southeast, Windward Haleakala, Kipahulu, Big Island East, Big Island North.
Wind Advisory until 6 AM HST Thursday for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST Thursday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.
Gale Warning until 6 AM HST Thursday for Alenuihaha Channel.

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