Photo Credit: Braden Jarvis

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 80 near the shore to around 68 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to around 56 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 79 near the shore to around 67 above 3000 feet. East winds up to 15 mph shifting to the south in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly cloudy with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 79. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 63 to 68. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 78. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 67 to 75 in the valleys to around 62 above 4000 feet. East winds up to 20 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 56 to 61 in the valleys to around 50 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers. Highs 66 to 74 in the valleys to around 61 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly cloudy with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs 72 to 79. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 59 to 68. Southeast winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 71 to 78. Southeast winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with occasional showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 72 to 79. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then scattered showers after midnight. Lows 57 to 69. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 71 to 78. East winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Wind speeds will gradually ease today through Wednesday, giving way to a land and sea breeze weather pattern Thursday as a front approaches from the northwest. The front will bring a period of wet weather to portions of the state Thursday night into Saturday, likely followed by unsettled conditions early next week.

Discussion

Wind speeds will decrease beginning today as a high far north of the islands passes northeastward. Expect typical trade wind weather to focus clouds and showers across windward slopes, along with afternoon clouds and spotty showers across leeward and interior areas of the Big Island, today into early Wednesday. By late Wednesday, trades may weaken enough for afternoon sea breezes to develop across leeward areas. This could produce enhanced afternoon cloud cover and a few leeward showers.
Models show developing upper troughing near and north of Hawaii later in the week. Local winds will become light southwesterly on Thursday as a front approaches from the northwest and the ridge aloft steadily erodes. Afternoon sea breezes will produce spotty interior showers, some possible heavy, followed by an increase in moisture Thursday night ahead of the front. The front will likely move over the western end of the state sometime Friday and fall apart over the central or southern end of the island chain Saturday. A stronger front may affect the area early next week as a deep low sets up north of Hawaii. Breezy to windy southwest flow could develop as early as Sunday, and wet and unsettled weather is becoming increasing likely.

Aviation

Breezy to locally strong trade winds will begin to ease as the day progresses, but remain moderate to breezy in most areas. Winds will ease further tonight. Showers, and accompanying MVFR conditions in lower ceilings and visibilities, will mainly affect windward and mauka sections statewide.
An AIRMET for mountain obscuration is in effect for portions of Kauai, Oahu, Molokai, Maui, and the Big Island. And the AIRMET for low-level turbulence downwind of higher elevations remains posted across the island chain.

Marine

Surface high pressure centered approximately 1,550 miles north northeast of Oahu is pressing a tight enough pressure gradient down across the islands to maintain fresh to locally strong trade winds through this afternoon. As this high moves away to the northeast and a large storm low replaces it north of the area, the regional pressure gradient will become slack enough to weaken local winds to more moderate magnitudes through mid-week. A cold front will approach the offshore waters from the west Thursday and further weaken winds while veering them around the southern half of the dial. Late week winds are forecast to become light to gentle northerly breezes before strengthening ahead of a strong storm system moving in from the northwest early next week. The Small Craft Advisory (SCA) for all waters (except windward Kauai and windward Big Island zones) will be scaled back to only include the typical windy areas around Maui County and south of Big Island through tonight.
A series of small size, medium period northwest to north swells will result in small rises to the surf along north and west-facing shores through Wednesday. A large northwest swell arriving Friday has the potential to lift surf to near High Surf Warning levels along many north and west-facing shores. In the long term, model guidance has been consistently bringing in a large, medium period northwest swell from a relatively close, favorable island direction long gale fetch source early next week. If this swell does materialize, it has a high chance of producing solid warning level surf for most north and western island exposures. Strong trades will keep eastern shore surf slightly elevated through the day. Rough eastern nearshore water conditions will noticeably improve through mid-week in response to weakening winds. South- facing shore surf will remain small with only background south swell energy passing through the next several days.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov