Photo Credit: Tyler Rooke

West Side

Today: Isolated showers between 9am and noon. Sunny, with a high near 85. Light and variable wind. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 68. Calm wind becoming east northeast 5 to 8 mph after midnight.

Wednesday: Sunny, with a high near 85. East northeast wind around 10 mph.

South Side

Today: Sunny, with a high near 81. Calm wind becoming northwest around 6 mph in the afternoon.

Tonight: Mostly clear, with a low around 64. Calm wind becoming east northeast 5 to 7 mph in the evening.

Wednesday: Sunny, with a high near 82. East northeast wind around 8 mph.

North Shore

Today: Sunny, with a high near 83. Breezy, with an east northeast wind 6 to 11 mph increasing to 12 to 17 mph in the afternoon. Winds could gust as high as 24 mph.

Tonight: Isolated showers after 7pm. Partly cloudy, with a low around 66. Breezy, with an east wind 11 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Wednesday: Isolated showers before 7am. Sunny, with a high near 83. Breezy, with an east wind 13 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Central Maui

Today: Sunny, with a high near 83. Northwest wind 7 to 13 mph becoming northeast in the morning.

Tonight: Isolated showers before 9pm, then isolated showers after midnight. Partly cloudy, with a low around 66. East northeast wind around 9 mph. Chance of precipitation is 20%.

Wednesday: Sunny, with a high near 84. East northeast wind 11 to 14 mph, with gusts as high as 18 mph.

Upcountry

Today: Scattered showers between 9am and 3pm. Mostly sunny, with a high near 70. Light and variable wind becoming west around 6 mph in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Mostly clear, with a low around 52. Calm wind becoming east 5 to 7 mph after midnight.

Wednesday: Scattered showers between 9am and 3pm. Mostly sunny, with a high near 70. East northeast wind 8 to 10 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

East Maui

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 78. East wind 3 to 6 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Mostly cloudy, with a low around 69. East wind 7 to 10 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers before 9am, then scattered showers after noon. Increasing clouds, with a high near 78. East wind around 11 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Isolated showers before 9am. Sunny, with a high near 75. Light and variable wind becoming northeast 8 to 13 mph in the morning. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 62. East northeast wind 9 to 13 mph.

Wednesday: Isolated showers before 9am. Sunny, with a high near 75. East northeast wind 11 to 13 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Sunny, with a high near 85. Light and variable wind becoming east 5 to 10 mph in the morning.

Tonight: Mostly clear, with a low around 70. East northeast wind 6 to 9 mph.

Wednesday: Sunny, with a high near 85. Breezy, with an east northeast wind 13 to 15 mph, with gusts as high as 21 mph.

Detailed Forecast

Synopsis

A ridge to our north will maintain moderate trade winds through Thursday. Showers will favor windward areas, especially during the night and morning hours. The ridge will move over the islands by Friday, bringing light and variable winds and afternoon showers across interior areas.

Discussion

A front far northwest of the main Hawaiian Islands continues to put a dent in the subtropical ridge to our north. However, the pressure gradient between this ridge and equatorial low pressure is steep enough to drive moderate trade flow across local waters this morning. Overnight soundings show a rather dry and stable airmass, with PW values between 1.0 and 1.1 inches and positive lifted index values. A strong capping inversion is noted near 6000 feet. Satellite loop shows patchy broken low clouds across windward areas, with scattered low clouds to clear skies noted across leeward areas. Radar shows isolated to scattered showers within these clouds.
Models show the ridge will remain north of the main islands through mid-week, allowing continued trade wind flow across local waters. Clouds and showers will continue to favor windward areas through this time, with weak ridging aloft limiting total rainfall. Toward the end of the week, the ridge will shift south over the islands. Winds will weaken and land and sea breezes will prevail Friday and Saturday. Sea breezes will produce afternoon clouds and showers, while nighttime land breezes will bring clearing skies. An upper trough forecast to dig south over the islands during the weekend will make the atmosphere less stable, possibly increasing shower coverage and intensity. Models show this upper trough will pass east of the islands by Sunday afternoon but, with the subtropical ridge fixed across the islands, light and variable winds will continue into next week.

Aviation

Light to moderate trades will persist with a strong inversion near 6kft feet capping cloud tops around that height. Prevailing VFR can be expected for all locations with isolated MVFR possible within any heavier showers. The low inversion and relatively weak trades will help confine shower activity to windward areas. The exception is Oahu where leeward drift of light showers will be common during the early morning.
No AIRMETs in effect.

Marine

Moderate to fresh easterly trade winds will continue through tonight, then increase into the fresh to locally strong range late Wednesday through Thursday. This will potentially translate to advisory-level winds in the typically windier channel waters between Maui County and the Big Island. Winds will shift out of the east-southeast late Thursday through Friday and diminish as a front passes to the north. This will result in a land and sea breeze regime statewide late Thursday night into the weekend. Seas will remain around the advisory-level of 10 ft across waters exposed to northwest swells through much of the week as a series of overlapping swells move through the islands.
Surf along exposed north and west facing shores will remain at or around advisory-levels each day through the week, and potentially into the weekend as a series of large overlapping northwest swells arrive and move through. The swell that arrived Monday peaked overnight and has begun to lower early this morning. Expect this downward trend to continue through the day and may drop just below the advisory levels for exposed north and west facing shores tonight.
The next northwest (320-330 deg) swell in the series from the active pattern across the northern Pacific is expected to arrive through the day Wednesday and peak Wednesday night. If this materializes as predicted, low-end warning-level surf will become a possibility by or come Wednesday night into Thursday. Warning- level surf could continue through Thursday night as a new, long- period northwest (around 330 deg) swell arrives and moves through. Surf will gradually lower Friday into the weekend as these overlapping swells ease.
Looking ahead, guidance is advertising a compact, storm- to hurricane-force low developing north-northwest of the islands Thursday, then passing just over 1000 nautical miles north of the state through the day Friday. ECMWF-Wave and WAVEWATCH III reflect this and show seas climbing into the 30 to 35 ft range focused at the islands within the 350 to 360 degree band relative to the islands. If this scenarios evolves as projected, a northerly swell will arrive late Saturday, with a peak Saturday night into Sunday at advisory levels for north facing shores.
Surf along east-facing shores will hold steady through the week below the advisory level due to a decent sized area of fresh breezes upstream of the state across the eastern Pacific.
Surf along south facing shores will remain small each day near the seasonal average with mainly a mix of small background, long- period south swells and shorter-period southeast trade wind swells.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Windward, Kauai Leeward, Waianae Coast, Oahu North Shore, Oahu Koolau, Molokai, Maui Windward West, Maui Central Valley, Windward Haleakala.
Small Craft Advisory until 6 PM HST Wednesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

Data Courtesy of NOAA.gov