Photo Credit: Tyler Rooke

West Side

Today: Isolated showers after noon. Mostly sunny, with a high near 84. Calm wind becoming east northeast around 5 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 67. East northeast wind 5 to 10 mph.

Wednesday: Sunny, with a high near 83. East northeast wind around 9 mph.

South Side

Today: Sunny, with a high near 84. East northeast wind 5 to 7 mph becoming calm.

Tonight: Mostly clear, with a low around 65. East northeast wind 7 to 9 mph.

Wednesday: Sunny, with a high near 83. Northeast wind 8 to 10 mph.

North Shore

Today: Isolated showers after noon. Sunny, with a high near 82. Breezy, with an east wind 8 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 66. Breezy, with an east wind 14 to 16 mph, with gusts as high as 22 mph.

Wednesday: Sunny, with a high near 81. Northeast wind around 14 mph, with gusts as high as 18 mph.

Central Maui

Today: Isolated showers after noon. Mostly sunny, with a high near 82. Light east wind increasing to 8 to 13 mph in the morning. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 64. East wind 8 to 13 mph. Chance of precipitation is 20%.

Wednesday: Sunny, with a high near 81. Northeast wind around 11 mph.

Upcountry

Today: Sunny, with a high near 70. East wind 3 to 8 mph.

Tonight: Mostly clear, with a low around 55. East wind 6 to 8 mph.

Wednesday: Sunny, with a high near 69. East wind 7 to 13 mph.

East Maui

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 80. Breezy, with a southeast wind 11 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 62. Breezy, with an east southeast wind 10 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers. Mostly sunny, with a high near 79. East wind around 10 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Scattered showers after noon. Mostly sunny, with a high near 76. North northwest wind 5 to 7 mph becoming calm in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Partly cloudy, with a low around 64. East northeast wind 3 to 7 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Isolated showers before noon. Mostly sunny, with a high near 75. East northeast wind 6 to 11 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Isolated showers after noon. Sunny, with a high near 81. Light northeast wind becoming east 9 to 14 mph in the afternoon. Winds could gust as high as 18 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 70. Breezy, with an east wind 13 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Wednesday: Sunny, with a high near 81. Breezy, with an east wind around 17 mph, with gusts as high as 24 mph.

Detailed Forecast

Synopsis

Showers will increase today as a band of moisture moves in from the east. These showers will be short-lived as a drier air mass begins to move in tonight. Breezy trades should return by Thursday, with widespread windy conditions expected around New Years Day. Showers will likely increase, especially across windward areas, as trades strengthen.

Discussion

Locally breezy southeast flow near the Big Island is blocked from reaching the smaller islands, resulting in either weak southeast flow or light and variable winds from Maui westward this morning. High pressure far northeast of the islands has been pushed eastward by an impinging frontal boundary far to our north and northwest. The result places the islands along the southwest periphery of the subtropical high. Overnight soundings show our airmass is stable and quite dry, with PW amounts between 0.9 and 1.2 inches. Satellite loop shows clear skies across the islands this morning, with a ragged band of broken low clouds 120 miles east of the islands slowly drifting westward. These clouds are expected to move in across the state starting this afternoon. Light to moderate showers should be on the increase as winds slowly swing back to northeasterlies during this time. Most of these showers should be focused over windward areas and only light rainfall amounts are expected.
A drier air mass is expected to move in tonight into Wednesday, likely causing showers to decrease. Starting Thursday, trade winds will increase again, with breezy conditions expected state wide. Showers will ride in on the strengthened trades, with showers expected to focus over windward and mountain areas. Trades are expected to become even stronger on New Years Day, with 20 to 30 mph wind speeds possible. Beyond Friday, a ridge of high pressure will remain far north of the state and we should continue to see breezy trade wind weather in the extended forecast.

Aviation

A front far north of the area has been slowing and shifting winds around the state. Winds near the Big Island remain from the east, but they veer to the southeast moving up the chain to Kauai. This regime will result in nighttime land breezes and daytime sea breezes developing over many locales. VFR will prevail over most of the land area, though a showery cloud band with brief or TEMPO MVFR conditions may begin to affect mainly windward sections from the Big Island to Molokai by the afternoon hours today.
No AIRMETs are in effect.

Marine

A cold front entering the far northwest offshore waters will weaken and become stationary today. This front will push a ridge slightly closer to the islands, producing moderate east to southeast winds over windward waters through mid week. Due to proximity to the ridge axis and island shadowing from the southeast winds, winds around Kauai will be light and variable. High pressure building in north of the island chain Thursday and Friday will reestablish and strengthen the trades into the fresh to locally strong category.
Recent observations at the Waimea nearshore buoy show a large, long-period northwest swell has arrived in the local waters and will continue to fill in through the morning. This swell will push surf to warning level for north and west facing shores of Niihau through Oahu, and advisory level for north and west Molokai and north Maui shores as it peaks tonight into early Wednesday. This swell will gradually lower into Thursday. A reinforcing, similar- size northwest swell is forecast to fill in Thursday with peak surf Thursday night into Friday, followed by a gradual lowering later Friday. These northwest swells will cause seas to exceed the 10 foot Small Craft Advisory (SCA) threshold over exposed waters. Thus, an SCA is in effect for all windward waters and island channels through at least Wednesday morning. See the High Surf Advisory, High Surf Warning, and Small Craft advisories for additional details. These may all have to be extended and expanded throughout the week. These swells, combined with high astronomical tides, may cause some coastal water inundation along low-lying areas, especially during early morning high tides.
East shore surf will slowly decline as the trades ease, especially for the western half of the state. However, due to a fairly long upstream fetch, waves may remain elevated for the eastern half of the state. East shore surf will rise again everywhere toward the end of the week with the strengthening trades.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Wednesday for Molokai, Maui Windward West, Maui Central Valley, Windward Haleakala.
High Surf Warning until 6 AM HST Wednesday for Niihau, Kauai Windward, Kauai Leeward, Waianae Coast, Oahu North Shore, Oahu Koolau.
Small Craft Advisory until 6 AM 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