Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 87. East winds 10 to 25 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 67 to 74. East winds 10 to 25 mph. Chance of rain 40 percent.

Sunday: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 76 to 87. East winds 15 to 25 mph. Chance of rain 40 percent.

South Side

Today: Sunny and breezy. Highs around 88. Northeast winds 10 to 25 mph.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 67 to 75. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Highs around 88. Northeast winds 15 to 25 mph.

North Shore

Today: Mostly cloudy. Breezy. Occasional showers in the morning, then showers likely in the afternoon. Highs 75 to 83 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows around 70 near the shore to 48 to 53 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 83 near the shore to around 64 near 5000 feet. Southeast winds 15 to 20 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 80 to 87. Northeast winds 10 to 25 mph shifting to the east 20 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 67 to 72. East winds 15 to 25 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 81 to 87. East winds 20 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 59 at the visitor center to around 55 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 44 at the visitor center to around 42 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 59 at the visitor center to around 56 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Breezy. Occasional showers in the morning, then showers likely in the afternoon. Highs 75 to 83 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows around 70 near the shore to 48 to 53 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 83 near the shore to around 64 near 5000 feet. Southeast winds 15 to 20 mph. Chance of rain 70 percent.

Lanai City

Today: Sunny and breezy. Isolated showers in the afternoon. Highs 72 to 80. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows 62 to 67. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Sunday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 81. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 66 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 57 to 74. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 66 to 88. East winds 15 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trade winds will persist through the weekend, supported by high pressure to the north. Clouds and passing showers will favor windward and mauka areas, with a few briefly heavy showers possible this weekend. Lighter trade winds and fewer showers are expected for the first half of next week, as a front slowly approaches the area from the north. The dissipating front may reach Kauai by Thursday, potentially spreading to the other islands by next weekend, bringing an increase in mainly windward showers.

Discussion

High pressure passing far N of the islands will maintain breezy trade winds through the weekend, pushing showery and stable low clouds into windward coasts and slopes, with a few showers spilling leeward on the smaller islands. Water vapor imagery highlights a trough aloft near Kauai, with early morning soundings indicating slight instability, with a weakened subsidence inversion in Hilo. Infrared satellite images indicate some cooler cloud tops moving along with the trade flow, and these taller clouds may bring a few soaking showers over the weekend as the trough develops into a cut off low NW of Kauai. Overnight, portions of windward Maui and Big Island did receive some briefly heavy downpours. Model guidance indicates mid-level cooling this weekend will be maximized near Kauai and Oahu, as 500 mb temps drop from -7C to -10C, which may allow some briefly heavy showers to move over those islands. The developing low aloft is expected to send some cirrus over the islands from the W from tonight into early next week.
As the cut-off low moves away to the W early next week, a ridge aloft will build over the islands from the SE. Additionally, a pair of surface lows will traverse the N Pacific, weakening the ridge to the N and pushing it toward the islands. This will lead to weaker E trade winds starting Monday, with winds becoming light NE Tuesday and Wednesday as a front associated with the first low presses S toward the islands. This combination will lead to fewer showers, with rainfall limited by a strong low-level subsidence inversion.
Latest guidance indicates the initial front slowing and stalling N of the islands, but then being reinforced by a front associated with the second low, which helps push associated moisture over Kauai as early as Thursday. The moisture associated with the dissipating front may potentially sag southward over the other islands Friday and Saturday. High pressure building N of the area will support strengthening trade winds, out of the NE initially, and push most of the assoicated moisture into windward areas. Still many questions as to how this will evolve, as one might expect with a 5-7 day forecast.

Aviation

High pressure north of the state will support continued breezy trade winds this weekend. The strongest winds will be over mountain ridges, through valleys, and in the channels. AIRMET Tango remains in effect for moderate low-level mechanical turbulence over and immediately south through west of mountains of all islands. This AIRMET will likely remain in effect through the day today, but may be able to be cancelled by late Sunday.
Satellite and radar imagery early this morning shows enhanced clouds and showers across windward sections of Maui and the Big Island and their adjacent waters. Occasional MVFR ceilings and visibilities have been observed within the heavier showers across these locations, and this trend is expected to continue for the next several hours. Therefore, AIRMET Sierra remains in effect for tempo mountain obscuration for windward sections of Molokai, Maui, and the Big Island, and will likely remain in place until later this morning. Elsewhere, showers and MVFR conditions will remain more isolated in nature and will favor north through east sections of the islands throughout the forecast period. Scattered showers are also possible across the interior of the Big Island this afternoon, though VFR conditions are expected to prevail at most locations.

Marine

High pressure north of the state will keep moderate to locally strong trade winds in place through the weekend. A Small Craft Advisory is now in effect for the typically windy waters around Maui and the Big Island through 6 PM Sunday. The trades are expected to ease into the light to moderate range Sunday night through the middle of next week as a cold front approaches from the north, and this will likely keep winds below SCA thresholds.
Surf along east facing shores will slowly lower through the weekend, but will hold close to normal levels. Surf will then slowly lower through the upcoming work week, with east shore surf dropping below normal during this time.
The current small northwest swell will keep some small surf in place along north and west facing shores through the weekend. A larger north-northwest swell is forecast to build late Tuesday and Tuesday night, then peak on Wednesday, with surf possibly nearing advisory levels along north facing shores. This swell will then gradually lower on Thursday, followed by a larger north to north- northeast swell Friday which appears to have a higher chance to bring advisory level surf to north facing shores.
Mainly background south swells will keep surf very small along south facing shores through early next week. The next small, long period south swell is forecast to reach the islands Tuesday and slowly lower through late next week.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov