Photo Credit: Randy Alona Gallegos

West Side

Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 81 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 67 to 74. East winds up to 15 mph. Chance of rain 40 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 81 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Highs 85 to 90. North winds up to 10 mph.

Tonight: Mostly clear. Lows around 68. North winds up to 15 mph.

Friday: Mostly sunny. Breezy. Highs 85 to 90. North winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon.

North Shore

Today: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 near the shore to around 52 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 80 percent.

Central Maui

Today: Breezy. Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs around 88. Northeast winds up to 20 mph shifting to the east 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 66 to 72. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Friday: Breezy. Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs around 88. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 63 at the visitor center to around 60 at the summit. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 46 at the visitor center to around 42 at the summit. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 63 at the visitor center to around 60 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 near the shore to around 52 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 80 percent.

Lanai City

Today: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 74 to 83. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 66. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight.

Friday: Breezy. Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 74 to 83. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Partly sunny. Isolated showers in the morning. Highs 79 to 89. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 61 to 72. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny. Breezy. Isolated showers in the morning. Highs 79 to 89. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds will continue today, then return to breezy levels Friday through early next week. Showers will favor windward and mauka locations, particularly during the overnight and early morning periods as areas of moisture move through.

Discussion

A broad surface trough (remnants of former TC Emilia), located around 200 miles north of Hilo, will continue westward today through tonight, weakening the local trades to moderate levels. This broad surface trough, combined with a mid-level trough and an increase in low-level moisture, will continue to support better shower coverage, primarily for windward and mauka locations. A few interior/leeward showers are possible this afternoon, where localized sea breezes form.
Breezy trade wind conditions are expected to return Friday through the weekend as the aforementioned trough begins to track away from the state and the deep-layer ridge strengthens. A modest increase in low-level moisture, accompanying another surface trough passing to the south, could translate to increasing shower coverage Sunday through Tuesday, most likely over the eastern end of the state.

Aviation

Moderate to locally breezy trades will deliver low clouds and brief showers to windward areas through the forecast period. A trough passing by to the north will weaken winds slightly, veer towards a more easterly direction, and allow an increase in low- level moisture over the western end of the state today. VFR conditions will prevail with isolated MVFR CIG over windward areas.
AIRMET Sierra has been issued for mtn obsc due to low cigs and SHRA. Otherwise, no other AIRMETs are in effect.

Marine

Moderate to locally strong trade winds will prevail through early next week. A weak surface trough passing by north of the islands will keep the trade winds below Small Craft Advisory today and tonight. The trades will strengthen back to SCA levels over the typically windy waters around Maui and the Big Island Friday, then hold at these levels through early next week.
Several small long-period swells from the south and southeast will produce small surf along south facing shores through the work week. A more significant south swell will arrive late Sunday and Sunday night, peak above the summertime average Monday, then slowly lower through the middle of next week.
Seasonally flat to tiny surf is expected through early next week for north facing shores. East shore surf will remain below normal during the next couple days, then trend higher over the weekend and rise to near seasonal levels early next week.
The combination of the full moon and water levels running around 0.5 ft higher than normal should produce minor coastal flooding each afternoon along the shorelines across the state beginning 8/18 and likely continuing through 8/20. A Coastal Flood Statement will eventually be needed as we get closer to the event.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov