Photo Credit: Tyler Rooke

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 75 to 81. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 64 to 71. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 75 to 80. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Highs around 84. North winds up to 15 mph shifting to the northeast in the afternoon.

Tonight: Partly cloudy. Breezy. Lows 61 to 72. North winds 10 to 20 mph decreasing to up to 15 mph after midnight.

Wednesday: Mostly sunny. Highs around 84. North winds up to 15 mph.

North Shore

Today: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs around 78 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 66 near the shore to around 48 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 76 to 81 near the shore to around 65 near 5000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Central Maui

Today: Partly sunny early in the morning then becoming mostly sunny. Breezy. Isolated showers early in the morning. Highs 79 to 85. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 62 to 68. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday: Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs 79 to 85. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs around 62 at the visitor center to around 55 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 45 at the visitor center to around 43 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with scattered showers. Highs around 62 at the visitor center to around 65 at the summit. East winds up to 15 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 around 78 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 66 near the shore to around 48 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 76 to 81 near the shore to around 65 near 5000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Lanai City

Today: Breezy. Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 71 to 79. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 59 to 64. Northeast winds 10 to 20 mph.

Wednesday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 70 to 77. Northeast winds up to 10 mph. Chance of rain 20 percent.

Kaunakakai

Today: Partly sunny early in the morning then becoming mostly sunny. Isolated showers early in the morning. Highs 67 to 84. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 55 to 71. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday: Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs 66 to 84. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate easterly trade winds will persist through midweek, with clouds and brief showers favoring windward and mauka areas. A cold front and upper disturbance approaching and moving into the area Thursday through Friday will disrupt the trades, potentially bringing another round of showers and thunderstorms to parts of the state. While residual moisture may keep rain chances in the forecast into Saturday, a more stable and dry air mass, along with a return of northeast trade winds, is possible by the end of the weekend.

Discussion

Short-term guidance remains in reasonable agreement through midweek, indicating rising upper heights over the region as the broad upper trough continues eastward and away from the state. Moderate trades will gradually weaken into the light to moderate range tonight through Wednesday as the surface ridge weakens and shifts southward, due to a front passing to the north. This setup will result in a mostly stable and dry trade wind pattern, with the best chances for showers in windward and mauka areas during the overnight and early morning hours.
Confidence in increasing with better model alignment, depicting the trades will be disrupted beginning Thursday as a cold front approaches and moves into the area. Increasing moisture and instability associated with lowering upper heights and the front will elevate the potential for showers and thunderstorms. Although most of the deep moisture and dynamics associated with this system will remain north of the state, some locally heavy rainfall and stronger storms interacting with island terrain will be possible.
By the weekend, the upper-level trough is expected to move east of the state, with ridging building in its wake, leading to more dry/stable conditions. Remnant moisture from the dissipating front may sustain rain chances into Saturday, though rainfall amounts should be minimal as the upper ridge becomes more established. Northeast trade winds could return by the end of the weekend as high pressure builds north of the area in the wake of the front.

Aviation

Moderate trades expected through Wednesday as a cold front passes north of Hawaii. Winds will focus low cigs and SHRA over windward and mauka areas. MVFR conds can be expected in SHRA but otherwise VFR should prevail.
AIRMET Sierra continues for mtn obsc for windward Big Island. Conds are slowly improving and this AIRMET will likely be dropped at next issuance.

Marine

Trade winds look to remain moderate to fresh through Tuesday before easing slightly Wednesday as the ridge to the north weakens and a front passes by to the north. A light wind regime is expected by Thursday through the end of the week as a potential cold front moves down the island chain. Associated with the front, an upper level trough may increase the potential for thunderstorms and numerous showers in the offshore and coastal waters as the front moves in from the northwest Thursday night and Friday.
The current moderate long-period northwest swell will continue to fill in overnight, peaking early Tuesday morning before slowly declining through the week. The High Surf Advisory (HSA) is currently in effect for north and west facing shores of Niihau, Kauai, Oahu, and Molokai and north facing shores of Maui through Tuesday.
A large long period northwest swell is expected to build Friday into Saturday from a closer, stronger storm that tracks generally towards the islands over the next few days. A High Surf Warning (HSW) is likely as satellite altimeter passes over the storm is already showing 40 foot seas. Through the first half of next week, a medium period northwest swell will likely fill in Monday keeping surf heights elevated over the forecast period.
Surf along south facing shores will remain very small through Wednesday. A moderate long period south swell is expected to start filling in Thursday, peak on Friday and slowly ease over the weekend. PacIOOS buoy observations located in Aunu'u, American Samoa is running above guidance suggesting surf may peak just below High Surf Advisory levels. Surf along east facing shores will hold relatively steady tonight then continue to decline through the end of the week. A small north swell could potentially elevate exposed shorelines Wednesday and Thursday.

Fire weather

No critical fire conditions anticipated during the forecast period.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov