West Side

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 67 to 73. East winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 79 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 67 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Tonight: Partly cloudy. Lows 65 to 74. Northeast winds up to 15 mph.

Wednesday: Mostly sunny. Highs around 87. Northeast winds up to 15 mph.

Wednesday Night: Partly cloudy. Lows 65 to 74. North winds 10 to 15 mph.

North Shore

Tonight: Breezy. Occasional showers. Lows around 70 near the shore to around 50 near 5000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs 77 to 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows around 70 near the shore to around 51 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Central Maui

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 70. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 81 to 88. Northeast winds up to 20 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Lows around 68. Northeast winds 10 to 15 mph.

Upcountry

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 45 at the visitor center to around 42 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs around 60 at the visitor center to around 64 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday Night: Breezy. Mostly cloudy with scattered showers. Lows around 45 at the visitor center to around 42 at the summit. East winds 15 to 25 mph. Chance of rain 50 percent.

East Maui

Tonight: Breezy. Occasional showers. Lows around 70 near the shore to around 50 near 5000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs 77 to 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows around 70 near the shore to around 51 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Lanai City

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 62 to 67. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Wednesday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 80. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Lows 62 to 67. Northeast winds up to 10 mph.

Kaunakakai

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 56 to 72. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 69 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Lows 57 to 73. East winds around 15 mph.

Detailed Forecast

Synopsis

Breezy trades will continue to produce showers across windward and mauka areas through the week. A developing low aloft could increase showers this weekend into next week.

Discussion

This afternoon, locally breezy trade winds continue to prevail across the island chain, steered by strong surface high pressure centered roughly 1500 miles northeast of Honolulu. Local satellite and radar imagery shows scattered clouds and showers embedded within the trade winds, favoring primarily windward and mauka areas. The central islands are seeing a bit more cloud cover upstream than the other islands this afternoon, but overall, rainfall amounts today have generally remained light. Meanwhile, onshore flow over the Kona slopes of the Big Island has also increased clouds and showers there.
Little change is expected in the overall weather pattern over the next few days. The Northeast Pacific High is expected to weaken a bit but also will be pushed southward by a series of low pressure centers further north near the Aleutian Islands. This will result in continued breezy trades across the Hawaiian Islands through at least Thursday afternoon. Throughout this period, showers embedded within the trades will favor windward and mauka sections of the islands, particularly during the overnight through early morning hours each day. The Kona slopes of the Big Island can also expect increased clouds and showers during the afternoons.
From Thursday evening into the weekend, the subtropical jet that is currently just south of the island chain will weaken and move to the east as a low aloft develops just southwest of the islands. This low aloft is then expected to move over the islands Saturday through Sunday, then linger overhead and weaken. As this occurs, it is possible that shower activity could increase, including across some leeward areas as well.
Early next week, the low aloft is forecast to weaken as ridging begins to build back in place. Guidance continues to show periods of increased moisture embedded within trade wind flow throughout the week.

Aviation

Breezy trades will persist through tomorrow and continue to focus clouds and showers over windward and mountain areas as pockets of moisture filter across the island chain. VFR conditions will generally prevail, but MVFR conditions can be expected in showers.
AIRMET Sierra is in effect for mountain obscuration along north and east slopes of the Big Island and Maui this afternoon. As this current plume of moisture works its way up the island chain, this AIRMET may need to be shifted towards Oahu overnight.
AIRMET Tango remains in effect for low level moderate turbulence over and downwind of island mountains due to the breezy tradewinds.

Marine

A strong high will remain far northeast of the state through the week and continue to bring fresh to locally strong trade winds to all local waters. A Small Craft Advisory (SCA) for the typical windy waters surrounding Maui and the Big Island remains in place through Wednesday evening. The SCA will likely need to be extended through the end of the week due to the persistent strong trades. Winds may ease slightly and veer toward the east-southeast over the weekend due to a weak front far northwest of the state.
The current moderate period south-southwest swell will slowly decline through Wednesday. By Thursday, mainly background energy is expected along south facing shores. A tiny long-period south- southwest is possible this weekend, but otherwise mainly background energy is expected into the middle of next week.
Surf along east-facing shores will be rough and choppy the next several days due to the fresh to locally strong trades. Surf along north facing shores will remain small with some background northwest energy moving through throughout the week and into the weekend.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov