West Side

Today: Sunny and breezy. Isolated showers in the morning. Highs 71 to 76. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly clear with isolated showers. Lows 61 to 67. East winds 10 to 20 mph. Chance of rain 20 percent.

Thursday: Sunny. Isolated showers in the morning. Highs around 75. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 78. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 58 to 68. North winds up to 20 mph.

Thursday: Sunny. Highs around 80. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

North Shore

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 73 near the shore to around 57 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows around 65 near the shore to around 45 near 5000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Thursday: Breezy. Mostly sunny with scattered showers. Highs around 74 near the shore to around 59 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Sunny and breezy. Isolated showers in the morning. Highs 73 to 78. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows 59 to 65. Northeast winds 10 to 20 mph.

Thursday: Sunny and breezy. Highs 75 to 80. Northeast winds up to 20 mph.

Upcountry

Today: Mostly sunny. Scattered showers in the morning. Highs around 55 at the visitor center to around 61 at the summit. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 40 at the visitor center to around 42 at the summit. Light winds. Chance of rain 50 percent.

Thursday: Mostly sunny. Scattered showers in the morning. Highs around 55 at the visitor center to around 64 at the summit. Light winds. Chance of rain 40 percent.

East Maui

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 73 near the shore to around 57 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows around 65 near the shore to around 45 near 5000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Thursday: Breezy. Mostly sunny with scattered showers. Highs around 74 near the shore to around 59 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Sunny and breezy. Highs 65 to 73. Northeast winds 15 to 25 mph.

Tonight: Mostly clear. Breezy. Lows around 59. Northeast winds 10 to 25 mph.

Thursday: Sunny. Highs 67 to 74. Northeast winds up to 15 mph.

Kaunakakai

Today: Sunny and breezy. Isolated showers in the morning. Highs 61 to 78. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows 52 to 67. Northeast winds 10 to 20 mph.

Thursday: Sunny. Highs 63 to 79. East winds 10 to 15 mph.

Detailed Forecast

Synopsis

High pressure far to the north of the state will maintain moderate to breezy trade winds through Thursday, with the trades then easing Friday and Saturday as a front approaches from the west. Fairly dry conditions will prevail, with light trade wind showers limited primarily to windward and mauka areas through the period. A weakening front may bring an increase in rain chances Sunday and Monday, as it moves into the western islands. A more typical trade wind pattern then looks to return Tuesday into the middle of next week.

Discussion

Currently at the surface, a 1030 mb high is centered about 1500 miles north of Honolulu, and is driving moderate to locally breezy northeasterly trade winds across the island chain. Infrared satellite imagery shows partly to mostly cloudy conditions, with cloud coverage the greatest in windward and mauka areas. Radar imagery shows scattered to numerous showers affecting windward slopes and coasts, particularly across the eastern islands. Drier conditions are in place in leeward areas, with a few showers spilling over from time to time. Main short term focus revolves around rain chances during the next couple of days.
High pressure will hold in place to the distant north, maintaining moderate to locally breezy trade winds across the island chain through Thursday. Showers will favor windward and mauka areas, with a stray shower reaching leeward communities from time to time. Overall there should be a decrease in shower coverage and leeward penetration of showers each day, as building low to mid-level ridging helps to lower inversion heights across the state.
A weakening front will approach the islands from the west Friday and Saturday, easing the trades and shifting boundary layer winds around to the east-southeast. The deeper moisture associated with the front will remain to the west of the islands during this time frame, while inversion heights remain suppressed due to low to mid-level ridging over the state. As a result, rather dry conditions will persist.
The operational GFS and ECMWF, there ensembles, and AI versions are split on the handling of the pattern evolution Sunday into early next week. Roughly half support keeping deep moisture west of the state, while the other half indicate the deeper moisture moving into at least the western islands. Overall, will take a blended forecast approach, showing a slight increase in rain chances over the western islands Sunday and Monday, with a transition back to a trade wind pattern Tuesday through the middle of next week.

Aviation

Moderate NE trades should veer more easterly today. Low cigs and SHRA are possible along windward and mauka areas, with some isol spillover into leeward areas. MVFR conds possible within SHRA, otherwise VFR prevails.
AIRMET Sierra for mtn obsc is in effect for Oahu, Molokai, Maui and the Big Island. Conds should improve in the mid morning hours.

Marine

Strong high pressure far north of the islands will maintain fresh to strong trade winds into Thursday. A Small Craft Advisory (SCA) has been extended through this afternoon for all waters due to a combination of these winds and elevated seas from a declining north-northeast swell, and the SCA has been pushed through Thursday for portions of the waters around Big Island and Maui County, where higher winds are typically encountered. Winds will ease over all waters and will gradually veer southeasterly around Kauai and Oahu Thursday night and Friday as a surface ridge is displaced toward the islands by an advancing front. The SCA will likely be dropped at this time. The front will stall and degrade into a trough over the weekend, possibly bringing increased chances for heavy showers by Sunday.
A large north-northeast (010-030 deg) swell will gradually decline during the next few days but will maintain elevated surf today. During the last few hours, NOAA buoy 51000 continued to show the swell above guidance at 10 to 11 feet 14 seconds, while the nearshore PacIOOS buoys have been measuring the swell at 9 to 10 feet. Given these observations, the High Surf Advisory for north and east facing shores of most islands has been extended through the afternoon, and the Marine Weather Statement continues for moderate to heavy surges in north facing harbors, mainly in Hilo and Kahului. Surf should fall below advisory levels by evening and continue a gradual decline through Friday. As east shore surf continues to decline this weekend, a small northwest swell will arrive. This swell will linger into early next week.
Surf along south facing shores will remain tiny through the week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov