Photo Credit: Pamela Goguen Lynch

West Side

Today: Windy. Mostly sunny with isolated showers. Highs 74 to 85. East winds 25 to 30 mph shifting to the northeast 15 to 30 mph in the afternoon. Gusts up to 50 mph. Chance of rain 20 percent.

Tonight: Windy. Partly cloudy with isolated showers. Lows 66 to 72. Northeast winds 10 to 30 mph with gusts to 50 mph. Chance of rain 20 percent.

Thursday: Windy. Mostly sunny with isolated showers. Highs 74 to 84. East winds 10 to 30 mph. Chance of rain 20 percent.

South Side

Today: Sunny and windy. Highs around 83. Northeast winds 10 to 30 mph with gusts to 50 mph.

Tonight: Mostly clear. Windy. Lows 65 to 72. Northeast winds 10 to 30 mph increasing to 20 to 30 mph after midnight. Gusts up to 50 mph.

Thursday: Sunny and windy. Highs 80 to 85. Northeast winds 25 to 30 mph with gusts to 50 mph.

North Shore

Today: Mostly cloudy. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to around 62 near 5000 feet. East winds 15 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Windy. Scattered showers in the evening, then numerous showers after midnight. Lows around 69 near the shore to 46 to 52 near 5000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds 15 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Windy. Isolated showers in the morning. Highs 79 to 85. Northeast winds 20 to 30 mph with gusts to 50 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Windy. Isolated showers in the evening, then scattered showers after midnight. Lows 65 to 70. Northeast winds 25 to 30 mph with gusts to 50 mph. Chance of rain 30 percent.

Thursday: Mostly sunny. Windy. Isolated showers in the morning. Highs 79 to 84. Northeast winds 25 to 30 mph with gusts to 50 mph. Chance of rain 20 percent.

Upcountry

Today: Windy. Mostly sunny with scattered showers. Highs around 59 at the visitor center to around 62 at the summit. East winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Windy. Partly cloudy with scattered showers. Lows around 48 at the visitor center to around 41 at the summit. East winds 10 to 30 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly sunny with scattered showers. Highs 55 to 66. East winds 15 to 25 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to around 62 near 5000 feet. East winds 15 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Windy. Scattered showers in the evening, then numerous showers after midnight. Lows around 69 near the shore to 46 to 52 near 5000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds 15 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Windy. Isolated showers in the afternoon. Highs 69 to 78. Northeast winds 15 to 30 mph with gusts to 50 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Windy. Lows 61 to 67. Northeast winds 15 to 30 mph with gusts to 50 mph.

Thursday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 69 to 78. East winds 20 to 25 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Windy. Highs 64 to 85. East winds 20 to 30 mph with gusts to 50 mph.

Tonight: Partly cloudy. Windy. Lows 56 to 72. East winds 20 to 30 mph with gusts to 50 mph.

Thursday: Mostly sunny. Windy. Highs 64 to 84. East winds 20 to 30 mph with gusts to 50 mph.

Detailed Forecast

Synopsis

A very strong high pressure system will set up north of the state today, leading to windy and gusty trade winds lasting into Friday. Periods of showers will favor typical windward and mountain areas. The stronger of these showers will briefly drift into drier leeward areas at times. Trade wind speeds will decrease to breezy levels by this weekend. A disturbance aloft will send high clouds over the islands today.

Discussion

A very strong high pressure system continues to build far north of the Hawaiian Islands today. This high center will weaken as it drifts south from Thursday through Sunday. Meanwhile a cutoff low continues to linger roughly 600 miles northwest of Kauai. A band of thunderstorms is forming this along the southeastern flank of the cutoff low. High level cirrus clouds will continue to drift over all islands through the evening hours, enhancing sunrise and sunset colors. Morning upper air balloon soundings at Lihue on the island of Kauai show temperature inversion heights in the 6,000 to 7,000 foot range. This inversion height along with the stronger trade winds should keep scattered to numerous showers over all windward areas through this evening. More isolated shower coverage remains in the forecast today for leeward areas.
Wet trade wind weather will continue into the weekend with higher shower coverage in the overnight to early morning hours. The upper level cutoff low northwest of the state will tend to add some instability into the mix over the western islands. Trade winds will blow across all islands at windy levels through Thursday. Wind advisories remain in effect for the windier zones of each island until Thursday evening. Some of these wind advisory areas may need to be extended into Friday. Maui and Big Island summits wind speeds will be lighter and remain below wind advisory thresholds during this event.
Trade winds will slowly ease over the weekend with breezy conditions. Mostly windward showers will favor the overnight to early morning hours. Slight drying trends will develop during the first half of next week as the low level ridge drifts over the islands ahead of a cold front farther to the north dives towards the island chain. Clouds and enhanced showers may briefly develop over all islands by the middle of next week as this weakening cold front moves quickly from north to south through the state.

Aviation

Breezy to windy easterly trade winds will persist, with clouds and showers favoring windward slopes and coasts. Expect periods with MVFR CIGs/VSBYs in showers, particularly overnight through the early morning hours as areas of moisture move through. Some showers will spill over into leeward areas of the smaller islands periodically.
AIRMET Sierra for mountain obscuration remains in effect for N through E sections of Oahu, Molokai, Maui, and the Big Island.
AIRMET Tango for moderate low-level turbulence over and southwest through northwest of mountains remains in effect for all islands.

Marine

The central pressure of a strong, slow-moving surface high far N of the islands will peak near 1052 mb today, driving strong to gale-force E trade winds. The high will drift S and gradually weaken from Thursday into Sunday, but wind speeds will be slow to diminish until later this weekend. A Gale Warning is posted for windier areas around Maui and the Big Island, and a Small Craft Advisory is in effect elsewhere. The Marine Weather Message (MWWHFO) contains the details.
A small to moderate, short-period (~10 seconds) N swell will peak today, then gradually diminish. The strong trade winds near and upstream of the islands are driving increasing short-period (8-10 seconds) wind waves toward the islands from the ENE, and latest near shore PacIOOS buoy observations indicate combined seas have increased to 10-12 feet. A High Surf Advisory has been issued for E facing shores of islands exposed to this trade wind swell, with details in the Coastal Hazard Message (CFWHFO). Elsewhere, a small, medium-period SSE swell is possible over the weekend.

Fire weather

Long-term conditions over leeward areas are drier than normal for this time of year. Though the Keetch-Byram Drought Index measured in Honolulu will remain well below the critical 600 mark this week, the strong and gusty trade winds will elevate the fire danger over the drier leeward areas through Friday.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST Thursday for windier areas of most Hawaiian Islands.
High Surf Advisory until 6 PM HST Friday for east facing shores.
Small Craft Advisory until 6 AM HST Saturday for all Hawaiian Waters outside of the Gale Warning areas.
Gale Warning until 6 AM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov