Photo Credit: Jeni Ji Cousins

West Side

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88. East winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 76. East winds up to 15 mph in the evening becoming light. Chance of rain 40 percent.

Thursday: Mostly sunny in the morning then becoming mostly cloudy. Scattered showers. Highs 81 to 87. Southwest winds around 10 mph. Chance of rain 30 percent.

South Side

Today: Sunny and breezy. Highs 86 to 91. Northeast winds 10 to 25 mph.

Tonight: Mostly clear. Lows around 69. North winds 10 to 15 mph.

Thursday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 85 to 90. Northwest winds around 10 mph. Chance of rain 20 percent.

North Shore

Today: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy with showers likely. Lows 67 to 73 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 85 to 91. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 74. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 84 to 90. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny with scattered showers. Highs around 61 at the visitor center to around 59 at the summit. East winds around 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 48 at the visitor center to around 45 at the summit. East winds up to 10 mph. Chance of rain 50 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 59 at the visitor center to around 57 at the summit. East winds 10 to 15 mph in the morning becoming light. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy with showers likely. Lows 67 to 73 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Lanai City

Today: Sunny. Isolated showers in the afternoon. Highs 76 to 83. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 66. East winds around 10 mph in the evening becoming light.

Thursday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 75 to 82. East winds around 10 mph. Chance of rain 50 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the morning. Highs 75 to 89. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 61 to 72. Northeast winds 10 to 15 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 74 to 88. Southeast winds around 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Moderate trade winds will decline through tonight, while continuing to deliver brief showers to windward areas. Winds will ease further and veer out of the east-southeast Thursday and Friday, allowing land and sea breezes to have an effect on island weather. Other than a few windward showers, the land breezes will lead to mostly clear skies during nights and mornings, while afternoon sea breezes will lead to clouds and a few showers over leeward and interior areas. Light to moderate trade winds are expected this weekend, with limited rainfall expected.

Discussion

A stable trade wind flow remains in place this morning, with moderate to locally breezy ENE winds being driven by a surface ridge far to the N, while a ridge aloft is supporting a subsidence inversion near 8000'. With the inversion at this height, incoming cumulus are growing vertically to the point that shower frequency and coverage have increased somewhat overnight, with showers primarily moistening windward areas. As cloud-top heating increases through the morning, shower coverage will follow the typical diurnal trend and diminish.
Trade winds will gradually decline through tonight as a developing cutoff low 900 miles N of Kauai weakens the surface ridge, and pushes it southward. Winds will weaken and veer to the SE, most notably over the western end of the state, as the low tracks SW and gradually weakens, with light to moderate E-SE winds prevailing into the weekend. Long term guidance appears to be trending toward weaker winds into next week as another low passes well N of the area, but confidence is low due to inconsistencies in run-to-run model output.
Even with the diminishing winds and the potential for land breeze development, a few showers are expected to move ashore over windward areas, mainly at night. Meanwhile daytime sea breezes are also expected to produce clouds and a few showers over leeward areas each afternoon. The ridge aloft will be slightly eroded by the low passing to the NW, leading to a brief decrease in stability Thursday night and Friday. While we cannot rule out a briefly heavy shower, mainly in the afternoon, odds favor moderate rainfall through the forecast period.

Aviation

The background trade wind flow is expected to weaken slightly later today and tonight. The atmosphere remains relatively stable, but pockets of increased moisture are moving in from the east. As a result, scattered to broken low clouds with embedded scattered showers are moving into the windward sections of most of the islands early this morning. This is likely producing brief periods of MVFR conditions along some windward facing slopes. Otherwise, VFR conditions will likely prevail across most of the island chain through this morning.
The somewhat lighter background trade wind flow may allow a few more clouds to form across some leeward sections this afternoon. Elsewhere, expect modest cloud cover and trade showers along windward sections from this afternoon into this evening, with only brief periods of MVFR conditions expected.
No AIRMETs are currently in effect, and none are anticipated.

Marine

A surface ridge north of the state will weaken over the next few days as low pressure develops northwest of the area. This will cause winds to become lighter and become more east-southeasterly. The low will move away to the west late Saturday and Sunday with the ridge restrengthening to our north, resulting in returning trade winds.
The current small northwest swell will lower through Thursday. A new long-period south swell will slowly fill in today, peak tonight through early Thursday, then lower late Thursday through Friday. Surf heights may approach low-end advisory levels during the peak of this swell. A slightly smaller south swell is expected over the weekend. Short-period choppy surf along east facing shores will become rather small over the next several days as trade winds diminish over and upwind of the state.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov