Photo Credit: Pamela Goguen Lynch

West Side

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 80 to 90. East winds up to 15 mph shifting to the west in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers. Lows 70 to 77. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 80 to 89. East winds 10 to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Scattered showers in the afternoon. Highs around 90. Northwest winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 68 to 77. Northeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Sunny. Isolated showers in the afternoon. Highs around 90. North winds around 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

North Shore

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 88 near the shore to around 69 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Lows around 72 near the shore to 50 to 56 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 88 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Central Maui

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 91. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 68 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the afternoon. Highs 85 to 91. East winds around 10 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 63 at the visitor center to around 58 at the summit. East winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Lows around 49 at the visitor center to around 46 at the summit. East winds around 10 mph. Chance of rain 40 percent.

Tuesday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 64 at the visitor center to around 58 at the summit. East winds around 10 mph. Chance of rain 40 percent.

East Maui

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 88 near the shore to around 69 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Lows around 72 near the shore to 50 to 56 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 88 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Lanai City

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 82. Northeast winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers early in the evening, then isolated showers late in the evening. Lows around 67. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Tuesday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 82. Northeast winds up to 10 mph. Chance of rain 40 percent.

Kaunakakai

Today: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 72 to 92. East winds 10 to 15 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Lows 60 to 76. East winds 10 to 15 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 72 to 92. East winds 10 to 15 mph. Chance of rain 30 percent.

Detailed Forecast

Synopsis

A weak surface ridge north of the area will maintain light east to southeast background winds to begin the week. The ridge and trade winds will gradually strengthen this week. Clouds and showers will increase across leeward areas and island interiors through Tuesday, before strengthening trades redirect showers across windward and mauka areas into the weekend.

Discussion

Radar trends this morning show scattered showers drifting across the state, in advance of drier air trying to move eastward into the region. Some of the most persistent showers this morning remain over the western end of the state, where slightly deeper moisture and better instability linger. Overall, rainfall intensity and areal coverage of showers should be more limited today when compared to Sunday, as drier and more stable air slowly move into the region.
The first part of this week will see a slow transition from light east-southeast trades and diurnal sea and land breeze circulations, towards strengthening trades. An area of high pressure well northeast of the state and surface boundary dropping slowly southward to within about 500 miles north-northeast of this islands, will maintain a weak pressure gradient and light background trade wind flow across the islands through the first half of the week. This will allow for the continued development of afternoon and early evening sea breeze showers across leeward areas and island interiors through Tuesday. The airmass is forecast to be drier to begin the work week across much of the central and eastern islands, when compared to Sunday. Moisture depths are forecast to drop from between 9k-11k feet as seen on Sunday, to below 8k feet today through Tuesday. Additionally, precipitable water values are also forecast to drop, from the values around 1.60 inches on Sunday, to around 1.30 inches or less by this afternoon. This drier airmass potential for today, matches well with the latest satellite estimates showing layer blended precipitable water values around 1.30 inches or less, already streaming toward the region from the east. This drier air should limit the areal coverage of showers through Tuesday, though expect scattered showers to once again develop across leeward areas and island interiors.
However, the surface boundary dropping southward toward the state, will increase moisture and enhance rainfall chances over the westerns islands into Wednesday. The southward sagging frontal boundary is forecast to erode by midweek, while the ridge north of the state begins to firmly reestablish itself. This pattern will begin to increase the easterly trades on Wednesday, before further strengthening to locally breezy by the weekend. There remains some model differences with respect to the exact timing of when trades finally strengthen across the islands. Though expect the chances for sea breeze showers will diminish across leeward areas Tuesday, with showers becoming redirected to mainly windward areas in a typical trade wind weather pattern through the weekend.

Aviation

Winds will be light to moderate through tonight, tending east to east-southeast during the period, as a ridge persists a couple hundred miles north of the islands. Under this regime, nighttime land breezes and daytime sea breezes will develop. Cloudiness has been gradually dissipating overnight and will again build up over the isles during late morning and the afternoon, with accompanying showers and MVFR conditions expected in various locales with the lower clouds and precipitation.
No AIRMETs are in effect.

Marine

Expect light to moderate trade winds through the first half of this week as a low far to our northwest moves farther away and high pressure builds to our north. Wind speeds may approach Small Craft Advisory threshold during the second half of the week.
South swell and surf will continue to decrease through today, leaving only background swell by the middle of the week. Minimal energy is expected from the south during the second half of the week. A small north-northwest swell is forecast to arrive Wednesday followed by a slightly bigger pulse over the weekend. Light trade winds will keep small surf in the forecast along east facing shores through at least Wednesday with a slight increase towards the end of the week as the trades strengthen.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov