Photo Credit: Tyler Rooke

West Side

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 83 to 90. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 65 to 72. Light winds. Chance of rain 40 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 83 to 90. East winds around 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.

South Side

Today: Mostly sunny. Highs 87 to 92. North winds up to 10 mph.

Tonight: Mostly clear. Lows around 66. Light winds.

Tuesday: Mostly sunny. Isolated showers in the afternoon. Highs 87 to 92. Northeast winds around 10 mph. Chance of rain 20 percent.

North Shore

Today: Mostly cloudy with scattered showers. Highs 82 to 88 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 69 near the shore to around 52 near 5000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 82 to 88 near the shore to 64 to 69 near 5000 feet. East winds around 10 mph. Chance of rain 50 percent.

Central Maui

Today: Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs around 90. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 64 to 70. East winds around 10 mph. Chance of rain 20 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs around 90. Northeast winds around 10 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 64 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 49 at the visitor center to around 46 at the summit. Light winds. Chance of rain 50 percent.

Tuesday: Mostly sunny with scattered showers. Highs around 62 at the visitor center to around 58 at the summit. Light winds. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy with scattered showers. Highs 82 to 88 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 69 near the shore to around 52 near 5000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 82 to 88 near the shore to 64 to 69 near 5000 feet. East winds around 10 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 75 to 84. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows around 67. Light winds.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs 75 to 84. Light winds. Chance of rain 30 percent.

Kaunakakai

Today: Partly sunny. Isolated showers in the morning. Highs 79 to 89. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 60 to 71. East winds around 10 mph. Chance of rain 20 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 89. East winds around 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Expect light to moderate trade winds as a large trough far north of the state breaks down the ridge and decreases the trade winds across the region. A hybrid wind pattern will develop starting today and lasting into Wednesday with leeward land and sea breezes along with lighter easterly trade winds lingering over windward areas. The high pressure ridge builds back in north of the islands on Wednesday afternoon with strengthening trade winds into the moderate to locally breezy range from Wednesday night onward.

Discussion

The early morning satellite picture shows a few bands of stable stratocumulus clouds drifting into each island on the weakening trade winds. A low level trough is slowly approaching the Big Island from the east and will pass south of most islands on Tuesday and Wednesday. This trough may bring a slight increase in showers over the eastern islands as it passes south of the state. A few high cirrus clouds associated with a weak subtropical jet stream will continue to drift over the state.
A long wave trough far north of the region is breaking down the subtropical ridge north of the islands and decreasing the trade wind flow into Wednesday. As these large scale trade winds weaken, local scale land and sea breezes will strengthen. This translates to a hybrid wind pattern for the next three days with land and sea breezes over leeward areas and light trade winds over the windward zones. Clouds and a few showers will tend to favor afternoons along convergence areas between the trade winds and sea breezes over leeward areas and island interior sections. Brief showers are also possible in this hybrid wind pattern over windward zones in the overnight to early morning hours. A minor wrinkle to this forecast is a passing low level trough drifting south of the state on Tuesday and Wednesday. Moisture around the eastern side of this trough may slightly increase clouds and shower activity over the Big Island and Maui. Chances for thunderstorms pick up over the higher elevations of the Big Island from Wednesday afternoon to evening as surface heating may trigger deeper convection or thunderstorms in the unstable layer above the trade wind inversion height.
The long wave trough will weaken and drift further northeastward by Wednesday, allowing the ridge build back in north of the island chain and strengthen the trade winds across the region. We will transition back to a trade wind pattern on Wednesday as the high pressure ridge builds back in north of the region. Expect moderate to locally breezy trade winds from Thursday through Sunday with diminishing land and sea breezes. Clouds and brief passing showers will trend back towards the windward and mountain sections of each island.

Aviation

Light to locally moderate trade winds will persist through twenty-four hours and beyond. Ragged bands of stratocumulus and light showers will favor east and northeast facing slopes and coasts. Leeward sea breezes will encourage cumulus development over Interior Big Island and the Kona Coast this afternoon.
A trade wind inversion around 07 kft will inhibit daytime cumulus development over island interiors. Nevertheless, brief moderate to heavy showers are still expected over interior Big Island in the late afternoon and early evening.
Increased shower activity expected across across windward Big Island and Maui beginning late this evening. Mountain obscuration could become a concern for portions of the Big Island tonight. Otherwise, VFR conditions will prevail except for brief MVFR conditions in passing showers.

Marine

Moderate to fresh easterly trades will continue to slowly ease today and hold in the gentle to moderate category tonight into Wednesday, as the ridge north of the state weakens. This pattern will translate to localized overnight land breezes and daytime sea breezes near the coasts beginning this afternoon. As typically observed with these patterns, pockets of fresh breezes near some coasts can lead to choppy conditions due to a combination of daytime heating and terrain-induced accelerations. A return of fresh to strong easterly trades is expected during the second half of the week as the ridge builds to the north, which may lead to Small Craft Advisory conditions for the windier waters and channels over the eastern end of the state.
After a quiet spell through the first half of August, a more active pattern unfolding within Hawaii's swell window around New Zealand will lead to an upward trend along south facing shores beginning next weekend. Until then, expect small conditions to persist with mainly a combination of background south and southeasterly energy moving through.
Surf along east facing shores will remain small through the first half of the week as the aforementioned trades ease. A return of choppy/short-period surf is expected by the end of the week as the trades fill back in from east to west.
A small, short period north swell will fill in today, hold tonight, then subside tomorrow, providing a small bump along north facing shores. Another small, short period north swell may fill in Wednesday night through Thursday, providing another small boost to north facing shore surf. Otherwise, flat summertime conditions will prevail.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov