Photo Credit: Jeni Ji Cousins

West Side

Today: Sunny and breezy. Isolated showers in the morning. Highs 81 to 88. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 66 to 73. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 81 to 88. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs 85 to 90. North winds up to 20 mph.

Tonight: Mostly clear. Lows around 67. North winds up to 15 mph.

Sunday: Sunny. Highs 85 to 90. North winds up to 15 mph.

North Shore

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 80 to 86 near the shore to 61 to 66 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 63 to 70 near the shore to around 51 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 70 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to 62 to 67 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 71. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs around 88. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Sunny. Scattered showers in the morning. Highs around 59 at the visitor center to around 55 at the summit. East winds up to 10 mph in the morning becoming light. Chance of rain 50 percent.

Tonight: Mostly clear with scattered showers. Lows around 46 at the visitor center to around 42 at the summit. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 60 at the visitor center to around 56 at the summit. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 80 to 86 near the shore to 61 to 66 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 63 to 70 near the shore to around 51 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 70 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to 62 to 67 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 72 to 83. Northeast winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows around 66. Northeast winds up to 20 mph decreasing to up to 10 mph after midnight.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 83. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Sunny and breezy. Highs 77 to 87. East winds 10 to 20 mph.

Tonight: Breezy. Mostly clear with isolated showers. Lows 61 to 72. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 78 to 88. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

High pressure north-northeast of the islands will keep moderate to locally breezy trade winds in place through the middle of next week. Clouds and showers will favor windward and mauka areas mainly at night and through the early morning hours, with a stray shower reaching leeward communities from time to time. Lighter winds may lead to sea and land breezes late next week, along with more interior and leeward shower development.

Discussion

Currently at the surface, a 1031 mb high is centered around 1650 miles north-northeast of Honolulu while a weak trough of low pressure is located around 600 miles north-northeast of Kauai. The gradient across the islands is producing moderate to locally breezy trade winds early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions in windward and mauka areas, with clear to partly cloudy skies in most leeward locales. Radar imagery shows scattered showers moving into windward areas of the smaller islands, with a few of these showers spilling into leeward communities. Meanwhile, numerous showers are affecting windward Big Island. The main focus during the next 7 days continues to revolve around trade wind trends and rain chances.
The trough of low pressure north-northeast of the islands will slide westward well to the north of the state during the next couple days, while the high to the distant north-northeast strengthens. The high will then remain nearly stationary through the middle of next week. Overall, very little change in trade wind strength is expected through early Wednesday, with moderate to locally breezy conditions prevailing. We should see a noticeable decrease in the trades beginning late Wednesday and continuing into Friday as the remnant trough of former tropical cyclone Estelle passes by just north of the islands. During this period of lighter trades, some localized land and sea breezes will be possible.
As for the remaining weather details, some deeper moisture will affect the Big Island today, and as a result, shower coverage will be the highest here. Across the smaller islands, after some early morning showers, fairly dry and sunny weather will dominate today. We should see dry conditions initially this evening, followed by a diurnal increase in showers overnight, primarily affecting windward and mauka areas.
Fairly typical trade wind weather will then prevail Sunday through the middle of next week. Showers will continue to be most prevalent at night and during the early morning hours, favoring windward and mauka areas as they typically due. We could see an increase in trade wind showers late next week as the remnant trough of Estelle moves north of the island chain. The latest trends indicate the Big Island and east Maui would see the most noticeable increase in trade wind showers, while the rest of the state would see more of a convective shower regime due to sea breeze influences, favoring interior and leeward showers in the afternoon and evening hours. There remains enough uncertainty in the later portions of the forecast to shy away from climatology for now, so we will continue to monitor model trends closely as the remnants of Estelle approach the islands from the east.

Aviation

Moderate to locally breezy trade winds will carry scattered showers off the Pacific towards the islands. Current satellite as of 3am Saturday, reveals a thick cloud band blanketing much of windward Big Island. AIRMET Sierra for mountain obscuration is now in effect from Upolu Point to Volcano. Conditions should improve around midday.
For leeward Big Island, light sea breezes will encourage cumulus development over the island's interior in the afternoon and evening hours. Locally heavy showers possible along the lower slopes.
Across the smaller smaller islands, Isolated MVFR CIG or VIS is possible in passing showers, especially along east and northeast slopes and coasts. Otherwise VFR conditions will prevail all areas.

Marine

Moderate to fresh trade winds will persist into the new work week as high pressure remains nearly stationary far north-northeast of the state. Trade winds have once again strengthened enough that a Small Craft Advisory (SCA) has been issued for the typically breezy zones around Maui County and the Big Island through Sunday afternoon. Too, the SCA may need to be extended beyond that time frame as trades are expected to remain somewhat elevated through the middle of next week.
Surf along south facing shores will remain at summertime background levels through today, followed by a small pulse of south swell Sunday and Monday. A larger, long-lived south swell will arrive Thursday and may push south shore surf to the High Surf Advisory level Friday and into next weekend.
East shore surf will fall from around seasonal heights to slightly below average this weekend, though some faint long-period swell from former Tropical Cyclone Estelle may appear. Short period trade wind swell will then build back to near average as elevated trade winds are expected to persist into next week. Typical, nearly flat summertime conditions will continue for north shores

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov