Hilo

Today: Mostly cloudy. Occasional showers in the morning, then showers likely in the afternoon. Highs around 83 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with showers likely. Lows around 68 near the shore to around 54 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 70 percent.

Sunday: Partly sunny with scattered showers. Highs around 84 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 69 to 75 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 40 percent.

Sunday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Partly sunny with scattered showers. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny with scattered showers. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then mostly clear after midnight. Lows around 70 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph shifting to the northeast after midnight. Chance of rain 40 percent.

Sunday: Breezy. Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy. Occasional showers in the morning, then showers likely in the afternoon. Highs around 83 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with showers likely. Lows around 68 near the shore to around 54 at 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 70 percent.

Sunday: Partly sunny with scattered showers. Highs around 84 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to 70 to 76 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 70 to 75 near the shore to 51 to 58 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Sunday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to 70 to 76 above 4000 feet. North winds up to 15 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