Hilo

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 82 to 87 near the shore to 66 to 75 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 62 to 69 near the shore to around 55 at 4000 feet. North winds up to 10 mph. Chance of rain 40 percent.

Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to 65 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny. Isolated showers in the afternoon. Highs 83 to 90 near the shore to around 72 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 68 to 73 near the shore to 48 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 88 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 69 to 89. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 61 to 67 near the shore to 53 to 61 near 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Friday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 68 to 88. East winds 10 to 15 mph. Chance of rain 40 percent.

Kohala

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 69 to 89. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 61 to 67 near the shore to 53 to 61 near 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Friday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 68 to 88. East winds 10 to 15 mph. Chance of rain 40 percent.

South Big Island

Today: Breezy. Mostly sunny with isolated showers. Highs around 86 near the shore to around 70 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 71 near the shore to around 50 near 5000 feet. Northeast winds 10 to 15 mph.

Friday: Sunny. Highs 82 to 87 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph.

Puna

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 82 to 87 near the shore to 66 to 75 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 62 to 69 near the shore to around 55 at 4000 feet. North winds up to 10 mph. Chance of rain 40 percent.

Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to 65 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny. Highs 82 to 91 near the shore to 69 to 76 above 4000 feet. North winds up to 15 mph.

Tonight: Mostly clear. Lows around 71 near the shore to 48 to 55 above 4000 feet. Northeast winds up to 10 mph.

Friday: Sunny. Highs 80 to 89 near the shore to 67 to 74 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Moderate trade winds will prevail across the state through the weekend, with some afternoon sea breeze development possible over sheltered leeward areas. Dry and stable conditions will limit shower coverage and intensity through Friday, with rainfall chances increasing some this weekend. Showers that do develop will favor mainly windward and mountain locations, especially during overnight and morning hours.

Discussion

Current radar trends show the areal coverage of showers, which had developed overnight, diminishing this morning and remaining largely focused along windward areas. Satellite trends show a similar pattern this morning, with limited clouds drifting across the islands, also favoring windward locations. Expect a similar diurnal transition today as Tuesday, with limited clouds and showers focused along windward areas and some sheltered leeward locations. Conditions this morning are already much drier and more stale when compared to 12z Tuesday soundings, with PHLI showing almost 800 j/kg sfc based cape at 12z Tuesday compared to 0 cape this morning, with a PW value of 1.4″ 12z Tuesday compared to 1.1″ this morning.
Stable conditions are expected through the remainder of the week, as surface and upper level ridging build over the region, while a weakening frontal boundary slowly sags southward toward the islands and deteriorates. This pattern will promote gentle to moderate background trade wind flow, an overall dry airmass, along with lowering inversion heights, while the depth of moisture remains around or below 7k ft through Friday. As a result, shower activity will remain limited across the state, primarily favoring windward and mountain locations during the overnight through early morning periods each day. The lighter background winds will also enhance sea breeze clouds and isolated shower potential across sheltered leeward and interior sections again each afternoon. The leeward clouds and showers will diminish each evening during the transition to land breeze circulations. However expect the overall sea breeze interactions to remain limited to a few sheltered locations, such as Oahu where shower activity increased Tuesday afternoon over Oahu's Waianae mountain range and leeward coast, and possibly across leeward sections of Kauai.
The frontal boundary lingering north of the islands will further deteriorate Friday night and Saturday, as the surface ridge tries to reestablish itself north of state. This will introduce some increase in easterly trade wind flow across the islands through the weekend. Additionally, a weakly organized upper level trough will quickly drift westward across the islands this weekend, increasing moisture depths and inversions slightly. This pattern, combined with some increase in easterly trades, will enhance the areal coverage and intensity of showers across the islands into Monday, focused mostly across windward locations. The upper low will exit west of Kauai early next week, with a drier airmass filtering back across the region from the east, reducing the areal coverage of showers in a developing typical trade wind flow weather pattern.

Aviation

Moderate trade winds are expected to prevail across the state today. In some sheltered leeward areas, sea breezes will develop this afternoon, increasing interior and leeward cloud coverage with a few showers also possible. However, dry and stable air has settled in place over the state and will linger for the next several days. This will help keep shower coverage and intensity in check.
Overnight, land breezes will return to leeward locations clearing any lingering cloud cover and shower activity. As light to moderate trade wind flow continues, clouds and showers will favor windward and mountain areas during the early morning hours.
VFR conditions are expected to prevail throughout the next 24 hours and beyond with only brief MVFR conditions possible in showers. There are currently no AIRMETs in effect, and none are expected today or tonight.

Marine

A weak ridge north of the area will keep gentle to moderate trade winds across the islands today. The ridge will strengthen slightly tomorrow, resulting in more moderate trade winds into next week. Wind speeds are not expected to reach the Small Craft Advisory level threshold through at least this weekend.
No significant surf, along any coastline is expected into next week. Background medium to long period south swells will keep small surf along the south facing shores. The next best chance for larger south swell activity may begin to develop in the first week of September from a low setting up just east of New Zealand. This next pulse of south swell energy may reach the south shores of Hawaii in about a week and a half.
Surf along east facing shores will build a little this weekend, but still staying in the average to just below average category.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov