Hilo

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 65 to 71 near the shore to 53 to 60 at 4000 feet. Northeast winds up to 15 mph shifting to the northwest after midnight. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 72 near the shore to 52 to 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Haze through the night. Lows around 73 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Haze through the day. Highs around 86 near the shore to 68 to 73 near 5000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.

Thursday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Haze. Lows around 74 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Breezy. Partly cloudy with isolated showers. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 65 to 86. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Thursday Night: Partly cloudy with isolated showers. Lows 64 to 71 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Kohala

Tonight: Breezy. Partly cloudy with isolated showers. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 65 to 86. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Thursday Night: Partly cloudy with isolated showers. Lows 64 to 71 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Big Island

Tonight: Partly cloudy. Breezy and haze. Lows around 75 near the shore to around 56 near 5000 feet. Northeast winds up to 20 mph.

Thursday: Sunny in the morning then becoming partly sunny. Breezy and haze. Highs around 87 near the shore to around 70 near 5000 feet. East winds up to 25 mph.

Thursday Night: Partly cloudy. Haze. Lows around 75 near the shore to around 56 near 5000 feet. East winds 10 to 15 mph shifting to the northeast after midnight.

Puna

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 65 to 71 near the shore to 53 to 60 at 4000 feet. Northeast winds up to 15 mph shifting to the northwest after midnight. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 72 near the shore to 52 to 59 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Isolated showers in the evening. Haze through the night. Lows around 74 near the shore to 52 to 57 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Haze. Highs 85 to 91 near the shore to 67 to 76 above 4000 feet. Northeast winds up to 15 mph shifting to the north in the afternoon. Gusts up to 35 mph.

Thursday Night: Mostly clear. Haze. Lows around 74 near the shore to 52 to 57 above 4000 feet. Northeast winds up to 10 mph in the evening becoming light.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will persist for the next few days, decreasing Friday and the weekend, and likely restrengthening early next week. Through Friday, modest shower activity will be focused over windward areas, and with the exception a few showers on the South Kona slopes each afternoon, leeward areas will be mostly dry. An increase in mainly windward rainfall is possible this weekend into Monday.

Discussion

Somewhat dry and locally breezy trade wind weather continues. Broad surface high pressure far north of the islands continues to drive moderate to locally breezy easterly trades, though a trough well west of Kauai is keeping winds more easterly than normal. A strong ridge aloft centered just south of the state is maintaining very stable conditions with an inversion based below 6,500 ft, and there is no sign of organized moisture in the trade wind flow. As a result, little rain has fallen over most windward areas today, and while extensive cloud cover on the Kona slopes of the Big Island may produce an isolated shower this afternoon, other leeward areas will remain dry.
Little change is expected through Friday. Stable and somewhat dry conditions will hold, favoring below normal rainfall windward and continued dry over most leeward areas. Even on the Kona slopes which have a summertime rainfall maximum, shower activity should remain suppressed. Trade winds will shift back out of a more typical east-northeast direction on Thursday as the trough west of Kauai moves away, and due to the local pressure gradient relaxing a bit, trades may ease slightly, though it will hardly be noticeable until Friday.
Trade winds will ease to gentle to moderate strength this weekend, and shower chances will increase as a weak surface trough moves near or over the islands. The trough, currently sitting about 600 miles east of Hilo, will be dissipating as it reaches the islands, but its shallow associated moisture may fuel increased humidity and higher chances for mainly windward showers on the Big Island and Maui County late Saturday and Sunday, moving to Oahu and Kauai Sunday and Monday.
Ensemble and recent operational guidance show strengthening trade winds early next week. The main source of uncertainty is the possible development of disturbances in the tropics.

Aviation

Moderate to breezy trade winds will maintain with winds backing easterly Friday from the more east southeasterly today. VFR conditions will prevail tonight with brief mountain obscurations and isolated showers windward.
No AIRMETs are currently in effect or expected tonight.

Marine

A high pressure ridge north of the Hawaiian Islands will continue to produce moderate to locally strong easterly trade winds across the region through Thursday. The Small Craft Advisory has been scaled back to the typical windy waters around Maui County and Big Island. The ridge will gradually weaken Friday, easing wind speeds into the gentle to fresh range and holding into early next week.
Pulses of background long period south and southwest swells will keep surf above flat levels along south and west facing shores through the weekend. Back to back gale force lows east of New Zealand are expected to send a series of small, long period south swells that could begin to fill in late Tuesday and produce above average surf along south facing shores through the second half of next week. In addition, tropical disturbances tracking south of the state from east to west Sunday into next week may also send a small, short to medium period south to southeast swells.
Small choppy surf along east facing shores will trend down slightly as winds locally and upstream ease.
Afternoon peak monthly high tides associated with the lunar cycle, combined with water levels that are running higher than predicted may cause minor flooding for shorelines and low-lying coastal areas mainly around Maui County and the Big Island. A Coastal Flood Statement remain in effect for these areas through Thursday.

Fire weather

A stable, somewhat dry, and locally breezy trade wind flow will persist for the next several days. Under this typical late July pattern, expect elevated, though not critical, fire weather conditions over drier leeward and some interior areas. A decrease in winds and increase in humidity are possible this weekend as an area of shallow moisture moves near or over the islands.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov