Photo Credit: James Grenz

Hilo

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to around 73 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 69 near the shore to around 54 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to around 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 82 to 87 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 72 to 77 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 82 to 87 near the shore to around 70 near 5000 feet. Southwest winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Waimea

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 82 near the shore to 76 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 69 near the shore to 57 to 62 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 20 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs around 82 near the shore to 76 to 81 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 82 near the shore to 76 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 69 near the shore to 57 to 62 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 20 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs around 82 near the shore to 76 to 81 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Breezy. Highs around 86 near the shore to around 71 near 5000 feet. East winds up to 20 mph.

Tonight: Partly cloudy. Lows 68 to 74 near the shore to around 53 near 5000 feet. East winds up to 15 mph in the evening becoming light.

Friday: Mostly sunny. Breezy. Highs around 86 near the shore to around 71 near 5000 feet. East winds up to 20 mph.

Puna

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to around 73 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 69 near the shore to around 54 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to around 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Breezy. Highs 83 to 88 near the shore to 70 to 76 above 4000 feet. Northeast winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows 72 to 77 near the shore to 51 to 58 above 4000 feet. East winds up to 20 mph.

Friday: Sunny in the morning then becoming partly sunny. Highs 83 to 88 near the shore to 70 to 76 above 4000 feet. Northeast winds up to 15 mph.

Detailed Forecast

Synopsis

Breezy easterly trade winds will continue today, then trend down tonight into the weekend as the ridge weakens to the north. Shower coverage will remain limited, with the best chances being overnight through the early mornings over windward and mountain locations. A modest increase in moisture combined with an upper disturbance moving into the area will support a brief increase in shower coverage through the second half of the weekend. A return of dry conditions and strong easterly trade winds is expected early next week.

Discussion

Guidance remains in good agreement through Saturday and depicts a weakness forming in the ridge due to a front far north of the area. This will allow the pressure gradient that has remained strong for much of July to begin to relax later today through tonight. The hi-res FV3 and ARW solutions reflect this trend and show the breezy easterly trades lowering to moderate levels tonight into Friday. The lighter trades combined with a suppressed environment associated with deep layer ridging in the area and a strong subsidence inversion will limit rainfall chances. The best chance for a few light showers will be over windward and mountain locations overnight through early mornings, with little to none expected over our parched leeward areas.
A transition period is anticipated Sunday through early next week as the ridge strengthens to the north and Hurricane Dora enters the central Pacific on a westward track. Some moisture is forecast to pool northward into the area as an upper disturbance settles southward over the region Sunday night into Monday. This moisture combined with trades potentially becoming strong as the gradient tightens will support a brief period with higher rainfall chances. Thereafter, very dry and windy conditions (low inversion w/ 50 kt winds at 850 mb) are expected across the state as upper heights rise and Dora passes well to the south.

Aviation

High pressure north of the islands will maintain moderate to locally breezy trade winds through tonight before the winds start to ease on Friday. Expect AIRMET Tango to remain posted for mountain lee turbulence through tonight.
Showers will continue to favor windward and mauka area, with greater coverage and intensity through the early morning hours. Expect mainly VFR conditions, with brief periods of MVFR cigs and vsbys under passing showers.

Marine

High pressure far north of the state will drive fresh to locally strong trade winds. The Small Craft Advisory (SCA) has been extended through tonight for the typically windy waters around Maui County and the Big Island. The high will subtly weaken and shift westward Friday into the weekend, decreasing trades slightly. Beginning Sunday night, trade winds will ramp up quickly to strong to near-Gale speeds through mid-week as Dora nears and passes south of the Hawaiian Islands.
A small, long-period southwest swell will keep surf heights elevated through tonight, then decline into the weekend. Choppy surf will continue along east facing shores before slightly declining by the end of the week. There is potential for a near- advisory east swell generated by Hurricane Dora that could impact east facing shores early next week. This east swell remains highly reliant on Dora's track, intensity, and the size of the fetch. This swell will gradually shift out of the southeast then south with a lowering period as Dora tracks close to, then south of the islands during the first half of next week.
Statewide water levels continue to run around a quarter to half of a foot higher than predicted, in combination with some of the highest tides of the year (near 3 feet). Minor coastal flooding is expected in the typical vulnerable low lying coastal areas and beaches during the peak high tide this afternoon. Please refer to the latest Coastal Flood Statement (CFWHFO) for more details. Tides are forecast to slowly lower thereafter, so coastal flooding will no longer be a threat.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov