Hilo

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 65 at 4000 feet. East winds 10 to 15 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows 62 to 69 near the shore to 52 to 58 at 4000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

Thursday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 82 near the shore to around 67 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kona

Today: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 83 near the shore to around 68 near 5000 feet. South winds around 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows around 70 near the shore to 47 to 55 near 5000 feet. Light winds becoming southeast around 10 mph after midnight. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. West winds around 10 mph in the morning becoming light. Chance of rain 40 percent.

Waimea

Today: Partly sunny with scattered showers. Highs around 77 near the shore to 69 to 75 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 63 near the shore to 53 to 61 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 65 to 83. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny with scattered showers. Highs around 77 near the shore to 69 to 75 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 63 near the shore to 53 to 61 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 65 to 83. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 81 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 70 near the shore to around 50 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the afternoon. Highs around 81 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 65 at 4000 feet. East winds 10 to 15 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows 62 to 69 near the shore to 52 to 58 at 4000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

Thursday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 82 near the shore to around 67 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny. Isolated showers in the morning. Highs around 82 near the shore to 64 to 71 above 4000 feet. Southeast winds around 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 66 to 72 near the shore to 48 to 54 above 4000 feet. East winds around 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Highs 79 to 85 near the shore to 64 to 70 above 4000 feet. Southeast winds around 10 mph shifting to the northeast in the afternoon.

Detailed Forecast

Synopsis

A ridge north of the main Hawaiian Islands will maintain a breezy trade wind pattern with passing showers focused over windward and mauka areas through the remainder of the week. Heading into the weekend, and increase in rainfall is likely with additional moisture and a more unstable airmass overhead.

Discussion

As expected, very little change in the forecast through the day Friday. Beyond that, some modifications have been made to account for the latest model consensus for the weekend weather.
Thunderstorms continue to be found along a trough about 650 miles northwest of Kauai. And high pressure to the northeast of the islands continues to bring moderate to locally breezy trade winds to the region. Passing showers being carried in on the trade wind flow continue to be focused over windward and mauka areas.
The surface trough to the northeast has an upper level trough associated with it, and this feature will bear watching as it tracks to the east. It is expected to reach the main Hawaiian Islands this weekend, where it will likely help to enhance shower activity. Remnant moisture from the surface feature is expected to move in from the north over the islands, and the upper level feature will bring in cold upper level temperatures Saturday night. Based on climatological values, the colder 500 and 700 mb temperatures and the increased moisture will lead to enhanced showers, and there is some support for thunderstorms. Model thunderstorm probability remains low, so at this time, will continue to monitor the situation to see what the model trends are. Have boosted the QPF values in the forecast for Friday night through Sunday in keeping with the enhanced shower activity expected with the upper trough.
Some high clouds are starting to make their way over the islands, and more are expected as the week wears on with the system to the west moving closer to the islands. This will likely lead to more and thicker high clouds during the second half of the week.

Aviation

Locally breezy trades will focus clouds and showers over windward and mauka slopes through the forecast period. VFR will prevail over the smaller islands with nothing more than very brief MVFR possible within any heavier showers. For Windward Big Island, the land breeze brought enough clearing of earlier widespread clouds and showers to allow AIRMET Sierra for mountain obscuration to expire, however pockets of showers and MVFR continue over some downslope areas.
Conditions remain borderline for moderate lee turbulence. Will continue to monitor and update AIRMET TANGO if necessary.

Marine

Surface high pressure located far northeast of the state is producing a tight enough pressure gradient back toward the islands to maintain moderate to locally strong trade winds. These wind magnitudes will persist into the weekend with a slight strengthening of trades across more exposed windward waters and western channels Thursday through Saturday. A Small Craft Advisory (SCA) is now in effect through Thursday night for the typically windier waters surrounding Maui County and south of Big Island.
Moderate to fresh trades over and upstream of the islands the past several days has generated a medium period east swell along with choppy wind generated, shorter period waves. This fetch will be gradually fading through the second half of the week that will have slightly elevated surf along many eastern exposures lowering the next couple of days. A series of very small northwest swells moving around the islands will keep north shore surf from going completely flat this week. The recent small bump in south swell will continue its slow decline today. The next round of slightly higher south swell is expected to arrive this weekend.

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