Hilo

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 84 near the shore to 65 to 72 at 4000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 50 to 57 at 4000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Highs 77 to 83 near the shore to 65 to 71 at 4000 feet. Light winds. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 81 to 87 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 67 to 72 near the shore to 43 to 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 81 to 87 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 61 to 84. North winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 61 near the shore to 51 to 59 near 3000 feet. Light winds. Chance of rain 40 percent.

Wednesday: Mostly sunny in the morning then becoming mostly cloudy. Scattered showers. Highs 62 to 84. Light winds. Chance of rain 50 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 61 to 84. North winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 61 near the shore to 51 to 59 near 3000 feet. Light winds. Chance of rain 40 percent.

Wednesday: Mostly sunny in the morning then becoming mostly cloudy. Scattered showers. Highs 62 to 84. Light winds. Chance of rain 50 percent.

South Big Island

Today: Sunny. Isolated showers in the afternoon. Highs around 82 near the shore to around 66 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers after midnight. Lows around 69 near the shore to around 48 near 5000 feet. North winds up to 15 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 82 near the shore to around 66 near 5000 feet. Northeast winds up to 10 mph in the morning becoming light. Chance of rain 50 percent.

Puna

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 84 near the shore to 65 to 72 at 4000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 50 to 57 at 4000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Highs 77 to 83 near the shore to 65 to 71 at 4000 feet. Light winds. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to 64 to 69 above 4000 feet. Northwest winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 63 to 72 near the shore to 44 to 53 above 4000 feet. Southeast winds up to 10 mph.

Wednesday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 80 to 86 near the shore to 64 to 69 above 4000 feet. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A surface trough will move over the islands, keeping winds light and variable for the next few days. An upper trough will pass over the area early Thursday through Thursday night, bringing unstable weather across the central and eastern parts of the state.

Discussion

A weak surface trough will move over the area, keeping local winds light and variable for the next few days. Our benign weather pattern across the islands continues this morning, with latest soundings indicating a stable airmass, with strong subsidence inversions and positive lifted index values. Satellite loop shows patchy broken low clouds lingering across Kauai but scattered low clouds across the other smaller islands. Broken to overcast low clouds remain across Kohala on the Big Island. Radar shows scattered showers across and around Kauai and passing through the Alenuihaha channel.
Expect the current pattern to hold through tonight, with daytime sea breezes increasing cloud and shower coverage across mauka areas, followed by nighttime land breezes and clearing. However, models show an area of showers tracking in from the east and reaching windward portions of the Big Island tonight. This moisture will stall and linger for a few days as the next weather system tracks in from the northwest. A light wind/convective pattern will continue statewide on Wednesday, with increased showers expected over the Big Island Wednesday afternoon.
Models show an upper trough digging southeastward across the islands and destabilizing our airmass Wednesday night through Friday. The cold pool will bring 500 mb temperatures down to -14 C as it passes over the smaller islands Thursday morning and over the Big Island later on Thursday. A cutoff surface low will deepen northeast of the state on Thursday, keeping our winds light and variable. Heavy rainfall and thunderstorms are possible, mostly on Maui and the Big Island, particularly Thursday afternoon as the lingering moisture taps into by the instability. There will also be a chance for snowfall/freezing rain on the Big Island summits.
The upper trough will depart on Friday, with weak ridging expected to build in from the west. Conditions will briefly stabilize this weekend, but models show a fairly active, wet weather pattern at the beginning of next week. Details will fill in as we get closer to the weekend.

Aviation

Land and sea breeze conditions will persist due to a weak front positioned nearby to the north. Some moisture associated with this boundary has made it to Kauai, leading MVFR CIGS/VSBYS in and around passing light showers. Elsewhere, shallow stratocumulus clouds will cause CIGS to periodically dip into the MVFR category through the early morning hours. Otherwise, VFR conditions will prevail.
AIRMET SIERRA for mountain obscuration due to clouds and showers remains in effect for windward and mauka locations on Kauai, Maui, and the Big Island.

Marine

The ongoing long-period west-northwest swell is continuing to subside. Surf heights will continue to lower through early Thursday before beginning to rise again by Thursday afternoon into Friday as another long-period west-northwest swell is expected to arrive. This swell is likely to peak Friday with surf heights possibly reaching low-end High Surf Advisory levels. Model guidance also indicates that a moderate northeast swell will also arrive around the same time period. Additional northwest swells are expected into the long range, beginning around Monday of next week.
Light to moderate trade winds will prevail through Wednesday as a front stalls and weakens north of the state. Winds will shift more northerly and increase to more widespread moderate speeds beginning Wednesday night as a surface trough develops northeast of the islands, though speeds are expected to remain below the Small Craft Advisory threshold. The trough will linger there for a day or two as an upper trough develops in tandem. This will allow for increased shower coverage, as well as a slight chance of thunderstorms for the windward coastal waters of Oahu, Maui County, and the Big Island. The system will likely move east of the area by Friday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov