Hilo

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Haze through the night. Lows 61 to 69 near the shore to 47 to 54 at 4000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Haze through the day. Scattered showers in the afternoon. Highs around 81 near the shore to 66 to 71 at 4000 feet. Southwest winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy with isolated showers. Haze. Lows 61 to 69 near the shore to 49 to 56 at 4000 feet. Light winds becoming south up to 10 mph after midnight. Chance of rain 20 percent.

Kona

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows around 71 near the shore to 44 to 51 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 85 near the shore to around 67 near 5000 feet. North winds up to 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows around 70 near the shore to 45 to 51 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Haze through the night. Lows 60 to 69 near the shore to 52 to 60 near 3000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 79 near the shore to 69 to 75 near 3000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Light winds. Chance of rain 20 percent.

Kohala

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Haze through the night. Lows 60 to 69 near the shore to 52 to 60 near 3000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 79 near the shore to 69 to 75 near 3000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Light winds. Chance of rain 20 percent.

South Big Island

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Haze through the night. Lows around 71 near the shore to around 48 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny. Breezy. Haze through the day. Isolated showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows around 71 near the shore to around 50 near 5000 feet. East winds up to 10 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Haze through the night. Lows 61 to 69 near the shore to 47 to 54 at 4000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Haze through the day. Scattered showers in the afternoon. Highs around 81 near the shore to 66 to 71 at 4000 feet. Southwest winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy with isolated showers. Haze. Lows 61 to 69 near the shore to 49 to 56 at 4000 feet. Light winds becoming south up to 10 mph after midnight. Chance of rain 20 percent.

Waikoloa

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Haze through the night. Lows around 71 near the shore to 47 to 53 above 4000 feet. Northwest winds up to 10 mph shifting to the southeast after midnight. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs 81 to 86 near the shore to 63 to 69 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Haze. Lows 68 to 73 near the shore to 48 to 54 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Rain chances will steadily increase through the week especially over the western half of the state as a frontal boundary moves over Kauai and stalls near Oahu Thursday into Friday. Breezy to locally strong trade winds should return on Friday with a showery trade wind pattern expected through the weekend. Once again, the trade wind showers should be most frequent over the western half of the state.

Discussion

Light to moderate south to southeasterly winds will weaken some on Wednesday but the wind direction will continue to remain out of the south or southeast. With the ongoing eruption of Kilauea and the southeasterly winds over the Big Island, we have had reports of Pele's hair falling onto Highway 11. The southeasterly winds should weaken this evening with land breezes developing overnight tonight. Southeasterly winds will likely develop during the day on Wednesday and with the general southeasterly flow, more widespread vog will be possible on Wednesday.
A frontal boundary currently located west of Kauai will slowly shift eastward over the next few days. Satellite imagery this afternoon is showing a broad NE to SW oriented line of showers and thunderstorms roughly 180 miles west of Kauai. This line of heavier showers is expected to slowly move east and gradually weaken as it approaches Kauai Wednesday into Thursday. Starting Wednesday as the frontal boundary nears Kauai, we could begin to see some heavier showers especially during the afternoon over the western half of the state. There are still quite a bit of uncertainty for precipitation amounts on Wednesday due to the uncertainty in the location of the frontal boundary. GFS ensembles brings the frontal boundary very close to Kauai, while the EC and Canadian ensemble members keeps the bulk of the moisture slightly further west of Kauai. Thus, the precipitation amounts still remain uncertain for Wednesday over Kauai and Oahu, but off and on scattered showers should be expected. For rest of the state, isolated to scattered showers will be possible on Wednesday with mostly light rainfall amounts.
On Thursday, there is better agreement with global models with the frontal boundary reaching Kauai. This should allow for some moderate to locally heavy showers over Kauai and Oahu. With generally light winds on Thursday, any showers will be slow moving and we could see some flooding concerns especially over north Kauai. The frontal boundary is expected to weaken and stall somewhere around Kauai or Oahu on Friday. Breezy to locally strong trade winds will also return on Friday with a showery trade wind pattern expected across the state over the weekend. The greatest moisture will once again continue to be across the western half of the state, especially Kauai. So overall, showery weather should be expected over Kauai and possibly Oahu from Thursday through the weekend. Passing showers should also increase for the eastern half of the state once the trade winds return.

Aviation

Moderate southerly winds will continue through tonight over the western half of the state as a cold front approaches from the northwest. Expect an uptick in shower activity across Kauai and Oahu as moisture streams in from the south ahead of the front, with periods of MVFR likely with the heavier showers.
Otherwise, the eastern half of the state will see moderate to locally breezy southeasterly winds continue into Wednesday, with localized sea breezes in sheltered areas. Conditions should remain mainly VFR.
No AIRMETs are currently in effect, but AIRMET Sierra for tempo mountain obscuration may be needed for Kauai and Oahu as showers become more widespread.
All areas will continue to see some Vog due to the ongoing eruption of Kilauea. However, the Vog is not expected to impact visibilities enough to warrant a mention in any TAF.

Marine

Small Craft Advisory (SCA) remains in effect through Wednesday morning for waters around the Big Island for local wind acceleration around and along the parallel coastlines to the wind direction. These winds will gradually ease during the morning Wednesday. Moderate to locally strong northeast trades are expected this weekend and early next week.
A moderate north-northwest (310-330) swell is expected to arrive on Friday and could produce advisory level surf. A large, long period, north to north-north west (340-360) swell is forecast to arrive this weekend and would likely produce warning level surf along north with advisory level surf across west and east facing shores. This swell, aside from being hazardous to small craft, could generate harbor surges along north facing bays and inlets.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Wednesday for Big Island Windward Waters, Big Island Leeward Waters.

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Data Courtesy of NOAA.gov