Hilo

Tonight: Mostly cloudy. Scattered showers and isolated thunderstorms in the evening, then scattered showers after midnight. Haze after midnight. Lows 61 to 68 near the shore to 49 to 55 at 4000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Mostly cloudy. Haze in the morning. Scattered showers in the morning, then numerous showers in the afternoon. Highs 78 to 84 near the shore to around 67 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Wednesday Night: Partly cloudy with isolated showers. Lows 62 to 69 near the shore to 48 to 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Kona

Tonight: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then partly cloudy after midnight. Haze after midnight. Lows around 71 near the shore to 44 to 51 near 5000 feet. Light winds. 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 82 to 87 near the shore to around 65 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers in the evening, then mostly clear after midnight. Haze through the night. Lows around 72 near the shore to 45 to 51 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Tonight: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then partly cloudy with isolated showers after midnight. Haze after midnight. Lows 61 to 70 near the shore to 52 to 60 near 3000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 50 percent.

Wednesday: Haze in the morning. Partly sunny with scattered showers. Highs around 79 near the shore to 70 to 77 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday Night: Mostly clear. Isolated showers in the evening. Lows 61 to 70 near the shore to 52 to 60 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Tonight: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then partly cloudy with isolated showers after midnight. Haze after midnight. Lows 61 to 70 near the shore to 52 to 60 near 3000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 50 percent.

Wednesday: Haze in the morning. Partly sunny with scattered showers. Highs around 79 near the shore to 70 to 77 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday Night: Mostly clear. Isolated showers in the evening. Lows 61 to 70 near the shore to 52 to 60 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then partly cloudy with isolated showers after midnight. Haze after midnight. Lows around 72 near the shore to around 50 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Breezy. 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 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Scattered showers in the evening. Haze through the night. Lows around 72 near the shore to around 50 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Puna

Tonight: Mostly cloudy. Scattered showers and isolated thunderstorms in the evening, then scattered showers after midnight. Haze after midnight. Lows 61 to 68 near the shore to 49 to 55 at 4000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Mostly cloudy. Haze in the morning. Scattered showers in the morning, then numerous showers in the afternoon. Highs 78 to 84 near the shore to around 67 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Wednesday Night: Partly cloudy with isolated showers. Lows 62 to 69 near the shore to 48 to 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Waikoloa

Tonight: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then mostly clear after midnight. Haze after midnight. Lows 69 to 74 near the shore to 48 to 53 above 4000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Haze in the morning. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 82 to 88 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. Scattered showers in the evening. Lows 69 to 74 near the shore to 47 to 53 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Light winds will allow land and sea breezes to continue through tonight. A cold upper level low east of the state will increase the chance of locally heavy showers and a few thunderstorms through this evening. Land breezes should keep most shower activity over the coastal waters or near the coast tonight. Trade winds return Wednesday, with a more typical windward and mauka shower pattern. Breezy trade winds expected Friday into early next week.

Discussion

Light winds continue across the state this afternoon as a weak surface trough lingers over the Kauai Channel and high pressure remains far northeast of the islands. Radar and visible satellite imagery show clouds and numerous moderate to locally heavy showers have developed over island interiors this afternoon as sea breezes matured, with several locations receiving over an inch of rain over the last couple of hours. Meanwhile, water vapor satellite imagery shows a deep upper level low just east of the state. This low is helping to enhance the instability across areas east of Kauai. Expect the threat for locally heavy showers and a few thunderstorms to continue through this evening as sea breezes continue. Land breezes should develop shortly after sunset and help to push shower activity to areas near the immediate coast or over the coastal waters tonight.
Wednesday will serve as a transition day where gentle to moderate trades will gradually build back as the surface trough dissipates west of the state. This will allow drier air to slowly filter in from the east. The airmass will also gradually become more stable as the upper level low shifts eastward and opens up to a trough, allowing a mid level ridge to build over the state. Moderate to locally breezy trades are expected to return Friday then hold through early next week as a pair of strong high pressure systems move north of the state. Expect showers to favor windward and mauka areas, particularly during the overnight and early morning hours.
Volcanic emissions and light background east southeast flow will keep vog in place over portions of the state tonight. The returning trades should clear the vog out of the smaller islands by late Wednesday.

Aviation

A weak trough of low pressure slowly passing over the islands will keep the background wind flow light and variable through tomorrow afternoon. This flow pattern will lead to land breezes in the morning hours and sea breezes in the afternoon and early evening hours. Diurnal heating, combined with instability aloft, will combine to generate locally heavy showers in the afternoon and evening hours. Slight chance of thunderstorms over inland areas tonight. Brief periods of MVFR/IFR conditions may occur with the more robust showers and storms.
AIRMET Sierra for mountain obscuration is currently in effect for Oahu, Molokai, Maui, Lanai, and northern Big Island. Conditions are expected to improve later this evening as winds shift from onshore to offshore.
SIGMET November for thunderstorm activity just northeast of the Islands has been canceled. The potential for thunderstorm redevelopment along the major flight routes between Hawaii and California will remain through late this evening.

Marine

A trough of low pressure near Kauai will linger through the night and continue to weaken the high pressure ridge over the Hawaiian Islands, maintaining light and variable winds across the region. This boundary combined with an upper level disturbance moving down the island chain will keep the potential for showers and thunderstorms over the coastal waters. Trades will build back in from tomorrow onward, strengthening to Small Craft Advisory levels for the typical windier coastal waters around Maui and the Big Island by Thursday.
A small northwest swell will continue to slowly fade into tomorrow morning, allowing surf along north and west facing shores to remain near or below average levels for this time of year (6 feet for the month of May). By Thursday, a moderate long period north- northwest swell is expected to arrive, producing surf above the seasonal average. This north-northwest swell will slowly decline over the weekend.
Multiple small south swells will maintain small background southerly energy today. A bump up in south-southwest swell energy will arrive tomorrow, peak Thursday producing moderate surf, and then slowly fade through the weekend. However, a mix of reinforcing south- southwest swell and new south-southeast swell energy will arrive this weekend and should help maintain surf near or above the summer average (5 feet). Then another pulse of south-southwest swell energy will arrive early next week.
Weak upstream trade wind flow will keep surf on the small side for east facing shores. An increase is expected by tomorrow as the trade winds return. Trade winds should strengthen through Friday with rough and choppy surf expected along east facing shores through the weekend.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov