Hilo

Tonight: Partly cloudy with scattered showers. Haze. Lows around 65 near the shore to around 51 at 4000 feet. South winds up to 10 mph shifting to the southwest after midnight. Chance of rain 50 percent.

Wednesday: Haze in the morning. Mostly sunny with scattered showers in the morning, then partly sunny with numerous showers in the afternoon. Highs around 84 near the shore to around 66 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy. Numerous showers early in the evening, then scattered showers in the late evening and overnight. Haze in the late evening and overnight. Lows around 66 near the shore to around 52 at 4000 feet. South winds up to 10 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy with scattered showers early in the evening, then mostly cloudy with isolated showers in the late evening and overnight. Haze through the night. Lows 65 to 72 near the shore to around 51 near 5000 feet. Light winds. Chance of rain 40 percent.

Wednesday: Haze in the morning. Mostly sunny with isolated showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs around 84 near the shore to around 69 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 60 percent.

Wednesday Night: Mostly cloudy. Haze through the night. Scattered showers early in the evening. Isolated showers in the late evening and early morning, then scattered showers early in the morning. Lows 66 to 71 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Haze. Lows around 64 near the shore to 49 to 58 near 3000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Wednesday: Haze in the morning. Mostly sunny with scattered showers in the morning, then partly sunny with numerous showers in the afternoon. Highs around 83 near the shore to 71 to 76 near 3000 feet. North winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy. Isolated showers until early morning, then scattered showers early in the morning. Haze through the night. Lows around 65 near the shore to 50 to 59 near 3000 feet. Light winds. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Haze. Lows around 64 near the shore to 49 to 58 near 3000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Wednesday: Haze in the morning. Mostly sunny with scattered showers in the morning, then partly sunny with numerous showers in the afternoon. Highs around 83 near the shore to 71 to 76 near 3000 feet. North winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy. Isolated showers until early morning, then scattered showers early in the morning. Haze through the night. Lows around 65 near the shore to 50 to 59 near 3000 feet. Light winds. Chance of rain 50 percent.

South Big Island

Tonight: Partly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Haze through the night. Lows around 66 near the shore to around 51 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Wednesday: Breezy. Haze in the morning. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Haze through the night. Lows around 67 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Puna

Tonight: Partly cloudy with scattered showers. Haze. Lows around 65 near the shore to around 51 at 4000 feet. South winds up to 10 mph shifting to the southwest after midnight. Chance of rain 50 percent.

Wednesday: Haze in the morning. Mostly sunny with scattered showers in the morning, then partly sunny with numerous showers in the afternoon. Highs around 84 near the shore to around 66 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Mostly cloudy. Numerous showers early in the evening, then scattered showers in the late evening and overnight. Haze in the late evening and overnight. Lows around 66 near the shore to around 52 at 4000 feet. South winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly cloudy with scattered showers early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Haze through the night. Lows 66 to 72 near the shore to 46 to 54 above 4000 feet. Southeast winds up to 10 mph in the evening becoming light. 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 around 84 near the shore to 65 to 72 above 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy. Haze through the night. Scattered showers early in the evening. Isolated showers in the late evening and early morning, then scattered showers early in the morning. Lows around 69 near the shore to 47 to 55 above 4000 feet. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

East southeast winds will ease tonight, with daytime sea breeze and nighttime land breeze pattern from Wednesday and continuing through Friday. A disturbance aloft moving over the islands could bring some heavier showers and thunderstorms Thursday and Friday. A return to a more typical trade wind regime along with a gradual increase in trade wind speeds will be possible over the weekend into early next week.

Discussion

At the surface, a 1025 mb surface high is centered far northeast of Hawaii driving gentle to moderate east southeast winds across the area. An approaching cold front is located around 650 miles northwest of Kauai, while an approaching weak trough is located 300 miles east of the Big Island.
Winds will taper off and veer southeasterly tonight as the front and trough converge towards the islands. Land breezes will keep most of the associated clouds and showers with both features offshore, but as sea breezes build in during the day Wednesday, clouds and showers will focus over the islands.
An upper trough will dig southeasterly across the islands late Wednesday night through Friday. The front will merge with the surface trough creating a pool of low level moisture over the state. As the upper trough moves through, 500 mb temperatures will lower to around -12 to -13C and precipitable water values will increase from around 1.2 currently to around 1.5 inches on Thursday. This will likely result in some heavier showers and a slight chance of thunderstorms Thursday and Friday (more of the focus will be on Big Island Friday). Possible minor ponding/flooding resulting from this rainfall, but holding off with a Flood Watch for now given the brief window of upper level forcing. Snow will be possible on the Big Island summits Thursday through Friday and will consider a Winter Weather Advisory. The upper trough will weaken and slide east of the state by late Friday returning to more a more stable atmosphere.
Light to moderate trade winds will gradually nose in over the weekend, with likely wetter-than-normal windward and mauka showers before the area of moisture is cleared to the west. A more typical trade wind pattern may slowly return over the weekend into early next week.

Aviation

Moderate trades will gradually ease into tomorrow and usher in SHRA and low cigs to windward and mauka locations. However, winds may begin to be light enough to see some sea breeze development that would bring some isol SHRA to leeward areas. MVFR conds will be possible in any SHRA, but VFR should prevail.
While the ongoing eruption of Kilauea is currently paused, there is degassing occurring. This could cause some hazy conds across the islands. It is not enough to impact vsbys at this time and not currently in any TAFs but was worth a mention.
No AIRMETs in effect.

Marine

Trade winds will continue to decline and shift out of the southeast through Wednesday as an advancing front weakens the surface ridge north of the state. Easterly trade winds are currently at moderate to fresh strength, and a morning ASCAT pass confirmed that winds around the Big Island have eased enough to allow the Small Craft Advisory (SCA) to be dropped. By Wednesday morning, gentle to moderate east to southeasterly winds will prevail statewide, followed by a brief period of variable winds around Kauai and possibly Oahu Wednesday afternoon and evening. Gentle to locally fresh east to east-southeast trade winds will dominate Thursday and Friday, and a slight increase in winds may require the SCA to be reissued around the Big Island and Maui during the weekend.
As trades diminish, chances for heavy showers and thunderstorms will increase. The main threat will develop around Kauai and Oahu late Wednesday night, slowly spread to the entire island chain Thursday, then diminish from west to east on Friday.
Small surf along exposed north and west facing shores will continue to lower through Wednesday as a northwest swell fades. A medium period north-northwest swell will build Thursday and will push surf near High Surf Advisory levels during the peak Thursday night and early Friday. This swell will steadily decline and shift out of the north later Friday and the weekend.
Surf along east facing shores will trend down tonight as trades ease. East shore surf will remain below April average through at least Saturday and will likely rise to around average on Sunday.
Surf along south facing shores will remain small through most of the week, with mainly overlapping background south swells moving through. A larger pulse of south-southwest swell may arrive Tuesday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov