West Side

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 61 to 67. Light winds. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then scattered showers and isolated thunderstorms in the afternoon. Haze through the day. Locally heavy rainfall possible in the afternoon. Highs 79 to 84. Light winds becoming southeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Thursday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers and isolated thunderstorms. Lows 61 to 67. Light winds becoming east up to 10 mph after midnight. Chance of rain 50 percent.

South Side

Tonight: Mostly cloudy. Scattered showers in the evening. Lows around 62. Light winds. Chance of rain 40 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then scattered showers and isolated thunderstorms in the afternoon. Haze in the afternoon. Highs around 85. Light winds. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then partly cloudy with isolated showers and thunderstorms after midnight. Lows around 62. Light winds becoming north up to 10 mph after midnight. Chance of rain 40 percent.

North Shore

Tonight: Mostly cloudy with scattered showers. Lows 59 to 65 near the shore to around 47 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then scattered showers and isolated thunderstorms in the afternoon. Highs 76 to 83 near the shore to around 61 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with numerous showers and isolated thunderstorms. Lows 59 to 65 near the shore to around 47 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.

Central Maui

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 60 to 65. Light winds. Chance of rain 40 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then numerous showers and isolated thunderstorms in the afternoon. Haze in the afternoon. Highs 81 to 86. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 60 percent.

Thursday Night: Mostly cloudy with scattered showers and isolated thunderstorms. Lows 60 to 65. Northeast winds up to 10 mph. Chance of rain 50 percent.

Upcountry

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 41 at the visitor center to around 37 at the summit. Southeast winds up to 10 mph. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers and snow showers in the morning, then numerous showers and isolated thunderstorms in the afternoon. Haze in the afternoon. No snow accumulation. Highs around 53 at the visitor center to around 49 at the summit. Southeast winds up to 10 mph. Chance of precipitation 70 percent.

Thursday Night: Mostly cloudy with scattered showers and isolated thunderstorms. Lows around 40 at the visitor center to around 36 at the summit. Southeast winds up to 10 mph. Chance of rain 50 percent.

East Maui

Tonight: Mostly cloudy with scattered showers. Lows 59 to 65 near the shore to around 47 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then scattered showers and isolated thunderstorms in the afternoon. Highs 76 to 83 near the shore to around 61 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with numerous showers and isolated thunderstorms. Lows 59 to 65 near the shore to around 47 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.

Lanai City

Tonight: Mostly cloudy. Scattered showers in the evening. Haze through the night. Lows around 62. Light winds. Chance of rain 40 percent.

Thursday: Partly sunny. Scattered showers in the morning, then isolated showers and thunderstorms in the afternoon. Haze through the day. Locally heavy rainfall possible in the afternoon. Highs 70 to 77. Light winds. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers and isolated thunderstorms in the evening, then partly cloudy with isolated thunderstorms after midnight. Lows around 64. Light winds. Chance of rain 30 percent.

Kaunakakai

Tonight: Mostly cloudy. Haze in the evening. Scattered showers in the evening, then isolated showers after midnight. Lows 60 to 69. Light winds. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then numerous showers and isolated thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 75 to 83. Light winds. Chance of rain 70 percent.

Thursday Night: Mostly cloudy with scattered showers and isolated thunderstorms. Lows 61 to 70. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A convective pattern with mostly light winds will hold in place during the next couple days, with showers favoring areas near the coast at night and the island interiors during the afternoon and evening hours. Light to moderate trade winds will return over the weekend into early next week, however lingering moisture will likely keep the pattern rather showery, even in leeward areas at times. A new storm system developing west of the state could bring southerly winds along with another chance for heavy rainfall and thunderstorms to the islands Tuesday and next Wednesday.

Discussion

Currently at the surface, a weakening stationary front is located around 350 miles northwest of Kauai, with broad troughing now present over the island chain. Meanwhile, a 1029 mb high is centered to the distant north-northeast. Winds are light and variable across the western islands, while light to moderate east- southeasterlies are present in unsheltered sections of Maui County and the Big Island. Infrared satellite imagery shows mostly cloudy conditions in place, with radar imagery showing most of the daytime heating driven shower activity fizzling out. Main short term focus revolves around the potential for heavy rain and thunderstorms during the next couple days.
Broad troughing will hold in place during the next couple days, keeping land and sea breezes common over the western end of the state. Light to moderate east-southeast winds will persist over the eastern islands, with land and sea breezes common in the more terrain sheltered areas. The broad troughing will dampen out by late Friday, allowing light to moderate trade winds to fill back in across the state Friday night and persist through early next week. A developing storm system west of the islands could bring moderate southerly winds to the areas Tuesday and next Wednesday.
As for the remaining weather details, a convective pattern is expected to continue through Friday, with showers favoring areas near the coast and night and the island interiors during the afternoon and evening hours. An upper level trough will move slowly eastward across the state tonight through Friday, with 500 mb temperatures of -12 to -14C and precipitable water values hovering around 1.5 inches. This is expected to bring some heavier showers to the area during the afternoon and evening hours. In addition, isolated thunderstorms will remain possible as the cold pool aloft moves eastward across the state. In fact, the lingers near the Big Island through the weekend, so a thunderstorm or two could develop here each afternoon. Elsewhere, we should see a hybrid trade wind pattern return over the weekend into early next week. Precipitable water values continue to hold close to 1.5 inches and the latest model trends have been for weaker trades. As a result, the pattern looks a bit showery through the weekend, with chances for showers each afternoon and evening in most leeward areas as well. A new storm system may bring another round of heavy rain and thunderstorms to the islands Tuesday and next Wednesday.

Aviation

A front will stall northwest of the state tonight and bring light and variable winds for Kauai and Oahu, with light to moderate southeast flow prevailing across the remaining islands. Conditions will become slightly more unstable aloft as the night progresses with scattered showers developing areawide and a slight chance of thunderstorms over Oahu and Kauai. Localized IFR CIG/VIS in +TSRA/+SHRA may accompany any of the heavier activity.
Beyond Thursday morning, light flow will lead to a sea breeze/land breeze pattern with periodic heavier showers and a slight chance of thunderstorms across all islands.

Marine

Light to moderate east-southeast winds will persist into Friday as a front remains stalled and slowly diminishes to the west. Over the western end of the islands, the light winds will allow a land and sea breeze pattern to develop near the coasts, which will persist into Friday. For the eastern end, light to moderate east to southeast breezes, with localized fresh pockets, will likely persist, particularly around the Big Island. A return to fresh to strong easterly trades is possible by the weekend as high pressure builds to the north.
Heavy showers and thunderstorms will remain possible, mainly over the western end of the state tonight, with chances increasing statewide Thursday into Friday. Conditions should begin to improve this weekend.
Surf along exposed north and west facing shores will trend up Thursday as a fresh north-northwest arrives and builds down the island chain. Surf may near the advisory levels for exposed north and west facing shores Thursday night into Friday as this swell peaks. A downward trend is then expected over the weekend, with the swell shifting out of north.
Surf along east facing shores will remain below the April average through at least Saturday, then steadily rise to around average by early next week.
Surf along south facing shores will remain small, 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