Photo Credit: Tyler Rooke

West Side

Today: Scattered showers, then showers likely and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 82. South southeast wind 10 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 70%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Occasional showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 67. South wind 8 to 13 mph becoming light and variable. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday: Showers likely and possibly a thunderstorm before 11am, then scattered showers and thunderstorms after 11am. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 81. Windy, with a northeast wind 7 to 12 mph increasing to 18 to 23 mph in the afternoon. Winds could gust as high as 32 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

South Side

Today: Isolated showers, then showers likely and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 82. Northeast wind 5 to 10 mph becoming southwest in the afternoon. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Occasional showers and possibly a thunderstorm, mainly before 2am, then scattered showers and thunderstorms after 2am. Some of the storms could produce heavy rainfall. Low around 65. South southwest wind 5 to 10 mph becoming light and variable in the evening. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

Saturday: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 80. Breezy, with a light and variable wind becoming north northeast 15 to 20 mph in the morning. Winds could gust as high as 28 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

North Shore

Today: Showers likely and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. Increasing clouds, with a high near 80. South southeast wind 7 to 10 mph becoming east northeast in the afternoon. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Occasional showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 66. South southwest wind 5 to 10 mph becoming light and variable. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday: Showers likely and possibly a thunderstorm before 11am, then scattered showers and thunderstorms after 11am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 78. Windy, with a northeast wind 10 to 15 mph increasing to 18 to 23 mph in the afternoon. Winds could gust as high as 32 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Central Maui

Today: Showers likely and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. Increasing clouds, with a high near 80. South southwest wind 7 to 10 mph becoming southeast in the afternoon. Chance of precipitation is 70%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Occasional showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 64. South southwest wind 5 to 10 mph becoming light and variable. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday: Showers likely and possibly a thunderstorm before 11am, then scattered showers and thunderstorms after 11am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 78. Windy, with a northeast wind 9 to 14 mph increasing to 20 to 25 mph in the afternoon. Winds could gust as high as 36 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Upcountry

Today: Showers likely and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. Increasing clouds, with a high near 67. Breezy, with a south southwest wind 7 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Tonight: Occasional showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 53. Southwest wind 6 to 11 mph becoming light and variable after midnight. Chance of precipitation is 80%. New rainfall amounts between 1 and 2 inches possible.

Saturday: Showers likely and possibly a thunderstorm before 11am, then scattered showers and thunderstorms after 11am. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 65. Breezy, with a light northeast wind becoming north northeast 16 to 21 mph in the morning. Winds could gust as high as 29 mph. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible.

East Maui

Today: Isolated showers, then showers likely and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 78. Calm wind becoming east around 6 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Occasional showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 62. Light and variable wind becoming north northeast 6 to 11 mph after midnight. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

Saturday: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 77. Breezy, with a north northeast wind 11 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Lanai City

Today: Scattered showers, then occasional showers and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. High near 74. Breezy, with a south southwest wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.

Tonight: Occasional showers and possibly a thunderstorm before 2am, then scattered showers and thunderstorms after 2am. Some of the storms could produce heavy rainfall. Low around 62. Breezy, with an east wind 5 to 10 mph becoming east northeast 11 to 16 mph after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 80%. New rainfall amounts between three quarters and one inch possible.

Saturday: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 72. Windy, with a northeast wind 24 to 29 mph decreasing to 13 to 18 mph. Winds could gust as high as 41 mph. Chance of precipitation is 50%. New rainfall amounts between a quarter and half of an inch possible.

Kaunakakai

Today: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 80. Breezy, with a south southwest wind 11 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Occasional showers and possibly a thunderstorm, mainly before 2am, then scattered showers and thunderstorms after 2am. Some of the storms could produce heavy rainfall. Low around 67. Breezy, with a light and variable wind becoming north northeast 13 to 18 mph after midnight. Winds could gust as high as 26 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 79. Windy, with a northeast wind 18 to 23 mph decreasing to 11 to 16 mph in the afternoon. Winds could gust as high as 32 mph. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Detailed Forecast

Synopsis

The wet pattern will continue as a front and upper disturbance approach and advance down the island chain later today through Saturday. Heavy showers and a few storms along and ahead of the front combined with saturated grounds will keep the threat for localized flash flooding in place across the state. Brisk trade winds will follow the front, which will focus clouds and showers over windward and mountain locations. A wet trade wind pattern will be possible Sunday through the first half of the upcoming week.

Discussion

Low pressure positioned west of the state will begin to lift northeastward and phase with the tail-end of a cold front passing to the north later today. Moist convergent southerly flow in place over the islands east of this feature combined with an upper trough will continue to support localized heavy rainfall and a few thunderstorms across the islands today. The low-level flow will shift out of the southwest later today as the front approaches, then to the northeast tonight into Saturday over the western end of the state. Despite the return of strong trades over Kauai and Oahu, rainfall chances will remain up into the weekend, especially over windward and mountain locations. More widespread rainfall and even a few storms will be expected over the eastern end of the state through Saturday as a potent shortwave trough and the cold front advance down the island chain. As a result, the Flash Flood Watch has been extended through early Saturday. Additionally, winter weather conditions can’t be ruled out over the Big Island Summits tonight through Saturday as this upper trough moves in.
Brisk trade winds should return statewide by the end of the weekend trailing the front, which will focus clouds and showers over windward and mountain locations. Forecast confidence diminishes for early next week due to considerable model changes from cycle to cycle. The latest model solutions now depict more of a wet pattern unfolding as an area low pressure drifts westward through islands. Confidence should improve over the weekend as conditions evolve.

Aviation

A surface low to the northwest of Kauai, combined with an upper level trough, will allow for more rounds of unsettled weather to persist over the next several hours. Expect MVFR or even IFR ceilings and visibility to occur with some of the heavier shower activity. In addition, isolated thunderstorms will remain possible due to the unstable air aloft.
Light southerly winds will shift southwesterly across Kauai and Oahu as the day progresses, then to the northeast tonight.
AIRMET SIERRA remains in effect for Kauai, Molokai, and Maui above 2500 feet due to clouds and showers.
AIRMET ZULU remains in effect for Kauai and adjacent waters between 15000 and 25000 feet due to tempo light icing.

Marine

A slow moving low pressure system west of Kauai will keep gentle southerly winds across Hawaiian waters today. A frontal system will move through the northwestern offshore waters today and into the coastal waters from tonight through Sunday. Strong to near gale northeast trade winds will build in behind the front as it moves into the region. Widespread heavy showers and thunderstorms will continue into the weekend with this unstable system. Unsettled fresh trade winds will continue into next week with an upper level disturbance keeping periods of wet weather in the long range forecast.
A background east swell will keep moderate surf heights along east facing shores into the weekend. This east swell will slowly fade from Saturday night through Monday. A high pressure system building into the central Pacific early next week will increase east swell heights from Tuesday onward. Small surf heights along north and west facing shores will continue today. A new large medium period north to northeast swell will arrive early Saturday morning quickly building surf heights along north and east facing shores to near High Surf Advisory (HSA) levels through the weekend. Small surf along south facing shores will rise a bit today and Saturday as a swell originating west of New Zealand reaches the area.

HFO Watches/Warnings/Advisories

Flash Flood Watch through late tonight for all Hawaii islands.
Small Craft Advisory from 6 PM this evening to 6 PM HST Sunday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters.

Data Courtesy of NOAA.gov