Photo Credit: James Grenz

Hilo

Today: Scattered showers, then showers likely and possibly a thunderstorm after 11am. Some of the storms could produce heavy rainfall. Cloudy, with a high near 80. West wind around 6 mph becoming light and variable in the morning. 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. Some of the storms could produce heavy rainfall. Low around 64. West southwest wind around 5 mph becoming calm after midnight. 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. Partly sunny, with a high near 80. Calm wind becoming east around 6 mph in the afternoon. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Kona

Today: Isolated showers, with thunderstorms also possible after 11am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 83. Light and variable wind becoming west northwest 5 to 8 mph in the morning. Chance of precipitation is 20%.

Tonight: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 64. North wind around 6 mph becoming calm after midnight. Chance of precipitation is 40%. New rainfall amounts between a quarter and half of an inch possible.

Saturday: Scattered showers and thunderstorms. Mostly cloudy, with a high near 83. West southwest wind 5 to 9 mph becoming calm in the afternoon. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Waimea

Today: Scattered showers, then showers likely and possibly a thunderstorm after 11am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 74. Windy, with a light northeast wind increasing to 18 to 23 mph in the morning. Winds could gust as high as 32 mph. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible.

Tonight: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 53. Breezy, with a northeast wind 11 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 60%. New rainfall amounts between 1 and 2 inches possible.

Saturday: Scattered showers and thunderstorms. Mostly cloudy, with a high near 74. Breezy, with a northeast wind 13 to 18 mph becoming southeast 5 to 10 mph in the afternoon. Winds could gust as high as 25 mph. Chance of precipitation is 50%. New rainfall amounts between a quarter and half of an inch possible.

Kohala

Today: Scattered showers, then showers likely and possibly a thunderstorm after 11am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 67. Very windy, with a light east northeast wind becoming east 26 to 31 mph in the morning. Winds could gust as high as 45 mph. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.

Tonight: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Cloudy, with a low around 45. Windy, with an east wind 23 to 28 mph decreasing to 10 to 15 mph after midnight. Winds could gust as high as 40 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday: Scattered showers and thunderstorms. Mostly cloudy, with a high near 67. Breezy, with an east wind 8 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

South Big Island

Today: Scattered showers, with thunderstorms also possible after 11am. Some of the storms could produce heavy rainfall. Cloudy, with a high near 83. Windy, with an east wind 23 to 28 mph, with gusts as high as 36 mph. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 70. Windy, with an east northeast wind 23 to 26 mph, with gusts as high as 34 mph. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Saturday: Scattered showers and thunderstorms. Partly sunny, with a high near 83. Windy, with an east wind 22 to 28 mph, with gusts as high as 36 mph. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Puna

Today: Scattered showers, then showers likely and possibly a thunderstorm after 11am. Some of the storms could produce heavy rainfall. Cloudy, with a high near 78. Light and variable wind becoming east 6 to 11 mph in the morning. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.

Tonight: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 62. East northeast wind around 6 mph becoming light and variable. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible.

Saturday: Scattered showers and thunderstorms. Partly sunny, with a high near 78. North northwest wind 5 to 8 mph becoming east in the afternoon. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Waikoloa

Today: Isolated showers, then scattered showers and thunderstorms after 11am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 80. Calm wind becoming northeast 5 to 9 mph in the afternoon. Chance of precipitation is 50%. New rainfall amounts between a quarter and half of an inch possible.

Tonight: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 63. East wind 9 to 13 mph. Chance of precipitation is 30%. New rainfall amounts between a quarter and half of an inch possible.

Saturday: Scattered showers and thunderstorms. Mostly cloudy, with a high near 80. East wind 8 to 13 mph becoming light and variable in the afternoon. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Detailed Forecast

Synopsis

Heavy showers and a few storms will remain possible through tonight as an upper disturbance and surface trough continue to influence the local weather. Conditions will gradually begin to improve and trend back toward a typical trade wind pattern over the weekend through early next week.

Discussion

Guidance remains persistent and continues to advertise a wet pattern holding over the state through tonight as an upper disturbance and surface trough remain in the area. Some showers may become heavy and lead to localized flooding concerns where they become focused for any duration. In addition to the rainfall, a few thunderstorms will be possible as instability associated with the upper low remains in place. The low-level flow will remain out of the east-southeast direction this morning, but should back around to a more easterly direction and become breezy this afternoon.
For the summits of the Big Island, a mid-level dry slot rotated around the upper low overnight which led to quiet conditions. Although a few convective bursts this afternoon could lead to periods of snow, accumulations should remain limited. Therefore, the advisory has been cancelled this morning.
Conditions should improve and trend back toward a typical trade wind pattern statewide over the weekend through early next week as drier air moves in and the upper disturbance lifts northward away from the state. Some residual moisture lingering over the western end of the state will keep the rainfall chances up into Saturday.

Aviation

High clouds are decreasing across the area as an upper trough drifts eastward across the Big Island. Showers and isolated thunderstorms are still possible, mainly across windward and southeast facing areas. Expect periods of MVFR ceilings and visibility to occur with this activity. Heavier showers and thunderstorms may bring brief IRF conditions.
AIRMET SIERRA for mountain obscuration above 2500 feet may be cancelled later this morning if low clouds decrease enough. AIRMET ZULU will likely be cancelled later as high clouds have decreased enough to eliminate the threat of icing across the area.

Marine

High pressure northeast of the islands has created a tight enough pressure gradient back toward the state to support fresh trade winds across the central and eastern island windward waters. A recent ASCAT satellite pass has revealed locally strong winds channeling around the Big Island’s Hamakua Coast and off South Point as well as through the Alenuihaha Channel. A Small Craft Advisory (SCA) is in effect today for the waters surrounding Maui County and the Big Island. This SCA may need to be extended to cover more western windward waters into Saturday. An upper trough positioned over the islands will continue to be the focus for scattered showers, possibly locally heavy rainfall and isolated thunderstorms through early Saturday.
A diminishing north northeast swell will maintain small surf along north and northeast facing shores through Saturday. An area of strong to near gale force winds along the southern periphery of a broad low near the west Aleutians will be focused along a northwest great circle path directed at the islands. This small, short to medium period northwest swell is scheduled to arrive and boost north and west surf late Saturday night into Sunday morning, hold this surf through Monday with a decline on Tuesday. A subtle increase in east facing shore surf will hold through early next week in response to trade wind wave swell propagating from fresh easterlies over and upstream of the islands. The arrival of a series of small, long period background south swells will provide a minor boost to south shore surf. A slightly higher, long period south southwest swell arriving Tuesday may hold southern coast surf to near seasonal levels through the middle of next week.

HFO Watches/Warnings/Advisories

Flash Flood Watch through late tonight for all Hawaii islands,
Small Craft Advisory through this afternoon for Pailolo and Alenuihaha Channels, Maalaea Bay, Windward Big Island and South Point waters.

Data Courtesy of NOAA.gov