Hilo

Tonight: Mostly cloudy with numerous showers. Lows around 68 near the shore to around 54 at 4000 feet. West winds up to 10 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 67 to 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Sunday Night: Numerous showers in the evening, then occasional showers after midnight. Lows around 68 near the shore to around 54 at 4000 feet. Northeast winds up to 10 mph shifting to the west after midnight. Chance of rain near 100 percent.

Kona

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 68 to 75 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Sunday Night: Partly cloudy. Lows 68 to 74 near the shore to around 54 near 5000 feet. Light winds.

Waimea

Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 82 near the shore to 72 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Kohala

Tonight: Mostly cloudy with scattered showers. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 82 near the shore to 72 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

South Big Island

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 68 near the shore to around 53 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 84 near the shore to around 73 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Isolated showers after midnight. Lows around 68 near the shore to around 53 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with numerous showers. Lows around 68 near the shore to around 54 at 4000 feet. West winds up to 10 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 86 near the shore to 67 to 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Sunday Night: Numerous showers in the evening, then occasional showers after midnight. Lows around 68 near the shore to around 54 at 4000 feet. Northeast winds up to 10 mph shifting to the west after midnight. Chance of rain near 100 percent.

Waikoloa

Tonight: Partly cloudy. Isolated showers in the evening. Lows 69 to 75 near the shore to 50 to 57 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to 68 to 74 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Lows 69 to 74 near the shore to 50 to 57 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will continue through the weekend with clouds and passing showers affecting mainly windward and mauka areas. A slug of tropical moisture will bring the potential for locally heavy rain and a few thunderstorms early next week, particularly over the Big Island. A front looks to then stall over or just north of the islands around the middle of next week while a new high builds to the north of the front. This is expected to bring a period of wet trades and breezy to locally windy conditions to the islands for the latter half of next week.

Discussion

High pressure far northeast of the state and a trough southeast of the islands continues to produce moderate to locally breezy trade winds this afternoon. Satellite and radar imagery depict fairly typical trade wind weather across the region with mainly partly cloudy skies under passing windward and mauka showers. Expect the typical diurnal uptick in windward and mauka showers tonight with little change in winds. A few showers could briefly move into leeward areas overnight.
Guidance continues to show the high to our north shifting eastward through early next week as a front approaches from the northwest. May see a slight decrease in trades on Sunday, but the incoming trough to the southeast of the Big Island should maintain a tight enough gradient to keep moderate to locally breezy trades going. Clouds and showers will continue to favor windward and mauka areas through the weekend with the typical diurnal uptick during the overnight hours. Some of the showers overnight may spill into leeward areas at times and Kona Slopes of the Big Island can expect to see afternoon clouds and showers as the sea breeze develops.
The through to the southeast of the Big Island will approach the state on Monday and pass to our south through Tuesday. A slug of tropical moisture will accompany the trough as it approaches the state. A passing upper level trough from the west will help to increase instability on Monday and will likely support locally heavy rain and a few thunderstorms across the Big Island so wouldn't be surprised if a Flood Watch for the Big Island was issued later tonight or tomorrow morning. At the moment the highest rainfall is expected across windward Big Island. Some guidance does suggest windward Maui could see some locally heavy rain as the trough passes by, but the latest trend keeps the bulk of the moisture south of Maui as a front approaches from the northwest and prevent the trough from lifting further north. Will continue to monitor this over the next several model runs.
Extended guidance continues to show the front to our northwest approaching the state towards the middle of next week then stalling over or just north of the islands. High pressure will rebuild behind the front for the latter half of next week. This will likely bring an uptick in northeasterly trade winds with breezy to locally windy conditions developing by late Wednesday across the state. Meanwhile, another upper level trough will move across the state from the west. This will likely bring wet trade wind conditions to the state late next week.

Aviation

The pressure gradient between high pressure centered far northeast of the islands and a trough to the southeast is producing moderate to locally breezy trade winds this afternoon across the state. Showers that were common earlier today across windward sections of the Big Island have since diminished, with only isolated to scattered showers now embedded within the trades. Additionally, afternoon sea breezes have resulted in cloud buildups across leeward Big Island, though these should diminish during the evening hours.
Additional upstream moisture could increase windward and mountain showers again tonight into early Sunday, especially across the eastern end of the state. Otherwise, trades are expected ease slightly through the rest of the weekend.
There are currently no AIRMETs in effect, and none are anticipated through this evening.

Marine

A surface ridge northwest of the area will gradually weaken through early next week as a front approaches the state. Nonetheless, the pressure gradient will likely stay tight enough to maintain moderate to locally strong trades the next few days. The front may eventually move through the state around midweek with strong northeast winds behind the front. Additionally, a surface trough developing over the state could bring unsettled weather especially around the Big Island waters Monday into Tuesday with the threat of heavy rain and thunderstorms.
Nearshore buoys are showing a decline in swell and surf along north and west facing shores should gradually decline through this evening. Another reinforcing swell from the northwest (325 degrees) is expected to fill in late tonight into Sunday with surf likely peaking Sunday afternoon into the evening. A High Surf Advisory remains posted for north and west facing shores through Sunday. The reinforcing swell should steadily decline early next week. A series of moderate northwest to north- northwest swells are possible during the second half of the week into next weekend.
Surf along east-facing shores will remain small and choppy with some wrap possible from the northwest swells at select exposures. An upward trend is possible later next week as the trades strengthen. Surf along south-facing shores will remain small with mainly background energy.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Sunday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov