Hilo

Tonight: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 50 to 56 at 4000 feet. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 82 near the shore to 63 to 69 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 49 to 56 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Kona

Tonight: Mostly clear. Isolated showers in the evening. Lows around 71 near the shore to 44 to 51 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 87 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows around 70 near the shore to 43 to 50 near 5000 feet. Light winds.

Waimea

Tonight: Partly cloudy with isolated showers. Lows 61 to 70 near the shore to 53 to 60 near 3000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 78 near the shore to 68 to 77 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Breezy. Partly cloudy with isolated showers. Lows 60 to 70 near the shore to 52 to 59 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy with isolated showers. Lows 61 to 70 near the shore to 53 to 60 near 3000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 78 near the shore to 68 to 77 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Breezy. Partly cloudy with isolated showers. Lows 60 to 70 near the shore to 52 to 59 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly clear. Isolated showers in the evening. Lows around 72 near the shore to around 51 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows around 71 near the shore to around 49 near 5000 feet. Northeast winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 50 to 56 at 4000 feet. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 82 near the shore to 63 to 69 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 49 to 56 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Isolated showers in the evening. Lows 68 to 73 near the shore to 47 to 53 above 4000 feet. Light winds. Chance of rain 20 percent.

Sunday: Sunny. Highs 82 to 87 near the shore to 64 to 71 above 4000 feet. East winds up to 15 mph shifting to the north in the afternoon.

Sunday Night: Mostly clear. Lows 67 to 73 near the shore to 46 to 52 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

Light to moderate easterly trades will gradually strengthen tomorrow with showers favoring windward and mauka areas overnight and isolated showers forming over island interiors in the afternoon. Next week, pockets of moisture will bring periodic showers to windward and mauka areas on the strengthening trades as high pressure builds to the north.

Discussion

Visible satellite and radar imagery show isolated showers moving into windward areas on the weak trades, as well as a few showers developing over leeward interiors this afternoon due to sea breeze activity. Models continue to show that light to locally moderate easterly trade winds will persist into tomorrow morning before gradually strengthening into next week. Winds will likely remain light enough across the state to allow for the development of land breezes overnight, which should help to clear out leeward areas by morning. As the trades begin to strengthen tomorrow, sea breeze activity will be hindered some, but will likely still occur across some of the more sheltered leeward areas. This hybrid pattern of redeveloping trades and sea breezes will support isolated to scattered showers across windward and mauka areas tonight with additional isolated showers over island interiors tomorrow afternoon.
Another front will approach from the northwest through Sunday. Models continue to show its tail end dissipating before it reaches the state, but batches of remnant moisture will move in on the strengthening trades early next week as high pressure strengthens to the north. These breezy to strong trades will persist through the week and into next weekend, focusing clouds and showers mainly over windward and mauka areas. Model guidance has been consistently showing an upper level shortwave trough move down the island chain early next week, then pinch off from the main trough to form a cutoff low south of the state before slowly retrograding westward through the week. The proximity of this feature may serve to help enhance windward showers, particularly over the southern end of the state, but no significant impacts are expected at this time.

Aviation

Light trade winds will compete with local sea breezes to drive local weather patterns. During the day, afternoon sea breezes will encourage shower development over island interiors. After sunset, land breezes will develop and promote overnight clearing, especially along leeward coasts. Light trade winds will carry bands of low- topped clouds towards windward coasts both day and night.
The air mass over the state will remain dry and stable through the weekend. A strong inversion aloft between 07 kft and 09 kft will keep available moisture trapped in the lowest levels. Any shower activity will be light to moderate in intensity and limited in scope.
High pressure to our northeast will gradually strengthen. Moderate to locally breezy trade winds will return to the Islands early next week.

Marine

High pressure building north of the state will bring strengthening trade winds to the region through Monday night. Light winds tonight will increase to moderate levels Sunday afternoon, with fresh to strong trades in place by Monday night. These fresh to strong trades will likely remain in place through the new week. Small Craft Advisory (SCA) level winds are expected in the typical windier waters near Maui County and the Big Island Monday, with additional waters impacted Tuesday based on the wind criteria. From Wednesday onwards, additional areas may be placed under a SCA due to increasing seas.
The current northwest (330 degree) swell has brought surf heights near High Surf Advisory (HSA) levels along exposed north and west facing shores of the smaller islands. Surf is expected to fall below advisory levels this evening, with the swell continuing to decline through Sunday. As such the HSA remains in effect until 6pm today. Another northwest (330 degree) swell is expected to arrive late Sunday night, bringing another round of advisory level surf to the smaller islands by Monday afternoon, and then declining Tuesday night. Surf will once again be boosted early Thursday with yet another northwest swell, which could briefly bring surf advisory levels. A small south swell will continue through Sunday, before diminishing early next week. Increasing trade winds will bring an increase in choppy trade wind swell to the east facing shores this week.

Fire weather

Critical fire weather conditions are not anticipated over the next several days. For this weekend, winds will be too light and relative humidity too high to be of any concern. For next week, even though trades will strengthen to become breezy to strong, relative humidity will remain sufficiently high to continue to preclude critical fire weather concerns.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.

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Data Courtesy of NOAA.gov