Hilo

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 64 to 69 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then showers likely after midnight. Lows 62 to 67 near the shore to around 52 at 4000 feet. West winds up to 10 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 64 to 69 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Mostly cloudy. Scattered showers in the afternoon. Highs 79 to 84 near the shore to around 64 near 5000 feet. West winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 66 to 71 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly cloudy. Scattered showers in the afternoon. Highs 79 to 84 near the shore to around 64 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Mostly cloudy with scattered showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 64 near the shore to 52 to 60 near 3000 feet. East winds up to 15 mph in the evening becoming light. Chance of rain 40 percent.

Sunday: Mostly cloudy with scattered showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Today: Mostly cloudy with scattered showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 64 near the shore to 52 to 60 near 3000 feet. East winds up to 15 mph in the evening becoming light. Chance of rain 40 percent.

Sunday: Mostly cloudy with scattered showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Partly sunny with isolated showers. Highs around 82 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 67 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Puna

Today: Cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 64 to 69 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then showers likely after midnight. Lows 62 to 67 near the shore to around 52 at 4000 feet. West winds up to 10 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 64 to 69 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 65 to 71 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 69 near the shore to 49 to 56 above 4000 feet. Light winds. Chance of rain 20 percent.

Sunday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 65 to 71 above 4000 feet. South winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Trade winds will trend down today through the holiday, likely enough for a localized land and sea breeze regime to become established. Clouds and showers will favor windward and mauka locations, except during the afternoon hours across leeward areas where sea breezes develop. A band of upper clouds lifting northward into the area will lead periods of cloudy skies through the weekend before moving out. A return of moderate to breezy trade winds is expected by Tuesday.

Discussion

Guidance remains in good agreement through the holiday weekend and depicts the trades trending down as the surface ridge weakens and shifts southward into the area. Radar wind profiles are already exhibiting more of an east-southeast low-level flow over the islands this morning. Although most of the shower coverage will favor windward and mauka locations, some may develop over our dry leeward areas through the afternoon periods where sea breezes form. Rainfall accumulations should remain on the light side given the very dry profiles above a strong trade wind inversion ranging from around 6000 ft over the western end of the state to around 8500 ft over the eastern end.
Southerly winds aloft is drawing moisture northward into the area due to a weakness that has formed in the upper ridge. Satellite imagery reflects this and shows a band of high clouds blanketing portions of the state this morning. Guidance suggests these high clouds will linger through the weekend, then scatter out early next week.
Looking ahead through the upcoming week, expect a dry and stable trade wind pattern with moderate to breezy easterly trades returning. Showers will remain limited, mostly favoring our typical windward and mauka locations through the overnight and morning periods as pockets of moisture move through.

Aviation

Easterly low lvl trade wind flow will continue today before trending southeast tonight, as an area of high pressure well north of the islands rotates slowly northeast. Current radar trends show showers increasing in areal coverage this morning, however showers area expected to trend more towards typical windward zones later this morning and through the remainder of the TAF period as winds shift southeast. Otherwise, sea breeze clouds and isolated showers are expected to develop this afternoon over sheltered leeward interior areas. Overall expect mainly VFR conditions through the TAF period. However, brief periods of MVFR cigs will maneuver across the islands this morning, as a broken SC cloud deck moves across the state underneath a strong low lvl trade wind inversion.
No AIRMETs are currently in effect. However, the possibility of moderate upper level turbulence continues today above FL240 continues across the islands, in response to a weakly organized jet streak lifting up toward the state.

Marine

Winds will weaken and veer toward the east-southeast across local waters over the weekend as a ridge north of the islands gradually moves south. Normal trades will likely return by early next week, at moderate to locally breezy levels, as the ridge shifts back toward the north.
A moderate south swell has arrived and has boosted surf on south facing shores into the low-end advisory range. Thus, a High Surf Advisory is in effect through tonight for south facing shores of all islands. As a reinforcing south swell moves up from the southern hemisphere and overlaps with weekend swells, surf will again be on the rise and may approach high-end advisory or low-end warning criteria by next Tuesday into Wednesday. A medium period northwest swell is expected to arrive by Sunday, holding into Monday. Surf along east facing shores will remain small and choppy through the weekend, though picking up by early next week as trades strengthen.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Sunday for south facing shores of all Hawaiian islands.

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Data Courtesy of NOAA.gov