Hilo

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 86 near the shore to 70 to 75 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 70 near the shore to around 56 at 4000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 86 near the shore to 70 to 75 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows 71 to 76 near the shore to around 57 near 5000 feet. Light winds. Chance of rain 30 percent.

Thursday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 40 percent.

Waimea

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Thursday: Mostly sunny. Scattered showers in the afternoon. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Thursday: Mostly sunny. Scattered showers in the afternoon. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows around 72 near the shore to around 55 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Thursday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Puna

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 86 near the shore to 70 to 75 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 70 near the shore to around 56 at 4000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 86 near the shore to 70 to 75 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 10 mph in the morning becoming light. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows around 74 near the shore to 53 to 60 above 4000 feet. Light winds. Chance of rain 30 percent.

Thursday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

The trades will ease today, with a few windward showers expected this morning, and a few interior and leeward showers developing this afternoon. Lighter trades will then prevail tonight through Saturday night, with localized land and sea breezes in leeward areas. Showers will favor windward slopes and coasts at night and the island interior and leeward areas each afternoon. A band of moisture may increase shower coverage statewide Sunday and Sunday night as the trades begin to restrengthen. Moderate trades and more typical trade wind weather should return early next week.

Discussion

Currently at the surface, a weak west-east oriented ridge of high pressure is located around 375 miles north of Honolulu, and is responsible for the light to moderate trade winds across the island chain early this morning. Infrared satellite imagery shows mostly clear to partly cloudy conditions across most of the state, with patches of a bit more extensive cloud cover moving through portions of the island chain at times. Radar imagery shows scattered showers moving into windward areas, with mainly dry conditions outside of a few spillover sprinkles in leeward locales. Main short term concern revolves around rain chances during the next few days.
The ridge north of the islands will weaken during the next few days as a cold front slowly settles southward and closer to the state. The front will then weaken into a trough north of the area on Friday, then retrograde westward over the weekend, with high pressure then building northeast of the state by early next week. A modified hybrid trade wind pattern is expected today through Saturday, with land and sea breezes developing in many of the more sheltered leeward areas, while light to moderate trades prevail in windward areas. It appears the trades could return to moderate levels as early as Sunday, but there is some indications that the lighter hybrid trade pattern could hold right through the weekend. Models are in good agreement showing moderate trades developing statewide by Sunday night and holding through early next week.
As for the remaining weather details, rather dry conditions should prevail across the state today. Shower coverage should remain fairly limited this morning with showers confined mainly to windward areas. This afternoon we should see showers diminish across windward areas, while a few showers develop as a result of daytime heating and localized sea breezes over the island interior and leeward areas. Shower coverage this afternoon appears highest over the Big Island, and to a lesser extent Kauai, where some slightly deeper moisture will exist, while shower activity over Oahu and Maui County should remain fairly sparse. A few downpours will be possible on the Big Island this afternoon, but substantial mid-level dry air should prevent any thunderstorms from occurring.
The pattern will change little tonight through Saturday night, with showers favoring windward slopes and coasts at night into the early morning hours, then transitioning over to the island interior and leeward areas each afternoon. A few of the showers could produce localized downpours each afternoon. Additionally, there might be enough mid-level moisture and instability to allow for a brief thunderstorm Thursday and Friday afternoons on the Big Island, but confidence in this occurring remains too low to include in the forecast at the moment. A band of moisture appears to accompany the returning trades Sunday and Sunday night, bringing an increase in shower coverage statewide as it moves through the islands from east to west. A return to more typical trade wind weather appears on tap for early next week.

Aviation

A weak ridge north of the state will keep light to moderate trade winds in the forecast with localized leeward afternoon sea breezes. A weak low level trough will pass south of the Big Island today enhancing moisture levels over the island. Clouds and showers will tend to favor windward and mountain areas of all islands, mainly in the the overnight hours. A few showers may develop over leeward areas in the afternoon to early evening time period, especially over the western Kona slopes of the Big Island.
No AIRMETs are in effect. AIRMET Sierra is possible for windward slopes of Maui and the Big Island today for tempo mountain obscuration.

Marine

An east to west oriented surface ridge, which is currently located about 325 nm north of Kauai, is expected to weaken and shift slowly toward the south. The close proximity of this feature to the islands will likely produce gentle to moderate trade winds across the state through Friday. The background flow may shift out of the east-southeast and strengthen slightly this weekend as a surface trough develops to the northwest, and a surface high pressure system builds far to the northeast.
The current south swell will gradually lower during the next few days. A short-period southeast swell is expected to maintain surf near the seasonal average along exposed south facing shores into this weekend. Forerunners from a new long-period south swell are expected to arrive next Tuesday. The modest background east to east-southeast winds will likely keep surf along east facing shores below the seasonal average through this weekend. Expect minimal surf along north and west facing shores through Friday. A short-period north swell may produce a slight bump in surf heights along north facing shores this weekend. A small northwest swell is expected to arrive next Monday, and continue through Tuesday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov