Photo Credit: James Grenz

Hilo

Today: Partly sunny. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs around 86 near the shore to 70 to 76 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Slight chance of showers early in the evening, then showers likely in the late evening and overnight. Lows around 69 near the shore to around 55 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 85 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with a 30 percent chance of showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. West winds up to 10 mph.

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 30 percent chance of showers early in the evening. Lows 70 to 75 near the shore to around 56 near 5000 feet. North winds up to 10 mph in the evening becoming light.

Friday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Mostly sunny with chance of showers in the morning, then partly sunny with slight chance of showers in the afternoon. Highs around 84 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy. Slight chance of showers early in the evening, then chance of showers in the late evening and overnight. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs around 83 near the shore to 69 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny with chance of showers in the morning, then partly sunny with slight chance of showers in the afternoon. Highs around 84 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy. Slight chance of showers early in the evening, then chance of showers in the late evening and overnight. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs around 83 near the shore to 69 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny in the morning, then mostly cloudy with a 30 percent chance of showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 30 percent chance of showers early in the evening. Lows around 71 near the shore to around 54 near 5000 feet. Northeast winds up to 15 mph.

Friday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 50 percent.

Puna

Today: Partly sunny. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs around 86 near the shore to 70 to 76 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Slight chance of showers early in the evening, then showers likely in the late evening and overnight. Lows around 69 near the shore to around 55 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs around 85 near the shore to 69 to 74 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with a 20 percent chance of showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. North winds up to 10 mph.

Tonight: Mostly cloudy early in the evening then becoming mostly clear. A 20 percent chance of showers early in the evening. Lows around 73 near the shore to 52 to 59 above 4000 feet. East winds up to 10 mph.

Friday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to 70 to 76 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will trend lighter through Friday, then remain on the lighter side this weekend, with wind speeds increasing again early next week. Clouds and showers will favor windward areas during nights and mornings, but the lighter winds will allow sea breezes to drive cloud and shower formation over leeward and interior areas in the afternoons. Showers may be a little more active Friday and Saturday.

Discussion

Thanks to shifting high pressure north of the main Hawaiian Islands, trade wind flow will prevail through the forecast period, trending lighter as the weekend approaches. Winds will strengthen again early next week, becoming locally breezy. A weak upper trough will move in north of Kauai Friday and Saturday, increasing shower coverage. Otherwise, trades will deliver a few showers to windward areas while afternoon sea breezes drive cloud and shower formation over leeward and interior areas. Expect little in the way of total rainfall in the short term as upstream moisture is rather sparse.
Convergence of light trade flow and afternoon sea breeze flow will produce clouds and showers over leeward and interior sections of the islands during the afternoons from Friday through the weekend. Winds may even be light enough as early as this afternoon for leeward convection to develop. Models show an increase in moisture Friday and Saturday, coinciding with the development of a weak upper trough north of Kauai. This will bring an increase in shower coverage as the mixed layer deepens. Otherwise, our airmass will be relatively stable and high pressure building north of the islands next week will drive increasing trade winds that will deliver brief passing showers to windward areas.

Aviation

Moderate trade winds will ease today and trend lighter through the weekend as surface high pressure far north of the state moves eastward and relaxes the local pressure gradient. Isolated to scattered showers will continue to impact windward slopes and coasts, especially during the overnight and early morning hours. Later this afternoon, sea breezes will be possible for sheltered leeward areas, increasing clouds and shower activity across interior locations. Regardless, VFR flight conditions are expected to prevail throughout the forecast period for most locations, with only brief MVFR ceilings and visibility within any showers that develop.
There are currently no AIRMETs in effect and none are expected at this time.

Marine

A high pressure system far north of the state will lift northward. Wind speeds will trend lower into gentle to moderate range by Thursday through the weekend. Trades will likely rebuild early next week. The Small Craft Advisory (SCA) was cancelled this morning and wind speeds will likely remain below SCA thresholds into early next week.
Expect small surf along all shores with only background swell expected through Friday. Long period forerunners from the next south-southwest swell are expected late Saturday with the swell building on Sunday. South shore surf will rise to above seasonal average as the swell peaks by Monday, then slowly decline through Wednesday. Decreasing trade winds upwind of the state will lead to a decline in east shore surf through Friday, while waves generated in the East Pacific by Hurricane Kay could send a small long period swell to east facing shores later this weekend and early next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov