Weather Forecast

Hawaii County Weather Forecast for August 12, 2021

August 12, 2021, 7:15 AM HST
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Hilo

Today: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 85 near the shore to 66 to 74 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 57 at 4000 feet. North winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 78 to 84 near the shore to 65 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 70 to 75 near the shore to 51 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.

ARTICLE CONTINUES BELOW AD

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 85 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

ARTICLE CONTINUES BELOW AD

Today: Breezy. Mostly sunny with isolated showers. Highs 67 to 86. East winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to 57 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 66 to 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kohala

ARTICLE CONTINUES BELOW AD

Today: Breezy. Mostly sunny with isolated showers. Highs 67 to 86. East winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to 57 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 66 to 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 67 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 73 near the shore to around 54 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Highs around 84 near the shore to around 67 near 5000 feet. East winds 10 to 15 mph.

Puna

Today: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 85 near the shore to 66 to 74 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 57 at 4000 feet. North winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 78 to 84 near the shore to 65 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Waikoloa

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 84 to 90 near the shore to 67 to 74 above 4000 feet. North winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 74 near the shore to 51 to 57 above 4000 feet. Southeast winds up to 20 mph.

Friday: Mostly sunny. Highs 83 to 89 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 15 mph shifting to the north in the afternoon.

Detailed Forecast

Synopsis

High pressure to the north will maintain moderate to occasionally breezy trades over the region through the weekend. Clouds and showers will be focused over the windward and mauka areas as a result.

Discussion

A surface ridge north of the islands is associated with high pressure far northeast of the islands. This will maintain a trade wind flow through the weekend. A northeast to southwest oriented mid to upper level trough is to the west of the islands, and helping to bring some high clouds to Kauai and adjacent waters. The upper level trough is slowly lifting northward and is pulling the high clouds away from the islands. High clouds have pretty much cleared Oahu overnight, but linger over and near Kauai.
Expect moderate trade winds today, with a bit of an uptick possible in the winds tomorrow and Saturday. The forecast has some weakening of the trades in place for the early part of the new week.
Very few changes to the general forecast philosophy have been made with the morning package. Models remain in agreement with high pressure to the north remaining the dominant feature into next week. However some changes in the strength of the high will alter the wind speeds at times. Meanwhile, clouds and showers will continue to be carried in on the trades. Precipitable water values from the overnight soundings have 1.25-1.50 inches near the islands which is at or just below normal. Expect slightly drier PW values through the weekend, which will likely result in lighter rainfall totals. An uptick in PW looks to be in store by Tuesday.

Aviation

High pressure north of the state will keep moderate trade winds in place during the next 24 hours, with locally breezy and gusty conditions at some of the terminals from mid morning through late this afternoon. Rather dry weather is expected statewide today, with just a few showers moving into windward slopes and coasts, and a few daytime heating driven showers developing over leeward sections of the Big Island. A more typical trade wind shower pattern should return this evening, bringing scattered showers to windward areas and sending a stray shower into leeward communities from time to time.
No AIRMETs are in effect and none are expected today.

Marine

A northeast to southwest oriented surface ridge located almost 750 nm north of Honolulu will maintain moderate trades today. A new surface high pressure system will build north of the islands as we head into the weekend. Locally strong trade winds are expected to return starting Friday with Small Craft Advisory (SCA) conditions likely developing across the typically windier waters adjacent to the islands of Maui County and the Big Island. This SCA will likely persist through Saturday for these waters. The trades are expected to gradually weaken from Sunday into early next week due to a surface trough passing by to the north of the state.
The current south-southwest swell is expected to gradually lower through tonight. A small, reinforcing southwest swell is expected to arrive Friday, followed by a larger swell from the same direction starting Sunday. The latter swell will likely be long- lived, with a peak in the Tuesday through Wednesday time period next week.
Tropical cyclone activity in the northwest Pacific has been sending small, back-to-back west-northwest swell energy toward the region. The current west-northwest swell will likely trend down through this morning. Another small, reinforcing west-northwest swell will likely reach the western islands later today. A slightly larger west-northwest swell may arrive this weekend, and persist through Tuesday.
Surf along east facing shores will continue to lower due to the lighter trade winds locally and upstream of the islands. There may be a tiny, short-period northeast swell this weekend, but surf will likely remain small along east facing shores into early next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov

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