Weather Forecast

Hawaii County Weather Forecast for August 04, 2021

August 4, 2021, 7:16 AM HST
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Photo Credit: James Grenz

Hilo

Today: Showers likely, mainly before 11am. Partly sunny, with a high near 80. Northeast wind 5 to 10 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 68. West wind 6 to 8 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Showers likely, mainly before noon. Partly sunny, with a high near 80. Calm wind becoming east 5 to 8 mph in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after 11am. Increasing clouds, with a high near 79. West wind 5 to 11 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers before 11pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 68. North wind 5 to 7 mph becoming east southeast after midnight. Chance of precipitation is 20%.

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Thursday: Scattered showers after noon. Mostly sunny, with a high near 81. West southwest wind around 5 mph becoming calm in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

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Today: Showers likely, mainly before 11am. Partly sunny, with a high near 73. Windy, with a northeast wind 25 to 28 mph, with gusts as high as 39 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 60. Windy, with a northeast wind 20 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Thursday: Scattered showers, mainly before noon. Mostly sunny, with a high near 72. East northeast wind around 14 mph, with gusts as high as 18 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

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Today: Showers likely, mainly before 11am. Mostly cloudy, with a high near 66. Windy, with an east northeast wind 26 to 28 mph, with gusts as high as 39 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 57. Very windy, with an east northeast wind 23 to 31 mph, with gusts as high as 45 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Showers likely, mainly before noon. Mostly cloudy, with a high near 67. Breezy, with an east wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 83. Windy, with an east northeast wind 26 to 29 mph, with gusts as high as 37 mph.

Tonight: Partly cloudy, with a low around 74. Windy, with an east wind 24 to 29 mph, with gusts as high as 37 mph.

Thursday: Sunny, with a high near 84. Windy, with an east wind 24 to 26 mph, with gusts as high as 34 mph.

Puna

Today: Showers likely, mainly before 11am. Mostly cloudy, with a high near 76. North northeast wind 11 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 65. North wind 9 to 11 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Thursday: Showers likely, mainly before noon. Partly sunny, with a high near 76. East northeast wind 9 to 13 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Sunny, with a high near 84. Windy, with an east northeast wind 16 to 25 mph, with gusts as high as 36 mph.

Tonight: Mostly clear, with a low around 67. Windy, with an east northeast wind 17 to 25 mph, with gusts as high as 36 mph.

Thursday: Sunny, with a high near 84. Breezy, with an east wind 12 to 17 mph becoming north northeast 6 to 11 mph in the afternoon. Winds could gust as high as 23 mph.

Detailed Forecast

Synopsis

High pressure to the north will keep breezy trade winds over the islands into the weekend. Low clouds will deliver a few showers, mainly to windward slopes during night and morning hours, while most leeward areas remain dry.

Discussion

Surface high pressure far NNE of the islands will drive breezy trade winds into the upcoming weekend as it shifts slowly W. The central pressure of the high is expected to be around 1030 mb for the next couple of days, thus locally breezy trade winds are not expected to change all that much. A low-level trough (remnants of what eventually becomes of T.S. Hilda and T.D. 9-E remnants) may approach and pass near or N of the islands in the long term, potentially leading to some reduction in trade wind speeds late this weekend and early next week, but confidence in this occurring is low.
Model guidance does not explicitly highlight any significant moisture source to bring enhanced rainfall to the islands, but does indicate that the center of a mid-level ridge will move N and away from the islands over the next couple of days. The cloud-capping subsidence inversion currently based between 8000-10000 feet will remain sufficiently high to allow low clouds arriving on the trades to deliver a few showers, while island terrain also helps to drive some shower formation. Most of this light to moderate rainfall will remain close to the windward mountains, and will be most likely during nights and mornings. Any light rain that occasionally falls over windward coastal areas, or that spreads to leeward communities, will do little to override the drying effects of the breezy trades and strong solar insolation.

Aviation

High pressure far northeast of the islands will continue to bring moderate to locally breezy trade winds to the region through tonight, and likely beyond. AIRMET Tango for low level mechanical turbulence to the lee of the mountains continues remains in effect. Anticipate this AIRMET to remain in place through tonight and likely beyond that.
VFR conditions are expected to prevail in most locations. Lingering clouds and showers are primarily impacting the east side of the Big Island early this morning, bringing brief MVFR conditions to the area. Satellite shows the back end of this cloud area is about 50 miles upstream of the Big Island, so expect conditions to improve later by midday.

Marine

A strong surface high pressure system located far north-northeast of the islands early this morning is maintaining strong trade winds across the area. This was confirmed by a scatterometer pass from last evening, which showed wind speeds of 25 to 30 knots across most Hawaiian waters. Since the trades have remained stronger than the guidance would suggest, the Small Craft Advisory (SCA) remains in effect through this afternoon for all Hawaiian waters. The trade winds are forecast to weaken slightly by this evening, so the SCA has been scaled back to only include the typically windier waters adjacent to the islands of Maui County and the Big Island from tonight through Friday. The latest forecast keeps SCA conditions for these same typically windy waters into Saturday, but the trades may weaken later this weekend.
Due to the continuing strong trade winds, rough surf will likely remain slightly above the seasonal average along east facing shores today. The most recent observations from the near shore PacIOOS buoys show the trade wind swell is 7 to 8 feet with periods of 7 to 8 seconds. As the trades drop a notch, expect surf along east facing shores to lower to near the seasonal average from tonight through Friday. Some additional lowering of the surf is expected along east facing shores from this weekend into early next week. Small south and southeast swells will keep small background surf along most south facing shores through Friday. A new small southwest swell is expected to arrive this weekend, followed by the potential for a slightly larger south swell spreading across the area early next week. If this swell does arrive, it may cause surf heights along south facing shores to reach, or possibly exceed, the seasonal average starting next Tuesday. Expect nearly flat conditions to persist along most north and west facing shores through this weekend.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov

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