Weather Forecast

Hawaii County Weather Forecast for July 17, 2021

July 17, 2021, 7:16 AM HST
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Hilo

Today: Occasional showers. High near 82. East northeast wind 6 to 9 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 69. East northeast wind around 7 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Showers likely, mainly before 1pm. Mostly cloudy, with a high near 81. East northeast wind 9 to 11 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Increasing clouds, with a high near 82. Light and variable wind. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Mostly cloudy, with a low around 68. Calm wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

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Sunday: Isolated showers after noon. Mostly sunny, with a high near 82. Calm wind becoming west around 6 mph. Chance of precipitation is 20%.

Waimea

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Today: Showers likely, mainly before noon. Partly sunny, with a high near 76. Breezy, with an east northeast wind 13 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 60%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Showers likely, mainly before midnight. Mostly cloudy, with a low around 59. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

Sunday: Scattered showers. Partly sunny, with a high near 76. Breezy, with an east northeast wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

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Today: Occasional showers. High near 69. Breezy, with an east wind around 21 mph, with gusts as high as 29 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 58. Breezy, with an east wind 16 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Showers likely. Mostly cloudy, with a high near 69. Breezy, with an east wind 17 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers. Partly sunny, with a high near 86. Breezy, with an east wind 20 to 22 mph, with gusts as high as 28 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly between 7pm and 1am. Mostly cloudy, with a low around 74. Breezy, with an east northeast wind around 22 mph, with gusts as high as 28 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Isolated showers before 1pm. Mostly sunny, with a high near 85. Windy, with an east wind 22 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Puna

Today: Occasional showers. High near 78. Breezy, with a northeast wind 11 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Occasional showers. Low around 66. Breezy, with a northeast wind 13 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Showers likely, mainly before noon. Mostly cloudy, with a high near 77. Breezy, with a northeast wind 15 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers after noon. Sunny, with a high near 84. North northeast wind around 7 mph. Chance of precipitation is 20%.

Tonight: Scattered showers before midnight. Mostly cloudy, then gradually becoming clear, with a low around 68. East wind 6 to 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Sunny, with a high near 84. North northeast wind around 9 mph.

Detailed Forecast

Synopsis

High pressure north of the islands will support breezy trade winds through the weekend. Stronger trades may develop early next week. Low clouds will move over the islands from the east, occasionally dropping showers over windward areas, with increased showers expected to move in later tonight and lasting into Saturday night.

Discussion

High pressure northeast and north of the islands will keep trade winds blowing across local waters for the foreseeable future. A high to the northeast will dissipate this weekend as a new high builds to our north. The central pressure of this new high may peak near 1036 mb early next week, steepening the pressure gradient enough to drive locally windy conditions Monday and Tuesday. Otherwise, breezy trade winds will prevail.
Satellite loop shows a vast field of stable low clouds between Hawaii and the mainland, with showery open-celled cumulus immediately upstream of the islands. These clouds will move in today through Saturday night as a weak mid-level trough replaces the current ridge. The subsidence inversion near 7000 feet will weaken and rise, leading to increased showers mainly across windward areas. Otherwise, expect patches of broken low clouds to provide a few windward showers, with rainfall favoring nights and mornings. Leeward areas will remain mostly dry, with only brief and light rainfall expected.

Aviation

Breezy easterly trade winds will continue through the weekend, with clouds and showers focusing over windward and mauka locations. MVFR CIGS/VIS are possible in and around passing showers. AIRMET Tango for low-level turbulence will remain in effect through the weekend.

Marine

Surface high pressure located far north of the area will maintain locally strong trade winds and rough seas across the state through this weekend. As a result, a Small Craft Advisory (SCA) remains in effect for the typically windier waters adjacent to the islands of Maui County and the Big Island this weekend. Due to additional strengthening of the trade winds early next week, it is likely the SCA will need to be expanded to include more Hawaiian Waters starting Monday.
Buoy observations from south of the state appear to indicate the current south swell, which has a period of around 16 seconds, will continue to build today. This will likely cause surf heights to increase to near or just above the summertime average along south facing shores from this afternoon into Monday. This south swell will gradually decline early next week, so expect surf to return to below normal heights along south facing shores by the mid-week. The gusty trade winds will produce near summertime average, choppy surf along east facing shores this weekend. The stronger trades, which are forecast early next week, are expected to produce elevated, rough surf along east facing shores starting Monday. Besides some localized wrap of trade wind swell, surf along most north facing shores will likely remain essentially flat through early next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov

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