Weather Forecast

Hawaii County Weather Forecast for July 22, 2021

July 22, 2021, 7:16 AM HST
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Hilo

Today: Showers likely, mainly before 1pm. Mostly cloudy, with a high near 81. Calm wind becoming northeast 5 to 9 mph in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after 7pm. Cloudy, with a low around 67. East northeast wind 5 to 8 mph becoming calm after midnight. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Showers likely, mainly before 1pm. Mostly cloudy, with a high near 82. Calm wind becoming east 5 to 9 mph in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Mostly cloudy, with a high near 79. Light and variable wind becoming west 5 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers before midnight. Mostly cloudy, with a low around 67. Light and variable wind. Chance of precipitation is 20%.

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Friday: Scattered showers after noon. Partly sunny, with a high near 80. West southwest wind around 6 mph becoming calm in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

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Today: Scattered showers, mainly before 1pm. Mostly cloudy, with a high near 75. Windy, with a northeast wind 20 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after 7pm. Mostly cloudy, with a low around 59. Windy, with a northeast wind 20 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Scattered showers, mainly before 1pm. Partly sunny, with a high near 76. Breezy, with a northeast wind around 21 mph, with gusts as high as 30 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

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Today: Showers likely. Mostly cloudy, with a high near 66. Windy, with an east wind around 26 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 54. Windy, with an east wind 25 to 28 mph, with gusts as high as 40 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Showers likely. Mostly cloudy, with a high near 67. Windy, with an east wind 23 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly cloudy, with a high near 80. Windy, with an east wind 24 to 28 mph, with gusts as high as 36 mph.

Tonight: Partly cloudy, with a low around 74. Windy, with an east wind 25 to 28 mph, with gusts as high as 36 mph.

Friday: Mostly sunny, with a high near 81. Windy, with an east northeast wind 22 to 26 mph, with gusts as high as 34 mph.

Puna

Today: Showers likely. Cloudy, with a high near 78. Breezy, with a north wind 10 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Frequent showers. Low around 65. Breezy, with a northeast wind 6 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.

Friday: Frequent showers. High near 79. East northeast wind 8 to 13 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Mostly cloudy, with a high near 83. Windy, with an east northeast wind 16 to 26 mph, with gusts as high as 38 mph.

Tonight: Mostly clear, with a low around 68. Windy, with an east northeast wind 21 to 26 mph decreasing to 14 to 19 mph after midnight. Winds could gust as high as 38 mph.

Friday: Mostly sunny, with a high near 84. Windy, with a northeast wind 14 to 24 mph, with gusts as high as 34 mph.

Detailed Forecast

Synopsis

Breezy easterly trade winds will continue into the weekend, then potentially ease slightly late Sunday through early next week. A transition from the dry summertime trade wind pattern to a wetter period appears possible over the weekend through early next week as areas of tropical moisture associated with former Tropical Cyclones Felicia and Guillermo move through from east to west.

Discussion

Guidance remains persistent and continues to advertise a moistening trend over the weekend as the remnant low/trough associated with former TC Felicia passes well to the south Friday into Saturday and former TC Guillermo approaches and moves through from east to west Sunday through Monday as a weak trough. Satellite-derived precipitable water (PW) imagery reflects the northern fringe of higher moisture (PW 1.5-8″) north of Felicia lurking east of the Big Island and a much larger area farther upstream associated with former Guillermo.
Shower coverage will respond and increase this weekend through early next week, especially over windward and mauka locations as these areas of moisture move through. Some of this activity will spill over into our dry leeward areas with the breezy trades in place. Trades may trend down slightly early next week, depending on exactly where the remnant trough moves through. In addition to the increasing moisture and rainfall chances, the lighter winds combined with dewpoints breaking into the lower 70s will lead humid conditions beginning around or by Sunday.

Aviation

Dense high clouds are obstructing the view of the low clouds riding in with the trade winds. Weather radar is showing a batch of showers about to move through Oahu and that is about it. Not much showers after that it appears. Should more showers appears, they will be favoring the windward and mountain areas causing some brief periods of MVFR ceiling and vis. The leeward slopes and Kona coast of the Big Island will see an increase in low clouds this afternoon along with a few showers. Tops of the showers will be 7k to 10k feet.
The dense cirrus clouds with bases as low as 15k feet are expected to thin out as the day progresses. The high level turb above fl300 will also be easing by 22z as the jet stream shifts north of the islands, thus lowering AIRMET Tango.
A broad surface high pressure located far north-northwest of Kauai will maintain moderate to strong trade winds through this evening. Hence, AIRMET Tango for low level turbulence will continue through this afternoon.

Marine

Trades will begin to decrease late today or Friday as high pressure north of the state weakens. A Small Craft Advisory (SCA) remains in effect for most Hawaiian waters through this afternoon. The SCA may be scaled back to the typically windy waters around the Big Island and Maui tonight through Saturday afternoon. The SCA may be dropped entirely on Sunday as trades ease to moderate strength.
The largest surf will be found along east and south facing shores. Rough trade wind swell will maintain east shore surf near or slightly above July average during the next couple of days, followed by a slow decline to below average this weekend and early next week. A swell from the south-southwest will bring south shore surf near July average today and Friday. No other significant swells are expected.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Saturday 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 Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.

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Data Courtesy of NOAA.gov

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