Hilo

Today: Scattered showers, mainly before noon. Mostly cloudy, with a high near 82. West southwest wind 6 to 9 mph becoming east northeast in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after midnight. Cloudy, with a low around 66. Northeast wind 5 to 9 mph becoming west after midnight. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers, mainly before noon. Mostly cloudy, with a high near 82. West wind 5 to 9 mph becoming northeast in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Partly sunny, with a high near 79. Calm wind becoming west around 6 mph in the morning. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly cloudy, with a low around 69. West wind around 6 mph becoming calm. Chance of precipitation is 20%.

Saturday: Isolated showers after noon. Partly sunny, with a high near 79. West wind 5 to 7 mph becoming calm in the afternoon. Chance of precipitation is 20%.

Waimea

Today: Isolated showers. Mostly cloudy, with a high near 76. Windy, with a northeast wind 20 to 28 mph, with gusts as high as 40 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly cloudy, with a low around 58. Windy, with a northeast wind 22 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 20%.

Saturday: Isolated showers. Mostly cloudy, with a high near 76. Windy, with a northeast wind 21 to 26 mph decreasing to 15 to 20 mph in the afternoon. Winds could gust as high as 38 mph. Chance of precipitation is 20%.

Kohala

Today: Scattered showers, mainly before noon. Cloudy, with a high near 67. Windy, with an east wind 26 to 28 mph, with gusts as high as 40 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Cloudy, with a low around 53. Windy, with an east wind 26 to 28 mph, with gusts as high as 40 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers, mainly before noon. 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 40%. 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 wind 24 to 29 mph, with gusts as high as 37 mph.

Tonight: Partly cloudy, with a low around 74. Windy, with an east wind 23 to 26 mph, with gusts as high as 34 mph.

Saturday: Mostly sunny, with a high near 83. Windy, with an east wind 22 to 25 mph, with gusts as high as 32 mph.

Puna

Today: Scattered showers, mainly before noon. Cloudy, with a high near 79. Breezy, with a north northeast wind 9 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Cloudy, with a low around 64. Breezy, with a northeast wind 10 to 15 mph becoming west northwest after midnight. Winds could gust as high as 21 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers, mainly before noon. Cloudy, with a high near 79. West northwest wind 10 to 14 mph becoming northeast in the afternoon. Winds could gust as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Mostly sunny, with a high near 83. Breezy, with an east wind 9 to 14 mph becoming east northeast 17 to 22 mph in the afternoon. Winds could gust as high as 31 mph.

Tonight: Mostly clear, with a low around 68. Breezy, with an east wind 17 to 22 mph, with gusts as high as 31 mph.

Saturday: Mostly sunny, with a high near 83. Windy, with an east northeast wind 19 to 24 mph decreasing to 6 to 11 mph in the afternoon. Winds could gust as high as 34 mph.

Detailed Forecast

Synopsis

Dry and breezy easterly trade wind conditions are expected through the holiday weekend and into early next week. Any showers that develop will favor windward and mauka areas, mainly through the overnight and early morning periods as pockets of moisture move through. With the exception of the Kona slopes of the Big Island through the afternoons, the drought conditions will persist over leeward areas with little to no rainfall expected. Trade winds should ease slightly by midweek as the ridge to the north weakens.

Discussion

Guidance remains in good agreement and depicts the subtropical ridge strengthening as high pressure builds to the north over the weekend. Trades will respond and increase into the breezy category. Clouds and showers will favor windward and mauka locations, with the best chances being overnight through the early morning hours as pockets of moisture move through. Dry and stable conditions aloft combined with a strong subsidence inversion should limit accumulations each day, with little to none expected over our parched leeward grounds. As a result, the drought conditions will continue to expand across most leeward locations. The preliminary rainfall summary for June reflects these conditions with Lihue, Honolulu, Kahului and Hilo all coming in below average (Hilo had 2.26 inches, which is around 5 inches below normal for June).

Aviation

Locally strong trade winds and a very stable island atmosphere will lead to moderate low-level turbulence over and downwind of the mountains on all islands. AIRMET TANGO will therefore remain posted for the foreseeable future. With a strong subsidence inversion keeping low clouds capped near 6000 feet, shower intensity and coverage will remain limited and VFR will prevail. Isolated MVFR will remain possible, mainly over windward areas.

Marine

A surface high pressure system, which is currently located far north-northeast of the state, is expected to build slightly as it moves west to a position far north of the islands this weekend. The tightening pressure gradient over the region will produce locally strong trade winds across the state through most of the Independence Day Holiday Weekend. These robust trades will also generate elevated, rough seas, especially through the channels. A Small Craft Advisory (SCA) is now in effect for the waters south of the Big Island, the Oahu Leeward Waters, and Maalaea Bay, in addition to the Kaiwi, Pailolo, Alenuihaha Channels. The pressure gradient is expected to become even tighter later today, so the SCA is also in effect starting this evening for the Kauai Northwest and Leeward Waters, the Kauai Channel, and the Oahu Windward Waters.
The current south-southwest swell will continue to slowly subside through Saturday. This will likely cause surf heights to decrease to near summertime average heights along south facing shores as we head into the weekend. The forerunners from a new long-period south-southwest swell are expected to spread up over the area starting Sunday. This swell will continue to increase, and will likely cause surf heights to peak above the High Surf Advisory threshold along south facing shores starting late Sunday night or Monday. This elevated surf may hold along south facing shores into the middle of next week based on the latest guidance.
A small northwest swell, which is expected to arrive later today, may cause a slight increase in surf heights along most north and west facing shores of the smaller islands from this evening through Saturday. This swell will gradually decline from Saturday night through Sunday. The locally strong trade winds will cause choppy surf to gradually increase along east facing shores into early next week.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov