Weather Forecast

Hawaii County Weather Forecast for April 17, 2021

April 17, 2021, 7:16 AM HST
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Photo Credit: James Grenz

Hilo

Today: Isolated showers. Mostly sunny, with a high near 77. Southwest wind 5 to 7 mph becoming east northeast in the afternoon. Chance of precipitation is 20%.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 63. East northeast wind around 5 mph becoming light and variable after midnight. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Showers likely, mainly before noon. Partly sunny, with a high near 77. East wind 3 to 8 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Sunny, with a high near 79. North wind 5 to 7 mph becoming west southwest in the afternoon.

Tonight: Isolated showers between 7pm and 1am. Partly cloudy, with a low around 63. Light and variable wind becoming south around 5 mph in the evening. Chance of precipitation is 20%.

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Sunday: Scattered showers after 1pm. Mostly sunny, with a high near 79. Calm wind becoming west southwest around 5 mph 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 after noon. Mostly sunny, with a high near 74. South southeast wind 5 to 9 mph becoming north northeast in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 52. Northeast wind 8 to 11 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Scattered showers, mainly after noon. Mostly sunny, with a high near 74. East northeast wind 5 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

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Today: Scattered showers, mainly after noon. Partly sunny, with a high near 70. West wind around 6 mph becoming east northeast in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 45. Breezy, with an east wind 6 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.

Sunday: Scattered showers. Partly sunny, with a high near 70. East wind 5 to 8 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 76. Breezy, with an east wind 8 to 15 mph, with gusts as high as 18 mph.

Tonight: Isolated showers after midnight. Partly cloudy, with a low around 71. Breezy, with an east northeast wind 13 to 16 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Sunday: Scattered showers, mainly after noon. Mostly sunny, with a high near 77. Breezy, with an east northeast wind 15 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Puna

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 76. South southwest wind 5 to 7 mph becoming northeast in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 61. East northeast wind around 6 mph becoming west after midnight. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers. Partly sunny, with a high near 76. East northeast wind 6 to 10 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Sunny, with a high near 80. West wind 5 to 9 mph becoming light and variable in the afternoon.

Tonight: Mostly clear, with a low around 61. Light and variable wind becoming east northeast 5 to 8 mph in the evening.

Sunday: Isolated showers after noon. Sunny, with a high near 80. Northeast wind around 5 mph becoming calm in the morning. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Cloud bands associated with the remnants of an old cold front drift into the islands from the northwest today. Trade winds will strengthen through Sunday, and then weaken to a light and variable pattern from Monday into Wednesday as another cold front approaches the islands from the northwest. High pressure building in north of the state will bring a return to moderate trade winds from late Wednesday onward.

Discussion

Cloud bands from a dissipated frontal boundary just north of the state continue to creep towards the islands in a light wind regime today. Brief showers are possible as these cloud bands drift into the area with a slight increase in shower activity over the smaller islands through the day.
Trade winds will slowly increase by this morning over Kauai and Oahu, with shower activity picking up a bit over the windward and mountain slopes of both islands. Lighter winds with land and sea breezes will continue for Maui and Hawaii Counties through this afternoon, with trade winds returning later tonight. Interior clouds and shower will build through the afternoon hours over these eastern islands and then shift to a more windward passing shower regime later tonight as trade winds return.
On Sunday, moderate east to northeast trade winds will push the remnant cloud bands slowly westward away from the region. Gentle easterly trade winds will veer towards a more southeasterly direction from Sunday night into Monday morning as another cold front approaches the state from the northwest direction. This frontal trough will break down the ridge north of the state producing light large scale winds across all islands from Monday into Wednesday. Converging daytime sea breezes and island heating will build clouds over island mountain and interior sections each day. A few showers will tend to develop in the afternoon to early evening hours over these areas as the surface heating and sea breezes begin to fade.
The latest global model guidance has the next cold front stalling out near Kauai on Tuesday and Wednesday with only modest rainfall amounts expected along the frontal zone. This rainfall forecast will tend to favor the island of Kauai, and the location of the front measured in tens of miles will make all the difference in how much showers will develop over the Garden Isle. If the front stalls northwest of Kauai a rather mild weather forecast will continue, however if the front stalls over the island then expect cloudy skies with periods of slow moving moderate showers. Global models continue to show slight differences in the movement and location of this next cold front. Stay tuned for weather forecast changes next week as the global models improve on their guidance with this next frontal system.
The high pressure ridge will strengthen north of the state from late Wednesday through Friday allowing moderate trade winds to spread across the region. Passing showers remain in the forecast for windward and mountain areas during this time period.

Aviation

Scattered showers appear to be on the downtrend over Kauai as the remnant moisture of an old front advances eastward to Oahu and Maui County. There are a few showers over the waters around the Big Island not associated with the remnant moisture. The showers are rather dispersed so Oahu might escape AIRMET Sierra for mountain obscuration. AIRMET Sierra now in effect for north and east Kauai, could be taken down by 16z. If not, by 20z. Tops of the showers are no higher than 12k feet. Models are indicating the remnant moisture to linger around the central islands into this evening until the east- northeast trade winds return and disperse them. Trade showers will also increase across the windward waters of the Big Island tonight in tandem with the returning east- northeast trades.
The wind pattern remains light all around, but the direction differs from from the north and north- northeast west of Maui to easterly elsewhere. These two wind component will blend together tonight, becoming a light to moderate east-northeast trade flow.

Marine

With low pressure far north of the area and a ridge nosing in from the northwest, winds will be north to northeast in the light to moderate range through tonight. As high pressure ridging becomes established north of the area late in the weekend and into next week, winds will become easterly initially, and then east to southeast as the ridge moves closer to the state and a front approaches from the northwest. Winds will likely remain below the Small Craft Advisory threshold of 25 knots through most of next week.
Short period north swells will keep surf well below the advisory level along north facing shores into the new work week. The north swells will also bring a slight uptick in surf to exposed east and west shores. Background southerly swells will maintain small surf along south facing shores with a slight bump possible over this weekend.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov

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