Weather Forecast

Hawaii County Weather Forecast for August 09, 2021

August 9, 2021, 7:16 AM HST
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Hilo

Today: Scattered showers. Partly sunny, with a high near 84. West northwest wind 5 to 10 mph becoming northeast in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 68. North northeast wind 5 to 7 mph becoming light and variable. Chance of precipitation is 90%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Occasional showers. High near 84. Light and variable wind becoming east northeast 5 to 8 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

Kona

Today: Scattered showers after noon. Mostly sunny, with a high near 80. Calm wind becoming west 5 to 8 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Partly cloudy, with a low around 67. Southwest wind around 5 mph becoming calm after midnight. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

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Tuesday: Scattered showers after noon. Mostly sunny, with a high near 80. Calm wind becoming west 5 to 8 mph in the morning. Chance of precipitation is 40%. New precipitation amounts between a quarter and half of an inch possible.

Waimea

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Today: Isolated showers. Mostly sunny, with a high near 79. Breezy, with a northeast wind 13 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Tonight: Scattered showers. Mostly cloudy, with a low around 60. Breezy, with a northeast wind 13 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 50%. New precipitation amounts between a quarter and half of an inch possible.

Tuesday: Showers likely, mainly after noon. Mostly cloudy, with a high near 79. Breezy, with a northeast wind 8 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 70%. New precipitation amounts between 1 and 2 inches possible.

Kohala

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Today: Scattered showers. Partly sunny, with a high near 65. East wind 5 to 9 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 55. Breezy, with an east wind 9 to 14 mph increasing to 15 to 20 mph after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Occasional showers. High near 65. Breezy, with an east wind 15 to 20 mph decreasing to 9 to 14 mph in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

South Big Island

Today: Sunny, with a high near 85. Breezy, with an east wind 13 to 21 mph, with gusts as high as 26 mph.

Tonight: Isolated showers. Partly cloudy, with a low around 76. Breezy, with an east northeast wind 13 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 20%.

Tuesday: Scattered showers, mainly after noon. Mostly sunny, with a high near 85. Breezy, with an east wind 13 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. Partly sunny, with a high near 83. Northwest wind 9 to 14 mph becoming northeast in the morning. Winds could gust as high as 18 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 66. North northwest wind 7 to 11 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

Tuesday: Occasional showers. High near 83. Northwest wind 7 to 10 mph becoming east northeast in the afternoon. Chance of precipitation is 90%. New precipitation amounts between three quarters and one inch possible.

Waikoloa

Today: Sunny, with a high near 85. East wind 7 to 14 mph becoming northwest in the morning. Winds could gust as high as 18 mph.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 68. East northeast wind 6 to 11 mph becoming light and variable. Chance of precipitation is 20%.

Tuesday: Scattered showers after noon. Mostly sunny, with a high near 85. North northwest wind around 6 mph becoming calm in the afternoon. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Detailed Forecast

Synopsis

Moderate trade winds and generally dry weather will prevail today. More showery weather is then expected Tuesday and Wednesday as an area of moisture moves in from the east, with the trades dropping off just a bit as well. More typical weather and slightly stronger trades will return Thursday through the weekend as high pressure strengthens to our north.

Discussion

Currently at the surface, a 1030 mb high is centered around 1350 miles north-northeast of Honolulu, and is driving moderate trade winds across the island chain early this morning. Meanwhile, the remnant trough of former tropical cyclone Jimena is located around 400 miles east of the Big Island. Infrared satellite imagery shows partly to mostly cloudy conditions in windward areas, with clear to partly cloudy skies in most leeward locales. Radar imagery shows a few showers moving into windward areas, with a stay shower reaching leeward locales every once in a while. Main short term concern revolves around increasing rain chances as the old tropical remnants move through.
High pressure north-northeast of the islands will keep moderate trade winds in place through the middle of the week, with only a slight easing expected as the remnant trough of Jimena moves through. Once the remnant trough exits west of the islands, high pressure north of the state will become more dominant, allowing the trades to increase back to moderate and locally breezy levels Thursday through the weekend.
As for the remaining weather details, fairly dry conditions should continue to hold in place today, with showers limited to mainly windward and mauka areas. The leading edge of deeper moisture associated with former tropical cyclone Jimena should begin to filter into the region from the east tonight and Tuesday, bringing an increase in showers particularly to windward areas. This deeper moisture will slowly pass westward across the islands through Wednesday night, likely bringing showery weather to windward areas and a few showers to leeward locales as well. We should see drier and more typical trade wind conditions return Thursday through the weekend, with showers favoring windward and mauka areas, mainly at night and during the early morning hours.
Some more humid weather is expected to accompany the remnants of Jimena as they pass through the islands as well. Dewpoints are forecast to climb into the 70s Tuesday and Wednesday, making it feel rather uncomfortable from what we’ve been experiencing lately. Drier more comfortable weather should then return beginning Thursday and continuing through the weekend.

Aviation

A high pressure system far north of the Hawaiian Islands will bring moderate trade wind speeds through at least Tuesday. Stable weather conditions today will transition to unstable showers by Tuesday. Expect predominantly VFR conditions across the state today, with brief MVFR ceilings at times over the windward slopes of the Big Island and East Maui. AIRMET Sierra for Mountain Obscuration may be needed for periods of low ceilings developing tonight over windward and mountain areas of the eastern Hawaiian Islands.

Marine

The northeastern movement of high pressure far north of the region will weaken the pressure gradient across the state. This will ease trade winds back to more gentle to moderate speeds through the middle of the week. The passage of a weak wave from the remnants of TS Jimena, with an influx of higher moisture, will increase shower probabilities from tonight through mid week. Trades may slightly increase towards the end of the week as high pressure builds back in north of the state.
In response to weakening trades, surf along east facing shores will gradually fall in the coming days. The next south swell is timed to arrive along the island’s southern shorelines late tonight and peak Tuesday into Wednesday. This should translate to slightly above normal surf along south facing shores Tuesday and Wednesday. A series of compact low pressure systems passing across the Northwest Pacific will produce small, low period west to northwest swells during the second half of the week. The first in a series of these overlapping west to northwest swells is expected to arrive late Tuesday followed by a slightly larger swell Friday into Saturday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov

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