Weather Forecast

Hawaii County Weather Forecast for August 01, 2021

August 1, 2021, 7:16 AM HST
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Photo Credit: James Grenz

Hilo

Today: Showers likely before noon. Partly sunny, with a high near 83. North wind 6 to 10 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 70. West northwest wind around 7 mph. Chance of precipitation is 30%.

Monday: Scattered showers, mainly before 1pm. Partly sunny, with a high near 83. North northeast wind 5 to 7 mph. Chance of precipitation is 30%.

Kona

Today: Isolated showers after noon. Increasing clouds, with a high near 82. Calm wind becoming south southeast around 6 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Mostly cloudy, then gradually becoming mostly clear, with a low around 71. East wind around 6 mph.

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Monday: Increasing clouds, with a high near 82. Calm wind becoming southeast around 6 mph in the afternoon.

Waimea

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Today: Isolated showers before noon. Mostly sunny, with a high near 77. Very windy, with a northeast wind 29 to 31 mph, with gusts as high as 49 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly after 11pm. Partly cloudy, with a low around 59. Windy, with an east northeast wind 22 to 25 mph, with gusts as high as 40 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers, mainly before 1pm. Mostly sunny, with a high near 77. Windy, with an east northeast wind 18 to 25 mph, with gusts as high as 36 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 before noon. Partly sunny, with a high near 74. Very windy, with an east northeast wind 30 to 32 mph, with gusts as high as 50 mph. Chance of precipitation is 50%.

Tonight: Scattered showers. Partly cloudy, with a low around 57. Windy, with an east northeast wind 25 to 29 mph, with gusts as high as 45 mph. Chance of precipitation is 30%.

Monday: Scattered showers, mainly before 1pm. Partly sunny, with a high near 73. Windy, with an east northeast wind 21 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 30%.

South Big Island

Today: Sunny, with a high near 82. Very windy, with an east wind 30 to 37 mph, with gusts as high as 40 mph.

Tonight: Mostly clear, with a low around 75. Windy, with an east northeast wind 21 to 26 mph, with gusts as high as 34 mph.

Monday: Sunny, with a high near 82. Windy, with an east wind 28 to 30 mph, with gusts as high as 39 mph.

Puna

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 81. Breezy, with a north wind 13 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 69. Northwest wind 8 to 11 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers. Partly sunny, with a high near 81. North northeast wind 10 to 13 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Sunny, with a high near 85. Very windy, with an east northeast wind 20 to 25 mph increasing to 26 to 31 mph in the afternoon. Winds could gust as high as 47 mph.

Tonight: Mostly clear, with a low around 70. Windy, with an east wind 21 to 26 mph decreasing to 15 to 20 mph after midnight. Winds could gust as high as 33 mph.

Monday: Sunny, with a high near 85. Windy, with an east northeast wind 16 to 26 mph decreasing to 6 to 16 mph in the afternoon. Winds could gust as high as 38 mph.

Detailed Forecast

Synopsis

Locally strong and gusty trade winds along with stable and rather dry conditions will persist today. Winds will gradually ease Monday through Wednesday as the high pressure far northeast of the state weakens. Rather dry conditions will prevail into Tuesday with an uptick in mainly windward showers expected by Wednesday.

Discussion

A rather dry, stable, and gusty trade wind flow remains in place. A 1032 mb high parked nearly 1500 miles northeast of the state is driving the trades, and a ridge aloft overhead is producing very stable conditions with a strong low level inversion. As a result, scant rainfall was observed on windward slopes yesterday and overnight, and aside from typical afternoon and evening showers on the South Kona slopes, leeward areas have been very dry, including sections of interior and leeward Big Island where a large wildfire continues to burn.
Trades will increase slightly today as high pressure to the northeast strengthens and edges slightly closer, and a firm ridge overhead will maintain stable conditions with limited rainfall. Due to the expected increase in trade winds, a Wind Advisory is in effect for portions of Maui, Lanai, and the Big Island, including the area where the large wildfire is burning. Another dry day is in store with meager windward rainfall and sunny skies over most leeward areas. Trades will gradually ease Monday and Tuesday as the high to the northeast weakens, though dry and stable conditions will likely hold.
Typical summer trade wind weather is expected by Wednesday. High pressure will remain to the north of the state, but trades will drop into the moderate to locally breezy range. A weakness in the ridge aloft should allow the inversion to raise slightly, and the GFS and ECMWF are hinting at an increase in low level moisture that would translate into more windward showers.

Aviation

Stable conditions will support prevailing VFR through the forecast period. Locally strong trades will focus occasional light showers over windward slopes, mainly overnight, but any MVFR due to clouds or shower activity will be fleeting. Low-level wind shear characteristic of strong trades will be possible in favored locations, namely around Maui and particularly in the vicinity of PHOG. Finally, areas of low visibility are still possible over sections of Leeward Big Island and adjacent waters due to wildfire smoke.
AIRMET Tango for lee turbulence below 8kft will remain in effect through the period.

Marine

Surface high pressure building far north-northeast of the state will produce strong trade winds and elevated, rough seas today. A Gale Warning has been issued for the typically windier waters adjacent to the islands of Maui County and the Big Island through this afternoon. A Small Craft Advisory (SCA) is also in effect for the remaining Hawaiian waters today. The latest forecast shows the trade winds weakening slightly by this evening. Expect locally strong trade winds to continue for the typically windier waters, so the SCA will likely be posted for these waters starting tonight, and continuing through mid-week. Note that some additional waters may require a SCA tonight.
Recent observations from the nearshore buoys at Pauwela and Kaneohe Bay show wave heights of around 6 feet with wave periods near 8 seconds, which likely reflects the strengthening trade winds. Expect the rough, slightly elevated surf to persist along east facing shores into Tuesday. Surf heights may decrease to near the summertime average along east facing shores by mid-week as the trade winds weaken slightly.
Small south and south-southeast swells will maintain small surf along south facing shores today. There will mainly be residual south-southeast swell energy keeping below normal summertime surf along south facing shores from Monday through mid-week. The forecast guidance shows a small southwest swell arriving next Friday, which may provide a small boost in surf heights along exposed south facing shores heading into next weekend.
The nearshore buoys at Hanalei and Barbers Point continue to show tiny west-northwest swell energy, which was generated by recent west Pacific tropical cyclone activity. This may produce a slight bump in surf along exposed west facing shores of Kauai, and possibly Oahu, today. Otherwise, expect nearly flat conditions along most north and west facing shores this week.

Fire weather

Near critical fire weather conditions will persist into Monday due to strong and gusty trade winds and a rather dry and stable atmosphere. The Keetch Byram Drought Index at Honolulu will be just shy of the critical 600 mark during the next couple of days, but winds and daytime relative humidity will be at or very close to critical thresholds today. A slight drop in winds is expected on Monday and Tuesday, but dry leeward conditions will hold.

HFO Watches/Warnings/Advisories

Wind Advisory from 6 AM this morning to 6 PM HST this evening for Lanai Mauka, Maui Leeward West, Kohala, Big Island Interior, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Big Island South, Big Island Southeast.
Gale Warning until 6 PM HST this evening 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 Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov

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