Photo Credit: James Grenz

Hilo

Today: Scattered showers, mainly before 2pm. Mostly sunny, with a high near 83. North northeast wind 5 to 7 mph. Chance of precipitation is 30%.

Tonight: Scattered showers, mainly after 7pm. Mostly cloudy, with a low around 70. North northeast wind around 5 mph becoming calm after midnight. Chance of precipitation is 40%.

Tuesday: Scattered showers. Partly sunny, with a high near 83. Calm wind becoming east northeast 5 to 8 mph in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Mostly sunny, with a high near 82. Calm wind becoming southeast around 6 mph in the afternoon.

Tonight: Isolated showers. Partly cloudy, with a low around 71. Southeast wind around 6 mph becoming calm in the evening. Chance of precipitation is 20%.

Tuesday: Scattered showers, mainly after noon. Mostly sunny, with a high near 81. Calm wind becoming west southwest around 5 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: 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.

Tonight: Scattered showers. Mostly cloudy, with a low around 59. Breezy, with an east northeast wind 14 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers, mainly before noon. Mostly sunny, with a high near 77. Breezy, with a northeast wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

Today: Scattered showers, mainly before 1pm. Mostly 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%.

Tonight: Scattered showers. Mostly cloudy, with a low around 57. Breezy, with an east northeast wind 16 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 40%.

Tuesday: Scattered showers. Partly sunny, with a high near 70. Breezy, with an east northeast wind 15 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

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

Tonight: Mostly clear, with a low around 75. Windy, with an east northeast wind around 28 mph, with gusts as high as 36 mph.

Tuesday: Sunny, with a high near 82. Windy, with an east northeast wind 24 to 28 mph, with gusts as high as 36 mph.

Puna

Today: 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.

Tonight: Scattered showers. Mostly cloudy, with a low around 69. North northwest wind 6 to 10 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers. Partly sunny, with a high near 81. Northeast wind 6 to 10 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Areas of smoke. 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.

Tonight: Mostly clear, with a low around 70. Southeast wind 3 to 6 mph.

Tuesday: Sunny, with a high near 84. North northeast wind 5 to 8 mph.

Detailed Forecast

Synopsis

Strong high pressure far north northeast of the main Hawaiian Islands will drive breezy to locally windy trade winds across local waters today. Winds will decrease slightly beginning Tuesday as the high weakens. Generally dry conditions will prevail into Tuesday. Expect an uptick in showers by the middle of the week, with rainfall favoring windward and mauka areas.

Discussion

The pressure gradient between a 1032 mb high far northeast of the state and equatorial low pressure is sufficiently steep to drive locally windy conditions across the islands today. Models show the high will weaken a bit Tuesday, resulting in a decrease in trade wind speeds Tuesday through Saturday. Satellite loop shows small patches of low clouds moving westward across local waters within trade flow. Cloud cover favors windward sections of the smaller islands. Windward and Kona sections of the Big Island continue to see broken to overcast low clouds as well. Radar shows isolated to scattered showers across the area, mainly across windward areas.
Rather stable conditions will continue over the next couple of days as upper ridging dominates. Dry weather will prevail with brief passing showers possible over windward and mauka areas. Upslope showers are possible over Kona slopes of the Big Island during afternoon and evening hours. Beginning Tuesday, a weak upper trough will move near the east end of the island chain, raising inversion heights. Showers may increase, especially for windward and mauka areas, and will be highly dependent on incoming moisture availability.

Aviation

Breezy to strong trade winds will persist through the day as robust high pressure remains far north of the state. Spotty shower activity will mainly affect windward and mauka sections on the individual isles. And as long as the fire in leeward Big Island persists near Waikoloa Village, smoky conditions with occasional MVFR visibilities will continue. VFR, however, will hold over most areas most of the time.
An AIRMET for low level turbulence to the lee of the mountains is in effect because of the strong trade winds. This AIRMET will likely be extended through tonight.

Marine

A strong high pressure system far northeast of the Hawaiian Islands will keep fresh to strong trade winds in the forecast through the week. A Small Craft Advisory (SCA) will decrease in coverage this morning to include all eastern Hawaiian waters. By Tuesday, the SCA will decrease further covering only the typically windier waters near Maui County and the Big Island, and these SCA winds will linger through much of the week.
The rough, slightly elevated surf continues along east facing shores driven by the strong trade winds. Expect these slightly elevated surf heights along east facing shores to persist into Tuesday, before decreasing to near the summertime averages by Wednesday onward as the trade winds weaken slightly. Swell energy from the south to southeast direction will continue to keep south facing shores from going flat from Monday through mid-week. The forecast guidance shows a small south-southwest swell arriving next Friday, which may provide a small boost in surf heights along exposed south facing shores heading into next weekend. Expect nearly flat conditions along most north and west facing shores this week.

Fire weather

Near critical fire weather conditions will persist today 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 by Tuesday, but dry leeward conditions will hold.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Tuesday for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov