Hilo

Today: Scattered showers, with thunderstorms also possible after 1pm. Cloudy, with a high near 82. West wind 6 to 8 mph becoming east northeast in the morning. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers and thunderstorms, then frequent showers after 7pm. Low around 62. Calm wind becoming west 5 to 8 mph in the evening. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Saturday: Frequent showers, with thunderstorms also possible after 1pm. High near 83. West wind around 6 mph becoming northeast in the afternoon. Chance of precipitation is 80%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Kona

Today: Scattered showers and thunderstorms after noon. Partly sunny, with a high near 84. East southeast wind around 5 mph becoming west southwest in the morning. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Isolated showers before midnight. Mostly cloudy, with a low around 62. East wind around 5 mph becoming calm in the evening. Chance of precipitation is 20%.

Saturday: Scattered showers and thunderstorms after noon. Partly sunny, with a high near 83. Calm wind becoming west southwest 5 to 8 mph. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Waimea

Today: Scattered showers, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 76. Windy, with a northeast wind 20 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Isolated showers and thunderstorms, then scattered showers after 7pm. Mostly cloudy, with a low around 51. Windy, with a northeast wind 20 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday: Scattered showers, with thunderstorms also possible after 1pm. Mostly cloudy, with a high near 75. Windy, with a northeast wind 20 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Kohala

Today: Scattered showers, with thunderstorms also possible after noon. Cloudy, with a high near 69. Windy, with an east wind 23 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Frequent showers. Low around 43. Windy, with an east wind 21 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Frequent showers, with thunderstorms also possible after noon. High near 67. Windy, with an east wind 21 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 80%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

South Big Island

Today: Mostly sunny, with a high near 83. Windy, with an east wind 21 to 26 mph, with gusts as high as 34 mph.

Tonight: Scattered showers after midnight. Partly cloudy, with a low around 68. Windy, with an east wind 21 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 30%.

Saturday: Scattered showers before noon, then isolated thunderstorms after noon. Mostly sunny, with a high near 83. Windy, with an east northeast wind 23 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 30%.

Puna

Today: Scattered showers, with thunderstorms also possible after noon. Cloudy, with a high near 79. Northwest wind 5 to 10 mph becoming northeast in the afternoon. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Frequent showers. Low around 60. North northeast wind 6 to 9 mph becoming northwest in the evening. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Saturday: Frequent showers, with thunderstorms also possible after noon. High near 81. Northwest wind 8 to 11 mph becoming northeast in the afternoon. Chance of precipitation is 80%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Waikoloa

Today: Mostly sunny, with a high near 82. Windy, with an east northeast wind 18 to 24 mph, with gusts as high as 34 mph.

Tonight: Mostly clear, with a low around 61. Windy, with an east southeast wind 16 to 23 mph, with gusts as high as 32 mph.

Saturday: Isolated showers and thunderstorms after noon. Mostly sunny, with a high near 81. Windy, with an east northeast wind 13 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Moderate to breezy easterly trade winds will persist through the weekend, with clouds and showers favoring windward and mountain locations. Windward shower coverage could increase later today through Saturday night as an upper low moves through from north to south. Warm and humid conditions, along with increasing rainfall chances, may return early next week as the trade winds diminish ahead of an approaching front.

Discussion

The surface trough northwest of Kauai that disrupted the trade winds earlier in the week will continue retreating westward and away from the area today. Easterly trade winds have returned, and will likely become breezy over the weekend as high pressure builds to the north. Windward showers may increase later today through Saturday night as an upper low drops southward into the area. Some showers could reach leeward locations as the inversion weakens and the trades increase – especially through the overnight and early morning hours. In addition to the increasing shower coverage, a thunderstorm or two can’t be ruled out over the Big Island slopes through the afternoon hours today and Saturday.
Models show the upper low briefly drifting south of the state Sunday through Sunday night, then lifting back through the area and merging with an upper trough passing to the north Monday through Tuesday. The subtropical ridge will weaken once again as a front approaches the region from the northwest. If this scenario evolves, a land and sea breeze regime, along with warm and humid conditions, will return and continue through the first half of next week. Rainfall chances will trend up through this time, with the best coverage setting up over interior and leeward locations through the afternoon hours.

Aviation

A high pressure ridge north of the Hawaiian Islands will maintain moderate trade winds today and tonight. Periods of mountain obscurations are possible for windward slopes, especially over the eastern slopes of Maui and the Big Island as cloud bands drift through the region. An upper level low north of the island chain will drift south across the state through Saturday. Instability with this upper low will likely enhance shower activity mainly over windward and mountain locations.
No AIRMETs are in effect. However mountain obscurations may be needed for windward Big Island later this morning.

Marine

A surface high passing north of the islands today will maintain fresh to locally strong trade winds through the weekend. A small craft advisory is in effect to until 6 am HST Sunday for the windier waters of Maui County and waters south of the Big Island. Trade winds are expected to trend down and become southeast on Monday, ahead of an approaching front from the northwest.
A northwest swell has peaked and will be subsiding slowly through Saturday. A small west-northwest swell is tabbed to arrive late Monday, peak Tuesday, then subside gradually through Wednesday. The source of this swell is from a long lived distant typhoon. A small short period northwest pulse is slated to arrive Wednesday night and Thursday.
Small surf will continue along the south facing shores into next week due to a series of long period swell from the southern hemisphere. The boost in the trade winds will raise the surf into the small to moderate range along the east facing shores into the weekend. The surf will trend smaller after Sunday as the trade wind diminishes.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov