Hilo

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 79 to 84 near the shore to 62 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Saturday: Cloudy with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 84 near the shore to 63 to 72 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 30 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to around 69 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows around 73 near the shore to 52 to 57 near 5000 feet. Light winds.

Saturday: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 86 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs 66 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 64 to 69 near the shore to 55 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs 67 to 87. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs 66 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 64 to 69 near the shore to 55 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs 67 to 87. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 73 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph.

Saturday: Mostly sunny. Breezy. Highs around 84 near the shore to around 67 near 5000 feet. East winds up to 20 mph.

Puna

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 79 to 84 near the shore to 62 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Saturday: Cloudy with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 84 near the shore to 63 to 72 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 30 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Breezy. Highs 82 to 89 near the shore to 67 to 74 above 4000 feet. Northeast winds up to 20 mph.

Tonight: Partly cloudy. Lows 70 to 75 near the shore to 51 to 58 above 4000 feet. East winds up to 15 mph.

Saturday: Sunny in the morning then becoming partly sunny. Highs 81 to 88 near the shore to 66 to 73 above 4000 feet. North winds up to 15 mph.

Detailed Forecast

Synopsis

Trades will steadily weaken and trend drier through the weekend with limited rainfall focused over windward slopes. A land and sea breeze pattern is likely early next week as background trades become increasingly light.

Discussion

A steady weakening of trades will take place between now and early next week due to the concurrent departure of the tropical low south of Hawaii and weakening of the governing surface high over the northeast Pacific. The latter will occur in response to an upper low in the Gulf of Alaska anchoring an expanding corridor of height falls for the next several days. High pressure over the northeast Pacific will subsequently weaken and be forced southward causing the local gradient to weaken and veer to easterly supporting an emerging hybrid sea breeze pattern this weekend. As said height falls force a decaying cold front southward toward the islands early next week, the gradient will further weaken and veer to ESEly and will most likely give rise to island scale land and sea breezes by Monday or Tuesday.
CIMSS PWAT imagery reveals a much drier and more stable upstream airmass crossing 150W and extending as far south as 15N at press time. This airmass, formed beneath persistent mid-level ridging east of the islands, will be ushered into the area by moderate trades as mid-level ridging builds aloft. The result will be a steady increase in stability, an increasing dry character to the trades, and warmer apparent temperatures as trades trend lighter. Shallow pockets of moisture trapped beneath the inversion will bring limited rainfall to windward slopes, mainly at night, but otherwise the vast majority of locations will stay quite dry.

Aviation

Moderate to breezy easterly trades will continue today, with clouds and light showers favoring windward and mountain areas. Although VFR conditions will prevail, brief periods with MVFR CIGS/VSBYS are possible in and around passing showers.
No AIRMETS are in effect and none are anticipated.

Marine

High pressure far northeast of the islands and a tropical disturbance passing well southwest of the state, are producing moderate to strong trade winds across the marine area. A Small Craft Advisory (SCA) remains in effect for the windier zones around Maui and the Big Island through 6 AM Saturday. As The disturbance moves steadily west or west-northwest and further away from the area, while the high northeast of the islands weakens, we should see a gradual decline in trade wind speeds through early next week. Winds should be below SCA speeds in all zones over the weekend, with gentle to moderate trade winds prevailing statewide early next week.
The combination of small, long-period south swells and short- period southeast swells will keep south shore surf near to below the seasonal average during the next 7 days. Choppy surf along east facing shores will gradually diminish as the trade winds ease during the next couple of days, with surf remaining below normal through late next week. North shore surf will remain nearly flat through the next 7 days.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov