Hilo

Tonight: Partly cloudy with scattered showers. Lows 65 to 72 near the shore to 54 to 60 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers. Highs 80 to 88 near the shore to 67 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 65 to 72 near the shore to 53 to 60 at 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 75 near the shore to 51 to 57 near 5000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 89 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy with scattered showers. Lows 72 to 77 near the shore to 51 to 56 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 72 near the shore to 56 to 64 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 66 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72 near the shore to 56 to 63 near 3000 feet. East winds around 10 mph. Chance of rain 30 percent.

Kohala

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 72 near the shore to 56 to 64 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 66 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72 near the shore to 56 to 63 near 3000 feet. East winds around 10 mph. Chance of rain 30 percent.

South Big Island

Tonight: Partly cloudy with isolated showers. Lows around 76 near the shore to around 58 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Sunny. Isolated showers in the afternoon. Highs around 87 near the shore to around 70 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday Night: Mostly clear with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 75 near the shore to around 58 near 5000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Puna

Tonight: Partly cloudy with scattered showers. Lows 65 to 72 near the shore to 54 to 60 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers. Highs 80 to 88 near the shore to 67 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 65 to 72 near the shore to 53 to 60 at 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows around 75 near the shore to 53 to 58 above 4000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Wednesday: Breezy. Sunny with isolated showers. Highs 85 to 92 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Wednesday Night: Mostly clear. Lows around 75 near the shore to 53 to 58 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

A high pressure ridge building back in across the Hawaiian Islands will bring moderate to locally breezy trades through Wednesday. A low level trough will move in Thursday weakening the trades and increasing clouds and showers through Friday. High pressure will build back in across the region will bring a return to moderate to locally breezy trade winds through early next week.

Discussion

Satellite and radar imagery this afternoon show a band of clouds moving in on the trades with some isolated showers mostly along windward and mauka slopes. A strong ridge aloft will cap shower activity and limit clouds through Wednesday with windward and mauka areas seeing clouds and showers overnight into the early morning hours. Trade winds will strengthen into the moderate to locally breezy range through Wednesday.
Thursday and Friday the weather pattern changes as an easterly wave drifting in on the trades moves into the eastern side of the state. Trades will decrease and local scale island heating will drive afternoon sea breezes across the state. Clouds and showers will increase from east to west across the island chain as dynamics associated with the passing trough lift inversion heights to around 8,000 feet through Friday evening.
This trough will drift away from the islands late Friday with the ridge building back into the region, bringing stable weather and increasing trades from Saturday onward into early next week.

Aviation

Moderate to locally breezy trade winds continue tonight with mainly VFR conditions expected.
AIRMET Sierra posted for tempo mountain obscurations above 2500 feet along windward sides of Oahu with VFR elsewhere.
Possible AIRMET Sierra for mountain obscurations along windward sides of the islands through the overnight and into Wednesday morning.

Marine

A weak ridge extending south from its parent surface high over the north Pacific is settling in over the islands as Hurricane Henriette continues to move far northwest of the islands. Moderate to locally strong trade winds are spreading across the island. A Small Craft Advisory (SCA) remains in effect for the windier waters and channels around Maui County and the Big Island through Wednesday afternoon. A weak surface trough will advance westward across the state around Thursday, resulting in a brief period of light easterlies which may become variable in direction at times. Locally fresh trades return Friday into the weekend.
The current south swell will continue to gradually decline through the middle of the week. A small long-period south swell is expected to fill in by Saturday to bring surf heights back up for the weekend, though likely remaining below advisory level.
Surf along east facing shores will see a slight uptick through Wednesday, before declining slightly Thursday and Friday. Short period chop increases this weekend again as stronger trades develop. Surf along north facing shores will remain tiny through the forecast period.

Fire weather

Wind speeds, humidity levels and weather conditions will likely remain below critical fire weather thresholds this week. Drier and more stable trade winds will return from Saturday onward into early next week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov