Hilo

Tonight: Cloudy with frequent showers. Lows 63 to 70 near the shore to 53 to 58 at 4000 feet. West winds up to 10 mph in the evening becoming light. Chance of rain 90 percent.

Thursday: Mostly cloudy with numerous showers. Highs 80 to 86 near the shore to around 68 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 63 to 70 near the shore to 53 to 58 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy after midnight. Lows around 73 near the shore to 48 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 83 to 88 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with isolated showers. Lows around 73 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy with numerous showers. Lows 62 to 71 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 70 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 65 to 84. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 56 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy with numerous showers. Lows 62 to 71 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 70 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 65 to 84. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 56 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows around 74 near the shore to around 52 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday Night: Mostly cloudy with isolated showers. Lows around 73 near the shore to around 52 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Cloudy with frequent showers. Lows 63 to 70 near the shore to 53 to 58 at 4000 feet. West winds up to 10 mph in the evening becoming light. Chance of rain 90 percent.

Thursday: Mostly cloudy with numerous showers. Highs 80 to 86 near the shore to around 68 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 63 to 70 near the shore to 53 to 58 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows around 74 near the shore to around 54 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny with isolated showers. Highs 83 to 88 near the shore to 67 to 73 above 4000 feet. Southwest winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Thursday Night: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows around 73 near the shore to 51 to 56 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate northeast trades will weaken over the next several days in response to a couple fronts north of the islands disrupting the trade wind flow. A trough moving in from the east will increase clouds and showers tonight into Friday. Some strengthening of the trades is expected early next week.

Discussion

A weakening surface trough to the east will slowly approach the islands tonight. The trough will continue to disrupt the trade wind flow, and will bring in clouds and showers. The southern end of the trough is expected to reach the Big Island tonight, while the northern portion of the trough will be slower to reach the smaller islands, and may dissipate before then. However, even if the trough weakens, left over moisture will be carried in on the background flow to mostly impact the windward sides of the islands beginning tonight for the Big Island, and for the rest of the state Thursday into Friday morning. An upper trough over the islands could help to enhance the showers associated with the surface trough. An upper level ridge building over the islands will help to stabilize the airmass bu Friday.
A couple of fronts passing north of the islands will maintain a light wind pattern over the islands into the weekend, with localized afternoon sea breezes. Trade winds are expected to strengthen over the islands early next week.

Aviation

Expect moderate trades through the rest of the week. Showers and low ceilings will bring brief MVFR conds to windward and mauka areas. VFR should prevail elsewhere.
No AIRMETs are currently in effect and none are expected through today.

Marine

A nearly stationary surface high pressure remains far northwest of the state generating moderate to fresh trades. Winds will gradually trend down tonight through Friday to more light to moderate speeds as a trough approaches the state from the east, breaking down the local pressure gradient. Further more, a front approaching from the north will maintain these weaker trades through the weekend. Small craft conditions may return early next week as a high rebuilds north of the state and moderate to locally strong trade winds return.
Afternoon buoy data is still showing 4 to 5 foot, 11 to 14 seconds, north northwest (330-350 degree) producing small surf along north facing shores. This swell will continue to slowly subside through Friday. A similar size north swell will reinforce surf heights Friday night into Saturday. The next significant northerly swell (350 degree) will likely arrive late Sunday into early next week and may be large enough to produce advisory level surf along north facing shores.
A south southwest (180-200 degree) swell, will continue to slowly lower through Friday producing small to tiny surf along south facing shores. Long period forerunners of the next long period south swell is poised to trickle in mid- day Thursday and will reinforce south shore surf Thursday night into Friday before gradually trending down over the weekend. Surf along west- facing shores will be influenced by a mixture of both north northwest and south southwest swells. Thus, expect western exposures to remain slightly elevated as well. Expect below normal small east- facing shore chop over the next several days as trade wind flow remains relatively weak locally and upstream.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov