Hilo

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 86 near the shore to 66 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Lows 66 to 73 near the shore to 56 to 61 at 4000 feet. Light winds. Chance of rain 30 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 83 near the shore to 66 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 88 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 74 near the shore to 53 to 59 near 5000 feet. Light winds. Chance of rain 30 percent.

Thursday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 88 near the shore to around 70 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 89. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 70 near the shore to 56 to 65 near 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 88. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 89. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 70 near the shore to 56 to 65 near 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 88. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 74 near the shore to around 55 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Puna

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 86 near the shore to 66 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Lows 66 to 73 near the shore to 56 to 61 at 4000 feet. Light winds. Chance of rain 30 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 83 near the shore to 66 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Waikoloa

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 90 near the shore to 67 to 75 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows around 74 near the shore to 51 to 59 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 89 near the shore to 67 to 75 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Light winds will hold over the western islands, while moderate east-southeast winds prevail over the eastern end of the state through Thursday. This will keep a land sea breeze pattern in place for the western islands and more sheltered areas over the eastern end of the state, with showers favoring windward areas overnight and leeward and interior areas during the afternoon and evening hours. The trades will return and strengthen from east to west across the state Thursday night and Friday, bringing a return of more typical trade wind weather, although it may be more showery over windward sections of the eastern islands. Moderate to locally breezy trades and typical trade wind weather will prevail Friday night through the weekend, with showers favoring windward and mauka areas along the occasional leeward spillover. The trades are forecast to ease slightly early next week, with typical trade wind weather continuing.

Discussion

Currently at the surface, a 1022 mb high is centered around 1550 miles northeast of Honolulu, with a ridge extending southwest to a location around 275 miles north of Kauai. Meanwhile, a weak trough of low pressure is located around 40 miles northwest of the Garden Island and is moving northwest around 10 mph. The resulting gradient is producing light winds over the western islands, with moderate east-southeast winds in unsheltered locations over the eastern end of the state. Infrared satellite imagery shows clear to partly cloudy skies over Oahu and Maui County, with partly to mostly cloudy conditions over Kauai and the Big Island. Radar imagery shows, scattered showers across Kauai, isolated showers over the Big Island, and very little if any rain on Oahu and Maui County. Main short term focus revolves around rain chances and wind trends during the next few days.
The trough near Kauai will lift northwest and eventually north as it slowly dissipates during the next couple days, keeping the western extent of the ridge axis north of the islands weak. As a result, moderate east-southeasterly winds will hold in place over the eastern end of the state through Thursday, while light and variable winds prevail over the western islands keeping a land and sea breeze pattern dominant. The ridge axis will begin to strengthen and lift northwest Thursday night and Friday. In response, trade winds will return and strengthen from east to west across the island chain, with moderate to locally breezy conditions expected over the weekend. The trades are forecast to ease into the gentle to moderate range early next week as ridging north of the island weakens.
As for the remaining weather details, we should see fairly dry conditions across most of the state this morning, with rain chances slightly higher over Kauai where some deeper moisture lingers in place. Daytime heating and sea breezes should bring another round of scattered interior and leeward showers this afternoon that should diminish fairly quickly this evening, with only a few windward showers again overnight. Not much change in the pattern is expected through Thursday, with showers favoring windward areas in the morning, and interior and leeward areas Thursday afternoon.
A mid and upper level disturbance will approach and move into the islands Thursday night and Friday, elevating inversion heights and bringing an increase in moisture to the state. As a result, we should see an increase in trade wind showers Thursday night and Friday, particularly over the eastern islands. Meanwhile over Kauai and Oahu, the trades may remain light enough to allow for some afternoon and early evening shower development over leeward and interior areas Friday afternoon. Fairly typical trade wind weather should then prevail Friday night through early next week, with showers favoring windward and mauka areas, along with an occasional shower reaching leeward communities from time to time.

Aviation

A low level trough, currently near Kauai, will continue to produce periods of MVFR low clouds and showers over Kauai this morning. A weak high pressure ridge north of the region will keep a hybrid light trade wind and sea breeze pattern in place over all islands today and tomorrow. Clouds and a few showers will build over island mountain and interior sections each afternoon with some clearing at night due to land breezes.
AIRMET Sierra for mountain obscuration remains in effect for the islands of Kauai and Lanai. These conditions will diminish later this morning.

Marine

A ridge just to the north of the islands, coupled with a weak low level trough near the western end of the island chain, has weakened the pressure gradient over the area, resulting in the light to moderate trade winds over the coastal and offshore waters. The trough is expected to continue to move to the west and weaken, and the ridge will lift northward this weekend. Expect winds to pick up some this weekend, and at least briefly approach Small Craft Advisory levels in some of the typical locations.
The current long period south swell will continue to lower gradually today. A much smaller south swell is expected Thursday through Sunday. The current small mid period northwest swell will lower gradually through Friday. Short period choppy surf along east facing shores will remain rather small through Friday with a gradual uptick expected over the weekend as trade winds gradually strengthen.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov