West Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 76 near the shore to around 67 above 3000 feet. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Wednesday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 86 to 93 near the shore to around 80 above 3000 feet. South winds up to 10 mph. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 76 near the shore to around 66 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 73 to 78. West winds 10 to 15 mph shifting to the southwest after midnight. Chance of rain 30 percent.

Wednesday: Partly sunny with scattered showers. Highs 80 to 91. South winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 72 to 78. Light winds. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 71 in the valleys to around 63 above 4000 feet. Southwest winds up to 20 mph in the evening becoming light. Chance of rain 40 percent.

Wednesday: Partly sunny with scattered showers. Highs 78 to 86 in the valleys to around 76 above 4000 feet. Light winds. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows around 72 in the valleys to around 63 above 4000 feet. Light winds becoming east around 10 mph after midnight. Chance of rain 50 percent.

North Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 68 to 77. South winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 75 to 89. Light winds. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 68 to 77. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 69 to 78. Southwest winds up to 20 mph decreasing to up to 10 mph after midnight. Chance of rain 20 percent.

Wednesday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 80 to 90. South winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 69 to 78. Light winds becoming northeast around 10 mph after midnight. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Light to moderate south to southwest winds have developed over the islands and will continue to diminish through tonight as Hurricane Lowell moves farther northwest of the area. Aside from a few heavy showers over the Big Island interior through early evening and moderate showers over the Kauai mountains, rainfall should be limited tonight. A diffuse band of moisture will move onto Big Island Wednesday and may bring a renewed threat of heavy showers, while sea breezes trigger spotty afternoon showers across the rest of the state. Trade winds will slowly build over the state late Wednesday and Thursday, but conditions will remain somewhat wet. Drier trade wind weather is expected to develop Thursday night and Friday.

Discussion

Hurricane Lowell continues to move northward away from the state, and its center is now located roughly 275 miles north-northwest of Kauai. Light to moderate south to southwest winds persist across much of the state, producing relatively light showers over interior sections. The exception is Big Island, where isolated heavy showers have developed under daytime heating.
Winds will continue to diminish into Wednesday, allowing a land and sea breeze pattern to produce interior afternoon showers over most areas. We are not expecting significant rainfall from Kauai to Maui overnight, but a diffuse band of moisture and convergence near and just east of Big Island could maintain shower activity there. The Flood Watch was cancelled for most islands but was extended for Big Island, as the band of moisture is expected to drift westward and may help trigger heavy showers and thunderstorms mainly Wednesday afternoon. Across the rest of the state, land breezes may lead to isolated heavy showers in the afternoon, and while isolated flooding may be possible, the risk has been deemed too low to continue the Flood Watch.
Trade winds will slowly build over the state late Wednesday and Thursday, but conditions will remain somewhat wet. Drier trade wind weather is expected to develop Thursday night and Friday. An upper level trough may create some instability with the trade wind flow this weekend.

Aviation

Hurricane Lowell continues to move northward away from the state of Hawaii. Deep and somewhat unstable tropical moisture continues to stream northward across all islands. Shower activity will linger even after Lowell begins to move farther northward away from the Hawaiian Islands today.
Periods of MVFR conditions with low cloud ceilings and showers will linger across the state. MVFR shower activity will gradually decrease through the morning hours. Surface winds will continue to steadily decrease today, though gusts up to 20-30kt remain possible. Flow generally remains from the south through the overnight hours, with the hint of the trade winds returning late Wednesday into Thursday.
AIRMET Sierra for low MVFR cloud ceilings remains in effect and will gradually diminish this afternoon and evening.
AIRMET Tango remains in effect for moderate low level turbulence affecting the island of Kauai and Oahu over and NW thru NE of island mountains. This AIRMET may be cancelled early this evening.

Marine

Hurricane Lowell is now lifting north of the offshore waters, and with it all of the Tropical Storm to Hurricane force winds. A Small Craft Advisory (SCA) remains in effect for the waters around Kauai due to 10 foot seas and is expected to be cancelled later tonight as seas are forecast to drop rapidly. For the western offshore waters, conditions are expected to improve late tonight as Lowell moves further north, and the hurricane warning will likely be cancelled at that time. For tomorrow, light and variable winds will gradually transition to light to moderate easterly trade winds through the remainder of the week.
Large and rough surf along south shores have already decreased significantly from this morning's peak, (Barber's Point reported 25 feet) and is expected to continue decreasing tonight. The exception will be the west facing shores of the Big Island where high surf could linger into the evening hours before dropping rapidly tomorrow morning. The high surf warning for south facing shores has been cancelled, as well as the advisory for the east facing shores. An exception however is for the Big Island where southwest swell could still impact shorelines through the evening hours. Moderate sized medium period south swell will linger for the next few days, keeping south shore surf heights from dipping below the September averages (5 ft) until the weekend when surf heights will become small.
Surf along east facing shores will remain elevated through tomorrow but stay below advisory thresholds. That swell will then fade through the next several days. Surf along north facing shores experienced a solid rise due to Lowell this morning. This swell will quickly fade through the week as Lowell weakens and tracks away from the islands.

Fire weather

Fire weather risk will remain low the next several days due rather light winds and lingering moisture. Expect a slight chance of thunderstorms over the Big Island on Wednesday afternoon and possibly Thursday afternoon. Temperature inversion heights are expected to remain elevated or weak.

HFO Watches/Warnings/Advisories

Flood Watch through Wednesday afternoon for Big Island.
High Surf Advisory until midnight HST tonight for Kona, Kohala.
Small Craft Advisory until midnight HST tonight for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters.

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Data Courtesy of NOAA.gov