Photo Credit: Jason Weingardt

West Kaua’i

Rest Of Today: Mostly sunny. Isolated showers in the afternoon. Highs around 82 near the shore to around 69 above 3000 feet. South winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 65 near the shore to around 56 above 3000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 82 near the shore to around 68 above 3000 feet. West winds up to 15 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

South Kaua’i

Rest Of Today: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 83. East winds up to 10 mph shifting to the southwest around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 64. West winds around 10 mph.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs around 80. West winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Rest Of Today: Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 79 in the valleys to around 63 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 57 to 63 in the valleys to around 53 above 4000 feet. Light winds becoming southwest up to 10 mph after midnight. Chance of rain 20 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs 74 to 80 in the valleys to around 63 above 4000 feet. Southwest winds up to 20 mph. Chance of rain 50 percent.

North Kaua’i

Rest Of Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 71 to 81. Southeast winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 58 to 66. South winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 71 to 81. Southeast winds up to 15 mph shifting to the west in the afternoon. Chance of rain 40 percent.

East Kaua’i

Rest Of Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers in the afternoon. Highs 72 to 82. East winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 57 to 68. West winds up to 10 mph.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 73 to 82. Southwest winds up to 20 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Weak troughing over the western islands will keep light winds in the forecast across with land and sea breezes over each island into Wednesday morning. Wind convergence shower bands will also pass into the western islands with a brief increase in shower trends for Kauai and Oahu. A cold front will sweep down the island chain from Wednesday night through Friday, dragging a band of clouds and showers with it. Cool, moderate to breezy north to northeast winds will fill in behind this front from Thursday into the weekend. Moderate to breezy trade wind weather continues through the first half of next week.

Discussion

Using a combination of satellite and local radar imagery we see brief shower bands moving through the western islands this morning with more stable conditions over Maui and the Big Island. The upper air soundings from 2 AM this morning support this analysis with subsidence inversion heights around 7,000 feet above mean sea level (MSL) at Lihue and around 5,500 feet above MSL at Hilo. These showers are associated with two wind convergence bands from the remnants of a dissipated cold front. Scattered showers are forecast over the western islands of Niihau, Kauai, Oahu and Molokai. More isolated shower coverage is likely over Lanai, Maui and the Big Island today.
Strong winds at the Big Island summit level have fallen below warning and advisory thresholds, therefore the High Wind Warning for the summits of Mauna Kea and Mauna Loa was cancelled this morning.
Weak troughing north of Hawaii will keep the subtropical ridge in a weakened state for one more day today. Light large scale winds will allow local scale land and sea breezes to continue to develop over all islands. Day time sea breezes will build clouds and a few showers over island mountain and interior sections in the afternoon to early evening hours. Bands of showers over the western islands will increase morning cloud and shower trends mainly over Kauai and Oahu.
Farther to the northwest a larger cloud band shown on satellite imagery is associated with the next cold front forecast to sweep into the western islands starting Wednesday night. This system will drag clouds and showers across each island as it passes quickly from west to east down the island chain. Expect a 12 hour period of wet weather for each island, followed by cool moderate to breezy northerly winds after frontal passage.
High pressure will rapidly build in behind the front, producing cooler temperatures along with moderate to breezy north to northeast winds from Thursday into the weekend. Model guidance remains in good agreement with this high confidence solution. Moderate to breezy trade winds with passing windward and mountain showers will continue through early next week as a fairly strong high pressure system passes by just north of the Hawaiian Islands this weekend.

Aviation

A weak flow regime persists again today. Some lower level moisture associated with a weak convergence boundary will bring increased cloud cover and isolated showers to Oahu and Kauai. Elsewhere, expect mainly dry weather and VFR conditions. Sea breeze development along the coastal regions early this afternoon may help generate isolated showers over the islands interiors.
No AIRMETs are in effect and none are expected during the forecast period.

Marine

Light and variable winds will hold today, shift out of the southwest tonight, then increase to moderate to fresh speeds through the day Wednesday as a front approaches. Guidance remains persistent and shows this front moving through Wednesday night through Thursday, with a ridge nosing eastward in its wake Thursday through Friday. The surface winds will quickly shift from southwest to northerly as the front moves through Wednesday night. These northerly winds may reach the moderate to fresh range Thursday through Friday as they gradually veer out of the northeast and increase into the fresh to strong category this weekend.
Surf along north and west facing shores will remain small through midweek, with mainly background, short-period northwest energy moving through. A significant northwest (320 degrees) swell associated with a storm-force low located around 2000 NM northwest of the state will arrive late Wednesday night, then rapidly build down the island chain through the day Thursday. This swell will peak late Thursday, then slowly ease Friday into Saturday. A more compact gale passing the state well to the north Friday through Saturday will send a large, medium-period north swell through the area Saturday night through Sunday. Expect surf heights to exceed warning levels Thursday through Friday as the northwest swell moves through, then remain above the advisory levels for exposed north facing shores over the weekend as the north swell arrives.
Coastal impacts associated with a swell of this magnitude Thursday into Friday could be significant due to a combination of moderate to fresh northerly (onshore) winds and the peak daily high tide potentially coinciding with the peak surf anticipated Thursday evening for some areas.
Surf along east facing shores will begin to trend up over the weekend as strong trades return.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov