West Kaua’i

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows around 71 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight.

Thursday: Partly sunny in the morning then becoming mostly sunny. Highs 83 to 89 near the shore to around 75 above 3000 feet. East winds up to 15 mph.

Thursday Night: Partly cloudy. Lows around 71 near the shore to around 62 above 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight.

South Kaua’i

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 72. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 87. Northeast winds around 15 mph. Chance of rain 30 percent.

Thursday Night: Partly cloudy with isolated showers. Lows around 72. Northeast winds around 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 67 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Highs 73 to 80 in the valleys to around 67 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows around 67 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Mostly cloudy with isolated showers. Lows 63 to 73. East winds up to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 70 to 84. East winds up to 15 mph. Chance of rain 40 percent.

Thursday Night: Partly cloudy. Isolated showers after midnight. Lows 63 to 73. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 75. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Thursday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 66 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will dominate our weather for the next week. We'll have typical moisture levels, so windward and mauka areas will see the majority of showers. Wind speeds will be moderate to breezy. No significant impact weather is expected.

Discussion

This afternoon's radar and satellite indicate isolated showers mainly windward and mauka, and mostly on Kauai. Skies were partly to mostly sunny, with winds averaging 10 to 15 mph sustained and gusts to near 30 mph in favored locations.
With an area of enhanced moisture moving off to the west this afternoon, we expect a return to a typical June trade wind pattern from tonight onward through the next week. Aloft, a broad, and at times strong upper level high will remain to our north. It will form part of a “high over low” pattern. The “low” part of this pattern will remain near the state, but guidance currently indicates the low will be too weak to have a noticeable impact on our weather. Rather, the “high” part to our north will help keep a strong surface high in place (also centered to our north) and this will keep the trade winds going. With climatologically normal PW values (1.2 to 1.4), we expect a normal amount of trade wind showers, mainly windward and mauka.
With that said, it is likely that small-scale increases in moisture will develop and move over the islands from time to time during the coming week. Each time this happens, we'll see a small increase in showers. These are not forecast well by the models until 2 to 3 days out generally, and none are showing up in that time frame in the latest guidance.
Finally, tropical storm Amanda remains far to our ESE and is not expected to become a factor in Hawaii's weather.

Aviation

A dry airmass over the islands will continue into tonight. VFR conditions will prevail across Hawaii tonight with the next round of light trade showers due in Thursday.
AIRMET Tango is posted for moderate turbulence below 6000 feet all leeward portions of the islands, and should continue as breezy trades are forecast over the next several days.

Marine

Fresh to strong easterly trades will prevail through at least the weekend as high pressure remains anchored far northeast of the islands. A Small Craft Advisory (SCA) for the typically windier channels and waters around Maui County and Big Island has been extended through Saturday and will likely be needed through at least Monday. Trades may ease slightly Tuesday.
A large south-southwest swell will begin to gradually decline tonight while maintaining south shore surf above the High Surf Advisory threshold into the day on Thursday. Offshore NOAA buoy 51002 has been showing a shift toward lower periods since the early morning hours, and nearshore PacIOOS buoys have recently been showing a slight decline in swell at 5 to 6 feet this afternoon. After remaining elevated near the High Surf Warning threshold through the afternoon, south shore surf will begin a slow decline tonight and is expected to drop below the High Surf Advisory threshold of 10 feet by Thursday afternoon. Surf will fall to moderate levels Friday and will fade Sunday, another long-period pulse of south-southwest swell early next week.
Along north-facing shores, a small medium-period north swell will arrive Thursday, peak Friday, then ease over the weekend. A small west-northwest swell is possible early next week. Surf along east- facing shores will gradually build to around seasonal average by Friday, though some areas exposed to wrapping north swell could be slightly larger Thursday night and Friday. Near average east shore surf will prevail this weekend and early next week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Thursday for Big Island South, Big Island Southeast, East Honolulu, Ewa Plain, Honolulu Metro, Kahoolawe, Kauai South, Kauai Southwest, Kona, Lanai Leeward, Lanai South, Maui Central Valley South, Maui Leeward West, Molokai Leeward South, Niihau, South Haleakala, South Maui/Upcountry, Waianae Coast.
Small Craft Advisory until 6 PM HST Saturday for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters, Maalaea Bay, Pailolo Channel.

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Data Courtesy of NOAA.gov