Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 89 near the shore to around 77 above 3000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 73 near the shore to around 62 above 3000 feet. Light winds. Chance of rain 50 percent.

Saturday: Sunny with isolated showers in the morning, then mostly cloudy with showers likely in the afternoon. Highs 86 to 92 near the shore to around 76 above 3000 feet. Southeast winds up to 10 mph shifting to the southwest around 10 mph in the afternoon. Chance of rain 60 percent.

South Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 83 to 91. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers. Highs 82 to 90. East winds 10 to 15 mph shifting to the southeast in the afternoon. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 75 to 86 in the valleys to around 68 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 64 to 71 in the valleys to around 59 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 90 percent.

Saturday: Partly sunny with scattered showers. Highs 75 to 86 in the valleys to around 67 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 89. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 73. Light winds. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 77 to 89. East winds up to 10 mph shifting to the north around 10 mph in the afternoon. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 75 to 88. Northeast winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 65 to 77. North winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers. Highs 75 to 88. East winds around 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Light to locally moderate trade winds are expected through the weekend, bringing a few showers to windward areas. Afternoon sea breezes will bring clouds and showers to leeward and interior areas. A low aloft will destabilize the island atmosphere Saturday night and Sunday, bringing the potential for some locally heavy showers and a chance for thunderstorms. Expect stronger trade winds to return next week.

Discussion

Light to moderate trade winds are being supported by a weakening high pressure cell far NE of the islands. Satellite and radar images show limited patches of stable and showery low clouds approaching most islands from the E, with showers in greater coverage upstream of windward portions of Maui and the Big Island.
The high to the distant NE will weaken today and trade winds will ease as the local low-level pressure gradient slackens. The light trades will persist through the weekend, allowing land and sea breezes to prevail over sheltered leeward areas. Nighttime land breezes will lead to mostly clear conditions leeward, with just a few windward showers. The afternoon sea breezes will drive cloud and shower formation over leeward and interior areas.
A low aloft currently about 800 miles NNW of Kauai near 36N 162W will dig S toward the islands through Saturday, and pass close to the islands Saturday night and Sunday. While there remains some uncertainty as to where the core of the low will eventually move, it will likely destabilize the island atmosphere during its closest approach. The potential for thunderstorms and/or locally heavy showers remains in the forecast for portions of the area. PWAT will be somewhat limited, thus widespread coverage of rainfall is not expected, but the showers that do occur will have the potential to become heavy. One of the more likely areas for this to occur would be the Big Island's Kona slopes on Sunday afternoon.
Trade wind speeds will increase early next week as new high pressure to the distant NW builds eastward. Stability will also increase as the low aloft weakens and moves away to the NE.

Aviation

High pressure north of the state will maintain moderate trade winds over the region through this evening and possibly beyond. Relatively dry and stable conditions are expected. VFR flight conditions will prevail at most locations, but brief MVFR ceilings and visibility will be possible within passing showers.
A weak eddy just southwest of the Big Island has kept the Kona and Kau coasts shrouded in clouds most of the night. Lee-side clearing should occur shortly after sunrise. In the afternoon, cumulus build- ups will redevelop along south and west facing slopes of the Big Island and linger through the evening.

Marine

Gentle to moderate trade winds are expected through Saturday, as a series of fronts pass far north of the state. Isolated thunderstorms could be possible Saturday night through Sunday for the windward waters as an upper low moves through the area. Winds should then gradually strengthen Sunday into the first half of next week as high pressure builds north of the state. Winds could potentially reach Small Craft Advisory levels for the windier waters and channels around Maui County and the Big Island by next week Monday.
For north facing shores, a pair of overlapping small, short period north swells should maintain small surf in place through this weekend. A short lived small, short to medium period northeast swell is expected Saturday night through Sunday. This will also give east facing shores a slight bump on Sunday. Although there is some uncertainty on how strong the event will be, there is the potential for the arrival of a moderate long period north- northwest swell as early as Sunday and likely peaking next Monday, below advisory levels for north facing shores. This swell could linger through the middle of next week as it slowly fades.
The current south southwest swell will continue to gradually ease today before a moderate, long period south swell is expected to slowly fill in Saturday, peak Sunday and hold into Monday then gradually decline through the middle of next week. This swell will may boost surf along south facing shores to near advisory levels during its peak.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov