Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Isolated light showers in the morning. Highs around 89 near the shore to around 77 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered light showers after midnight. Lows around 72 near the shore to around 62 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: 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. East winds 10 to 15 mph. Chance of rain 40 percent.

South Kaua’i

Today: Partly sunny. Breezy. Scattered light showers in the morning, then isolated light showers in the afternoon. Highs 84 to 90. East winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Isolated light showers in the evening, then scattered light showers after midnight. Lows around 73. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs 85 to 90. East winds 10 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny. Breezy. Light showers likely in the morning, then scattered light showers in the afternoon. Highs 74 to 85 in the valleys to around 67 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered light showers in the evening, then light showers likely after midnight. Lows around 68 in the valleys to around 61 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs 75 to 84 in the valleys to around 67 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny. Breezy. Scattered light showers in the morning, then isolated light showers in the afternoon. Highs 78 to 88. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Isolated light showers in the evening, then scattered light showers after midnight. Lows 66 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs 78 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny. Light showers likely in the morning, then isolated light showers in the afternoon. Highs 75 to 87. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Isolated light showers in the evening, then scattered light showers after midnight. Lows 66 to 78. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs 76 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trade winds will continue into next week, with low clouds and brief showers favoring windward and mauka areas, especially night and morning.

Discussion

Slow-moving surface high pressure to the distant N of the islands will support breezy trade winds through the next week, with subtle day-to-day fluctuations. A nearby mid-level ridge will support a strong and relatively low subsidence inversion (currently based near 5000 feet) that will limit rainfall coverage and amounts, with brief showers over windward areas favoring nights and mornings. A persistent and seasonable trough aloft to the N of the islands will bring periods of thin high clouds through the next week.
The Big Island's leeward slopes will see afternoon and evening clouds that will drop a few showers before gradually dissipating overnight. Even with the strong stability in place, a few spots (Kealakekua and Waiaha) received close to an inch of rain in the 12 hour period ending at 2 am this morning.
Current satellite images show broken to overcast low clouds streaming over the islands from the E, with radar detecting randomly distributed light showers. Some diurnal decrease in cloud cover is expected by this afternoon, only to increase again overnight. An area of increased PWAT currently near 140W may arrive late Saturday into Sunday, bringing the potential for an increase in windward shower coverage.

Aviation

Breezy trade winds will continue through the 24-hr forecast and beyond, with clouds and light showers favoring windward and mountain areas. The broken stratus/stratocumulus deck will lead to periods of MVFR CIGS through the morning hours across windward areas, especially in and around any light showers that move through.
AIRMET Tango remains in effect for tempo moderate turbulence below 9000 feet over and immediately south through west of mountains on all islands.
AIRMET Sierra is now in effect for mountain obscuration over windward areas/slopes, which will likely persist through the morning hours.

Marine

Surface high pressure far northwest of the state will slowly move east southeast the next few days. The pressure gradient south of the weakening high will remain tight enough to maintain generally fresh to locally strong trade winds across our nearshore waters through next week. This morning's ASCAT pass across the eastern third of the island chain observed a wide swath of Small Craft Advisory (SCA) level winds through the notoriously windier Alenuihaha Channel and around Big Island's South Point. Areawide trades are forecast to slightly back off the next couple of days as the center of the high moves closer to the state but still stay up around Maui County and Big Island's coastal waters into next week.
No significant arriving swell from any direction the next several days will equate to small surf across all shores into early next week. Choppy surf primarily driven by trade wind energy along east- facing shores will remain relatively small. Very small, long period south southwest (200 degree) swell will move around the islands from Sunday through Tuesday. This background energy will provide a small bump to the south-facing shore surf heights.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov