Photo Credit: Brendan Stephen

West Kaua’i

Today: Partly sunny with isolated showers. Highs around 83 near the shore to around 70 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Lows around 68 near the shore to around 59 above 3000 feet. Northeast winds 10 to 15 mph.

Saturday: Mostly sunny with isolated showers. Highs around 83 near the shore to around 71 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 78 to 84. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 80 to 86. Northeast winds around 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Mostly cloudy with showers likely. Highs 70 to 77 in the valleys to around 61 above 4000 feet. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 61 to 66 in the valleys to around 57 above 4000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 72 to 78 in the valleys to around 62 above 4000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 72 to 82. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 70. East winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with showers likely. Highs 70 to 80. Northeast winds around 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 73. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 70 to 83. Northeast winds around 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A cloudy and breezy trade wind pattern will persist through today, with passing showers favoring windward and mauka areas. Expect clearer skies and fewer showers over the holiday weekend and into next week, with lighter winds Sunday and Monday.

Discussion

A sharp trough aloft NW of Kauai is sending broken to overcast mid- and high-level clouds over the area from the SW, while also destabilizing the island atmosphere. Consolidating high pressure passing far N of the islands will support breezy trade winds through Saturday. Latest radar imagery shows scattered showers along windward and mauka areas. Scattered windward showers will remain in the forecast through tonight as an area of enhanced moisture remains over the state.
Clearer skies along with a drier and more stable air will start to settle over the state this weekend. This is in response to the upper level trough moving SE through Saturday and a mid- level ridge building over the islands from the W. The surface high will also shift far NE of the area during this time and its associated E-W oriented ridge will move further S on Sunday, easing winds speeds to light and variable into Monday. As mid- level temps warm into next week, a strong low- level subsidence/inversion and more stable island atmosphere will develop. Light winds will allow for land/seabreeze regime, but the low available moisture will limit measurable rainfall to mainly mauka regions in the afternoon and clearing overnight.
Outlook for next week shows a pair of large and powerful low pressure systems racing eastward across the N Pacific as new fast- moving high building NW of the islands Monday night and Tuesday. This will allow a short-lived period of increased NE trade winds and weather while also pushing a weak and shallow frontal boundary down the island chain. This high quickly weakens Wednesday, and winds will diminish again in response. Another fast-moving high may push another shallow frontal boundary near or over the islands Thursday. The GFS is more progressive in pushing the front over the central islands before dissipating with breezy NE winds following. The EC shows the front dissipating N of Kauai and has a weaker NE winds following the front. Given either scenario, showers will be limited, with island weather becoming more consistent with our wet season outlook that anticipates a drier than normal winter.
Looking into the extended period, (consistent with El Nino) a strong and zonal jet is expected to extend across the entire N Pacific along ~35N, generally leading to a continued dry and stable weather regime as we approach the end of the year.

Aviation

Breezy trade winds will persist through tonight. AIRMET TANGO for tempo moderate turbulence remains in effect below 8000 feet over and immediately south through west of all island terrain. AIRMET TANGO also remains in effect for tempo moderate turbulence between FL180 and FL320 due to strong winds aloft from an upper trough. Expect winds to trend weaker late tonight and over the weekend.
Low clouds and showers will continue to favor windward and mauka areas with periods of MVFR possible. AIRMET SIERRA remains in effect for mountain obscuration above 2500 feet for windward sections of all islands. Expect lower clouds to persist through the morning hours.
Mid/high clouds associated with a subtropical jet will bring light icing in the 140 to FL250 layer over Maui and the Big Island. This cloud layer is expected to shift east of the area late tonight.

Marine

Fresh to strong easterly trades will continue through Saturday, then trend down Sunday into Christmas Day as a weakness forms in the surface ridge to the north due to a passing front. The tail- end of this front will slowly advance down the island chain late Monday through midweek. Guidance shows light winds with early morning land breezes on Christmas morning followed by a shift out of the north and ramping up into the moderate to fresh range over the western end of the state by sunset Monday. The fresh to strong north-northeast winds will fill in Monday night and persist through Tuesday, then shift out of the east and trend down Tuesday night through midweek as another front approaches.
Surf along exposed north and west facing shores is steadily building this morning as a northwest swell fills in. Early morning observations at the Waimea and Pauwela PacIOOS buoys show the peak energy associated with the swell centered within the 16-18 sec band out of the northwest (310-320 deg). Similar energy is shown at the offshore buoys, and when extrapolated to our exposed beaches reflect the surf peaking today just below the advisory levels.
Moving forward through the holiday weekend and upcoming week, guidance depicts a progressive and more of an El-Nino pattern evolving over the northern Pacific with overlapping swell events. As the current swell eases into the weekend, a fresh, long-period north-northwest (330 deg) swell will arrive Saturday night, peak Sunday, then hold Christmas Day (should be below advisory levels) before moving out. The week will continue with back-to-back, warning-level north-northwest swells, with the first one peaking Tuesday night and the second one (larger) late Thursday through Saturday. Although confidence is lower being so far out, guidance depicts this trend continuing into 2024.
Surf along east facing shores will steadily lower through early next week as the trades ease locally and upstream over the eastern Pacific.
Surf along south facing shores will hold above flat levels today, then trend down over the weekend as the background south-southwest swell moves out. Another similar south-southwest swell is possible Tuesday night through Wednesday.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov