West Kaua’i

Tonight: Breezy. Mostly clear with isolated showers. Lows around 68 near the shore to around 58 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs around 83 near the shore to around 72 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Isolated showers after midnight. Lows around 68 near the shore to around 59 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 67 to 72. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 66 to 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 60 to 67 in the valleys to around 57 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 79 in the valleys to around 64 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Saturday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 67 in the valleys to around 56 above 4000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 62 to 71. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 75 to 82. East winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 62 to 70. East winds around 10 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 62 to 72. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 72 to 82. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with scattered showers. Lows 62 to 72. Northeast winds around 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trades weaken during the weekend as they deliver clouds and showers windward and mauka. Winds further diminish next week.

Discussion

Benign weather for the forseeable future as trades deliver showers to windward and mauka areas, mainly overnight. Deeper moisture and a higher/weaker inversion beneath the resident closed upper low will favor comparatively increased coverage over Windward Big Island and possibly Maui through tomorrow. Trades then weaken this weekend into early next week as height falls spread across the Central Pacific. This will cut into shower coverage and make interior zones feel hotter. Extended guidance indicates further weakening of trades next week with potential for a light/variable pattern establishing over the islands as a weak and shallow remnant frontal zone approaches Kauai from the west. Resulting sea breezes in the presence of high stability will produce little or no afternoon shower activity except perhaps over Kauai where moisture along the aforementioned frontal zone will be slightly deeper.

Aviation

An upper-level low remains anchored northeast of the state and will continue to enhance cloud and shower activity across windward and mountain areas, resulting in primarily MVFR conditions within showers. Otherwise VFR conditions prevail. Moderate to breezy trade winds continue through today, but will slightly weaken this weekend.
AIRMET Tango remains in effect for tempo moderate turbulence across leeward sides of all islands below 8000 feet due to the breezy trade winds. These conditions may improve tomorrow as winds begin to weaken.
AIRMET Sierra is in effect for mountain obscuration over windward areas of Oahu, Molokai, Maui and the Big Island. Expect these conditions to continue through tonight.

Marine

Little change to the forecast this afternoon. The incoming swell seems largely on track, so no change to that timing. The Small Craft Advisory remains in place for all waters until 6pm or so today, and then will be scaled back to the typical windier waters near Maui County and the Big Island.
A high pressure ridge remains to the north of the islands, driving trade winds to the region. The ridge will weaken through the weekend as a front passes north of the islands. Winds in turn will weaken over the weekend, and further ease Tuesday into the middle of the week.
An incoming northwesterly swell will bring rising surf to north and west shores overnight. The longer period energy has been slow to reach Buoy 51001 to the northwest of the islands. Continuing to monitor to see if the swell arrives large than expected. Surf heights could approach advisory levels during the peak of the swell arrival. This swell is expected to gradually ease through the weekend. Another, slightly smaller northwest swell is expected early next week, maintaining elevated surf along north and west- facing shores. Looking ahead, guidance indicates yet another long- period northwest (320 deg) swell may arrive late next week, generated by a developing storm near Japan that is forecast to lift northeast near the Kuril Islands over the weekend.
Surf along south-facing shores will trend up over the weekend as a long-period south-southwest pulse arrives. Expect a peak later in the weekend and into Monday before lowering.
As trade winds weaken this weekend, expect surf along east- facing shores to trend downward.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov