West Kaua’i

Tonight: Mostly clear. Breezy. Lows around 71 near the shore to around 61 above 3000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Saturday: Sunny and breezy. Highs 83 to 88 near the shore to around 74 above 3000 feet. East winds up to 20 mph.

Saturday Night: Partly cloudy. Breezy. Lows around 70 near the shore to around 61 above 3000 feet. Northeast winds up to 20 mph.

South Kaua’i

Tonight: Breezy. Partly cloudy with isolated showers. Lows 69 to 74. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 77 to 86. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Saturday Night: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 69 to 74. Northeast winds 15 to 20 mph. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows around 66 in the valleys to around 59 above 4000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Saturday: Breezy. Mostly sunny with scattered showers. Highs 72 to 79 in the valleys to around 65 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 40 percent.

Saturday Night: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 66 in the valleys to around 59 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 62 to 73. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 69 to 84. East winds up to 20 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 72. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 40 percent.

East Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 74. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 75 to 82. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Saturday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 73. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trade winds will persist through the weekend and at least the first half of next week, pushing showers over mostly windward and mountain areas.

Discussion

A 1030 mb high far north of the islands will remain in place through the first half of next week, bringing stable breezy trade winds and showers to mainly windward and mountain areas. Showers will also favor the night time and early morning hours, and minor fluctuations in coverage are expected based on periodic areas of moisture moving through with the trades.
By the later half of next week, a front passing by far to the north of the islands could push the surface high pressure east, decreasing trade wind speeds.

Aviation

Moderate to breezy trades and isolated to scattered showers will continue through tonight. Showers will primarily move over windward and mauka areas, but will occasionally spill over into leeward areas. Mostly VFR. In the strongest showers, there's a 50% chance of brief MVFR and a 10% chance of brief IFR.
AIRMET Sierra is in effect for mountain obscurations across windward and mountain areas of Oahu. We expect this to continue due to continued clouds below 8000 feet and intermittent showers.
AIRMET Tango is in effect for moderate turbulence below 8kft for areas downwind of terrain due to breezy trade winds. We expect this to remain in effect for the next several days due to steady trades.

Marine

Fresh to strong easterly trades will prevail as high pressure remains far northeast of the islands through the weekend and beyond. Most of the high resolution guidance shows a slight uptick in wind speeds tonight through Saturday night as the high to the far northeast edges closer to the state. As a result, the Small Craft Advisory (SCA) has been expanded to include all Hawaiian coastal waters and is in effect through Saturday night. Trade winds may ease slightly early next week as high pressure once again shifts away to the northeast.
The south-southwest swell that produced advisory-level surf along south-facing shores for the past few days will gradually ease into this weekend. Nearshore buoys are reporting this swell to still be near 3 feet, 14 seconds this afternoon, but offshore buoy 51002 has dropped through the day, hinting at the drop to follow along south-facing shores through the weekend. A fresh, long- period south swell is expected to arrive late Sunday and peak on Monday. The source of this new swell is a storm-force low that passed southeast of New Zealand last weekend, producing a large swath of 50 knot winds and 30 to 45 foot seas, with the bulk of its energy aimed east of Hawaii. However, a fraction of this long- period energy will reach our south- and west-facing shores late Sunday into Monday, with a slightly larger error bar in regards to its size. Most likely it will be a small to moderate sized swell that is expected to bring below advisory-level surf. This swell will gradually fade into midweek.
Along north-facing shores, a small, medium-period north swell peaked early this morning and will continue to fade over the weekend. A tiny west-northwest swell is possible early next week. Surf along east-facing shores will remain choppy and near or slightly above average this weekend into early next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Sunday for all Hawaiian waters,

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Data Courtesy of NOAA.gov