West Kaua’i

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 60 above 3000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 83 to 89 near the shore to around 75 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Lows around 70 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph.

South Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 71. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 81 to 88. East winds 10 to 20 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with isolated showers. Lows around 70. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 69 in the valleys to around 59 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers. Highs 75 to 81 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 61 to 69 in the valleys to around 58 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 64 to 72. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 50 percent.

Saturday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 86. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Mostly cloudy with isolated showers. Lows 63 to 72. Southeast winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 75. East winds 10 to 15 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 73 to 85. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Saturday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 75. Northeast winds up to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

An area of high pressure well north of the islands will aid in maintaining breezy trade winds through the remainder of this week into next week, gradually increasing in strength toward the latter half of next week. Periods of showers will favor windward and mountain areas, with leeward areas remaining mostly dry.

Discussion

The latest observations show isolated shower activity the vicinity of the islands under a typical trade wind pattern, expected to increase in strength over the upcoming weekend and into next week. Latest model guidance is in good agreement showcasing a broad, 1029 mb area of high pressure will persist north of the islands, expecting to move eastward over the next couple days, with an elongated frontal passage in its immediate wake. The area of high pressure will aid in maintaining a relatively stable environment, with only subtle changes in the wind direction through late Monday of next week.
By next week, a new, stronger area of high pressure will propagate eastward while remaining well north of the islands. The aforementioned frontal passage is expected to weaken as it gets overrun by the established trades, implying trades will remain moderate to breezy through much of next week. Expect periods of showers to favor primarily windward and mountain areas, while limited rainfall will be expected on leeward areas with exception to occasional isolated showers during the overnight hours.

Aviation

VFR conditions are expected to prevail across most of the state tonight with brief MVFR ceilings in showers across windward Big Island and Maui overnight. Breezy trade winds and stable conditions will bring tempo moderate turbulence below 7000 feet (all islands) where AIRMET Tango is posted, and will likely continue in the coming days. No other AIRMETs are in effect or expected tonight.

Marine

Surface high pressure north northwest of the state will strengthen and move east over the weekend. This will result in continuing moderate/fresh to locally strong trade winds. A Small Craft Advisory (SCA) remains in effect through Sunday morning for the typical windier channels and bays surrounding Maui County and south of Big Island. This could be extended further into the beginning of next week if trade wind speeds hold. Trade winds could then further strengthen around the middle of next week as a new stronger high is forecast to build north of the islands.
The current small, medium period north northwest swell (4 feet 13 seconds) is producing head to slightly over head high surf along north facing shores and will hold today before gradually declining this weekend. A series of smaller northwest to north swells are expected next week that should produce near head high surf.
A near 3 foot, medium to long period south southwest swell that peaked late last night will linger through Saturday. This swell has resulted in fun above summer average surf heights (5 to 6 foot on face) across many south-facing surf zones. This surf will hold today and Saturday before slowly subsiding early next week. A mix of both a reinforcing long period south southwest swell and new short period south southeast swell energy should maintain near to above seasonal average surf this weekend. South-facing shore surf will generally decline next week, but small south southwest swells will hold surf at near summertime averages through the middle of next week. East facing shores will remain rough and choppy from the trade winds.

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.

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