West Kaua’i

Tonight: Partly cloudy with isolated showers. Haze. Lows around 70 near the shore to around 59 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 83 to 88 near the shore to around 71 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Partly cloudy. Lows around 70 near the shore to around 60 above 3000 feet. East winds up to 10 mph.

South Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Haze through the night. Lows around 70. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 70. East winds around 10 mph. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Haze through the night. Lows 64 to 69 in the valleys to around 57 above 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Sunday: Partly sunny with scattered showers. Highs 73 to 82 in the valleys to 61 to 66 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 66 in the valleys to around 57 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Haze. Lows 64 to 72. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 76 to 84. Southeast winds up to 15 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 64 to 71. East winds 10 to 15 mph. Chance of rain 40 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Haze. Lows 64 to 74. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 84. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A complex upper-level low over the islands will produce unsettled weather with moderate wet trades prevailing for the next several days. Heaviest showers will impact primarily windward and mountain areas, though leeward sides may also see brief periods of showers. Expect only slight variations in shower activity throughout the forecast period.

Discussion

The latest water vapor imagery continues to reflect model guidance, showcasing a complex upper-level low centered over the islands that is producing unsettled weather across the region. The soundings from the 2 PM HST (00Z) balloon launches at Hilo and Lihue show a temperature inversion around 12,000 feet and 8,000 feet, respectively, allowing for continued bands of showers to move through the state today. Current satellite and radar imagery imagery shows a dissipating band of clouds and showers over the Big Island and Maui slowly moving westward, as well as a few isolated thunderstorms just outside the coastal waters south of Kauai. Elsewhere, partly to mostly cloudy skies prevail, with light to locally moderate showers mainly over windward sections of the islands.
Winds have shifted slightly out of the east-southeast today and are beginning to decreasing slightly in strength. A pocket of drier air moving through the smaller islands today has kept shower activity less prevalent and intense there, along with enough of an easterly component to the wind direction to prevent much island shadowing and subsequent leeward sea breezes. Enough instability remains over the eastern end of the state to keep a slight chance of thunderstorms in the forecast into this evening over interior Big Island.
The previously mentioned upper-level low remains quasi-stationary throughout the weekend and into next week with only slight variations in activity across the island chain. Trades are expected to decrease slightly to more moderate levels tonight into early next week. Shower trends will also decrease in coverage a bit from Sunday to Tuesday across most islands as the upper low briefly weakens and drier air moves in. Global models are hinting at another upper low moving over the islands around Wednesday with increasing shower trends for the second half of next week.

Aviation

Moderate east to east-southeast trades will continue to hold through Sunday. Trade winds will be light enough for localized land breezes tonight and daytime sea breezes across select areas during the day Sunday. A plume of moisture currently located over the Big Island will be spreading across the rest of the island chain through tonight. Expect periods of MVFR conditions with any showers. Due to an upper level low adding some instability, brief IFR conditions will also be possible with the heavier showers.
AIRMET Sierra for mountain obscuration remains over the Big Island and will likely hold through this evening. Conditions should improve tonight. AIRMET Sierra will be possible for the other islands tonight as the moisture spreads westward and showers increase across windward and mountain areas.

Marine

High pressure will reside to the northeast of the state through early next week, with another high building to the north by the middle of the week. A trough far northwest of the islands will slightly ease the trades tonight through Monday and could allow for some east-southeast winds at times. Light to moderate trades are expected through at least the middle of next week.
Surf along north and west-facing shores will remain very small during the next 7 days as small northwest swell fades. Surf along south facing shores will hold at background levels through today before a series of small south and south-southwest swells modestly boost south shore surf on Sunday. A further boost up to seasonal averages are possible during the middle to latter part of next week.
Surf along east-facing shores will remain rough and choppy during the next 7 days.

HFO Watches/Warnings/Advisories

None.

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