West Kaua’i

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 69 near the shore to around 58 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs around 81 near the shore to around 69 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Friday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 68 near the shore to around 57 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 70. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy with scattered showers. Lows 64 to 69. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 58 to 63 in the valleys to around 52 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Breezy. Showers likely early in the morning, then scattered showers in the late morning and afternoon. Highs 68 to 76 in the valleys to around 63 above 4000 feet. East winds up to 20 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 70 percent.

Friday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 57 to 62 in the valleys to around 51 above 4000 feet. Northeast winds 10 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 61 to 70. East winds 10 to 15 mph. Chance of rain 60 percent.

Friday: Partly sunny. Showers likely early in the morning, then scattered showers in the late morning and afternoon. Highs 73 to 80. East winds up to 15 mph. Chance of rain 60 percent.

Friday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 60 to 69. Northeast winds 10 to 15 mph. Chance of rain 60 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 59 to 71. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny. Showers likely early in the morning, then scattered showers in the late morning and afternoon. Highs 73 to 80. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Friday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 58 to 70. Northeast winds 10 to 15 mph. Chance of rain 60 percent.

Detailed Forecast

Synopsis

Breezy to windy east-northeast trade winds will persist through next week, bringing periods of windward and mauka showers as bands of moisture move through. One of the many bands of moisture should be arriving tonight and persist through Friday morning.

Discussion

A ridge of high pressure far north of the state will maintain breezy to windy trades through next week. A front passing north of the state today has weakened the pressure gradient slightly and the trades have weakened a touch from yesterday. Bands of moisture will ride in with the trades from time to time and will be capable of producing brief downpours during the next several days. On visible satellite imagery this afternoon, there is one large band of moisture that looks to move in tonight and will likely produce some showery weather over windward and mauka areas through Friday morning.
Over the weekend, a stronger high will build north of the state and will likely strengthen the trade winds a notch with widespread windy trade winds expected especially on Sunday. Bands of moisture will continue to ride in with the trade winds and passing showers should be expected over windward and mauka areas with a few leeward showers as well. Winds could reach wind advisory thresholds for some of the windier areas but at this time, the trade wind inversion does not look very strong to produce really gusty conditions over leeward areas.
For next week, windy trades will persist across the state and may even strengthen even more by the middle of next week as another strong high builds far north of the state. Remnant moisture from the front passing far north of the state today should ride in with the strong trades around Monday of next week. The remnants of the front will likely bring higher amounts of moisture and could produce some moderate rainfall over windward and mauka areas. While there is good agreement between the GFS and the ECMWF on this band of moisture, there are subtle timing differences between the model with the GFS showing the moisture moving in Sunday night, while the ECMWF brings it in on Monday.

Aviation

Expect breezy to locally windy trades to continue for the next several days. Low ceilings and showers will favor windward and mauka locations. Brief periods of MVFR conditions are likely in showers, though VFR should prevail. Periods of lower visibility are also possible from Volcano around South Point to PHKO and over the leeward Big Island waters due to VOG emissions from Kilauea.
AIRMET TANGO remains in effect for moderate low-level turbulence below 080 over and downstream of island terrain. This AIRMET will likely be extended through the next couple of days due to the stronger trade winds.

Marine

Strong to near gale-force easterly trade winds will persist as strong high pressure remains over the Northeast Pacific. Seas will remain rough, with a combination of wind-driven seas and northwest swells moving through. A Small Craft Advisory due to a combination of strong winds and elevated seas is in effect through Saturday morning for all Hawaiian coastal waters and will likely be extended through the weekend.
Surf along exposed north and west-facing shores will slowly rise tonight as a northwest (310-330 degrees) swell builds into the coastal waters. This swell looks to peak Friday night and Saturday and may push surf heights above advisory levels. A downward trend is then expected in the northwest swell Sunday through early next week.
Surf along east-facing shores will remain rough through the weekend and into next week due to strong easterly trade winds.
Surf along south-facing shores will remain small, with mainly background south and southeast swells.

HFO Watches/Warnings/Advisories

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

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