Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 73 to 78 near the shore to around 64 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the afternoon. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 88. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 71 to 77. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs around 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 85 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 64 to 69 in the valleys to around 59 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 85 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 81 to 90. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 67 to 77. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 30 percent.

Thursday: Mostly sunny with isolated showers. Highs 81 to 90. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 81 to 89. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 65 to 78. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 81 to 89. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

High pressure north-northeast of the islands will keep breezy trade winds blowing through Friday, with a slight easing of the trades into the moderate to locally breezy range expected over the weekend into early next week. Relatively dry trade wind weather is expected to prevail, with low clouds and showers favoring windward and mauka areas, primarily at night and during the early morning hours, with a stray shower reaching leeward communities from time to time. An increase in trade wind showers is possible Saturday through Monday as a disturbance aloft moves over the island chain.

Discussion

Currently at the surface, a 1029 mb high is centered around 1500 miles north-northeast of Honolulu, while the remnant low of former Tropical Cyclone Fernanda is located around 600 miles southwest of Kona. The gradient locally is producing moderate to locally breezy trade winds across the island chain early this morning. Infrared satellite imagery shows partly cloudy conditions in windward areas, with mostly clear skies in leeward locales. Radar imagery shows isolated showers moving into windward slopes and coasts with mainly dry conditions in leeward areas. Main short term focus revolves around rain chances and trade wind trends.
Strong high pressure will remain anchored to the distant north- northeast of the state through Friday, keeping breezy trade winds blowing across the island chain. The high will then weaken as it shifts southward and closer to the islands over the weekend into early next week, easing the trades slightly into the moderate to locally breezy range. High pressure looks to strengthen to the north-northeast of the state around the middle of next week, bringing a return of breezy trade winds to the islands.
As for the remaining weather details, very little change in the overall weather pattern is expected through early next week, with pockets of moisture periodically moving through the islands. Showers will favor windward and mauka areas, particularly at night and during the early morning hours, with a stray shower occasionally reaching leeward communities. There could be a bit of an increase in trade wind shower coverage and intensity over the weekend and into Monday as a mid/upper level trough moves over the island chain.

Aviation

Dry breezy trade winds will continue through the week. Lower clouds and showers will tend to favor windward and mauka areas, particularly through the morning hours and again tonight. Expect mainly VFR conditions with brief MVFR conditions possible under passing showers.
AIRMET Tango looks to remain in effect for moderate lee turbulence through much of the week.

Marine

Fresh to strong easterly trades will continue through the upcoming weekend as high pressure remains north-northeast of the area. The Small Craft Advisory (SCA) remains in effect through Friday afternoon for the typically windier waters adjacent to the islands of Maui County and the Big Island, which will likely need to be extended through the weekend. Trades may slightly ease early next week as a weakness in the ridge forms north of the area.
Surf along east facing shores will remain up today due to a long- period easterly swell moving through from recent Hurricane Hilary in the far eastern Pacific. Overnight observations at NDBC buoy 51004 southeast of the Big Island and the nearshore PacIOOS buoys continue to reflect this energy centered around the 15 second band. As this source fades through the second half of the week and into the weekend, surf will lower below the summertime average due to a recent stretch of weaker trades far upstream of the state over the eastern Pacific.
Surf along south facing shores will remain small through early next week with mainly a mix of south-southeast and south swells moving through. Looking out into the extended period, guidance doesn't show any significant southerly sources developing within our typical swell windows across the southern Pacific, which will translate to the small conditions persisting into September.

Fire weather

The combination of dry fuels, low relative humidity values, and breezy trade winds, will bring elevated fire danger to leeward areas across the island chain during the next few days. Fires that start could become difficult to control as a result of these conditions.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov