Photo Credit: Braden Jarvis

West Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. Northeast winds around 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Tonight: Mostly clear. Lows around 70 near the shore to around 60 above 3000 feet. Light winds.

Monday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. Light winds. Chance of rain 40 percent.

South Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 82 to 87. Northeast winds around 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 68 to 73. Northeast winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85. East winds around 10 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Mostly cloudy. Scattered showers in the morning, then showers likely in the afternoon. Highs 73 to 79 in the valleys to around 66 above 4000 feet. East winds around 10 mph. Chance of rain 70 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows 62 to 67 in the valleys to around 57 above 4000 feet. East winds around 10 mph. Chance of rain 30 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 80 in the valleys to around 66 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 76 to 85. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows 64 to 72. East winds around 10 mph. Chance of rain 30 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 77 to 85. East winds around 10 mph. Chance of rain 30 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 74 to 85. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 62 to 74. Northeast winds around 10 mph in the evening becoming light. Chance of rain 30 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 75 to 85. East winds around 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Light trade winds will deliver a few windward showers into Monday, with the potential for an increase in showers over windward and southeast Big Island tonight. Winds will become light and variable by Tuesday, then remain that way through the week, with mostly dry weather. Expect mostly clear nights and mornings giving way to afternoon interior clouds and isolated showers. Trade winds may return next weekend.

Discussion

A relatively weak (1021 mb) surface high centered about 800 miles NW of the islands is supporting a light to locally moderate trade wind flow this morning. The high pushed moisture associated with a dissipated front over Kauai overnight, leading to some beneficial rainfall. This moisture band is now becoming increasingly diffuse and lifting away from Kauai, so shower coverage should be trending down. Radar currently shows isolated small showers moving into windward coasts of all islands, while morning soundings indicate a strong subsidence inversion near 5000 feet at PHTO, with the inversion a little higher and weaker at PHLI.
The short term forecast expects the light to moderate trade winds to persist, delivering just a few showers to windward areas. Winds will likely be sufficiently light to allow afternoon sea breezes to drive some cloud development. A surface trough about 450 miles SE of the Big Island will move W at 15 to 20 mph, and guidance indicates that some of the associated moisture may clip the Big Island later today into Monday, bringing an increased chance of showers to the Kau, Puna and Hilo Districts. The stable island atmosphere will likely limit rainfall totals over areas that could use a soaking rain.
The high will weaken tonight and Monday before dissipating on Tuesday. In its place, a surface ridge is expected to extend over the islands from the E, with trade winds becoming light and variable. The light winds will allow for mostly clear skies during nights and mornings, with some interior and upslope clouds in the afternoons. With a strong mid-level ridge building overhead, rainfall chances will be minimal. This pattern is expected to persist through Friday, with another weak front potentially nearing Kauai by next weekend, potentially leading to increasing trade winds.

Aviation

Trade winds will steer bands of light showers off the Pacific towards mainly windward slopes and coasts. Light sea breezes will return to leeward coasts this afternoon and will serve to focus afternoon shower activity over island interiors. A sharp trade wind inversion around 06 kft over the eastern half of the state will serve to restrict any shower development over the Big Island to the lower elevations.
Brief MVFR ceilings and visibilities are to be expected in showers, otherwise VFR conditions will prevail all areas.

Marine

A brief increase in trade winds will develop today with light to moderate trades lasting into Monday, as a surface ridge builds far to the north. Wind speeds will weaken yet again from Tuesday onward and turn more from the southeast direction as another cold front approaches the islands from the northwest.
A small, declining, short period north-northwest swell will be reinforced by a medium period north-northwest (340 degrees) swell today. This swell will decline on Tuesday, though a similarly sized pulse of northwest swell is due late Wednesday or Thursday.
The series of late season south swells will continue through the week. Long period, south-southwest swell (190-200 degrees) will hold today. An overlapping pulse of south swell (180-190 degrees) will maintain similarly sized surf Monday, with a gradual decline on Tuesday and Wednesday. Another pulse of southwest swell is due late next week.
Aside from areas exposed to wrapping north-northwest swell, east shore surf will continue to be small due to the lack of significant upstream trade winds.
Higher than predicted water levels have been observed across the Hawaiian Islands this past week. Minor coastal flooding is possible during the early morning high astronomical tides through Tuesday, with Monday seeing the highest tides. A Coastal Flood Statement continues for all vulnerable coastal areas.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov