Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs 86 to 91 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Numerous showers early in the evening, then scattered showers in the late evening and overnight. Lows around 72 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny. Scattered showers and slight chance of thunderstorms in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the morning. Highs 82 to 90. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening, then numerous showers in the late evening and overnight. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 82 to 90. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy with numerous showers. Highs 76 to 87 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 in the valleys to around 59 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy with numerous showers. Highs 76 to 86 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 78 to 89. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening, then numerous showers in the late evening and overnight. Lows 66 to 74. Southeast winds up to 10 mph. Chance of rain 70 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 89. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny with scattered showers and slight chance of thunderstorms. Locally heavy rainfall possible in the morning. Highs 74 to 87. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers and slight chance of thunderstorms early in the evening, then numerous showers in the late evening and overnight. Lows 65 to 77. Northeast winds up to 10 mph. Chance of rain 70 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 87. Northeast winds up to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Gentle to moderate trade winds will continue through today. A hybrid tradewind/seabreeze pattern will develop this afternoon with clouds and showers developing over select leeward and interior areas. Instability from a low aloft will continue to support locally heavy showers and a slight chance of thunderstorms over portions of the state today. Stronger trade winds and increasingly stable conditions will develop Monday through midweek.

Discussion

Forecast remains on track with gentle to moderate trade persisting across the state through today. Latest satellite and radar imagery show mostly scattered light to brief, locally heavy showers mainly along windward and mauka locations. Most of the persistent heavy showers have remained over leeward coastal waters where convergence is more prevalent. The morning soundings show slightly more unstable conditions near Kauai and a slightly weaker inversion near the Big Island, resulting from the upper level low that appears to be circulating near Kauai and Oahu. Expect clouds and showers to develop along leeward and interior areas as the day progress and seabreezes develop. Due to the instability created by the upper low a slight chance of thunderstorms remains possible through today, especially for the upslope areas of the Big Island later this afternoon.
As we head into the evening hours expect more of a tradewind pattern to take over as land breezes develop and the chances of heavier showers shifts more towards windward areas during the overnight and early Monday morning hours. The absence of a deep moisture profile will continue make forecasting when and where the heaviest showers or thunderstorms may develop and will remain localized.
Models trends still show trade winds gradually increasing later today into Monday as a new high pressure to the distant northwest builds eastward. Instability may linger through Monday, but generally, increasingly stable trade wind conditions should return by Tuesday and persist through much of next week as the upper low weakens into a broad trough and shifts just east of the state. With the return of a more typical trade wind pattern, expect clouds and showers to favor primarily windward and mauka areas.

Aviation

Moderate trade winds will continue with afternoon sea breezes decreasing in coverage over terrain sheltered leeward areas. An upper level low moving over the islands today will increase low cloud and shower trends. Periods of MVFR conditions this weekend will favor windward and mountain areas, including converging sea breeze boundaries along the leeward slopes. There remains a slight chance of thunderstorms over the state today.
No AIRMETs are currently in effect.

Marine

A weakened ridge to the northeast of the islands is driving gentle to moderate trades across the region this morning. An upper low remains just northeast of the islands and, as a result, a chance for thunderstorms remains in the forecast for the offshore and coastal waters near the upper low through tonight. After tonight, the low is forecast to lift back to the north. A ridge is rebuilding to the north of the islands and this will help strengthen trades cross the region. By Monday morning, Small Craft Advisory (SCA) level winds are possible in the typical windier coastal waters near Maui County and the Big Island. Once SCA winds return, we can expect those to continue through at least mid- week.
A pair of overlapping small, short period north swells should maintain small surf across north facing shores through today. A short lived small, short to medium period northeast swell is expected through this morning, which will also boost surf along east facing shores. There is the potential for a moderate long period north-northwest swell today, which would peak Monday below advisory levels for north facing shores, with the swell lingering into the middle of the new week. A moderate, long period south swell should fill in today, hold into Monday, and then gradually decline through the middle of next week. This swell may boost surf along south facing shores to near or slightly below advisory levels during its peak.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov