Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 70 to 75 near the shore to around 61 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 68 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Occasional showers in the morning, then scattered showers in the afternoon. Highs around 85. East winds 10 to 15 mph. Chance of rain 90 percent.

Kaua’i Mountains

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Mostly cloudy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.

North Kaua’i

Today: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 87. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 74. Southeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 87. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 86. Northeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 75. Northeast winds up to 10 mph. Chance of rain 70 percent.

Tuesday: Mostly cloudy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 78 to 86. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 90 percent.

Detailed Forecast

Synopsis

Moderate trade winds will prevail today as the surface ridge to the north remains weak. Rainfall will favor windward and mauka locations, but a few showers, some heavy, may develop across leeward areas as a disturbance aloft moves overhead. Locally breezy trades and more stable conditions will return Tuesday and persist through the weekend.

Discussion

Currently at the surface, a ridge of high pressure is located around 900 miles north of Honolulu, with broad but weak troughing present between the ridge and the Hawaiian islands. Aloft a closed upper low can be seen in water vapor imagery around 100 to 150 miles to the north of Oahu and Kauai. The broad surface troughing has kept the pressure gradient a bit weaker than normal, with generally moderate trade winds blowing across the island chain early this morning. Infrared satellite imagery partly to mostly cloudy conditions in windward areas, with partly cloudy skies in most leeward locales. Radar imagery shows scattered showers moving into windward slopes and coasts, with a few of these showers reaching leeward communities at times. Main short term focus is on rain chances and trade wind trends.
The broad trough of low pressure over and north of the state will gradually dampen out and shift westward during the next couple days. Moderate trades will prevail today with localized sea breezes developing in some of the more sheltered leeward areas this afternoon. The trades will increase a bit tonight and hold at moderate to locally breezy levels Tuesday through Friday. The trades may ease a bit this weekend as the ridge to the north weakens.
As for the remaining weather details, the airmass will remain unstable with the upper level low near the western islands today and tonight. This will allow some more robust showers to move in on the trades and produce brief downpours. Additionally, some locally heavy showers could develop in leeward areas with the assistance of sea breezes during the afternoon and early evening hours, before fizzling out overnight. A mid-level ridge building in from the east will bring a more stable airmass to the islands Tuesday through Thursday. This should result in a return to typical trade wind weather featuring mainly windward and mauka showers. Another disturbance aloft could bring a slight increase in trade wind showers Friday through the weekend.

Aviation

Moderate trades will usher in low clouds and showers to windward and mauka areas, with a few showers occasionally spilling over to leeward sides. Sea breezes will develop along some wind-protected areas this afternoon, leading to low cloud and shower development over those areas. Then trades will strengthen slightly heading into tomorrow.
MVFR conditions can be expected in any showers. Otherwise, VFR should prevail.
No AIRMETs are in effect. AIRMET Sierra for tempo mountain obscuration may be needed tonight for the eastern end of the state as a plume of moisture rides in on the trades.

Marine

High pressure generally north of the state will drive moderate to locally fresh trades today. High pressure northwest of the islands will strengthen through the middle of the week. This will produce fresh to locally strong trades from Tuesday through the remainder of the week. A Small Craft Advisory may be necessary for the windier waters surrounding Maui County and Big Island Tuesday.
Surf along north and west-facing shores will remain very small today. A small to moderate size, long to medium period northwest swell (330 degrees) is timed to arrive Tuesday from a passing North Pacific cold front. This swell will increase mid week north- facing shore surf to well above head high along reefs and shorelines where northwest energy is best focused. North shore surf is expected to remain well under the High Surf Advisory levels. South-facing shore surf will remain small as a mix of small, medium period southwest swells pass through the next few days. Eastern shore waves will remain small in response to recent light trades. An upward trend in eastern chop will occur later today and will persist through the week in response to strengthened trades.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov