Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Scattered showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy. Lows 65 to 70 near the shore to around 56 above 3000 feet. Light winds.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs around 88 near the shore to around 76 above 3000 feet. Light winds becoming west around 10 mph in the afternoon. Chance of rain 30 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs around 84. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 69. Northeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the afternoon. Highs around 85. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 56 to 61 in the valleys to around 51 above 4000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. Light winds. Chance of rain 30 percent.

North Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 86. East winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 59 to 69. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs 78 to 87. Light winds. Chance of rain 30 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 77 to 85. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 57 to 71. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 86. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The trade winds will ease today as a cold front approaches from the northwest. Showers will favor windward and mauka areas, but a few showers could develop over interior and leeward areas this afternoon with the assistance of localized sea breezes. A light wind regime will become dominant across the entire state Tuesday and Wednesday, with sea breezes allowing for a few afternoon showers each day, while land breezes keep most showers offshore or near the coast at night. The trade winds will return from east to west across the state on Thursday, bringing more typical windward and mauka showers focused showers, with this pattern then holding through the weekend.

Discussion

Currently at the surface, a 1028 mb high is positioned around 1600 miles northeast of Honolulu, while a cold front is located around 950 miles northwest of Kauai. The gradient locally has weakened overnight, with light to moderate trade winds in place early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions in windward areas, with clear to partly cloudy skies in most leeward locales. Radar imagery shows isolated showers moving into windward areas, with coverage the highest on Oahu. Main short term focus revolves around trade wind trends and rain chances.
The trades will steadily ease during the next couple days as a cold front approaches from the northwest, with a land and sea breeze pattern expected statewide Tuesday and Wednesday. The front is forecast to stall out just northwest of Kauai Wednesday night, then weaken into a trough and shift westward through the remainder of the work week while ridging rebuilds to the northeast of the islands. This should bring a return of the trades from east to west across the state Thursday, with moderate trades then holding in place Friday through the weekend.
As for the remaining weather details, a few windward showers will be possible across the state this morning. The weakening trades and boundary layer winds shifting southeasterly could then allow for a few sea breeze driven showers over interior and leeward areas this afternoon. A land and sea breeze pattern should then develop over most of the state tonight through Wednesday, with showers remaining near the coast at night and over interior and mauka areas each afternoon. The trades will begin to return Thursday bringing more typical windward and mauka focused showers which should last through the weekend. Relatively dry weather should prevail during the next 7 days as the deepest moisture associated with the front remains northwest of the state.

Aviation

Moderate trade winds will gradually weaken today and the pattern will trend towards localized land and sea breeze activity as the local pressure gradient relaxes in response to an approaching cold front. Clouds and showers will still favor windward and mountain locations this morning, then will start to form over leeward and inland locations later today as localized sea breezes begin to develop. VFR conditions will generally prevail, but brief MVFR conditions will be possible in any heavier showers this morning.
Tempo moderate low level turbulence has ended, and currently no AIRMETs are in effect. Looking aloft, with the Hawaiian Islands on the tail end of a moderate to strong jet streak, will continue to monitor for the potential need to issue AIRMET Tango for some tempo upper level moderate turbulence later this morning.

Marine

The Small Craft Advisory has been cancelled as winds have eased below advisory levels. Trades will continue to weaken through today as the ridge of high pressure moves south over the state. Emerging light southeastly flow may be variable at times through mid week, before the trades return and restrengthen Thursday into next weekend.
A small, medium period north- northwest (330) swell will peak today, bringing small surf to north and northwest facing shores. A moderate, medium period northwest (310-320) swell will then build throughout Tuesday and peak during mid-week as it brings small to potentially moderate surf to favored shores. The swell source that provided much of the surf this week is currently north of the state and has a swath of severe gales aiming at the state based on latest ASCAT passes. This will revive the swell as it transition to a more north- northwest (340-350) direction late Wednesday night, before peaking Thursday and slowly subsiding Friday into the weekend.
Small surf along south facing shores is anticipated for the next couple of days as a small, medium period south- southeast swell persists. A small, long period south- southwest (200) swell will arrive late tonight and linger into Thursday. A slightly larger, long period south- southwest swell will arrive Friday concurrent with a slightly larger, medium period southeast swell which will help boost surf along south facing shores.
Short period, choppy surf along east-facing shores slowly subside over the next couple of days as winds become light and variable.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov