Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 69 near the shore to around 58 above 3000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 87 near the shore to around 75 above 3000 feet. Light winds becoming southwest up to 10 mph in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 83 to 88. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 68. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 83 to 88. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 75 to 82 in the valleys to around 66 above 4000 feet. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 58 to 64 in the valleys to around 55 above 4000 feet. East winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 75 to 82 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 78 to 86. Northeast winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 61 to 70. East winds around 10 mph in the evening becoming light.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 78 to 86. Light winds. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 86. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 60 to 72. Northeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 76 to 86. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Fair weather will continue as diminishing trade winds will produce a land and sea breeze weather pattern through Tuesday. Unsettled and wet weather conditions will move in on Wednesday and Thursday as a weakening cold front stalls out over the islands. Expect increasing shower trends mainly along the frontal cloud band over the northwestern islands with a brief period of moderate to locally breezy trade winds forecast in the wake of the front. Wet weather continues over the islands of Oahu and Kauai through Friday with brief periods of showers forecast elsewhere through Saturday. More stable conditions with drying trends are forecast on Sunday and Monday as moderate trade winds return to the region.

Discussion

A few bands of low clouds linger around the islands in light easterly background winds this morning. A cold front shows up in the big picture satellite imagery roughly 900 miles northwest of the Kauai and this system remains on track to bring the next round of wet weather into the Hawaiian Islands later this week. The upper air soundings from Lihue and Hilo this morning show a stable temperature inversion height of around 5,000 feet elevation. This inversion height will limit cloud heights and shower activity today. These stable weather trends will continue through Tuesday in a land and sea breeze island weather pattern.
A weakening cold front diving in from the northwest on Wednesday will bring wet weather to the region. The highest chances for rainfall are forecast along the frontal cloud band mainly affecting Kauai and Oahu. The front eventually dissipates and stalls near Molokai on Thursday with moderate trade winds spreading across the state. The dissipated front becomes a trough at this point, and the trade winds will push this cloud band westward back over Oahu and Kauai, producing another round of lighter showers for both islands through Friday. Elsewhere brief periods of showers are forecast through Saturday with perhaps some enhancement along the southeastern slopes of the Big Island during a brief period of southeasterly wind flow from Thursday to Friday afternoon.
Stable conditions return from Sunday onward as an upper level ridge sets up a subsidence (downward vertical motions) zone over the Hawaiian Islands. Strong subsidence under this ridge will lower the trade wind inversion heights and limit shower coverage statewide.

Aviation

With high pressure to the northeast, and a cold front approaching from the northwest, the ridge north of the islands is beginning to be pushed southward towards the main Hawaiian Islands. Light winds are expected to continue today, with some localized land and sea breezes setting up. A relatively dry airmass over the region, combined with an inversion around 5100 feet, will limit clouds and shower activity. VFR conditions are expected to prevail, however brief MVFR conditions are possible over the interior of the islands with afternoon sea breezes. No AIRMETs are in effect, and none are expected into tonight.

Marine

A cold front approaching from the northwest on Monday will result in lighter winds over the islands through Tuesday. The front is forecast to reach Kauai and possibly Oahu Tuesday night through Wednesday. Stronger north to northeast winds will fill in behind the front, possibly reaching Small Craft Advisory (SCA) speeds near Kauai and Oahu waters. As the front weakens and drifts back westward Friday, winds will become lighter across the area.
A new, moderate-sized northwest swell (320-340 degrees) has arrived at the Hanalei nearshore buoy and will continue to fill in through the morning, peaking at low end advisory levels today, and then lower through Tuesday. Buoys northwest of and near Hawaii are trending higher than current guidance therefore, a High Surf Advisory (HSA) has been issued through Monday night for all north facing shores of Niihau, Kauai, Oahu, Molokai, and Maui. Due to the northwest direction and swell shadowing, the Big Island is not included in this advisory. A HSA has also been issued for west facing shores of Kauai through Monday night. A larger, but shorter-period, north swell (360 degrees) is expected to arrive Wednesday and may bring low-end advisory level surf to north facing shores Wednesday night and early Thursday, before lowering Thursday night through Saturday. It will also likely bring SCA level seas to exposed waters.
Small background south swells (180 degrees) are expected through Tuesday, with a series of slightly larger, long- period south swells expected Wednesday through Saturday. With no significant trade wind flow over and upwind of the state, most surf along east facing shores will be from north swell wrap.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov