West Kaua’i

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to around 57 above 3000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 79 to 86 near the shore to around 72 above 3000 feet. Light winds. Chance of rain 20 percent.

Tuesday Night: Mostly clear. Lows 65 to 70 near the shore to around 58 above 3000 feet. East winds up to 10 mph.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows around 67. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 79 to 86. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows around 68. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy. Lows 57 to 67 in the valleys to around 56 above 4000 feet. Light winds.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs 73 to 79 in the valleys to around 65 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 30 percent.

Tuesday Night: Partly cloudy with scattered showers. Lows 58 to 68 in the valleys to around 56 above 4000 feet. East winds up to 10 mph. Chance of rain 30 percent.

North Kaua’i

Tonight: Partly cloudy. Lows 60 to 68. Light winds.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs 74 to 82. Northeast winds up to 15 mph. Chance of rain 30 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 61 to 68. Southeast winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 60 to 70. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 72 to 84. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 62 to 71. East winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Benign weather prevails through the week as moderate winds hold out of the southeast quadrant over the eastern end of the state. Further west, a land and sea breeze pattern prevails through mid- week before winds turn southerly bringing a chance of showers to Leeward Oahu and Kauai during the second half of the week.

Discussion

A strong zonal Pacific jet extends across the Pacific Basin roughly along 35N. Broad ridging remains established south of this feature and extends over the Hawaiian Islands where active mid- level subsidence will keep a lid on any shower activity. The trade wind belt has consequently been shunted into the low latitudes with the eastern end of the state barely hanging on to moderate ESE winds. The diminished gradient over the islands will support a land and sea breeze pattern over the western end of the state through mid-week with afternoon clouds and just a few spotty showers followed by offshore flow and crisp overnight low temperatures for island interiors. Frontal passages will be hard to come by in the present pattern with no mechanism to force southward progress of any approaching fronts, but a modest buckle in the flow will allow a shallow cold front to approach Kauai by week's end thereby allowing winds over the western end of the state to veer to southerly. Increased moisture advection over Oahu and the presence of the frontal band near Kauai will support a slight uptick in coverage of light showers for those islands Wednesday night into Friday.

Aviation

Light to moderate east-southeasterly trades will weaken this evening in response to an approaching front and may deliver a few isolated showers to windward Big Island from time to time. Winds have become light enough across the western half of the state this afternoon to support sea breeze development, bringing some cloud build ups and a few light showers over leeward and interior areas. However, a strong temperature inversion around 6,000 ft is helping to limit shower activity. Overnight, land breezes will take over and help to clear some leeward and interior areas.
The approaching front will dissipate just north of the island chain and its driving high pressure system will fill in across the state in its wake, allowing moderate east-northeast trades to build across the area tomorrow. A modest increase in moisture may also lead to a slight uptick in cloud cover and showers for the western half of the state early tomorrow morning before drier air filers in.
Overall, VFR conditions should prevail over the next 24 hours, with brief MVFR possible in isolated showers.
No AIRMETs are in effect.

Marine

A ridge of high pressure will slowly drift over the islands today as a front passes north of the islands, giving way to light east to southeast flow through tonight across most waters. A weak high building north of the state will produce light to gentle north to northeast flow on Tuesday. Another front approaching the islands Wednesday will cause the winds to shift out of the southeast to south through Friday before the front lifts northward and trades slowly return through the weekend.
The current west-northwest swell has been lowering steadily through the day and has now dipped just below advisory levels. Therefore, the High Surf Advisory (HSA) has been cancelled for all existing north and west facing shores. This swell will continue to lower through Tuesday morning. A similar- sized northwest swell is expected to build in late Tuesday and linger through Wednesday, resulting in peak surf heights at or slightly above advisory levels for north and west facing shores. An even larger northwest swell is expected to build late Thursday into Friday, potentially reaching High Surf Warning level for most north and west facing shores.
Surf along south facing shores will remain tiny with mainly background energy through the week. Surf along east facing shores will also remain tiny to small through the week due to mostly light background wind flow, with a potential slight uptick early next week with the return of the trade winds.

HFO Watches/Warnings/Advisories

None.

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