West Kaua’i

Tonight: Haze in the evening. Partly cloudy with isolated showers in the evening, then mostly cloudy after midnight. Lows around 66 near the shore to around 56 above 3000 feet. Light winds becoming northeast up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the afternoon. Haze in the afternoon. Highs 78 to 85 near the shore to around 72 above 3000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows around 66 near the shore to around 56 above 3000 feet. Light winds.

South Kaua’i

Tonight: Mostly cloudy. Haze in the evening. Lows around 67. Northeast winds around 10 mph.

Monday: Sunny. Haze in the afternoon. Highs 78 to 84. East winds up to 10 mph.

Monday Night: Mostly clear. Lows around 66. Light winds.

Kaua’i Mountains

Tonight: Haze in the evening. Mostly cloudy with isolated showers. Lows 56 to 66 in the valleys to around 55 above 4000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly clear with isolated showers. Lows 56 to 66 in the valleys to around 54 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Tonight: Mostly cloudy with isolated showers. Lows 60 to 68. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 74 to 82. Southeast winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Mostly clear with isolated showers. Lows 60 to 67. Light winds. Chance of rain 20 percent.

East Kaua’i

Tonight: Haze in the evening. Mostly cloudy with isolated showers. Lows 60 to 70. Light winds. Chance of rain 20 percent.

Monday: Sunny with isolated showers. Highs 72 to 83. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly clear with isolated showers. Lows 59 to 70. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A ridge of high pressure near Kauai will keep light to moderate trades blowing over the eastern islands while land and sea breezes remain common over the western end of the state through mid week. Rather dry weather will prevail during this time, with a few showers along windward slopes and coasts each night and over the island interiors each afternoon. An approaching front will strengthen south to southeast winds and increase rain chances Thursday and Friday, mainly over the western islands. A ridge building over the state should bring drier conditions and lighter winds Saturday, with a new approaching front strengthening south winds and increasing rainfall chances next Sunday.

Discussion

Currently at the surface, a 1035 mb high is centered just off the Pacific Northwest coast of the CONUS, with ridging extending southwestward to near Kauai. Light to locally moderate trades are present across the island chain this evening, with the lightest winds over the western end of the state. Infrared satellite imagery shows daytime heating driven cloud cover decreasing, with radar imagery showing minimal shower activity confined primarily to the windward slopes of the Big Island. Main short term focus revolves around trade wind trends and rain chances.
The surface ridge axis will remain near Kauai through Wednesday, keeping moderate east-southeasterly trades blowing over the eastern end of the state. Lighter winds will prevail over the western islands, where overnight land breezes and daytime sea breezes will be common, particularly in the more sheltered leeward areas. Rather dry weather will prevail during this time. A few showers will be possible along windward slopes and coasts at night and during the early morning hours, and over the interior and leeward sections of the islands each afternoon.
An approaching front will allow winds to pick up out of the south and southeast Thursday and Friday, potentially bringing an increase in showers to the western islands, particularly Kauai. Meanwhile, rather dry weather will persist over the eastern end of the state. The front appears to stall out near or just north of Kauai late in the week, then weaken into a trough and lift northward over the weekend. A surface ridge axis should build over the state on Saturday, keeping winds rather light, and shower activity minimal. A stronger front appears to approach from the west next Sunday, bringing an increase in south to southwest winds and higher chances for showers and potentially thunderstorms.

Aviation

Light to moderate ESE winds and land/sea breezes expected through tomorrow night. With that being said interior and leeward SHRA will be possible. MVFR conds will be possible in SHRA but in general VFR conds should prevail. A few SHRA will also be possible along windward and mauka locations.
While Kilauea has once again paused in its eruption cycle, there is some degassing occurring causing some hazy conditions across some portions of the state. While this hasn't been enough to add to any TAFs its worth mentioning there could be some haze.
No AIRMETs are currently in effect.

Marine

Weak surface ridging north of the islands will steer light to moderate ESE winds through much of the week before turning southerly as deep low pressure tracks north of the area.
Forerunners of a moderate, long period NW (310) continues to fill in at the offshore NDBC buoys (51001 and 51101) this evening near guidance and should arrive locally after midnight tonight and peak through the Monday morning hours before subsiding Monday night. Since this swell appears to follow guidance well a High Surf Advisory (HSA) is not needed at this time. A slightly larger, long period NW (300-310) swell will build into the area late Monday night into Tuesday easily reaching HSA thresholds and potentially reaching low-end warning criteria along exposed N and W facing shores. This swell will hold through mid- week and then decline Thursday. Another slightly larger, long period NW (320) swell will build late Thursday night, peak Friday night into Saturday well into High Surf Warning thresholds, before slowly subsiding through Sunday.
Surf along E and S facing shores remains small through the period.

HFO Watches/Warnings/Advisories

None.

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