Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Highs 82 to 87 near the shore to around 73 above 3000 feet. Southeast winds up to 10 mph.

Tonight: Partly cloudy with isolated showers. Lows around 66 near the shore to around 54 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 82 to 87 near the shore to around 74 above 3000 feet. South winds up to 10 mph. Chance of rain 30 percent.

South Kaua’i

Today: Mostly sunny. Highs 78 to 85. East winds up to 10 mph shifting to the south in the afternoon.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows around 65. Light winds. Chance of rain 20 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 78 to 86. Southwest winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 72 to 81 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 58 to 64 in the valleys to around 52 above 4000 feet. Light winds becoming southwest up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 81 in the valleys to around 65 above 4000 feet. Southwest winds up to 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny. Highs 74 to 84. South winds up to 10 mph in the morning becoming light.

Tonight: Partly cloudy. Lows 59 to 67. Light winds becoming south up to 10 mph after midnight.

Monday: Mostly sunny with isolated showers. Highs 74 to 84. South winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny. Highs 71 to 83. South winds up to 10 mph.

Tonight: Partly cloudy with isolated showers. Lows 58 to 69. Light winds becoming southwest up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 72 to 83. Southwest winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Lighter large scale winds today will allow land and sea breezes to expand in coverage over all islands. Conditions should remain fairly stable and dry through Wednesday, with low clouds and a few light showers each afternoon will favor island interior and mountain areas. Rainfall trends will increase from Thursday into Friday as a weak cold front moves into and stalls out over the islands. Periods of passing showers and moderate to locally breezy northeasterly winds, wet trade wind weather, will linger into next weekend.

Discussion

The satellite imagery this morning remains fairly stable looking with bands of stable clouds near the islands and a few cirrus clouds drifting into the state from the north. Expect a light and variable wind pattern to start today with expanding land and sea breezes over all islands lasting through Wednesday.
The upper level subtropical ridge axis will linger just south of the state through Wednesday keeping fairly stable weather conditions in the forecast. Expect brief showers in a light wind afternoon onshore sea breeze weather regime. Clouds and a few showers will develop by late morning to afternoon over island mountain and interior sections through Wednesday. Rainfall amounts will remain on the lighter side due to the large scale atmospheric stability.
By Thursday, long range model guidance continues to show a shallow cold front creeping into the western islands from the northwest direction. Widespread showers and breezy trade winds will develop along the weakening frontal band as it passes through each island. The latest model guidance continues to show this frontal cloud and shower band stalling out near Maui by Friday morning. All islands will benefit from a period of enhanced showers along the frontal band, especially along the windward and mountain slopes of each island. The frontal band will then break apart by Friday afternoon, with remnant unstable cloud bands drifting into each island on the strengthening easterly trade winds, producing a wet trade wind pattern lasting through much of next weekend.

Aviation

Light to locally moderate trades will continue to weaken through the rest of today, allowing for land/sea breezes development. Isol SHRA should favor mauka and interior areas of each island due to sea breeze development each afternoon, then clear out overnight with the land breezes. Brief MVFR conds will be possible in SHRA, otherwise VFR should prevail.
No AIRMETs are currently in effect.

Marine

Light background flow will shift to southeasterlies today. A front will approach from the northwest early this week and keep gentle south to southeast winds in place. The Small Craft Advisory (SCA) for windward waters due to large swell has been cancelled.
The current northwest (310-320) swell continues to slowly decline this morning, but a High Surf Advisory (HSA) remains in effect for affected north and west facing shores of the smaller islands through noon today. The HSA for west facing shores of the Big Island has been cancelled. Surf should drop below advisory levels everywhere by this afternoon. The first of a series of overlapping northwest swells, ranging from large to potentially extra-large, will arrive Tuesday. A larger one will peak Wednesday into Thursday. Surf along east facing shores will remain slightly elevated through today due to a lingering short-period north- northeast swell. Surf along east facing shores will then become small. Surf along south facing shores will see an uptick heading into the week from a series of consecutive southwest pulses. This will result in small to moderate surf, peaking Monday and Tuesday.

Fire weather

Critical fire weather conditions are not expected through at least Wednesday as winds remain below warning thresholds. Daytime relative humidity levels may briefly touch critical levels over drier leeward zones. Increasing moisture and rainfall trends will develop from Thursday into next weekend as a weakening cold front moves down the island chain, stalls out and then breaks up near Maui.

HFO Watches/Warnings/Advisories

High Surf Advisory until noon HST today for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Koolau Windward, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.

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