West Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 68 to 73 near the shore to around 60 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs 84 to 89 near the shore to around 72 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows around 70. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 86. East winds 10 to 20 mph. Chance of rain 70 percent.

Monday Night: Breezy. Mostly cloudy with scattered showers. Lows around 70. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows 63 to 68 in the valleys to around 58 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 90 percent.

Monday: Mostly cloudy. Breezy. Showers in the morning, then scattered showers in the afternoon. Highs 73 to 83 in the valleys to 61 to 66 above 4000 feet. East winds 10 to 20 mph. Chance of rain 80 percent.

Monday Night: Mostly cloudy. Numerous showers in the evening, then showers after midnight. Lows 64 to 69 in the valleys to around 58 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 72. Southeast winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 70 percent.

Monday: Partly sunny with scattered showers. Highs 77 to 86. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 71. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 75. East winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 84. East winds 10 to 15 mph. Chance of rain 70 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 74. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trades will deliver clouds and showers to windward and mauka areas through the upcoming week, with an increase in coverage during the overnight and early morning hours.

Discussion

Water vapor satellite imagery continues to show a broad area of strong subsidence east of Oahu this afternoon. Meanwhile, the upper-level low west of Kauai continues to slowly drift towards the state as a cold front stalls northwest of the region. Expect our moderate to locally breezy trades to weaken slightly tonight through Monday as the mid- and upper-level ridge get eroded by the aforementioned features. Visible satellite and radar imagery shows rather dry conditions across the state this afternoon, with pockets of clouds and showers across windward and mauka areas. Shower trends will increase across the state tonight into Tuesday as the upper-level low approaches and lifts the trade wind inversion across the islands. Breezy trade winds are then expected beyond Tuesday as high pressure rebuilds north of the state. Guidance continues to suggest an uptick in shower activity Tuesday night into Wednesday as the remnants of the cold front gets embedded in the trades and drifts across the islands. Otherwise, expect clouds and showers to continue favoring windward and mauka areas, with an increase in coverage expected during the overnight and early morning hours.

Aviation

Moderate to breezy easterly trade winds will persist through Monday. Very stable conditions will produce VFR conditions over most areas through the evening, with isolated pockets of moisture producing MVFR conditions along windward terrain. An approaching upper-level trough will gradually erode the ridge aloft tonight and Monday, causing the inversion to lift and weaken and bringing a thin shield of high clouds. Only a slight increase in the coverage of showers and MVFR conditions is expected for Monday. AIRMET Tango for moderate low-level turbulence will remain marginal, though it may need to expanded from from Molokai to Big Island to cover all islands on Monday, and some increase in turbulence above FL350 will be possible as the upper-level trough approaches.

Marine

No changes to the forecast with the afternoon package. High pressure to the northeast will maintain moderate to locally strong trades through Monday, and then a bit of an uptick is expected Tuesday through the end of the work week. The current Small Craft Advisory (SCA) is in effect for the typically windier waters near Maui and the Big Island through Monday afternoon. With winds expected to remain elevated through the week, expect the SCA to be extended in time, and additional waters may need to be added as the winds increase.
A new long-period south-southwest swell has made an appearance today, and will continue to build in tonight. This swell will peak Monday through Tuesday, and then decline Wednesday through Thursday. A larger south swell will arrive late in the work week, peaking near advisory levels along south facing shores next weekend. Surf along east-facing shores will hold steady near seasonal averages through late this week with the upstream trade winds. A series of small northwest and north swells will move through the islands keeping surf from going flat this week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.