West Kaua’i

Tonight: Mostly clear with isolated showers. Lows 70 to 75 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 84 to 91 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 70 to 76 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

South Kaua’i

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 71 to 77. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 79 to 89. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 72 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows around 67 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 73 to 81 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows around 68 in the valleys to around 61 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 62 to 74. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 71 to 86. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered showers. Lows 63 to 75. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 67 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 76 to 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 77. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate trades turn breezy mid-week delivering showers windward and mauka through the period.

Discussion

Deeper moisture (relative to last night) lurks immediately upstream and will be ushered through the forecast area tonight through Tuesday by persistent moderate trades in the lowest levels. For the most part, a typical distribution of showers focused windward and mauka is expected. However, veering winds within the deepening boundary layer (up to approximately 10kft) yields potential for some leeward convergence downwind of Maui County potentially bringing enhanced shower coverage to Leeward Oahu mainly after midnight tonight continuing into Tuesday morning. As this moisture advances west of the islands mid-week, trades rebound under a broad low amplitude subtropical ridge. Breezy trades, high stability, and limited showers focused windward and mauka then prevail through the weekend.

Aviation

Moderate to locally breezy trade winds will persist through Tuesday and increase slightly Wednesday. This morning, an area of enhanced moisture moved onto windward Maui County, where widespread MVFR conditions have necessitated AIRMET Sierra for mountain obscuration, and as the moisture spreads westward, the AIRMET will likely be expanded to additional islands overnight. VFR conditions will prevail over most leeward areas. Drier conditions are expected to build in from the east late Wednesday.

Marine

The trade winds will hold at mostly moderate speeds today through Tuesday as very broad troughing has produced a weakness in the subtropical ridge to the northwest of the Hawaiian Islands. Trade winds strengthen to fresh and locally strong speeds Wednesday through Friday as high pressure strengthens north of the island chain.
Surf observations continue to show advisory level surf affecting south facing shores today. A High Surf Advisory remains in effect through Tuesday afternoon, during which time the swell is expected to hold and keep surf at lower-end advisory levels. This swell will then slowly fade during the middle of the week. A new long-period south swell arrives Tuesday night, builds on Wednesday, and peaks on Thursday, keeping surf elevated above the summertime average through the weekend.
Surf along east-facing shores will remain slightly below seasonal levels today through Wednesday as the trades ease upstream of the islands. East shore surf should then build back close to seasonal levels late this week and through the weekend as stronger trades return over and upstream on the islands. Additionally, swell generated by former tropical cyclone Elida may give a slight boost to east shore surf during the middle of the week. This weekend, larger surf for east shores generated by Tropical Storm Fausto is possible.
Surf along north-facing shores will remain at flat to tiny levels through the weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Tuesday for all south, facing shores.

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Data Courtesy of NOAA.gov