West Kaua’i

Tonight: Partly cloudy with a 20 percent chance of showers. Lows 72 to 77 near the shore to around 63 above 3000 feet. East winds 10 to 15 mph.

Tuesday: Mostly sunny. A 20 percent chance of showers in the morning. Highs 87 to 93 near the shore to around 79 above 3000 feet. East winds 10 to 15 mph.

Tuesday Night: Partly cloudy. Lows 71 to 76 near the shore to around 63 above 3000 feet. East winds 10 to 15 mph.

South Kaua’i

Tonight: Mostly cloudy with showers likely. Lows around 75. East winds around 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with chance of showers in the morning, then mostly sunny with slight chance of showers in the afternoon. Highs 84 to 91. East winds around 15 mph. Chance of rain 50 percent.

Tuesday Night: Partly cloudy with slight chance of showers in the evening, then mostly cloudy with chance of showers after midnight. Lows around 74. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 67 to 72 in the valleys to around 61 above 4000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Tuesday: Partly sunny with a 50 percent chance of showers. Highs 77 to 86 in the valleys to around 69 above 4000 feet. East winds 10 to 15 mph.

Tuesday Night: Breezy. Mostly cloudy with a 50 percent chance of showers. Lows 65 to 71 in the valleys to around 60 above 4000 feet. East winds 10 to 20 mph.

North Kaua’i

Tonight: Mostly cloudy with a 50 percent chance of showers. Lows 67 to 76. East winds 10 to 15 mph.

Tuesday: Mostly sunny. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs 79 to 90. East winds 10 to 15 mph. Chance of rain 40 percent.

Tuesday Night: Partly cloudy in the evening then becoming mostly cloudy. A 20 percent chance of showers. Lows 66 to 75. East winds 10 to 15 mph.

East Kaua’i

Tonight: Mostly cloudy. Chance of showers in the evening, then showers likely after midnight. Lows 67 to 79. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with chance of showers in the morning, then mostly sunny with slight chance of showers in the afternoon. Highs 75 to 89. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Slight chance of showers in the evening, then chance of showers after midnight. Lows 66 to 78. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will continue through the week as high pressure builds over the region behind a departing trough. Scattered clouds and showers continue over the western half of the state tonight, with passing windward and mauka showers elsewhere. Another plume of moisture looks to bring a slight increase in windward and mauka showers on Wednesday. Otherwise, expect a gradual drying trend through the week, with typical summertime trade wind weather (stable and mostly dry conditions).

Discussion

Radar and satellite imagery continue to show a weak surface trough associated with the remnants of former Tropical Cyclone Ivo moving across the western half of the state this afternoon. Will continue to see scattered clouds and showers through tonight over parts of the western islands, with isolated windward and mauka showers elsewhere.
High pressure will continue to build over the Hawaiian Island tonight as the trough departs to the west, with moderate to locally breezy trade winds continuing through the week. Will continue to see drier air filter into the region from the east late tonight, with less clouds and showers expected on Tuesday. Guidance continues to show another plume of moisture moving across the islands on Wednesday which may bring a slight increase in clouds and showers over windward and mauka areas. Otherwise, the gradual drying trend will continue through the week with typical summertime trade wind weather expected under dry and stable conditions. With dry and breezy conditions expected later this week we will see elevated fire weather concerns, especially across leeward areas. For more details see the Fire Weather section below.

Aviation

Moderate to locally breezy trades are expected through the forecast period. Periods of low cigs and SHRA are possible over windward and mauka areas overnight prompting brief MVFR conds. Otherwise, VFR conds will prevail.
No AIRMETs are in effect at this time. AIRMET Sierra may be needed overnight due to potential increases in low clouds and SHRA along windward and mauka regions. AIRMET Tango may be issued if low level wind speeds increase tomorrow.

Marine

A ridge of high pressure far north of the state will help maintain fresh to locally strong trade winds throughout the week. A Small Craft Advisory (SCA) for the typical windy waters around Maui and the Big Island remains in effect and will likely persist throughout the week.
A series of small, medium period south (170-190 degree) swells are expected throughout the week with surf holding near the summer average. Surf heights should decrease Sunday into early next week as these swells fade. Choppy conditions will continue for east- facing shores through the forecast period due to the persistent fresh trades. Meanwhile, expect surf to be flat to tiny along north facing shores.
Peak monthly high tides combined with water levels that are running higher than predicted will lead to minor flooding along the shoreline and in low-lying coastal areas starting as early as Tuesday afternoon and likely peaking Wednesday and Thursday afternoons. Coastal flooding is possible around the daily peak tide, which will be during the afternoon hours. A Coastal Flood Statement has been issued for minor coastal flooding this week.

Fire weather

Moderate to locally breezy trade winds expected this week as high pressure builds over the state behind a departing trough. Borderline fire weather conditions possible on Tuesday as drier air starts to filter into the region. Another plume of moisture may bring a slight increase in humidity and showers on Wednesday. Elevated fire weather conditions possible beyond Wednesday as stable and drier conditions develop and the trade wind inversion lowers to around 5000-6000 feet. Breezy trade winds and afternoon relative humidity in the upper 40s to lower 50s may require Fire Weather headlines to be issued in the coming days. Stay tuned for details.

HFO Watches/Warnings/Advisories

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

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