Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 90 near the shore to around 79 above 3000 feet. Northeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 73 to 78 near the shore to around 64 above 3000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs around 90 near the shore to around 78 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs around 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 71 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 87. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly sunny with scattered showers. Highs 78 to 85 in the valleys to around 69 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with numerous showers after midnight. Lows 64 to 69 in the valleys to around 59 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 77 to 84 in the valleys to around 68 above 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 81 to 90. East winds up to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with scattered showers. Lows 67 to 77. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Saturday: Mostly sunny with scattered showers. Highs 80 to 89. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 81 to 89. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 65 to 78. Northeast winds around 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 80 to 88. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Rather dry trade wind weather will prevail through the weekend, with brief showers favoring mainly windward and mauka areas. The trades will increase beginning late Sunday and become breezy Monday through Tuesday as the remnant trough of former Tropical Cyclone Fernanda passes by to the south of the state. Deep tropical moisture associated with Fernanda will move into the eastern islands Sunday night, spread to the rest of the state Monday and Monday night, with drier conditions building in from east to west across the island chain on Tuesday. Some wet weather and locally heavy rainfall can be expected across windward areas, with leeward portions of the islands seeing some rain as well. More typical trade wind weather and continued breezy conditions are expected Tuesday night through late next week.

Discussion

Currently at the surface, a 1033 mb high is centered around 1850 miles north of Honolulu, while the post-tropical remnant low of Greg is located around 600 miles southwest of South Point and the post-tropical remnant low of Fernanda is located around 1200 miles east of Hilo. The gradient locally continues to produce moderate trade winds in unsheltered portions of the island chain early this morning. Infrared satellite imagery shows mostly clear to partly cloudy conditions across the smaller islands, with mostly cloudy skies over much of the Big Island. Radar imagery shows a few light showers moving into windward areas of the smaller islands, with scattered showers over windward Big Island. Mostly dry conditions prevail in leeward locales. Main forecast focus revolves around the potential for some heavier rainfall associated with the remnants of Fernanda early next week.
A weak trough of low pressure passing westward far to the north of the state will ease the trades into the moderate range today through the weekend, with a slight increase in trades expected late Sunday as the remnant trough of former Tropical Cyclone Fernanda approaches from the east. The trades will strengthen to breezy levels Monday and Tuesday as the remnant trough of Fernanda slides by to the south of the state, then hold at breezy levels through late next week as strong high pressure builds to the distant northeast.
As for the remaining weather details, very little change to the overall weather forecast is expected during the next few days, with rather dry trade wind weather prevailing. There will be some light showers affecting windward and mauka areas, particularly at night and during the early morning hours each day, with mainly dry conditions persisting in leeward locales.
The persistent dry pattern we've been experiencing for quite some time appears to come to an abrupt halt beginning Sunday night over the eastern end of the state as deep tropical moisture associated with the remnant trough of Fernanda moves in. The deep tropical moisture will spread westward across the state Monday and Monday night. Periods of wet weather with locally heavy rainfall can be expected in windward areas as the remnants of Fernanda move through, and even leeward communities will see some rainfall, although the rain shadowing effects of the terrain should limit rainfall totals here. Drier conditions are forecast to move in from east to west across the island chain on Tuesday, with more typical trade wind weather featuring brief windward and mauka showers and the occasional leeward spillover then prevailing through late next week.

Aviation

Moderate to locally breezy trade winds will weaken slightly today. A band of moisture moving into windward portions of the Big Island will continue to bring scattered low clouds and light showers this morning resulting in occasional MVFR cigs and vsbys. Otherwise, expect mainly VFR conditions across the state with isolated low clouds and showers across windward and mauka areas.
AIRMET Sierra for mountain obscurations may be needed later this morning if low clouds continue to persist over windward coast and slopes of the Big Island. Otherwise, no other AIRMETs are expected.

Marine

Surface high pressure far north of the state will provide moderate to locally fresh levels today through Sunday as Post Tropical Cyclone Greg continues its trek westward. The Small Craft Advisory has been cancelled for typical windy waters around Maui county and the Big Island. Trades become locally strong once again Sunday night through Wednesday as the remnants of Tropical Storm Fernanda pass just south of the islands.
Small northwest swell will keep north shore surf up above typical summertime flat levels today as it slowly fades this weekend. South shore surf will remain small through Saturday with a slight reinforcement Sunday into early next week.
East shore surf will remain below normal levels through the weekend due to lack of strong trades upstream of the island chain. Long period east swell generated from Hurricane Hillary off Baja California could impact east facing shores beginning Monday night or Tuesday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov