Photo Credit: Brendan Stephen

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 71 to 76 near the shore to around 62 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 86. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 69 to 75. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Saturday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 85. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 67 in the valleys to around 57 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny with scattered showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 75. East winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs 78 to 87. East winds 10 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 79 to 87. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs 78 to 86. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

High pressure north of the islands will keep breezy trade winds blowing through the weekend. Rather dry trade wind weather will prevail with light showers favoring windward and mauka areas mainly during nights and mornings and a stray shower reaching leeward areas from time to time. The remnants of former tropical cyclone Adrian could ease the trades and increase shower coverage and intensity Monday and Tuesday. Moderate to locally breezy trades and drier trade wind weather should return late Wednesday through the end of the work week.

Discussion

Currently at the surface, a 1029 mb high is centered around 1500 miles north-northeast of Honolulu, and is driving moderate trade winds in unsheltered portions of the island chain early this morning. Infrared satellite imagery shows variable cloud cover across the state, with coverage generally the highest over windward areas. Radar imagery shows scattered showers moving into windward areas, with some of these showers spilling over into leeward communities. Main short term focus revolves around trade wind trends and rain chances during the next several days.
High pressure north of the islands will settle southward and closer to the islands during the next few days, strengthening the pressure gradient across the state. Moderate trades early this morning will strengthen to breezy levels across the entire area this afternoon into Sunday. The ridge north of the islands will weaken late Sunday through early next week as the remnants of former tropical cyclone Adrian approach and move through the area. This should ease trades back to moderate levels across the islands. Once the remnants of Adrian shift west of the state late next week, we should see a return to moderate to locally breezy trade winds.
As for the remaining weather details, strong mid-level ridging and below normal precipitable water values should keep shower activity light and focused primarily over windward and mauka areas through the weekend. Showers will be most prevalent during nights and mornings, with a stray shower reaching leeward areas from time to time. We could see an increase in trade wind shower coverage and intensity as the remnant moisture from former tropical cyclone Adrian moves through Monday and Tuesday, with more of these showers reaching leeward communities as well. Things appear to dry out pretty good following the passage of the remnants of Adrian, with drier than normal trade wind weather expected late Wednesday through the end of the work week.

Aviation

Moderate to locally breezy trade winds will continue through twenty-four hours and beyond. AIRMET Tango for moderate low level turbulence over and downstream of higher terrain remains in effect. Trade wind showers will favor windward slopes and coasts and be most active in the late night and morning hours. Convective showers are expected over the lower slopes of leeward Big Island in the afternoon and early evening hours. Brief MVFR ceilings and visibilities are likely in showers, but VFR conditions will predominate all areas.

Marine

A high pressure ridge will remain far north of Hawaii, producing moderate to locally strong trade winds over and upstream of the islands lasting into early next week. The Small Craft Advisory (SCA) was extended in time through Saturday night and expanded in coverage to include windier waters and channels across the state. This SCA will likely continue into the first half of next week.
Surf along all shores will remain small today. Two small medium to long period swells arriving from the south-southwest (190-210) and south-southeast (150) will build surf heights along south facing shores this weekend, with surf heights peaking on Sunday. Western shores will also benefit from a wrap of the slightly bigger south-southwest swell. Small south swell pulses will continue to boost surf heights into the middle of next week.
North facing shores will also see a boost in surf from a small medium period (330-350 degree) north-northwest swell arriving tonight. This swell energy will peak on Saturday and then diminish through the first half of next week. East facing shores will continue to see small choppy surf into the middle of next week from a moderate to strong trade wind fetch.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Sunday for Kauai Northwest Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov