Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Highs around 88 near the shore to around 76 above 3000 feet. Northeast winds up to 15 mph shifting to the west in the afternoon.

Tonight: Partly cloudy. Lows 69 to 74 near the shore to around 60 above 3000 feet. Northeast winds up to 10 mph.

Thursday: Mostly sunny. Highs around 88 near the shore to around 76 above 3000 feet. Northeast winds up to 15 mph shifting to the northwest in the afternoon.

South Kaua’i

Today: Partly sunny. Breezy. Isolated showers in the morning. Highs around 85. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 67 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the morning. Highs around 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 60 to 65 in the valleys to around 55 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 78 to 87. Southeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 63 to 73. Southeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny with isolated showers. Highs 78 to 87. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with isolated showers. Highs 78 to 86. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 61 to 75. Northeast winds up to 10 mph. Chance of rain 20 percent.

Thursday: Partly sunny with isolated showers. Highs 78 to 86. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trade winds will continue through tonight, then ease from Thursday into the weekend as the surface ridge weakens to the north. A dry airmass will limit rainfall chances through Thursday, with the best chances remaining over windward and mauka locations during the overnight through the morning periods. A slight increase in moisture associated with a disturbance aloft could lead to increased shower coverage Thursday night through the upcoming weekend.

Discussion

Short-term guidance shows dry trade wind conditions prevailing today as a deep layer ridge remains in place. The upper air soundings reflect this pattern, showing strong subsidence inversions around 5,000 to 6,000 ft with limited moisture available. Peak 24-Hr rainfall totals from the gauges around the state are mostly under a quarter of an inch for windward areas and up to 0.35 inches for leeward sections of the Big Island. No accumulations were recorded over leeward areas of the smaller islands, where drought conditions continue to worsen. Any brief showers that form will favor the typical windward and mauka locations, primarily during the overnight and early morning periods.
The mid- to upper-level ridge will begin to weaken during the second half of the week and into the upcoming weekend as a weak upper low settles north of Kauai and a mid-level trough approaches from the east. The surface ridge will respond by weakening, resulting in the trades easing to light to moderate levels. Upper-level height falls combined with increasing low- level moisture could lead to better windward shower coverage, especially over the weekend as the mid-level trough moves through from east to west. Additionally, a few showers could form over dry leeward areas during the afternoon where localized sea breezes develop.

Aviation

Moderate to locally breezy trade winds will continue. Mostly VFR conditions will prevail with brief periods of MVFR possible in the overnight to early morning hours along windward and mountain slopes.
AIRMET Tango remains in effect for moderate turbulence over and immediately south through west of all island mountains due to the breezy trade winds.

Marine

A surface ridge north of the state will support moderate to locally strong trade winds through tonight. The ridge should weaken somewhat thereafter, with trade wind speeds slowly diminishing in response. A Small Craft Advisory (SCA) remains in effect for the typical windy waters around Maui and the Big Island through tonight. As the trades ease Thursday, seas will also subside, and the SCA will go away.
The current short-period south swell will fade today. A small, longer period south southwest swell should fill in on Friday and peak over the weekend with surf heights near or slightly above the summer average.
The current small, short-period north-northwest swell will continue to fade out. A few small pulses from the northwest and north northwest are expected tonight into Thursday and will likely keep the surf from going completely flat along north facing shores through the weekend. Short-period wind waves generated by the trade winds will gradually decline over the next several days as the trades ease. Small, long-period E swells from increased E Pacific tropical cyclone activity may arrive from over the next few days, especially over the weekend, leading to a subtle increase in surf heights.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov