Photo Credit: Jason Weingardt

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: Mostly clear with isolated showers. Lows around 70 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Breezy. Highs around 87 near the shore to around 76 above 3000 feet. East winds up to 20 mph.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 82 to 88. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows around 71. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 81 to 87. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 75 to 83 in the valleys to around 68 above 4000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 68 in the valleys to around 58 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 74 to 83 in the valleys to around 67 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 89. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 63 to 73. East winds 10 to 15 mph. Chance of rain 40 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 88. East winds 10 to 20 mph. Chance of rain 30 percent.

East Kaua’i

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 85. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

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

Thursday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 73 to 84. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Broad high pressure north of the state will drive moderate to breezy trade winds for the next few days with a slight decrease expected by the weekend. Stable conditions will focus showers over windward areas, and leeward areas will be rather dry, though leeward Big Island will experience clouds and showers each afternoon and evening.

Discussion

High pressure remains situated to the north of Hawaii driving stable trade wind weather expected over the next week. Current infrared satellite and radar show scattered showers tracking over the islands from the trade wind flow. 12Z soundings show a weaker and more elevated inversion than previous ones with inversion height between 6 to 7 kft. Precipitable water values skipped a bit higher to around 1.5 to 1.6 inches. Persistent mid-level ridging will maintain stability, so rainfall totals will not be significant. Thus, expect a more typical pattern of windward rainfall to persist through midday, and possibly filling in again tonight into Thursday. Leeward areas should stay mostly dry, but upper leeward slopes will see occasional passing showers. Leeward Big Island will continue to see typical afternoon cloud build ups and showers, then clearing at night, into next week.
A slight decrease in trade winds is expected heading into the weekend. The ridge to the north will be pushed southward on Friday and Saturday, then meander about 400 to 600 miles north of Kauai into early next week. With the ridge a little closer to the islands, we should experience a slight decrease in the trades. A typical distribution of trade wind showers over mainly windward slopes will prevail. A typical summertime upper low will move over the islands over the weekend and may provide a little bit of enhancement to the incoming clouds and showers.

Aviation

Moderate to breezy ENE trade winds will deliver clumps of showery low clouds that will primarily focus over windward coasts and slopes, producing periods of relatively short-lived MVFR VIS/CIG in SHRA. Otherwise, VFR conditions will prevail.

Marine

Fresh to strong easterly trades will continue through the weekend, as the surface ridge remains north of the area. This supports the Small Craft Advisory continuing for the windier channels and waters around Maui County and the Big Island each day.
Surf along south facing shores will slowly ease through Thursday as the current south-southwest swell fades. Expect a mix of this the fading south-southwest swell and a small, medium-period southeast swell through Thursday. A fresh, long-period south swell is expected to arrive Thursday night into Friday, then peak late Friday into Saturday. This swell will hold through early next week as it slowly fades.
Surf along north-facing shores will remain up above the summertime average (flat) through a good portion of the week as small, short-period north to north-northwest swells move through.
Surf along east-facing shores will remain small and choppy over the next several days due to limited trade wind fetch upstream of the islands.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov