Photo Credit: Brendan Stephen

West Kaua’i

Today: Sunny and breezy. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 20 mph.

Tonight: Mostly clear. Lows around 70 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph.

Saturday: Mostly sunny. Highs around 89 near the shore to around 77 above 3000 feet. North winds up to 15 mph shifting to the southwest in the afternoon.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 82 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 72. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 83 to 90. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 85 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 64 to 69 in the valleys to around 58 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 75 to 84 in the valleys to around 68 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 76 to 89. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 64 to 73. Southeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 78 to 89. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 75. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 76 to 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds and a stable pattern of mainly light windward showers will prevail through Monday. Increasing trade winds and slightly wetter conditions are possible around the middle of next week, with breezy trades continuing into the weekend.

Discussion

A broad surface ridge far north of the islands continues to drive moderate trade wind flow, while a deep mid- to upper-level ridge parked overhead maintains very stable conditions with inversions at Lihue and Hilo based at 5000 and 6500 ft,respectively. After the passage of a short-lived low-level dry slot overnight, another batch of moisture is moving in with windward showers on the increase early this morning, especially over and upstream of Oahu. However, the stable airmass will keep rainfall amounts on the modest side.
This stable, summertime trade wind weather pattern will dominate into early next week with only minor fluctuations in moisture levels and wind speeds. The surface ridge north of the state will weaken slightly tonight and Friday, leading to a small decline in winds through the weekend. The ridge aloft will remain anchored over the region, keeping stable conditions in place and a temperature inversion fluctuating between 5000 to 8000 feet. Precipitable water will be generally below the seasonal average, so rainfall will remain modest and windward-focused. Aside from a few afternoon showers on the Kona slopes of the Big Island, leeward areas will be rather dry.
No big changes to the overall pattern are noted through the second half of next week. Trades look to increase to breezy levels around Monday night or Tuesday as the ridge to the north strengthens. Stable conditions will persist, but the GFS and ECMWF are hinting at a possible modest increase in windward showers around Tuesday.

Aviation

Moderate to locally breezy trades will continue through the next couple of days. SHRA and brief MVFR conds will generally be confined to windward and mauka locations, but a few SHRA may make it over to leeward areas. Otherwise VFR conds should prevail.
AIRMET Sierra is in effect for mtn obsc for Oahu, Molokai and Maui as several bands of SHRA move into the islands. Conds should improve later this morning.

Marine

The pressure gradient over the local waters will remain weak the next several days in response to lower pressure over the eastern Pacific. High pressure will better establish itself northeast of the state, re-tightening the upstream pressure gradient, and this will restrengthen winds by the middle of next week. Trades holding at their current moderate speeds will maintain 4 to 6 foot sea heights through early next week.
No significant swells are expected from any direction for the remainder of the week. A series of small, medium period south southeast swells will produce fun south-facing shore waist to chest high surf. A recent small fetch of strong northeast winds off the U.S. Pacific Northwest coast has generated a small, medium period northeast swell. This swell is scheduled to arrive Sunday and reinforce the resident short period wind wave swell. Some of this northeast swell will wrap into more northern exposures.
Higher than normal water levels, in tandem with new moon tides, has increased water levels around Big Island and Maui County. Peak water levels of between 3.0 to 3.5 feet above Mean Lower Low Water (MLLW) are expected during periods of high tides. This will continue to create minor coastal flooding issues through the weekend. A Coastal Flood Statement highlighting this flooding threat remains in effect for both Big Island and Maui County.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov