Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 87 to 92 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Lows around 73 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 89 near the shore to around 78 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 82 to 90. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Partly cloudy with isolated showers. Lows around 74. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 82 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 87 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 64 to 72 in the valleys to around 59 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 76 to 87 in the valleys to around 67 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 90. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 74. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 89. East winds up to 15 mph. Chance of rain 30 percent.

East Kaua’i

Today: Mostly cloudy with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 77. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 75 to 87. East winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail today and then decrease slightly to moderate levels from Sunday into next week. Showers will favor windward and mountain areas in the overnight to early morning hours, especially through this morning as a weak disturbance passes over the state. A slightly drier trade wind pattern is expected later this afternoon through Monday, followed by subtle wetter trends from Monday night into Wednesday.

Discussion

Local radar imagery this morning shows scattered showers moving through the windward and mountain slopes of each island on the easterly trade winds. This shower activity is enhanced by a weak disturbance aloft and these wet trends will continue into the early morning hours.
In the big picture, the high pressure ridge north of the Hawaiian Islands will begin to weaken slightly starting on Sunday as a cold frontal system passing through the Central Pacific basin. Trade wind speeds will decrease to moderate levels across the state through much of next week.
In the rainfall forecast, we continue to see subtle changes in the day to day shower activity over each island. A weak disturbance shown clearly on the 700 mb streamlines will continue to track westward over the islands, keeping a slight increase in shower activity that favors the windward and mountain areas through the early morning hours. Brief drying trends will develop from Saturday afternoon through Monday. Additional bands of clouds, likely the remnants of an old East Pacific frontal boundary, will then drift into the state on the trade winds from Monday night into Wednesday; with increasing shower trends favoring the overnight through early morning hours.&&
.AVIATION… Moderate trades through the weekend. Windward and mauka SHRA can be expected with some spillover to leeward locations. Brief MVFR conds are possible in any SHRA, but VFR should generally prevail.
AIRMET Sierra is in effect for mtn obsc for windward portions of all islands. Conds expected to improve with sunrise.

Marine

Gentle to fresh trade winds will prevail through at least early next week as weak surface high pressure holds north of the island chain. Winds are reaching Small Craft Advisory (SCA) levels around the Big Island and Maui and SCA conditions will linger through early Sunday morning. Wind speeds will decrease slightly below SCA levels from sunrise on Sunday morning into much of next week.
A small, medium period north-northwest swell will build in today and produce north shore surf near September average heights starting later tonight through Sunday morning. A small, medium period northwest will arrive on Tuesday, then shift directions out of the north on Wednesday and then hold into Friday.
The current mix of small, long period south-southwest swell and short period southwest swell will decline today. Another pulse of inconsistent southwest swell originating from the Tasman Sea will push south shore surf to near seasonal average late Sunday and Monday. A more consistent south-southwest swell is expected on Tuesday and Wednesday.
East shore surf will remain well below normal through the week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov