Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 86 to 91 near the shore to around 76 above 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly clear with isolated showers. Lows around 71 near the shore to around 61 above 3000 feet. Northeast winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Sunday: Sunny and breezy. Isolated showers in the afternoon. Highs around 88 near the shore to around 77 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Gusts up to 40 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 88. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

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

Sunday: Breezy. Mostly sunny with isolated showers. Highs 81 to 88. Northeast winds 15 to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 73 to 84 in the valleys to around 66 above 4000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 20 mph with gusts to 45 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 73 to 84 in the valleys to around 66 above 4000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Partly sunny with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 76 to 89. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 64 to 74. East winds 10 to 20 mph. Chance of rain 40 percent.

Sunday: Breezy. Mostly sunny with scattered showers. Highs 76 to 89. East winds 10 to 20 mph. Chance of rain 40 percent.

East Kaua’i

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 73 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.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 73 to 85. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

High pressure far north of the islands will maintain breezy and gusty trade winds through early next week. Somewhat wet conditions will give way to a more typical pattern of passing windward showers later today and Sunday.

Discussion

Breezy, gusty, and somewhat wet conditions are in place early this morning. A 1030 mb surface high sitting about 900 miles north of the state is driving the breezy trade winds, and a mid- level ridge is maintaining stability. This will keep the gusty trade wind flow just below Wind Advisory strength. A band of shallow moisture moving along the trade wind flow has dropped more than a half of an inch of rainfall across many windward areas in the past 12 hours, though the onset of showers on windward Big Island has been a bit delayed. Expect the wet conditions to linger into the morning from Kauai to Maui, where periodic showers will blow over leeward areas, followed by drier weather in the afternoon. Windward Big Island will remain wet through the day, and likely into the evening, while showers develop along the Kona slopes in the afternoon.
The strong surface high will remain anchored north of the state Sunday through at least Monday, maintaining the breezy and gusty trade winds near current strength. A stable and rather typical summertime rainfall pattern will prevail, leading to modest rainfall over windward slopes. Aside from afternoon showers on the Kona slopes of the Big Island, leeward areas will be mostly dry.
Trades will decline to moderate strength around Tuesday or Wednesday as the high to the north finally weakens. Some increase in showers will be possible as a disturbance aloft approaches late next week.

Aviation

Breezy to locally windy trades will continue across the region through Monday. A band of clouds drifting in on the trade winds will bring showers with periods of MVFR conditions to windward mountain slopes of each island at least through the early morning hours. Decreasing shower trends are forecast to start after 10 AM HST.
AIRMET Sierra remains in effect for tempo mountain obscuration for north and east slopes of Kauai, Oahu, Molokai, and Maui. Including the entire island of Lanai and eastern slopes of the Big Island. This AIRMET will diminish in coverage around noon HST.
AIRMET Tango remains in effect for mod low level turb over and downwind of island terrain due to the breezy trade winds. This AIRMET will likely continue through Monday.

Marine

Strong easterly trades will continue into early next week, supporting the Small Craft Advisory in place for all waters. Seas will remain rough, with heights hovering around and just under the advisory level over exposed waters. Guidance shows a slight downward trend Tuesday through midweek due to the surface ridge potentially weakening to the north.
Surf along east-facing shores will remain rough through early next week due to the aforementioned strong trades locally and upstream of the state. A gradual downward trend is possible Tuesday through midweek.
Surf along south-facing shores will continue to trend up this weekend as a small south swell moves through. This should be short-lived, with a downward trend expected early next week. Despite a blocking high that has set up over our typical swell window near/southeast of New Zealand, a gale has formed to its northeast with the head of the fetch aimed at the islands within the 180 to 200-degree directional band. Given the shorter travel distance, surf associated with this source should trend up late next week.
Surf along north-facing shores could trend up above flat levels early next week due to a small, medium-period northwest swell from a marginal gale lifting northeastward near the Aleutians. On its heels is a compact storm-force low, currently several hundred nautical miles east of Japan, that could send a similar northwest swell through the area late next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for all Hawaiian waters.

Data Courtesy of NOAA.gov