Photo Credit: Braden Jarvis

West Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs 86 to 92 near the shore to around 78 above 3000 feet. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 71 near the shore to around 61 above 3000 feet. Light winds.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 75 above 3000 feet. Light winds. Chance of rain 40 percent.

South Kaua’i

Today: Sunny. Highs 86 to 92. Northeast winds 10 to 15 mph.

Tonight: Partly cloudy. Lows around 72. Light winds.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84. Light winds. Chance of rain 40 percent.

Kaua’i Mountains

Today: Sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 84 in the valleys to around 69 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 64 to 69 in the valleys to around 59 above 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 73 to 79 in the valleys to around 68 above 4000 feet. Light winds. Chance of rain 50 percent.

North Kaua’i

Today: Sunny. Highs 79 to 88. Southeast winds up to 15 mph shifting to the northeast in the afternoon.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 65 to 73. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 75 to 84. Light winds. Chance of rain 40 percent.

East Kaua’i

Today: Sunny. Highs 78 to 89. Northeast winds up to 10 mph.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 64 to 76. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 75 to 85. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate trade winds will ease today, and land and sea breezes will overpower the weaker trade winds this weekend into early next week. The air mass will be somewhat dry, with mainly isolated showers favoring windward areas at night and interior sections each afternoon. A shallow band of moisture may increase showers on Kauai Saturday night and spread to Oahu on Sunday.

Discussion

Moderate trade winds are easing as stable and somewhat dry conditions remain in place. Trades are on the decline as a surface ridge about 600 miles north of Kauai is weakened by an advancing North Pacific front. A ridge aloft is maintaining stable conditions with a strong inversion between around 5,000 to 6,000 ft, and a narrow band of shallow moisture is producing scattered light showers over windward slopes of Maui County, while mostly dry conditions prevail elsewhere. The declining trade winds will continue to focus modest rainfall over Maui County today, and afternoon sea breezes will drive higher shower chances over leeward terrain on those islands. Aside from a few showers over leeward Big Island this afternoon, showers will be minimal elsewhere.
Trade winds will decline this weekend as the surface ridge to the north is weakened and pushed toward the state. Overnight land breezes and daytimes sea breezes will become more prevalent, resulting in a hybrid trade wind/convection pattern. Modest rainfall will favor windward slopes at night, and sea breezes will drive afternoon clouds and a few showers over interior terrain. A shallow band of moisture moving down from the north will bring higher shower chances to Kauai Saturday night and possibly to Oahu Sunday.
The surface ridge will move southward near Kauai late Monday and Tuesday, further disrupting the trade wind flow. A purely land and sea breeze pattern is expected, though shower chances will remain low. Trade winds will likely return during the middle of next week as surface high pressure rebuilds to the north.

Aviation

Weak trade wind flow will develop today allowing for local land and sea breezes. Expect localized clouds and showers to develop over the interior during the afternoon, then dissipate shortly after sunset. VFR will prevail, with brief MVFR possible under passing showers.
No AIRMETs are currently in effect, nor expected through Friday.

Marine

A surface ridge located about 500 nm north of Honolulu early this morning continues to produce light to moderate trade winds across the main Hawaiian Islands. A front will move down over the north central Pacific to the north of the ridge. This will push the ridge south closer to the state through early Saturday, which will cause the trade winds to become light to locally moderate tonight. The ridge will weaken as it moves down into the vicinity of the islands this weekend. This will likely cause the background flow to become light and variable across the western islands, while weak trade winds may linger across the eastern end of the island chain from Saturday into early next week. Note that a large northwest swell arriving Tuesday may result in Small Craft Advisory conditions due to combined seas of 10 feet or greater developing over portions of the coastal waters.
The current medium-period northwest (310-320 degrees) swell will produce moderate surf along most north and west facing shores through early Saturday. A new, moderate, long-period north- northwest (320-330 degrees) swell arriving Saturday will likely maintain moderate surf along exposed north and west facing shores into early next week. The large, long-period northwest (320 degrees) swell mentioned above may cause surf to reach the High Surf Warning criteria along most north and west facing shores of the smaller islands starting late Tuesday. Surf may also be near the High Surf Advisory threshold along portions of the west facing shores of the Big Island starting Tuesday night.
Small surf will persist along south facing shores due to a series of medium- to long-period south to south-southwest (190-200 degrees) swells moving through the area. A long-period south- southwest (200-210 degrees) swell will likely arrive Monday, resulting in above seasonal average surf along south facing shores early next week. Elsewhere, the weakening trade winds will result in diminishing surf along east facing shores during the next couple of days, with nearly flat conditions possible along most east facing shores by late this weekend.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov