Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 91 near the shore to around 79 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 73 near the shore to around 63 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 91 near the shore to around 78 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 82 to 90. Northeast winds around 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 74. Northeast winds around 15 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy with showers likely in the morning, then sunny with scattered showers in the afternoon. Highs 82 to 90. East winds around 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 88 in the valleys to around 67 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then occasional showers after midnight. Lows 65 to 72 in the valleys to around 60 above 4000 feet. East winds 15 to 20 mph. Chance of rain 90 percent.

Sunday: Breezy. Mostly cloudy with occasional showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 75 to 87 in the valleys to around 67 above 4000 feet. East winds 15 to 20 mph. Chance of rain 90 percent.

North Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 91. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny in the morning then becoming sunny. Scattered showers. Highs 77 to 91. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs 75 to 87. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 66 to 77. Northeast winds around 15 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs 75 to 87. East winds around 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Locally breezy trade winds will continue into next week, delivering passing showers that will favor windward areas. Deeper moisture will move over the islands Sunday night and Monday, likely bringing increased shower coverage, especially over the Big Island, where some heavy showers may develop.

Discussion

A lingering low-level trough about 700 miles NNW of the islands will move W and finally dissipate this weekend, allowing consolidating surface high pressure along 40N to drive breezy and locally gusty trade winds into next week. The returning trade wind flow has been gradually moistening the last couple of days, and radar this morning shows scattered showers moving ashore over windward areas, with a few small heavy rain cores noted. This gradual moistening is likely to continue through the weekend, leading to passing showers over windward areas occasionally bringing a few sprinkles to leeward areas through Sunday, especially night and morning.
Model guidance indicates that a sharp 700 mb trough currently about 700 miles SE of the Big Island (from 11N to 18N along ~146W) will move W and bring increased low- and mid-level moisture over the islands from Sunday night through Monday. Although low-level winds may only veer slightly to the ESE, the 700 mb flow will become southerly as the trough passes, leading to moisture extending as high as 12-15 kft, mainly over the Big Island. With PWAT expected to exceed 2″, the forecast includes mention of heavy showers over the Big Island Sunday night into Monday. While the moisture increase over the smaller islands is not expected to be as deep, an increase in windward showers is likely, with low-level dew points in the low- to mid-70s making it feel muggy statewide.
After the trough moves W of the islands Tuesday and Wednesday, a fairly typical trade wind weather pattern is expected. As we approach the end of the dry season however, we anticipate increased interruptions to the trade wind flow as the N Pacific storm track begins to get started. Though confidence is low, guidance has been trending toward a solution that would lead to decreasing and veering winds for a short period around the the end of next week, with trade winds increasing again in about 7-8 days.

Aviation

Moderate to locally breezy trades expected through the weekend. SHRA and low cigs with periods of MVFR conds should be focused over windward and mauka areas. VFR conds should prevail elsewhere.
AIRMET Sierra is in effect for mtn obsc for windward Big Island.

Marine

Moderate to locally strong trades continue into next week as broad high pressure develops over the NE Pacific. A Small Craft Advisory (SCA) remains posted for the typical windier waters of Maui County and the Big Island through Sunday night. The SCA may eventually require an extension through the first half of next week as the high remains nearly stationary.
Choppy surf along east facing shores will hold through the first half of next week due to persistent trades locally and upstream. A small, long period south- southwest swell will peak today generating small surf then hold into Sunday before declining Monday. Background southeast and south swells will then keep tiny surf along south facing shores through much of next week. North facing shore surf will remain nearly flat through much of next week. Models show a gale low developing and tracking along the Aleutian Islands early next week that may send a small northwest swell locally toward the end of next week.
Water levels at local tide gauges are running over half a foot above predicted and are expected to reach above the 1 foot Mean Higher High Water threshold this afternoon due to above normal water levels coinciding with the spring tides. This may result in nuisance coastal flooding around the peak high tide each afternoon through Monday. A Coastal Flood Statement has been issued to highlight this threat.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov