Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 77 near the shore to around 65 above 3000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 63 near the shore to around 52 above 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs around 79 near the shore to around 67 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

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

Tonight: Partly cloudy with isolated showers. Lows 59 to 64. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 78. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 64 to 72 in the valleys to around 59 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 52 to 57 in the valleys to around 46 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 66 to 74 in the valleys to around 61 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 69 to 76. East winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 55 to 64. East winds up to 15 mph. Chance of rain 40 percent.

Sunday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 71 to 78. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 69 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 53 to 65. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Sunday: Partly sunny with isolated showers. Highs 71 to 78. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moisture associated with a dissipating stationary front just south of the state will continue to bring showery weather to windward Big Island today through early Sunday, while conditions continue to improve with fewer showers and more sunshine expected over the smaller islands. Trade wind showers may increase again toward the middle of next week as a strong trough aloft develops over the islands, but the lack of deep moisture should limit shower coverage somewhat.

Discussion

Currently at the surface, a nearly stationary front has slipped just south of the Big Island, while a 1020 mb high is centered around 450 miles north-northwest of Kauai. Moderate north to northeast winds persist across most of the island chain early this morning. Infrared satellite imagery shows mostly cloudy to overcast conditions across Maui and the Big Island, with partly to mostly cloudy skies over the remainder of the state. Radar imagery and rain gage observations indicate light showers continue to filter into windward sections of the smaller islands, while more persistent showers continue to affect north and northeast facing slopes of the Big Island. Main short term focus revolves around rain chances.
The nearly stationary front will gradually dissipate just south of the Big Island today. Meanwhile, weak high pressure will slide northeast, well to the north of the islands. Moderate northeast winds will prevail today. Ridging will strengthen north of the islands Sunday and Sunday night, boosting the trades back to moderate and locally breezy levels. A front approaching well northwest of the state appears to ease the trades back to moderate levels Monday, with the trades generally holding at moderate levels through the middle of next week. A new high building north of the islands could potentially bring a return of breezy trades Thursday and Friday.
As for the remaining weather details, lingering moisture along and north of the stationary front will allow showers to persist over windward Big Island today, while conditions gradually improve across Maui County. The showery weather may continue tonight across windward Big Island, with improving conditions expected for Sunday. Meanwhile, mostly dry weather will prevail on Oahu and Kauai with only a few light showers affecting mainly windward areas at times through the weekend. Rather dry trade wind weather is expected statewide Sunday night and Monday as mid- level ridging builds overhead. A gradual moistening of the boundary layer is then expected as troughing aloft develops over the state Monday night through late next week, bringing some more trade wind showers to the islands.

Aviation

IFR to MVFR CIGs/VSBYs will persist through a good portion of the day for N thru NE facing slopes and coasts of Maui and the Big Island due to a combination of moderate NNE winds and a band of low-level moisture lingering in the area. Conditions will gradually improve from west to east over the weekend as drier air fills in and moderate easterly trades return tonight into Sunday.
AIRMET Sierra is in effect for IFR CIGs/VSBYs over the eastern end of the state for N through NE facing slopes and coasts of Maui and the Big Island. Mountain obscuration due to clouds and showers remains in effect for N through NE facing slopes and coasts of Molokai.

Marine

A stationary front just south of the Big Island, continues to enhance showers over the southeast waters. High pressure to the north-northwest of the islands will gradually drift eastward, resulting in moderate north-northeast winds today and tonight. Winds are expected to be locally strong the Alenuihaha Channel and Leeward Big Island waters today however, where a Small Craft Advisory is now in effect through 6 AM Sunday. Trade winds get a boost up to moderate and fresh levels for Sunday, with some of the typically windy waters around Maui in the Big Island flirting with SCA levels. An approaching front should drop the trades back to moderate levels Monday through Wednesday, with strong trades potentially returning Thursday and next Friday as a new high builds north of the islands.
A large long-period, northwest swell will continue to gradually lower through the weekend. A High Surf Advisory remains in effect for most north and west facing shores of the smaller islands and west facing shores of the Big Island through 6 PM this evening. A reinforcing northwest swell should arrive late tonight, keeping moderate-sized surf along north and west facing shores through early next week. Another long-period northwest swell reinforcement may push surf up to advisory levels Wednesday, before declining through the end of the work week.
South shore surf will remain tiny today, with a slight boost expected Sunday through Tuesday as a new long-period south swell moves through. Surf looks to return back to tiny levels Wednesday through late next week. East shore surf will also remain small through early next week, with a slight increase possible during the middle to latter part of the upcoming work week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 AM HST Sunday for Alenuihaha Channel, Big Island Leeward Waters.

Data Courtesy of NOAA.gov