West Kaua’i

Rest Of Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 69 near the shore to around 56 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 79 to 85 near the shore to around 71 above 3000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows around 66 near the shore to around 57 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers. Lows around 67. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 77 to 84. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Sunday Night: Mostly cloudy in the evening then becoming partly cloudy. Haze. Lows around 67. Northeast winds around 10 mph.

Kaua’i Mountains

Rest Of Tonight: Partly cloudy with isolated showers. Lows 57 to 66 in the valleys to around 54 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with scattered showers. Highs 72 to 78 in the valleys to around 63 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy with isolated showers. Haze. Lows 56 to 66 in the valleys to around 54 above 4000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

North Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers. Lows 59 to 67. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 74 to 81. Southeast winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with isolated showers. Haze after midnight. Lows 60 to 68. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

East Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers. Lows 60 to 71. East winds up to 10 mph shifting to the northwest after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 71 to 82. East winds up to 10 mph. Chance of rain 30 percent.

Sunday Night: Mostly cloudy with isolated showers. Haze. Lows 60 to 70. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Mostly dry and stable conditions will persist through the weekend and into next week, with light to moderate ESE trades. Rain chances will increase from the west late next week.

Discussion

Current radar and satellite imagery show clouds with isolated showers moving into windward coasts and slopes and building over a few leeward and interior areas as diurnal heating induced sea breezes across the better wind-protected areas this afternoon. In addition, bands of cirrus can be seen sweeping across the state, courtesy of an upper level jet streak nosing south over the region. A surface ridge centered to the NE of the state will help to maintain light to moderate ESE trades through the weekend. This surface ridge combined with mid level ridging building in from the west and a dry airmass moving in from the east (with precipitable water values below an inch across most of the state) will allow dry and stable conditions to persist…with tomorrow expected to look a lot like today.
High pressure to the NE will weaken next week, allowing the local pressure gradient to relax. Winds across the western end of the state will become lighter and somewhat variable…typically displaying more of a southerly component, while the eastern end of the state will be impacted by slightly stronger easterlies. The weaker winds across the western half may allow for isolated sea breeze activity with afternoon clouds and showers forming over a few leeward and interior areas, and the stronger winds across the eastern half will yield a more typical trade wind weather regime with showers favoring windward areas overnight and leeward slopes of the Big Island each afternoon. The ESE flow for the western half of the state may also allow island plumes (downstream convergence from island terrain) to bring showers to leeward areas at times. However, even as the boundary layer moistens a bit with small pockets of moisture riding in on the lighter trades and dew points increase a tad, mid level ridging will strengthen over the area and help to suppress shower activity…so mostly dry and stable conditions should continue through midweek.
A low pressure system centered north of 40 N will drag the tail end of a front near the state sometime Friday into Saturday. While the integrity of the front this far south remains questionable, model guidance indicates that this feature may bring a band of increased moisture to the western end of the state, increasing rain chances for these areas Friday and Saturday. With this surface boundary looking rather weak along with unimpressive upper level support, not expecting widespread major impacts with this event. However, current model guidance shows precipitable water values increasing to 1.4 to 1.6 inches across the western end of the state (above the 90th percentile), indicating that periodic heavy showers may be possible.

Aviation

A ridge of high pressure just north of the state will produce stable and mostly dry conditions with light to moderate east to east-southeast low-level flow through the weekend. The light winds should give way to sea breezes during the afternoon and land breezes at night.
A strong upper level jet moving its way down toward the state will produce moderate upper level turbulence across the state through tonight and linger over the eastern end of the state on Sunday. AIRMET TANGO is in effect for moderate turbulence between FL280 and FL350.

Marine

A weak surface ridge will remain north of the Hawaiian Islands through Wednesday. Light to moderate east-southeast winds will prevail in a fairly stable weather pattern.
A long period northwest swell that is currently moving through the region should reach its peak this evening and then slightly decline overnight into tomorrow morning. A High Surf Advisory is in effect for north facing shores of Niihau, Kauai, Oahu, Molokai and Maui until 6 AM HST.
A larger northwest swell will build into the islands from Monday evening into Wednesday, with surf heights easily exceeding advisory levels and flirting with High Surf Warning levels along exposed north and west facing shores.
Surf heights along east facing shores will continue to decline. Mainly background swell energy will keep surf heights small along south facing shores.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Sunday for Niihau, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala.

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.