Photo Credit: Jason Weingardt

West Kaua’i

Today: Sunny and haze. Highs 79 to 84 near the shore to around 71 above 3000 feet. Southeast winds up to 10 mph.

Tonight: Mostly clear. Haze. Lows 64 to 69 near the shore to around 55 above 3000 feet. Northeast winds up to 10 mph.

Saturday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 80 to 85 near the shore to around 72 above 3000 feet. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Sunny and haze. Highs 79 to 84. East winds up to 10 mph.

Tonight: Mostly clear. Haze. Lows 61 to 67. Light winds.

Saturday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 80 to 85. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny. Haze. Highs 72 to 78 in the valleys to around 65 above 4000 feet. Light winds becoming south up to 10 mph in the afternoon.

Tonight: Partly cloudy. Haze. Lows 55 to 60 in the valleys to around 53 above 4000 feet. Light winds.

Saturday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 73 to 79 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Today: Sunny and haze. Highs 73 to 82. Southeast winds up to 10 mph.

Tonight: Mostly clear. Haze. Lows 58 to 66. Southeast winds up to 10 mph.

Saturday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 74 to 82. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny. Haze. Highs 72 to 82. South winds up to 10 mph.

Tonight: Partly cloudy. Haze. Lows 56 to 68. Light winds.

Saturday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 73 to 83. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Stable and dry conditions will continue to suppress rainfall chances through Saturday. Light to moderate east- southeasterly winds are expected over the eastern end of the state with lighter winds further west. Afternoon sea breezes will give way to overnight land breezes through Saturday with hazy conditions statewide. A brief return to typical trade wind flow could provide a modest increase in windward showers late Saturday and Sunday. As a front passes north of the state early next week, showers may increase further.

Discussion

Early this morning, surface high pressure is rooted just northeast of the island chain with a ridge axis aloft directly over the state. Subsidence from this feature is keeping conditions stable and dry, suppressing any shower activity. Inversion heights remain remarkably low, with observed 12z soundings at Lihue and Hilo revealing inversions below 5,000 feet. Background flow is light across the western islands, allowing land breezes to develop and keeping island interiors mostly clear. Meanwhile, light to moderate southeast flow is prevailing from Maui to the Big Island.
The surface high will gradually shift east over the next couple of days as light to moderate winds veer out of the southeast. For the western islands, speeds will be lighter which will result in a developing land and sea breeze pattern. Interior clouds will increase during the afternoons followed by clearing skies and cooler than normal nights as land breezes develop each night. Also of note, the southeasterly wind direction will allow any vog emitted from Kilauea's ongoing eruption to spread northwest across the smaller islands through Saturday creating hazy conditions in these areas.
Models indicate that precipitable water and moisture depth will increase by Saturday evening, particularly over the eastern half of the state. This will increase shower chances across eastern sections of the Big Island and Maui Saturday and Sunday with drier conditions further west. Monday night through early Wednesday, a front passing north of the state will increase moisture (and therefore shower chances) as winds become light and variable. Early indications are that another front moving across the western islands during the second half of the work week could increase shower chances even further as they become more widespread over the islands. However, at this time, there is a great deal of uncertainty among models regarding the amplitude and placement of this front which will ultimately determine rain chances over the islands.

Aviation

A very dry and stable air mass will remain in place, with light E-SE winds bringing little to no rainfall. VFR conditions will prevail, with any CIGS that develop being above 030.

Marine

A large north (350 degrees) swell is on the downward trend today as the High Surf Warning (HSW) has been cancelled but remain well in the High Surf Advisory (HSA) range. Large surf will persist for most north and west facing shores through the weekend as another powerful long period northwest (310 degrees) swell is expected to rise Saturday and hold through Sunday. Therefore, a HSA is in effect for most north and west facing shores through Sunday afternoon which may need to be extended as the swell lingers through Monday. Additional details are contained in the latest Coastal Hazard Message (CFWHFO), Marine Weather Statement (MWSHFO), and Surf Zone Forecast (SRFHFO). Surf for east facing shores will remain small except areas exposed to the north swell which may see some wrap through Saturday.
After this long- lived swell eases, surf heights early next week looks to remain below HSA heights along all shores as moderate- sized northwest swells arrive, with a small south swell possible this weekend.
A Small Craft Advisory is in effect for all zones (except Maalaea bay) through this afternoon, as combined seas remain above 10 feet. Seas should lower below 10 feet by tonight, but will approach 10 feet again over the weekend.
An eastward-moving weak surface high is centered about 400 nm northeast of Oahu. The high will move east through today then remain relatively stationary about 600 nm east northeast of the islands through the weekend. The high will then move far northeast of the state early next week. Light to moderate east to southeast winds will persist through Saturday, but may get a little stronger and back out of the east when the ridge, associated with the high, moves north briefly on Sunday. The ridge is expected to weaken as a front approaches the state during the first half of next week, weakening winds slightly and veering winds back out of the east to southeast.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Sunday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
High Surf Advisory until 6 PM HST this evening for Olomana, Koolau Windward, Big Island East, Big Island North.
Small Craft Advisory until 6 PM HST this evening for all Hawaiian waters except Maalaea Bay,

Data Courtesy of NOAA.gov