Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85 near the shore to around 71 above 3000 feet. South winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 68 near the shore to around 59 above 3000 feet. Light winds.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 85 near the shore to around 72 above 3000 feet. North winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 77 to 84. Light winds. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 68. Light winds.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 71 to 78 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 59 to 68 in the valleys to around 56 above 4000 feet. Light winds.

Sunday: Mostly sunny. Scattered showers in the afternoon. Highs 72 to 79 in the valleys to around 64 above 4000 feet. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 82. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 61 to 69. Light winds.

Sunday: Mostly sunny. Scattered showers in the afternoon. Highs 74 to 82. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 30 percent.

East Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 72 to 83. Light winds. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 62 to 71. Light winds.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 72 to 83. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Stable and mostly dry conditions, accompanied by light winds, will prevail through tomorrow. Trade winds will return tomorrow night, bringing a few windward showers, with winds expected to ease slightly and veer to the east-southeast later in the week.

Discussion

Current satellite imagery shows mostly clear to partly cloudy skies over land areas across the island chain early this morning as land breezes help to clear out the low-level clouds and showers from earlier in the evening. Satellite imagery also shows some thin cirrus passing over the eastern end of the state. Winds will remain light across most of the island chain through the weekend as surface ridging remains overhead. This pattern will allow for the development of land breezes overnight (as we've seen overnight) that will help to clear out clouds and showers across land areas by morning, and sea breezes during the day that will bring low clouds and a few showers to island interiors by the afternoon.
Fairly dry and stable conditions will persist through the weekend and most of next week with minimal rainfall expected, despite another front that is expected to approach the western end of the state tomorrow night. Model guidance suggests that this weak front will slowly sag close to Kauai, or even edge in across the western end of the state late tomorrow night into Monday morning, then dissipate across the area. Increased low level moisture in the vicinity of this front may help to boost windward shower activity across Kauai and Oahu tomorrow night into Monday, but probabilistic QPF values still show that rainfall accumulations would likely remain under a few hundredths of an inch. Whether the front actually makes it into the western end of the island chain or stalls just north of the area, model guidance is in good agreement that easterly trades winds will fill in across the state beginning tomorrow night, strengthen through Monday, then veer to the east- southeast as high pressure builds to the north and slides eastward. Pockets of moisture will move in on the trades through the week, but generally dry and stable conditions will persist as ridging aloft dominates.
Heading into next weekend, the ridge aloft may finally weaken in response to an upper level trough digging into the area. Instability from this feature along with the potential for some increasing low- level moisture may lead to some much-needed rain across the state.

Aviation

A strong high pressure ridge over the Hawaiian Islands will keep light and variable large scale winds with island scale land and sea breezes in the forecast through the weekend. Converging sea breeze winds over island interior sections may lead to isolated mountain and interior showers each day with brief periods of MVFR conditions. Otherwise VFR conditions will prevail.
No AIRMET's in effect and none are expected.

Marine

An extended period of hazardous marine conditions will persist into early next week, driven by overlapping, winter-caliber northwest swells associated with a progressive storm pattern across the northern Pacific. This pattern features storm- to hurricane-force lows advancing eastward well north of the state. Recent satellite data and observations indicate a hurricane-force low centered approximately 1,300 nautical miles north of the islands, with seas in the core of its fetch estimated up to 65 feet. A SOFAR drifter buoy recorded seas up to 60 feet, exceeding model forecasts by several feet. While the bulk of the energy from this system is directed northeast of Hawaii due to the west- to- east fetch orientation, the head of the fetch has nosed southward to within 700 nautical miles of the islands overnight. This southward extension increases confidence in the predicted timing of the swell's arrival tonight, followed by a rapid rise early Sunday morning, a peak through the day Sunday, and a gradual decline Sunday night into early next week. Surf associated with this swell will remain well above warning levels through the weekend, then return to advisory levels for exposed north and west facing shores around Tuesday of next week.
The prolonged duration of this active period will lead to coastal impacts, including significant beach erosion along exposed shorelines and potential overwash onto vulnerable coastal roadways and properties, especially during Sunday's peak. These impacts will remain likely despite the monthly tidal minima, underscoring the significance of the swell. In addition to the coastal impacts, these conditions maybe be challenging for mariners transiting in and out of exposed harbors, where strong currents and occasional breaking waves are expected.
Local winds will remain light and variable through Sunday as a surface ridge lingers over the region. By late Sunday into Monday, moderate northerly winds will develop ahead of an approaching cold front, with breezy trade winds returning early next week as the ridge strengthens to the north in the wake of the front.

Fire weather

Critical fire weather conditions are not anticipated through the forecast period. For this weekend, winds will remain light and relative humidity (RH) values will remain above 45 percent. Trades will strengthen early next week and then weaken slightly for the latter part of the week, but RH will remain above critical levels to continue to preclude critical fire weather conditions.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 AM HST Monday 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.
High Surf Advisory until 6 AM HST Monday for Big Island East, Big Island North.
Small Craft Advisory until 6 AM HST Monday for all Hawaiian waters except Maalaea Bay,

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