Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 77 to 85 near the shore to around 72 above 3000 feet. East winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Haze through the night. Lows 65 to 70 near the shore to around 59 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Partly sunny. Scattered showers in the afternoon. Highs 77 to 85 near the shore to around 71 above 3000 feet. Southeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 50 percent.

South Kaua’i

Today: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 77 to 84. Southwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows around 69. West winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 77 to 84. Southwest winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs 72 to 79 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Haze through the night. Lows 59 to 68 in the valleys to around 57 above 4000 feet. Southwest winds up to 10 mph. Chance of rain 30 percent.

Sunday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 80 in the valleys to around 63 above 4000 feet. Southwest winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs 74 to 81. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 62 to 68. South winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 75 to 82. Southeast winds up to 15 mph shifting to the north in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs 73 to 84. Southwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 62 to 72. Southwest winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 72 to 84. Southwest winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate winds will veer out of the south this weekend as a front approaches and stalls to the northwest. With this lighter flow, overnight land breezes and afternoon sea breezes will prevail before southwesterly winds strengthen for the western end of the state early next week. A cold front may move over portions of the state by mid week and bring beneficial rain and breezy winds.

Discussion

Current radar and satellite imagery show isolated to scattered showers moving into the Big Island from the southeast and moving from south to north across the rest of the island chain this morning. These showers are primarily remaining over the waters as land breezes have helped to clear out land areas overnight. As a weak cold front inches closer and stalls north of the state this weekend, local winds will continue to weaken and veer out of the south and then eventually southwest across the western end of the island chain. During this period, land and sea breeze activity will become more widespread, allowing for limited cloud and shower development over leeward and interior areas during the day and clearing at night.
An upper level trough will dive down and sweep across the central Pacific and finally help to drive the next weak cold front through at least a portion of the island chain by mid week next week. Ahead of the front, the southwesterly flow will strengthen across the western half of the state late this weekend into early next week, which may be enough to overcome the land and sea breeze pattern for Kauai and Oahu and focus clouds and showers over leeward areas…especially if any prefrontal convergence bands materialize in the southwesterly flow. The latest global model runs continue to bring the front to Kauai's doorstep on Tuesday evening, then have it slowly move through the middle of the island chain by Wednesday evening before it stalls. This frontal passage looks to bring some beneficial rain to the area, along with breezy north- northeasterly winds for the western half of the state. Convergence along this dissipating frontal boundary, an abundance of upstream moisture, and a new plume of moisture associated with a low level disturbance moving towards the eastern end of the state will keep rain chances in the picture through the latter part of the week. Rainfall will mainly be focused over windward and mauka areas for this period as high pressure builds behind the front and trades return.
Finally, a hot spot over Halemaumau Crater on the Big Island continues to be seen on infrared satellite imagery. As winds weaken and shift out of southeast, south, and southwest this weekend into early next week, SO2 emissions are expected to to increase across some of the smaller islands.

Aviation

A ridge over the islands will maintain light winds through the weekend. While the background flow will be southerly, winds over the islands will be light enough for daytime sea breezes and overnight land breezes. Clouds and showers will form over the interior of the islands with the daytime sea breezes, and largely clear out overnight.
No AIRMETs are in effect, and none are expected through today.

Marine

Forerunners of the first of a series of large to potentially extra large northwest swells has reached the offshore buoys and is now trickling in at the CDIP Hanalei and Waimea Bay buoy in the 22+ second range. Big Island west facing shores has been added to the High Surf Warning (HSW) that remains in effect for north and west facing shores of Kauai, Niihau, Oahu, Molokai, and for north facing shores of Maui starting noon today through Sunday. Expect surf to quickly build this morning and afternoon. A Small Craft Advisory (SCA) has also been issued for all waters except Maalea Bay as seas quickly build 10 ft or higher for waters exposed to the swell.
Another round of large to extra large northwest swell is expected Monday through Thursday next week as the storm low that will be producing the weekends' swell, regroups and continues to maintain a sizable and strong fetch aimed at Hawaii. Surf may briefly drop below HSW levels Sunday night and Monday between swells before likely building back to extra- large HSW levels Tuesday through Thursday. Surf along east and south facing shores will remain small through the forecast period.
A surface ridge will remain centered over the state producing light and variable over the western half of the state and gentle to locally fresh east southeast winds over the eastern half of state. A front approaching from the northwest may gradually strengthen southwest winds to moderate to fresh speeds around Kauai and Oahu Sunday then to moderate to strong speeds Tuesday while the eastern half becomes light and variable. The front may reach Kauai as early as Tuesday night with moderate northerly winds filling in behind it before stalling and dissipating over the central islands during the second half of next week. Moderate to fresh trades may return during this time as a high builds north of the state behind the front. The front will bring the chance for thunderstorms over the far northern offshore waters later today through Tuesday.

Fire weather

No critical fire weather conditions are expected for the next seven days. A daytime sea breeze and overnight land breeze pattern will continue into early next week as a weak southerly background flow takes over. Relative humidities will stay above critical levels through the forecast period. An approaching front is expected to move through part of the state from mid-to late week next week, bringing breezy northeasterly winds and providing much needed rainfall to leeward locations.

HFO Watches/Warnings/Advisories

High Surf Warning from noon today to 6 PM HST Sunday 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, Big Island South.
Small Craft Advisory from noon today to 6 PM HST Sunday for all Hawaiian waters except Maalaea Bay,

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