Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Frequent showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs around 81 near the shore to around 69 above 3000 feet. Southeast winds up to 15 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Numerous showers and isolated thunderstorms early in the evening, then isolated showers in the late evening and overnight. Lows around 66 near the shore to around 55 above 3000 feet. East winds up to 10 mph. Chance of rain 60 percent.

Saturday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 84 near the shore to around 72 above 3000 feet. Southeast winds around 10 mph. Chance of rain 40 percent.

South Kaua’i

Today: Frequent showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs around 78. South winds up to 10 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Numerous showers and isolated thunderstorms early in the evening, then scattered showers in the late evening and overnight. Lows 62 to 67. Light winds. Chance of rain 60 percent.

Saturday: Partly sunny with scattered showers. Highs around 81. South winds around 10 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Frequent showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs 68 to 75 in the valleys to around 59 above 4000 feet. South winds up to 15 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy with numerous showers and isolated thunderstorms early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Lows 55 to 60 in the valleys to around 48 above 4000 feet. Light winds becoming south up to 10 mph after midnight. Chance of rain 60 percent.

Saturday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. South winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Cloudy. Frequent showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs 71 to 81. South winds up to 15 mph shifting to the west in the afternoon. Chance of rain 90 percent.

Tonight: Mostly cloudy with numerous showers and isolated thunderstorms early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Lows 58 to 66. South winds up to 10 mph. Chance of rain 60 percent.

Saturday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 74 to 84. South winds up to 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.

East Kaua’i

Today: Frequent showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs 71 to 80. South winds 10 to 15 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Numerous showers and isolated thunderstorms early in the evening, then isolated showers in the late evening and overnight. Lows 55 to 68. Southwest winds up to 10 mph. Chance of rain 60 percent.

Saturday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 83. South winds around 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Humid and wet conditions with light southeast winds will continue into the weekend as an upper disturbance drifts eastward over the state. Some showers may be heavy at times, which could lead to localized flooding concerns today. Southeast winds will linger into the weekend, with a transition back to easterly trade winds and drier conditions late Saturday through early next week.

Discussion

Short-term guidance remains in good agreement through the weekend and shows the upper low centered near Kauai drifting eastward over the state through tonight, then opening up and shifting east of the area over the weekend. Southerly flow ahead of it will continue to draw deep tropical moisture northward over the islands. This influx of moisture, coupled with enhanced lift and added instability associated with upper height falls, will keep the chances up for localized heavy showers and a few thunderstorms. Early morning radar trends support this and show plenty of moderate to heavy showers developing near the upper low over the leeward/southern Kauai waters, with another burst of convection located around 100 miles south of Oahu/Maui County.
The timing and spatial extent of this activity will be mostly influenced by the progression of the aforementioned upper low moving through. Based on the current high-resolution guidance, the heavy showers developing over and around Niihau will continue and gradually shift eastward to Kauai by or around daybreak, then to Oahu and the eastern end of the state later today through tonight. The initial concern will remain over Kauai and whether or not the heaviest activity stays off the coast to the south or fills in over the island this morning. If the latter scenario evolves, the potential for localized flooding will increase, especially since some areas have already received 2-4 inches over the past 12 to 24 hours. A similar threat will be in place over Oahu and Maui County through the day, then the Big Island this evening through early Saturday. In addition to the rainfall potential, the threat of a wintry mix remains in place over the Big Island Summits through early Saturday as the cold pool aloft associated with the upper low moves through.
Improving conditions are expected over the weekend through early next week as the weakening upper low departs and upper heights rise. This will shift the deep moisture in the area westward with surface high pressure building to northeast. This pattern shift will result in a more typical easterly trade wind set up with showers returning to windward and mauka locations each day.

Aviation

Early this morning, light showers and layered clouds are impacting much of the state as a low aloft moves over the islands and tracks east through tonight. Reduced visibilities and MVFR ceilings can be expected in and around showers tracking from the southwest. Deeper convection is observed on radar imagery in the waters southwest of the islands, and this activity will have the potential to spark isolated thunderstorms and occasional heavy rain through the morning.
Scattered shower activity and occasional MVFR conditions are expected to continue throughout the day, particularly for the western islands, before diminishing by tonight as the upper low opens up and shifts east of the state. Easterly trade winds will fill back into the region this weekend.
AIRMET Sierra remains in effect for tempo mountain obscuration for Kauai this morning. Additionally, with thick layered clouds overhead, light icing remains possible from roughly 13,000 through 23,000 feet statewide.

Marine

A surface trough will linger over western waters through today and will produce moderate southeast to south winds across most areas with locally fresh southeast winds across select areas of Maui and the Big Island. The threat for isolated thunderstorms over western waters remain and moderate rainfall will be possible at times especially around the waters of Kauai and Oahu. The surface trough will dissipate on Saturday, leading to a return of easterly trade winds and Small Craft Advisory conditions possible over typical windy waters around the Big Island and Maui county. Trades will likely strengthen to strong speeds early next week as high pressure strengthens far northeast of the state.
A small, short-period north-northeast swell will steadily decline tonight through the day. Some of this swell will wrap into exposed eastern shores, but otherwise, east shore surf will be below May average as the nearby trade wind flow will be weaker than normal into Saturday. A small northwest swell is possible early next week, while returning strong trade winds will increase east shore surf.
A mix of small south-southwest and south-southeast swell should produce inconsistent surf near the seasonal average through the weekend. Expect south shore surf to be at summertime background heights from Monday through the middle of next week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov