West Kaua’i

Tonight: Partly cloudy with isolated showers. Haze. Lows around 69 near the shore to around 59 above 3000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs around 82 near the shore to around 72 above 3000 feet. Light winds becoming southwest around 10 mph in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy in the evening, then mostly cloudy with isolated showers after midnight. Lows 66 to 71 near the shore to around 59 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Haze through the night. Lows around 69. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers. Haze. Highs 78 to 85. Light winds becoming southwest around 10 mph in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy in the evening, then mostly cloudy with scattered showers after midnight. Lows around 69. West winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Kaua’i Mountains

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 61 to 68 in the valleys to around 58 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Haze. Highs 72 to 79 in the valleys to around 64 above 4000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Friday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 60 to 68 in the valleys to around 57 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

North Kaua’i

Tonight: Partly cloudy. Haze through the night. Lows 63 to 70. Light winds.

Friday: Mostly sunny. Haze in the morning. Isolated showers in the afternoon. Highs 74 to 82. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Friday Night: Partly cloudy. Isolated showers after midnight. Lows 63 to 70. West winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly clear. Isolated showers in the evening. Haze through the night. Lows 63 to 73. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 72 to 83. Light winds. Chance of rain 40 percent.

Friday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 73. Light winds. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Light winds will prevail over the next several days as a surface ridge axis remains stretched across the islands. Thus, expect the sea breeze regime to continue with some clouds and showers developing over the interior of the islands each afternoon, then clearing at night. A cold front will approach the islands from the northwest Sunday night and bring a line of showers quickly down the chain on Monday. A much drier airmass moves in right behind the front bringing a seasonable chill to the air late Monday into early Tuesday. Another, possibly stronger, frontal system could affect the islands by the middle of next week.

Discussion

A surface ridge axis anchored across the islands has once again allowed for light background flow with afternoon sea breeze development. In general, scattered clouds and isolated showers were sparse and limited to mainly interior regions of the islands. However, a patch of deeper moisture did manage to affect eastern portions of the Big Island and bring greater shower coverage. A handful of sites in that region reported rainfall totals, since midnight, of just over half an inch. This area of enhanced showers will likely hang around until this late this evening, then wane overnight.
Friday into Saturday, a frontal system is progged to stall then dissipate just north of Kauai, with winds around state remaining light and variable. Residual moisture from this dissipating feature could bring a brief uptick in shower activity over Kauai and to a lesser extent Oahu. Elsewhere, expect fair skies with isolated afternoon showers over the interior regions. Skies should clear overnight with the loss of diurnal heating.
On Sunday, latest runs of both the GFS and ECMWF deepen a longwave upper level trough north of the state and show a pronounced cold front approaching the island front the northwest. In response, light to locally moderate flow will turn south or southeasterly. With model timing being nearly identical, confidence is increasing of a surface frontal passage down the island chain during the day Monday. Along and ahead of the front, a band of steady rain will likely push through. However, due to the quick moving nature of the front, not expecting much in the way of flooding concerns. Immediately behind the frontal passage, breezy northwest to north winds will advect in a cooler and drier airmass with dewpoints dropping into the mid-50s and low temperatures Monday night down to the mid-60s. Northerly winds behind the front will quickly veer to typical northeast trades by Tuesday.
In the extended, late Wednesday into Thursday of next week, both the GFS and ECMWF both indicate yet another frontal passage through the island chain from the northwest. If current trends hold, this system would be stronger than the previous and may bring a period of heavy rain and gusty winds.

Aviation

A ridge over Hawaii will result in light southeast winds and land breezes tonight. Most areas will clear out tonight except for windward and southeast Big Island where some showers will linger along the coast and offshore. Currently, AIRMET Sierra is posted for this area for tempo mountain obscurations above 2500 feet, and will likely linger into the evening. Othwerse, expect VFR conditions to prevail. Clouds and showers from a weak front will make its way to Kauai during the day Friday.

Marine

A high pressure ridge has shifted south over the central waters as a front approaches from the northwest, which will cause light to gentle southeast to southerly winds to rule over the marine waters through Friday. As the front dissipates and its remnants lift northward, gentle east to southeast winds will prevail Saturday and early Sunday, giving way to southerly winds again late Sunday. Due to these lighter winds, land and sea breezes are possible through the weekend. A stronger front will move down the island chain Monday and Tuesday, likely ushering in fresh northerly winds in it wake.
Surf along north facing shores will remain small to moderate due to a gradually declining west-northwest swell through Friday. A storm low deepening south of the Aleutian Islands will generate a larger north-northwest (330 degrees) swell that will build in rapidly on Saturday and peak through Sunday, producing surf near High Surf Warning (HSW) levels along north and some west facing shores. Another storm low is expected to develop closer to Hawaii this weekend and generate a larger long period northwest (320-330 deg) swell. This swell will likely produce surf above the HSW thresholds late Monday and Tuesday. Stay tuned as the low develops.
Surf along east facing shores will continue to decline through the weekend as winds over and upwind of Hawaii remain weak. Some increase in east shore surf is possible early next week. Along south shores, surf will remain very small through the forecast period.

HFO Watches/Warnings/Advisories

None.

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

Check out their Kaua‘i Helicopter Tours today!

Data Courtesy of NOAA.gov