Photo Credit: Sebastien Gabriel

West Kaua’i

Rest Of Today: Cloudy and breezy. Numerous showers and chance of thunderstorms in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the morning. Highs around 77 near the shore to around 65 above 3000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 67 near the shore to around 56 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Sunday: Mostly sunny with isolated showers. Highs around 80 near the shore to around 68 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Rest Of Today: Cloudy and breezy. Frequent showers and chance of thunderstorms in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the morning. Highs around 76. Northeast winds 20 to 25 mph decreasing to 10 to 25 mph in the afternoon. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 68. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny with numerous showers in the afternoon. Highs around 79. East winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Rest Of Today: Breezy. Frequent showers and chance of thunderstorms in the morning, then occasional showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the morning. Highs 64 to 72 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 56 to 61 in the valleys to around 50 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Partly sunny with numerous showers. Highs 67 to 75 in the valleys to around 62 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Rest Of Today: Cloudy and breezy. Frequent showers and chance of thunderstorms in the morning, then occasional showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the morning. Highs 69 to 76. Southeast winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 90 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 68. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 72 to 79. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Rest Of Today: Breezy. Frequent showers and chance of thunderstorms in the morning, then occasional showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the morning. Highs 69 to 76. Northeast winds 10 to 20 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy with scattered showers. Lows 57 to 69. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 72 to 79. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Update

Increased the chance of thunderstorms through the morning for Kauai and surrounding waters based on current radar and lightning observations.

Synopsis

Unstable, wet trade wind weather expected through this weekend with locally heavy showers and isolated thunderstorms possible, mainly over the western end of the state. A more typical trade wind pattern will return for next week.

Prev discussion

/ISSUED 317 AM HST Sat Feb 4 2023/
Currently at the surface, a 1029 mb high is located around 900 miles north of Honolulu, while a trough of low pressure is positioned over the western end of the state. These features are producing moderate to locally breezy trade winds in unsheltered areas across the island chain early this morning. Infrared satellite imagery shows mostly cloudy to overcast conditions. Radar imagery shows scattered to numerous showers affecting windward slopes and coasts, with a few showers reaching leeward areas at times. Additionally, a few thunderstorms have developed in the vicinity of Kauai and Oahu overnight. Main short term focus continues to revolve around rain and thunder chances.
The trough over the western islands will gradually shift westward and dampen out today, while the strong high shifts eastward well to the north of the state. As a result, we should see breezy trades develop across the entire island chain today. Strong high pressure will anchor northeast of the islands Sunday through late next week, keeping breezy trade winds blowing across the state.
As for the remaining weather details, mid and upper level troughing will slide slowly eastward just to the south of the smaller islands today and tonight, then pass over the Big Island on Sunday. The airmass will remain unstable and moist enough through Saturday, that a few thunderstorms will be possible, with the highest chances for some downpours and thunder over the western islands in closest proximity to the surface trough. The airmass will gradually stabilize from northwest to southeast down the island chain Saturday night and Sunday, with showery conditions and a slight chance of thunderstorms continuing over the Big Island. Mid and upper level ridging will continue to stabilize the airmass Sunday night, with fairly typical trade wind weather featuring mainly windward showers and the occasional leeward spillover prevailing through late next week.

Aviation

A weakening surface trough will continue to drift into the islands today as an upper level low slowly moves eastward across the island chain through Sunday. Enhanced showers will continue to produce periods of MVFR/IFR conditions mainly over the western islands from Kauai to Molokai. Increasing shower trends will spread brief periods of MVFR/IFR to the eastern islands later today with locally heavy showers favoring windward airfields. Isolated thunderstorms are also expected at least through this evening with the passage of the upper low. Deep layer moisture will continue to produce light icing across the state today.
AIRMET Sierra for tempo mountain obscuration will continue across Kauai and Oahu. This area will likely expand eastward in coverage later this morning.
AIRMET Tango for moderate low level turbulence will also continue over and down wind of island mountains including the islands of Kauai, Oahu and Molokai. This area will likely expand eastward in coverage later this morning as trade winds strengthen across the state.

Marine

A front passing north of the state, combined with high pressure building to the northwest, will bring fresh to strong northeast winds to the coastal waters through tonight. A Small Craft Advisory (SCA) remains in effect for call coastal waters through Saturday night. The SCA is primarily in place because of the strong winds, however seas are also expected to reach 10 feet today in some areas exposed to the northwest and north swells. Winds will trend down a bit on Sunday, likely resulting in the SCA being scaled back to the more typical areas near Maui County and the Big Island.
An upper level low to the southwest of the islands, combined with the front to the north is providing instability that is sparking some thunderstorms over the coastal and offshore waters. Expect more stable conditions to settle into the coastal waters by Sunday. The chance for thunderstorms will linger longer over the offshore waters.
The current northwest swell (310 degrees) will continue fade today, however additional north-westerly swells expected into the middle of the new week will help keep surf elevated along north and west facing shores. A medium- period north- northwest (340-350 degrees) swell is expected to arrive later today, then hold into Sunday before fading. On Monday, a long- period northwest swell (320 degrees) will slowly fill in through the day Monday, then peak sometime Tuesday through Wednesday, before lowering into the latter half of next week. A reinforcing swell from the same direction will fill in later Thursday. This swell could be slightly larger, with surf potentially near advisory levels for exposed north and west facing shores of the smaller islands as this swell peaks. Surf along south facing shores will ease through the weekend as a long- period south swell fades. Surf along east facing shores will trend up through the early part of the new week as a belt of fresh to strong easterly trades develops over and far upstream of the islands.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Sunday for all Hawaiian waters,

Data Courtesy of NOAA.gov