Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 70 near the shore to around 61 above 3000 feet. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Juneteenth: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 88 near the shore to around 77 above 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 88. Northeast winds 10 to 25 mph increasing to 20 to 25 mph in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 72. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Juneteenth: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 88. East winds 15 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 74 to 85 in the valleys to around 67 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 70 in the valleys to around 58 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Juneteenth: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 73 to 84 in the valleys to around 66 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 89. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 74. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Juneteenth: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 88. East winds up to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 85. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Juneteenth: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 72 to 84. East winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Surface high pressure north of the state will maintain breezy trade winds through tonight, with trades strengthening into the breezy to strong range Wednesday through the weekend. Fairly typical windward and mauka-focused shower activity is expected through much of the week. Remnants of an old frontal boundary could increase windward shower activity late Friday into Saturday.

Discussion

A weak upper-level low, centered a couple hundred miles southeast of Oahu, continues to sending high clouds northward across the eastern half of the state this morning. Expecting a fairly typical trade weather pattern through Tuesday night, with breezy wind speeds and passing showers focused on the windward and mauka areas. Shower activity will be slightly higher than usual, due to the upper low, with some moderate showers possible over windward areas at times, mainly during the overnight and early morning hours.
As the upper-level low gradually moves westward and weakens over the next few days, we should see inversions lowering, with drier conditions around mid-week. Beginning Wednesday into Thursday, the surface high centered far north of the state will strengthen, increasing the trade wind speeds into the breezy to strong range during the second half of the week and into the weekend. The global models are showing an area of enhanced moisture, associated with an old frontal boundary, riding in on the trades toward the end of this week. This could produce enhanced windward showers late Friday into Saturday.

Aviation

Breezy trades will continue, with SHRA and low cigs favoring windward and mauka locations. Periods of MVFR conds are possible in any SHRA. Otherwise, VFR conds should prevail.
AIRMET Sierra is in effect for mtn obsc for windward portions of all islands.
AIRMET Tango is in effect for mod turb between 140 and FL300 from the Big Island up through Molokai.

Marine

Fresh to strong easterly trades will strengthen later today through the second half of the week as the surface ridge builds north of the state. This has resulted in the Small Craft Advisory expanding up the island chain from the typically windier waters around Maui County and the Big Island. Additional marine zones may need to be added in later packages. Seas will quickly respond and build to the advisory level across the Alenuihaha Channel and waters near South Point beginning around Wednesday.
Surf along south-facing shores continues to ease this morning, and that trend will persist today. Expect mainly background south to south-southwest pulses moving through until Friday. A slight upward trend is possible by the end of the weekend from a small, long-period south swell. Guidance shows this arriving Saturday night into Sunday, then lingering into early next week.
Surf along east-facing shores will hold around average today, then gradually trend up through the second half of the week due to the aforementioned trades strengthening locally and upstream of the islands over the eastern Pacific.
Surf along north-facing shores will return to the typical summertime (flat) levels later today through midweek as a small northwest swell moves out. As the trades increase, some northern exposures could see a gradual increase later this week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Thursday for Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov