Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 72 near the shore to around 58 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Juneteenth: Mostly sunny with isolated showers in the morning, then partly sunny with numerous showers in the afternoon. Highs around 85 near the shore to around 73 above 3000 feet. East winds up to 15 mph. Chance of rain 70 percent.

South Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 65 to 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Juneteenth: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 82. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds up to 15 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 58 to 63 in the valleys to around 53 above 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

Juneteenth: Mostly cloudy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 72 to 79 in the valleys to around 63 above 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

North Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 76 to 85. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 61 to 71. East winds up to 15 mph. Chance of rain 70 percent.

Juneteenth: Partly sunny with numerous showers. Highs 75 to 84. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 84. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 59 to 72. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Juneteenth: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 83. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

The trades will ease today, with fairly dry weather continuing. A few showers will affect windward slopes and coasts this morning and interior and leeward areas this afternoon. A band of enhanced moisture and a disturbance aloft will bring a period of wet trade wind weather tonight and Monday, with drier air working in from the east Monday night and Tuesday. A more typical trade wind pattern should return Tuesday night and Wednesday with showers favoring windward areas along with the occasional leeward spillover. This pattern will change little through the end of the week into next weekend, although the trades will strengthen to breezy and locally windy levels Thursday through next weekend.

Discussion

Currently at the surface, a 1031 mb high is centered around 1400 miles north-northeast of Honolulu, and is driving moderate trade winds across the island chain early this morning. Infrared satellite imagery shows variably cloudy conditions across the state, with cloud coverage the highest in windward areas. Radar imagery shows scattered showers moving into windward areas, with a few showers spilling leeward at times. Main short term focus revolves around trade wind trends and rain chances.
High pressure to the distant north-northeast will remain nearly stationary during the next few days while a cold front edges eastward before stalling out around 800 miles north of the Aloha state. This will lead to a slight easing of the trades today, with a general light to moderate trade wind pattern then holding in place tonight through Tuesday. The front will weaken into a trough and begin to shift westward Tuesday night and Wednesday allowing the trades to re-strengthen back to moderate and locally breezy levels, with the trades becoming breezy to locally windy statewide Thursday through next weekend.
As for the remaining weather details, shower coverage should decrease fairly quickly this morning as some drier air moves into the state, with a few leeward and interior showers possible this afternoon due to daytime heating and localized sea breezes. A band of enhanced moisture along with a closed upper low setting up over the islands, should bring a notable increase in trade wind showers as the night progresses tonight. This rather wet trade wind pattern will hold through Monday and possibly into Monday evening, before drier air works in from the east. Relatively dry trade wind weather should then return later Monday night through Tuesday, with showers favoring windward areas at night through the early morning hours, and interior and leeward areas during the afternoon and early evening hours.
As the trades strengthen Tuesday night and Wednesday, we should see a return of more typical trade wind weather with showers favoring windward and mauka areas and the occasional shower spilling over into leeward communities. This pattern is then expected to hold in place through next weekend.

Aviation

A high pressure system far north-northeast of the Hawaiian Islands will produce moderate trade winds today and tonight. An unstable upper low will produce passing showers over all islands and brief MVFR conditions, mainly over windward and mountain areas. These showers will favor the overnight to early morning hours. Outside of showers mostly VFR conditions will prevail.
No AIRMETs in effect and none are expected.

Marine

Easterly trade winds have backed off over the past 24-hours, and that downward trend should continue into the start of the week due to a weakness forming in the ridge well north of the islands. Recent satellite data confirmed this and didn't reflect any Small Craft Advisory level winds over the windier waters between Molokai and the Big Island. As a result, the Small Craft Advisory has been canceled. For the upcoming week, guidance remains in decent agreement and depicts the easterly trades surging back Wednesday through the second half of the week as the ridge strengthens.
Surf along exposed north and west facing shores will rise later today through tonight, then peak on Monday as a moderate (medium period) west-northwest swell moves through from former Typhoon Guchol. SOFAR drifter buoys near the fetch region depicted the model guidance is now slightly under doing it or lower than observed through the overnight hours. If this translates downstream over the islands tonight through Monday, as it peaks, deep water swell heights may reach the 5-6 ft range. This will linger into Tuesday, then fade through midweek. There has been a compact system trailing this feature east-northeast of Japan, which could keep the surf from going flat Wednesday through Thursday with a small swell holding out of the same west- northwest direction.
Surf along east facing shores will remain small/choppy and gradually ease over the next couple of days as the aforementioned ridge weakens. An upward trend is expected Wednesday through the rest of next week as the local and upstream trades return to fresh levels.
Surf along south facing shores will remain small each day through the week with mainly background south-southwest to south- southeast swell energy moving through. Although high pressure is currently parked in our typical swell window southeast of New Zealand, a powerful gale- to storm-force low currently evolving far south of the Tuamotus and Tahiti will be enough to generate a long-period south-southeast (170 deg) swell for next weekend (24th-26th). Satellite data confirmed Saturday and showed seas up to 30 ft with winds around 50 kt in the fetch region.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov