Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 85 near the shore to around 72 above 3000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 66 to 71 near the shore to around 59 above 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny. Scattered showers in the afternoon. Highs around 85 near the shore to around 72 above 3000 feet. East winds up to 10 mph shifting to the south in the afternoon. Chance of rain 30 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 80 to 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67. Northeast winds around 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 82. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny with isolated showers. Highs 71 to 78 in the valleys to around 62 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows 58 to 63 in the valleys to around 52 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Sunday: Mostly sunny with scattered showers. Highs 71 to 78 in the valleys to around 62 above 4000 feet. Light winds. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 62 to 70. East winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Sunday: Mostly sunny with isolated showers. Highs 74 to 84. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 83. Northeast winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 58 to 71. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Sunday: Mostly sunny with isolated showers. Highs 74 to 83. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A ridge to the north will weaken and shift southward during the next couple days, gradually easing the trade winds and bringing mostly dry weather to the islands. The ridge will lift northward early next week, increasing the trades back to moderate levels levels, with rather dry weather persisting through Tuesday. The trades will hold at moderate levels Tuesday night through late next week, but an increase in moisture caught up in the trades will bring a more typical windward and mauka focused shower pattern to the islands along with a few leeward spillovers.

Discussion

Currently at the surface, a weak ridge of high pressure is positioned around 450 miles north of Kauai, while a cold front is located close to 850 miles northwest of the Garden Isle. The gradient locally remains primarily influenced by the ridge to the north early this morning, with light to moderate trade winds prevailing in unsheltered areas. Infrared satellite shows a scattered to broken high clouds moving over the islands along with some low clouds being carried onshore into windward areas with the trades. Radar imagery shows a few light showers moving into windward slopes and coasts, with mainly dry conditions in leeward areas. Main short term focus revolves around trade wind trends and rain chances during the next several days.
The cold front to the distant northwest will shift east-southeast during the next couple days, weakening the ridge and displacing it southward and closer to the state. Moderate trades will hold today, with localized leeward sea breezes expected. The trades will ease into the light to locally moderate range Sunday through early Monday, with sea and land breezes more common in leeward locales. The front will stall out north of the islands late Monday, with the ridge to the north strengthening and lifting slowly northward. This should bring a return of moderate trades to most areas by late Monday, although sea breezes will likely continue in some leeward areas. Ridging north of the islands will then remain nearly stationary Tuesday through late next week, with moderate trade winds prevailing.
As for the remaining weather details, very dry conditions are expected to persist today as precipitable water hover around 1 inch. As a result, nothing more than isolated shower coverage is expected. The airmass should moisten up a bit tonight, bringing a slight increase in shower coverage to windward areas. Rather dry weather will persist Sunday through Tuesday. Showers will favor windward areas at night and interior and leeward areas each afternoon through Monday. A return to trade wind weather is expected Monday night and Tuesday, however it should remain a drier than normal trade wind regime. The air mass appears to moisten up slightly Tuesday night through late next week, bringing a return of typical trade wind weather featuring windward showers and the occasional leeward spillover.
Periods of scattered to broken high cloud cover will continue to move overhead at times through early next week, with model guidance showing the highest coverage over the eastern half of the state.

Aviation

Light to moderate trade winds will ease this weekend while maintaining limited showers across windward areas. The lighter winds will generate a few afternoon sea breeze clouds and isolated showers across sheltered leeward areas. Mainly VFR conditions expected through tonight.
AIRMET Tango remains in effect for tempo moderate turbulence statewide between FL250 and FL350 due to upper level jet dynamics over the islands. The jet will linger around the state through the weekend, maintaining high clouds across the eastern portion of the state.

Marine

Moderate to fresh northeast to easterly trade winds will ease into the light to moderate range over the weekend as a weakness forms in the ridge to the north. Despite the lighter winds, expect localized pockets of fresh breezes to develop near the coasts during the late morning and afternoon hours due to a combination of the orientation of the terrain, wind direction, and heating. Guidance shows a return of moderate to fresh trades around midweek as the ridge strengthens.
Surf along south facing shores will remain small through next week with mainly background long-period southerly swells. The next swell should begin to move through late Saturday from a recent Tasman Sea source (south-southwest direction), then continue into early next week. A mix of this south-southwest swell and a fresh south-southeast medium period swell from a system passing well south of Tahiti and the Tuamotus at the end of May is expected from late Monday through midweek. As these sources fade by Thursday, another small background south-southwest swell is expected Friday into next weekend.
Surf along north facing shores will remain near the seasonal average each day through the first half of next week. Although guidance does show a decent out of season northwest swell arriving late next week, confidence is low at this point due to the source quickly lifting north-northeast over the far northwest Pacific Sunday and Sunday night.
Surf along east facing shores will remain small through next week due to the light trades locally and far upstream of the state over the far eastern Pacific.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov