West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85 near the shore to around 71 above 3000 feet. East winds up to 10 mph shifting to the southeast around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 69 near the shore to around 56 above 3000 feet. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs 79 to 85 near the shore to around 71 above 3000 feet. East winds around 10 mph in the morning becoming light. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 77 to 84. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs 77 to 84. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny with scattered showers. Highs 72 to 79 in the valleys to around 64 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 57 to 66 in the valleys to around 54 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 72 to 78 in the valleys to around 63 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 81. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 59 to 67. Southeast winds around 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs 74 to 81. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 71 to 82. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 60 to 71. East winds around 10 mph. Chance of rain 20 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny in the afternoon. Highs 71 to 82. East winds around 10 mph. Chance of rain 30 percent.

Detailed Forecast

Synopsis

Mostly dry and stable conditions will persist through the weekend and into next week, with light to moderate ESE trades. Rain chances will increase from the west late next week.

Discussion

A surface ridge centered to the NE of the state will help to maintain light to moderate ESE trades through the weekend. This surface ridge combined with mid level ridging building in from the west and a dry resident airmass (CIMSS MIMIC precipitable water values currently below an inch across most of the state) will allow dry and stable conditions to persist through the weekend.
Early to mid week next week…high pressure to the NE will weaken, allowing the local pressure gradient to relax. Winds across the western end of the state will become lighter and somewhat variable…typically displaying more of a southerly component, while the eastern end of the state will be impacted by slightly stronger easterlies. The weaker winds across the western half may allow for isolated sea breeze activity with afternoon clouds and showers forming over a few leeward and interior areas, and the stronger winds across the eastern half will yield a more typical trade wind weather regime with showers favoring windward areas overnight and leeward slopes of the Big Island each afternoon. The ESE flow for the western half of the state may also allow island plumes (downstream convergence from island terrain) to bring showers to leeward areas at times. However, even as the boundary layer moistens a bit with small pockets of moisture riding in on the lighter trades and dew points increase a tad, mid level ridging will strengthen over the area and help to suppress shower activity…so mostly dry and stable conditions should continue through midweek.
Friday into Saturday…A low pressure system north of 40 N will drag the tail end of a front near the state. While the integrity of the front this far south remains questionable, model guidance indicates that this feature may bring a band of increased moisture to the western end of the state, increasing rain chances for these areas Friday and Saturday. With this surface boundary looking rather weak along with unimpressive upper level support, not expecting widespread major impacts with this event. However, current model guidance shows precipitable water values increasing to 1.4 to 1.6 inches across the western end of the state (above the 90th percentile), indicating that periodic heavy showers may be possible.

Aviation

A ridge of high pressure just north of the state will produce stable conditions with light to moderate east to east-southeast low-level flow through the weekend. The light winds should give way to sea breezes later this morning with afternoon clouds and showers over interior and leeward areas. Brief periods of MVFR ceilings will be possible with any showers.
A strong upper level jet moving its way down toward the state will produce moderate upper level turbulence across the state through tonight and linger over the eastern end of the state on Sunday. AIRMET TANGO is in effect for moderate turbulence between FL280 and FL350.

Marine

A weak surface ridge will remain north of the Hawaiian Islands through Wednesday. Light to moderate east-southeast winds will prevail in a fairly stable weather pattern.
A long period northwest swell currently moving through the region will continue to decline today. Another long period northwest swell begins to build into the region later this morning. This should peak this afternoon into the evening just below High Surf Advisory (HSA) levels, and then slowly decline through Monday.
A larger northwest swell will build into the islands from Tuesday into Wednesday, with surf heights easily exceeding advisory and possibly reaching High Surf Warning levels along exposed north and west facing shores.
Surf heights along east facing shores will continue to decline. Mainly background swell energy will keep surf heights small along south facing shores.

HFO Watches/Warnings/Advisories

None.

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