West Kaua’i

Tonight: Partly cloudy. Lows around 67 near the shore to around 57 above 3000 feet. Light winds.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85 near the shore to around 71 above 3000 feet. Light winds. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 66 near the shore to around 57 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Tonight: Partly cloudy. Lows around 66. Light winds.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85. Light winds. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 66. Light winds becoming north around 10 mph after midnight. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy. Lows 57 to 67 in the valleys to around 55 above 4000 feet. Light winds.

Saturday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 79 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 30 percent.

Saturday Night: Partly cloudy. Lows 56 to 66 in the valleys to around 55 above 4000 feet. Light winds becoming north up to 10 mph after midnight.

North Kaua’i

Tonight: Mostly clear. Lows 60 to 67. South winds up to 10 mph in the evening becoming light.

Saturday: Mostly sunny. Scattered showers in the afternoon. Highs 74 to 81. Light winds. Chance of rain 30 percent.

Saturday Night: Partly cloudy. Lows 60 to 67. Light winds becoming northeast up to 10 mph after midnight.

East Kaua’i

Tonight: Partly cloudy. Lows 60 to 69. Light winds.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 83. Light winds. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 60 to 70. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to locally moderate trade winds and mostly dry conditions will prevail through early next week, with a few showers possible along windward slopes and coasts at night and over the island interiors each afternoon. A series of cold fronts will approach from the northwest next week, bringing an increase in showers, particularly over the western end of the state around the middle of the week and again towards the end of the work week.

Discussion

This afternoon's radar and satellite imagery show clouds and a few showers moving into windward areas as a plume of moisture rides in on the ESE trades, as well as forming over leeward and interior areas with the localized sea breezes. Only light rainfall amounts are expected with these brief passing showers due to limited available moisture and increasing stability as mid-level ridging builds in from the west.
A progressive pattern to our north will bring a series of fronts to our doorstep over the next several days, periodically disrupting the trades and bringing an increase in showers to the western end of the state. Between each front, the surface ridge to the northeast of the state will try to reestablish itself, but will have a hard time doing so as each front will be followed closely by its successor. In this pattern, the main forecast focus will continue to revolve around wind trends and rain chances.
The first of these fronts will approach tomorrow into Sunday, then dissipate northwest of the state. As this boundary approaches, it will act to weaken the local pressure gradient and maintain light winds across the region through early next week. Since the moisture associated with this frontal boundary isn't expected to reach the state, rain chances will be driven by the light ESE trades that will allow for clouds and showers to generally focus over windward and mauka areas overnight, then transition to focus over leeward and interior areas with sea breeze development each afternoon.
The second front will approach early to mid week next week and may increase rain chances over the western end of the state Tuesday night into Wednesday as the frontal boundary dissipates near Kauai. However, model guidance shows both the boundary and its moisture field mostly dissipating before reaching the state, so not expecting much of an uptick in shower activity with this front either.
Then ahead of the third front, winds will turn southerly across the region Wednesday and Thursday, allowing the boundary layer to moisten up and inversion heights to rise, bringing a slight increase in shower activity, particularly over the western end of the state. The third front looks to approach towards the end of the work week, potentially bringing another, slightly more significant bump in rain chances for the western end of the state Thursday night into Friday.

Aviation

A surface ridge just north of the islands gradually shift southward, which will bring light and variable winds across many areas of the state tonight into Saturday. Afternoon clouds today should decrease this evening and tonight as land breezes develop across many areas. Sea breezes developing during the day on Saturday will bring an increase of clouds and a few showers during the afternoon on Saturday. Brief MVFR ceilings will be possible with any shower development during the afternoon.
No AIRMETs are expected.

Marine

Strong high pressure remains over the northeastern Pacific, with a ridge extending southwest to just north of Hawaii. The ridge will shift south this evening, causing low-level winds to weaken and shift more southeasterly by late evening, then become light and variable over the western end of the island chain late tonight into Saturday. Light to moderate easterly trade wind flow will return Sunday into next week as high pressure rebuilds north of the state.
The current west-northwest swell will continue its gradual decline through tonight. The next significant northwest swell is due late Saturday into early next week, with peak surf heights nearing and potentially reaching warning levels along north and west facing shores Saturday night and Sunday. Will likely need a High Surf Advisory or Warning issued sometime Saturday. Another similarly- sized northwest swell is expected to build in Tuesday night and linger through Wednesday.
Small surf is expected along east facing shores over the next week as trade winds remain light. Surf along south facing shores should see a small boost through Saturday as a small south swell fills in.

HFO Watches/Warnings/Advisories

None.

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