West Kaua’i

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 67 near the shore to around 57 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 79 to 87 near the shore to around 74 above 3000 feet. Light winds. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows around 67 near the shore to around 57 above 3000 feet. Light winds becoming northeast up to 15 mph after midnight.

South Kaua’i

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

Sunday: Sunny and haze. Highs 81 to 87. Northeast winds up to 15 mph.

Sunday Night: Mostly clear. Isolated showers after midnight. Lows around 68. Northeast winds 10 to 15 mph. 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.

Sunday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 74 to 80 in the valleys to around 66 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with scattered showers. Lows 58 to 67 in the valleys to around 56 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

North Kaua’i

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

Sunday: Sunny and haze. Highs 75 to 83. Northeast winds up to 10 mph.

Sunday Night: Partly cloudy with isolated showers. Lows 61 to 69. Southeast winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly clear. Lows 61 to 70. South winds up to 10 mph in the evening becoming light.

Sunday: Sunny. Haze through the day. Isolated showers in the afternoon. Highs 75 to 85. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 61 to 72. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Stable and rather dry southerly winds will give way to a less humid, developing trade wind flow on Sunday, while areas of volcanic haze affect much of the island chain. Trades will gradually become breezy and gusty Monday and Tuesday as modest showers become focused over windward slopes. By Wednesday, a weak disturbance aloft combined with increased moisture will produce breezy conditions and a possible increase in mainly windward showers.

Discussion

Deep ridging over the island chain will maintain stable and dry conditions through tonight while humidity eases. A surface ridge has been creeping northern today and currently sits near Kauai, resulting in gentle south winds around Kauai, southeasterlies across Oahu and Maui County, and developing easterly trade winds on the Big Island. Only one gage across the entire state managed to measure any rainfall since mid morning, as a ridge aloft maintains very stable conditions with little available moisture. The southerly winds have kept dew points in the upper 60s to lower 70s across most islands today, maintaining elevated humidity by winter standards, and multispectral satellite imagery suggests that the greatest concentrations of volcanic haze (vog) remain confined Maui County and leeward Big Island. As the surface ridge creeps northward tonight, the rather dry east to southeast flow and vog will spread as far west as Oahu. Rainfall will continue to be sparse, and humidity will ease as dew points fall into the low to mid 60s.
Gentle to moderate trade winds will spread across the entire island chain on Sunday, as the surface ridge moves northward and a stronger area of high pressure develops far to the northwest. The persistent ridge aloft will maintain stable and rather dry conditions. The highest chance of any rain will be across windward slopes, but since Kauai will be the last island to experience the resurgent trades, leeward areas may see afternoon clouds with a chance of light showers. In addition, vog should be clearing Maui County and Oahu.
Trade winds will strengthen on Monday and Tuesday. The above mentioned surface high will build to 1032 mb roughly 700 miles north of Kauai, driving moderate to locally breezy trade winds. Stable conditions will persist, but expect some increase in mainly windward showers. That said, shower chances may be higher on windward Kauai as moisture from a dissipated front drifts close to or over Kauai.
Shower frequency will likely increase within the breezy and gusty trade wind flow by Wednesday. A disturbance aloft will move overhead and produce modest instability as the inversion is eliminated. The above mentioned frontal remnant may serve as a source of enhanced moisture to fuel increased, mainly windward, rainfall later in the work week.

Aviation

A weak surface ridge over the state will produce light to moderate southerly flow across the western islands and southeasterly flow across the eastern islands. Moderate easterly trade winds fill in by Sunday.
VFR conditions will prevail with no AIRMETs expected.

Marine

A ridge of high pressure over the islands is currently weakening as a front approaches from the northwest. Light to moderate south to southeasterly winds will gradually give way to moderate trade winds tomorrow as the front stalls out and weakens, allowing trade winds to strengthen. A new high building north of the state early next week will bring strong trade winds to the island chain which will continue through late next week. A Small Craft Advisory will likely be needed for winds across a large portion of the marine area much of next week.
The current northwest swell will continue to decline through the remainder of the weekend until a new moderate to large northwest swell arrives Monday. This swell could bring another round of advisory level surf to most north and west facing shores late Monday through Tuesday. This swell will then gradually lower through Thursday with a new large northwest swell possibly bringing another round of advisory level surf to north and west facing shores late next week.
A small bump in surf along south facing shores is possible tomorrow and Monday before before fading out and returning to very small levels through late next week. Surf along east facing shores will remain small through tomorrow then increase with the returning trades tomorrow night and Monday. Surf should then rise to above normal levels Tuesday through late next week as the trade winds further strengthen.

HFO Watches/Warnings/Advisories

None.

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