West Kaua’i

Tonight: Mostly clear. Scattered showers early in the evening. Haze early in the evening. Lows 67 to 72 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 82 to 89 near the shore to around 75 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy with isolated showers in the evening, then clear after midnight. Lows 67 to 72 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Haze early in the evening. Isolated showers. Lows around 70. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 80 to 87. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Monday Night: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 70. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Haze early in the evening. Scattered showers. Lows 61 to 68 in the valleys to around 57 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 74 to 80 in the valleys to around 65 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows 62 to 68 in the valleys to around 58 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Haze early in the evening. Partly cloudy with isolated showers. Lows 64 to 71. Southeast winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 84. East winds up to 15 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy with scattered showers. Lows 63 to 71. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 40 percent.

East Kaua’i

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Haze early in the evening. Scattered showers. Lows 63 to 74. East winds 10 to 15 mph shifting to the northeast after midnight. Chance of rain 40 percent.

Monday: Partly sunny with scattered showers. Highs 73 to 84. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday Night: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to breezy trades deliver clouds and showers to windward and mauka areas through next week. Localized areas of heavy rainfall may develop in the afternoon early this week and again toward the end of the week.

Discussion

Relatively low stability environment prevails this afternoon, a consequence of the weak upper low that has stagnated over the state during the last few days. This low has allowed pockets of heavy rain to develop over portions of leeward Big Island and Oahu during the last couple of days as transient bands of trade wind moisture have capitalized on the softened inversion. At press time, the islands reside between shower bands leaving little in the way of moisture to work with as the last vestiges of cyclonic flow aloft depart to the northeast. Residing on the southwest periphery of said cyclonic flow, Leeward Big Island may see another healthy convective response on Monday as another band of enhanced moisture transits the forecast area. This potentially amounts to nuisance type flooding, mainly limited to more flood prone areas.
Height rises then commence on Tuesday as shortwave ridging builds during mid-week. This period of mid/upper subsidence will be brief and unlikely to make a considerable difference in the existing thermodynamic profile, but a temporary decrease in shower intensity is still likely as increasing stability puts a firmer lid on convective depths.
During the latter half of next week, guidance indicates another closed low developing over, or in the vicinity of, the islands. Of mid-latitude origin, this low will feature a notably colder mid- level cold pool and has the potential to bring more meaningful instability to the area as moderate to breezy trades persist at the surface.

Aviation

Moderate east to east-southeasterly trades will persist through Monday, with wind speeds decreasing slightly. Expect VFR conditions to prevail, though MVFR conditions may arise in any shower activity.
No AIRMETs are currently in effect.

Marine

High pressure will remain centered far northeast of the state throughout much of this week. A weakening cold front to the northwest will weaken the ridge over the next few days, allowing trades to ease to gentle to fresh east to southeast winds across the region through Monday night. An upper level disturbance lingering near the islands will keep brief periods of wet weather in the forecast for coastal and offshore waters throughout the next several days.
A series of small south and south-southwest swells will maintain small south shore surf through Monday. A slightly larger south swell will further boost south shore surf up to seasonal averages during the middle to latter part of the week.
Surf heights along north and west-facing shores will remain small during the next 7 days. Surf heights along east-facing shores will remain choppy, particularly from Tuesday onward as trade winds increase a bit once again.

HFO Watches/Warnings/Advisories

None.

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