West Kaua’i

Tonight: Mostly clear. Lows around 70 near the shore to around 59 above 3000 feet. Northeast winds up to 10 mph in the evening becoming light.

Tuesday: Mostly sunny. Highs around 85 near the shore to around 72 above 3000 feet. East winds up to 15 mph shifting to the southeast in the afternoon.

Tuesday Night: Partly cloudy. Lows 67 to 72 near the shore to around 58 above 3000 feet. Light winds.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows around 69. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the morning. Highs 78 to 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows around 70. Northeast winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy with isolated showers. Lows 63 to 69 in the valleys to around 57 above 4000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the morning. Highs 72 to 82 in the valleys to around 64 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 63 to 69 in the valleys to around 57 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening. Lows 63 to 71. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs 76 to 84. Southeast winds up to 15 mph.

Tuesday Night: Partly cloudy. Lows 63 to 71. Southeast winds up to 10 mph.

East Kaua’i

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 74. Northeast winds up to 10 mph shifting to the north after midnight. Chance of rain 30 percent.

Tuesday: Mostly sunny. Isolated showers in the morning. Highs 72 to 83. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 63 to 74. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Passing weather systems to the north will keep light to moderate east to east-southeast winds and drier conditions in place for much of this week. A cold front will approach the state during the second half of the week, but likely stall out and diminish west of Kauai over the weekend.

Discussion

A surface ridge remains just north of the islands with plenty of mid- to upper-level ridging. The CIMMS MIMIC precipitable water shows a large area of drier air moving in to the area from the east, which is also reflected in the afternoon soundings from Hilo and Lihue. As a result, the visible satellite imagery shows only scattered clouds over most of the island chain this afternoon, moving into windward areas and developing over some leeward terrain where sea breezes have developed in the more wind- sheltered spots. This dry and stable weather pattern will continue for much of this week with little variation overall. Trade wind speeds will be somewhat subdued as a series of cold frontal systems pass by farther to the north this week, weakening the ridge.
By Wednesday evening, a stronger cold frontal system moves closer to the state, driving the weakened ridge farther south over the Hawaiian Islands from Thursday to Friday. Lighter east to southeast winds will develop from Thursday onward into the weekend, expanding the coverage of daytime sea breezes to leeward areas of all islands. Not much in the way of showers expected during this time period as well, with the ridge over the islands keeping conditions fairly stable. One exception to this rule will be along the southeast slopes of the Big Island, where southeasterly wind flow will lift clouds up the slopes of Mauna Loa, potentially enhancing clouds and showers over Kau and Puna Districts.
These lighter winds will continue through the weekend as the approaching cold front appears to stall out and dissipate just west of Kauai. Light southerly winds ahead of this front may increase shower activity over Kauai and Niihau for Saturday and Sunday, however, model solutions are fairly inconsistent on this from run to run. The rest of the state will likely remain on the drier side in a hybrid sea breeze/east- southeast wind pattern. Long-term guidance is hinting at another cold front approaching the islands early next week that may bring some southerly winds and wet weather to portions of the state.

Aviation

A surface ridge to the north will maintain light to moderate trade winds over the next few days, weakening slightly tomorrow. Terrain sheltered areas could see afternoon seabreezes as well. Strong ridging aloft is currently keeping showers brief and isolated, this should continue through the forecast period. TEMPO MVFR is possible in any passing showers.
No AIRMETs in effect and none are expected.

Marine

A ridge of high pressure located a few hundred miles north of the state will gradually move southeast and will be near or over the state by Wednesday or Thursday. This will cause our current moderate to locally fresh easterly trade winds to gradually weaken over the next several days and veer toward the southeast. The forecast beyond Thursday will be highly dependent on the evolution of a large North Pacific storm developing Thursday into Friday. Latest global models and its ensemble members are in line with a front approaching the state from the northwest Friday into Saturday with the front stalling and weakening within the vicinity of Kauai Saturday into Sunday. Although the details remain uncertain regarding thunderstorm chances, confidence is increasing for large seas above the Small Craft Advisory thresholds (10 ft or higher) Saturday night into Sunday. A smaller but still large northwest to north- northwest swell could also push seas near the SCA threshold over Thanksgiving.
The current northwest swell will steadily decline through Tuesday. A large long-period northwest to north-northwest (320-330 degree) swell is expected to fill in throughout the day Wednesday and will likely exceed advisory thresholds sometime Wednesday afternoon. Altimeter passes from this morning show the swell running several feet above guidance thresholds, which increases confidence for the swell to peak well above advisory thresholds Wednesday night into Thursday. The NW-NNW swell could briefly near warning thresholds late Wednesday night into Thursday morning.
A large storm force low is expected to develop across the West Central Pacific (roughly 1500 nm NW of Oahu) on Thursday and could send our first extra large northwest swell of the season Saturday night into Sunday along north and west facing shores. There are still some differences regarding the intensity of the low with each model run, but nonetheless we should see an extra large swell by next Sunday. Although it will be highly dependent on the intensity, the size of the low and the close proximity of the fetch gives potential for possible giant surf next Sunday.
Surf along east facing shores will decline over the next several days due to the trade winds weakening.

Fire weather

Winds and humidity levels will remain below critical fire weather thresholds this week. Brief passing showers will tend to favor island interiors during the afternoons and windward areas overnight into the early mornings.

HFO Watches/Warnings/Advisories

None.

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