West Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 64 to 69 near the shore to around 57 above 3000 feet. Light winds. Chance of rain 40 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 77 to 85 near the shore to around 71 above 3000 feet. Light winds. Chance of rain 40 percent.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 67 near the shore to around 58 above 3000 feet. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

South Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 67. Northeast winds up to 10 mph. Chance of rain 40 percent.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 84. East winds around 10 mph. Chance of rain 20 percent.

Monday Night: Mostly cloudy with isolated showers. Lows around 67. Light winds becoming northeast around 10 mph after midnight. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 57 to 67 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 50 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 40 percent.

Monday Night: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows 57 to 66 in the valleys to around 55 above 4000 feet. East winds around 10 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 60 to 68. Light winds. Chance of rain 40 percent.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 80. East winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 61 to 68. East winds around 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 61 to 71. Light winds. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers. Highs 72 to 83. East winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 60 to 71. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

Detailed Forecast

Updated

UPDATED FOR HIGH SURF WARNING FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI OAHU MOLOKAI AND NORTH FACING SHORES OF MAUI.
.SYNOPSIS…
Light to occasionally moderate east to southeasterly winds are expected to continue through most of the week and into next weekend, with only slight variations in speed and direction. In this flow, clouds and showers will favor windward areas overnight and leeward and interior areas in the afternoon where sea breezes develop. Overall, shower activity will be limited. However, moisture from a front expected to stall just north of Kauai may bring an up tick in shower to the western end of the state tonight into tomorrow and an upper level disturbance may bring another uptick in showers midweek.

Discussion

This afternoon's radar, satellite imagery and surface observations show that sea breezes are in full swing with clouds and isolated showers building over island interiors.
The approach of a cold front from the northwest will keep the ridge axis shifted south of its usual position and nearly atop of the island chain, maintaining a light east-southeasterly flow across the state through tomorrow. The cold front will stall north of the state tonight, along with the bulk of its moisture. However, if the front manages to sag a bit further south than what current model guidance is showing, its moisture field could bring a slight bump in shower activity to the western end of the state tonight into tomorrow. Otherwise, in this lighter flow, the east- southeasterly winds will help to focus low clouds and showers over windward areas, particularly overnight, while land breezes will help to bring clearing to leeward areas by morning. Sea breezes will then bring cloud buildups and a few showers to leeward and interior areas during the day. Overall, shower activity will be limited as mid-level ridging tries to build overhead, increasing atmospheric stability, and drier air continues to filter in from the east.
This pattern is expected to persist through most of the week and into next weekend as a progressive pattern to the north keeps the surface ridge relegated south of its usual position and light to moderate east to southeasterly winds persist across the state. A possible deviation from this pattern may occur Tuesday into Wednesday as a perturbation in the flow aloft moves overhead and increases atmospheric instability, which may lead to a slight uptick in shower activity as pockets of moisture move in on the east to southeasterly flow. Then models show reasonable agreement on mid- level ridging building back overhead for the latter part of the week and into the weekend, which will help to suppress shower activity once again.

Aviation

Light east-southeast winds through Monday as a cold front passes north of the area. Daytime sea breezes will continue through sunset that will bring interior clouds with with isolated showers, followed by clearing tonight with land breezes.
AIRMET Sierra is posted for tempo mountain obscurations over Kauai above 2500 feet. These clouds will dissipate around sunset and the AIRMET will be dropped. No other AIRMETs are expected through Monday morning.

Marine

Moderate to locally fresh east southeast winds will continue to ease through the day in response to a surface ridge weakening and settling south into the area as a front approaches. This front is expected to stall just north of Kauai later tonight into Monday, resulting in light to locally moderate east-southeast winds across the area through Monday, with the lightest winds near Kauai. Winds will then increase slightly and shift out of the southeast across much of the island chain through Tuesday night, as low pressure develops far northwest of the state. Little change is expected in this pattern through Friday.
A long-period northwest (305-325 degrees) swell is quickly building down the island chain tonight, as reflected in the nearshore buoy obs, and will peak tonight through early Monday. The High Surf Advisory (HSA) has been upgraded to a High Surf Warning for most north and west facing shores of the smaller islands through Monday afternoon. A HSA will likely be issued for west facing shores of the Big Island in morning package. A Small Craft Advisory has been issued for exposed waters due to seas expected to exceed 10 feet with this swell. The swell will gradually ease Tuesday through midweek as it shifts out of the north.
Choppy east shore surf, already below seasonal averages, will drop further through the rest of the weekend and remain small through the upcoming week as wind speeds remain on the lighter side. South shore surf will remain seasonably small, though a small bump is possible around midweek.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Monday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 PM HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters.

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