Photo Credit: Brendan Stephen

West Kaua’i

Tonight: Mostly cloudy with isolated showers. Lows 67 to 72 near the shore to around 58 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly cloudy in the morning then becoming mostly sunny. Isolated showers. Highs around 88 near the shore to around 76 above 3000 feet. Northwest winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Monday Night: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows 67 to 72 near the shore to around 58 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 71. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Mostly cloudy with scattered showers. Highs around 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 65 to 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Cloudy with numerous showers. Lows 58 to 63 in the valleys to around 53 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Monday: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 58 to 63 in the valleys to around 53 above 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy with scattered showers. Lows 61 to 71. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy with scattered showers. Highs 78 to 87. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 61 to 71. Southeast winds up to 10 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Cloudy with scattered showers. Lows 59 to 73. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday: Mostly cloudy with scattered showers. Highs 78 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 59 to 73. North winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Localized heavy showers and a few thunderstorms remain possible along a dissipating frontal boundary stalling over Maui County tonight through Monday. Although most of this activity will favor windward areas with moderate to breezy northeast winds filling in, some showers will make it into leeward areas periodically. As drier and more stable conditions set up over the western end of the state behind the front, a transition to a wet pattern will be possible for the Big Island Wednesday through the second half of the week as an area of tropical moisture moves in from the southeast.

Discussion

Guidance remains in good agreement and shows the frontal boundary that has moved into the area stalling and diminishing tonight through Monday around Maui County. This front has already brought heavy showers and thunderstorms through Kauai and portions of the state today, and more can't be ruled along its boundary out before it diminishes. A shortwave trough quickly diving southward toward the area supports this potential continuing through Monday. For this reason, thunderstorms have been included through Monday for Maui County and the Big Island where the best source of deep moisture and instability will setup. Trade winds will briefly strengthen along and behind the front due to high pressure building to the north, but should begin to weaken slightly by Monday night. While the trades will focus most of the rainfall across windward areas, both windward and leeward areas could see locally heavy showers.
Some drier air and more stable conditions are expected for the western end of the state Monday through Tuesday as the frontal boundary stalls and diminishes over the eastern end of the state. An area of tropical moisture moving in from the southeast could lead to a wet pattern setting up for windward and southeast portions of the Big Island through the second half of the week. Some of this moisture may spread far enough north that the trade winds carry a small bit of it over the smaller islands by next weekend.

Aviation

A front slowly pushing across the central smaller islands, will stall near Maui, and maintain widespread showers through tonight. This will generate periods of MVFR cigs and vsby, with pockets of IFR conds also possible. Additionally, a few thunderstorms will linger along and near the front into early Monday. The drier conditions near the Big Island this afternoon, will diminish tonight as the band of moisture drops southeastward, beginning to deteriorate conditions over windward areas.
AIRMET Sierra continues for tempo mountain obscuration across portions of the western and central islands, as abundant moisture continues MVFR continues through tonight.

Marine

A weakening front is currently moving over portions of the area from the north. Locally heavy showers and isolated thunderstorms can be expected along the frontal boundary. The front is expected to stall near Maui or the Big Island on Monday and gradually dissipate. Northeast trade winds will fill in behind the front but will generally remain at light to locally moderate levels through Friday.
A series of small to medium size swells from around the compass can be expected over the next several days. The current small and rather short period north swell will linger through tonight before being reinforced by a slightly larger and somewhat longer period north swell Monday and Tuesday. This swell will then lower gradually through Wednesday night before another similar size north swell fills in during the Thursday through Saturday time period. Also a couple of small pulses from the northwest can be expected through Thursday. A new small south swell will continue to fill in tonight, peak on Monday then lower gradually into the middle of the week. Mainly background south swell energy is then expected Thursday and Friday with a larger south swell possible by around Saturday. Due to the lack of trade winds over and upwind of the state, short period choppy surf will remain rather small through the week with most east facing shore surf coming from north swell wrap.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov