West Kaua’i

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 86 to 91 near the shore to around 77 above 3000 feet. East winds up to 15 mph shifting to the south in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 71 to 76 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 86 to 92 near the shore to around 78 above 3000 feet. Light winds. Chance of rain 50 percent.

South Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 83 to 91. Northeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 83 to 91. Northeast winds around 10 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 85 in the valleys to around 67 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 64 to 71 in the valleys to around 60 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 76 to 85 in the valleys to around 68 above 4000 feet. East winds around 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening, then mostly cloudy with scattered showers after midnight. Lows 66 to 74. Southeast winds up to 10 mph. Chance of rain 40 percent.

Tuesday: Partly sunny with scattered showers. Highs 79 to 89. East winds up to 10 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 76 to 88. South winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 65 to 78. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 76 to 88. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Drier air moving into the stable, light to moderate trade wind flow over the islands will limit shower activity on most islands. Hurricane Kiko is forecast to pass north of the island chain Tuesday and Wednesday, disrupting the trade winds, producing increased humidity with areas of heavy rainfall, and generating large surf along east facing shores.

Discussion

No changes to the first few days of the forecast, with only minor changes in the forecast beyond that. Satellite derived precipitable water imagery shows a drier slot of air moving over the islands this morning. This drier air will help to limit shower activity today.
A trough to the northwest of the islands continues to move west away from the islands. This will allow a bit of an uptick in wind speeds today, however some localized land and sea breezes will remain a possibility. Hurricane Kiko is about 425 miles east of Hilo this morning, and is moving to the northwest. Towards sunset, moisture along the western flank of weakening Kiko will near the windward coasts of the Big Island and Maui.
The latest National Hurricane Center forecasts continue to show Kiko weakening to a tropical storm as it passes north of the islands Tuesday and Wednesday. Confidence in this scenario is increasing, though interests in Hawaii should continue to monitor official forecasts for Kiko. Moisture along the periphery of the system will spread over the state Monday night and Tuesday. Initially, this will provide an increase in clouds and mainly windward showers, but as trade winds become disrupted, afternoon sea breezes will likely trigger spotty interior rainfall. These showers could be locally heavy in places, and we cannot rule out a brief thunderstorm as the atmosphere destabilizes on Tuesday. As dew points creep into the low to mid 70s, rather humid conditions will prevail. In addition, large surf will affect east facing shores, and see the marine section of this discussion for more details.
As Kiko moves off to the northwest of the state on Wednesday night and Thursday, moderate trade winds and a ridge aloft are expected to build in from the east. The resulting stable conditions will bring a drier air mass with a typical pattern of windward rainfall and dew points dropping back into the mid 60s.

Aviation

Light to moderate trades expected today with localized land/sea breezes. An increase in clds and SHRA is expected this afternoon. MVFR conds possible in SHRA. VFR should prevail otherwise.
Tropical Cyclone Kiko will approach the islands from the southeast over the next few days. The National Hurricane Center is currently forecasting Kiko to pass north of the islands on Tuesday. Any deviation south of this forecast track may result in wind and rain impacts to the state.
AIRMET Sierra for mtn obsc is in effect for Oahu. Conds should improve by mid-morning. AIRMET Sierra may be needed this afternoon and evening for mtn obsc as moisture from Tropical Cyclone Kiko moves into the area.

Marine

A weak trough northwest of the state will continue to drift westward, away from the state today. A brief stint of moderate to locally fresh trade winds are expected through tonight.
Hurricane Kiko, which was located approximately 375 NM E of Hilo this morning continues to track west- northwest in the Central Pacific. According to the latest forecast from the National Hurricane Center, Kiko is expected to enter the eastern offshore waters this evening as a Tropical Storm. Kiko will then continue to weaken and move west-northwest through the offshore waters. A Tropical Storm Warning is in effect for the offshore waters with Tropical Storm conditions expected over the E and NE offshore waters tonight through Wednesday. The latest forecast for the coastal waters, shows strong confidence for Kiko to stay north of the coastal waters. Although no wind impacts are expected over the coastal waters, a quick rise of wave heights are expected tonight into Tuesday as Kiko passes.
Surf along east facing shores will slowly rise today as swell energy from Tropical Cyclone Kiko arrives. Latest buoy observations from buoy 51004 has started to pick up energy in the 11 to 13 second spectral bands throughout the night. Surf will likely come in below advisory thresholds through today. But, as Kiko moves northwest, a rapid rise of a short lived east swell is expected to fill in, peak potentially at low end High Surf Warning levels Tuesday, before declining through Wednesday. A High Surf Warning for east facing shores will likely be issued this afternoon. Note, peak surf heights will be highly dependent on the track and intensity of Kiko as it nears the state.
A moderate long period south-southwest swell has filled in overnight, likely peak this morning and will slowly decline this afternoon before another reinforcing swell out of the south- southwest is expected on Tuesday. This should help maintain surf near or slightly above the summer average throughout the first half of the week. Additionally, multiple small pules of northwest swell energy will generate small surf along north facing beaches throughout the week.

Fire weather

Winds are forecast to remain below critical fire weather thresholds for the next few days. A narrow slot of very dry and stable air will move over the islands from east to west on the weak trade wind flow today. This could push the inversion down to around 4,000 feet and produce very low humidity at higher elevations of the Kaala Fire in the Hamakua District of the Big Island. Increased humidity and higher chances for rainfall are expected Monday night into Wednesday and Tropical Cyclone Kiko passes north of the state.

HFO Watches/Warnings/Advisories

None.

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.