West Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening. Lows 72 to 77 near the shore to around 63 above 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Saturday: Sunny. Highs 87 to 93 near the shore to around 80 above 3000 feet. East winds 10 to 15 mph.

Saturday Night: Mostly clear. Lows around 74 near the shore to around 63 above 3000 feet. East winds 10 to 15 mph.

South Kaua’i

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 76. East winds 10 to 15 mph. Chance of rain 30 percent.

Saturday: Mostly sunny. Breezy. Scattered showers in the morning. Highs 83 to 91. East winds 15 to 20 mph. Chance of rain 30 percent.

Saturday Night: Partly cloudy with isolated showers. Lows around 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 65 to 71 in the valleys to around 61 above 4000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 86 in the valleys to around 69 above 4000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Saturday Night: Breezy. Partly cloudy with isolated showers. Lows 66 to 72 in the valleys to around 61 above 4000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 67 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 79 to 90. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Isolated showers in the evening. Lows 66 to 76. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 67 to 79. East winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 88. East winds 10 to 15 mph. Chance of rain 40 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 67 to 79. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

High pressure building over the region will maintain moderate to locally breezy trades through early Sunday. A low-level trough associated with the remnants of former Tropical Cyclone Ivo will move into the vicinity of the Hawaiian Islands on Sunday bringing an increase in clouds and showers over mainly windward and mauka areas through Monday. Dry and stable conditions return on Tuesday and continue through the week.

Discussion

Satellite imagery shows a low-level trough northwest of Kauai departing the region towards the west this afternoon. This has allowed moderate to locally breezy trades to return to the islands as a surface ridge builds to the north. CIMSS MIMIC PW continues to show drier air filtering into the eastern half of the state this afternoon as a pocket of moisture moves across the western islands. This will result in a bit more clouds and showers over Kauai County and Oahu this evening compared to the rest of the state. Otherwise, expect typical summertime trade wind weather to continue into Saturday with limited clouds and showers moving into windward and mauka area.
Guidance continues to show another low-level trough associated with the remnants of former Tropical Cyclone Ivo moving near the state on Sunday and Monday. As the trough moves into the vicinity of the islands on Sunday expect humidity levels to steadily increase. Inversion heights will also lift to around 8,000 to 9.000 feet on Sunday and Monday which will help to enhance clouds and showers in a moderate to breezy trade wind weather pattern. However, confidence on the track of this trough remains low as remnant tropical systems tend to be smaller in size and can oscillate off the current track as time passes. If the system tracks further north than currently depicted there will be fewer clouds and showers across the islands, but any shift towards the south could result in a day or two of wet trades across some or all of the islands. Will continue to update the forecast as hi-res model data becomes available.
The trough looks to exit the region towards the west by Tuesday with high pressure quickly rebuilding across the area. This will result in dry and stable conditions returning to the state under moderate to breezy trades. Expect a return to typical summertime conditions on Tuesday, with limited clouds and showers over mainly windward and mauka area.

Aviation

Moderate trades gradually strengthen during the forecast period. Clouds and showers remain focused windward and mauka during this time. Isolated MVFR possible within showers but VFR prevails.
No AIRMETs in effect at this time.

Marine

A surface trough north of the islands will continue to move westward over the next couple of days. In its wake, surface ridging will allow trade winds to strengthen tonight through the weekend. Wind speeds are expected to reach Small Craft Advisory (SCA) level tonight, so that product has been issued and will go into effect at 6pm HST this evening.
Surf along south facing shores saw a slight bump this morning and will likely experience another small bump Saturday through early next week as a series of small long-period southerly swells move through. A small, medium-period northeast swell will keep surf somewhat elevated along east facing shores through the weekend. As this swell declines, the short-period energy will fill in and take over as trade winds increase into the weekend. North facing shores will remain flat to tiny through the forecast period except for areas that may be exposed to the small northeast swell.

Fire weather

Conditions should remain below critical fire weather thresholds into early next week. A low-level trough associated with the remnants of former Tropical Cyclone Ivo will across the region on Sunday and Monday bringing an increase in humidity and shower activity. Lower humidity and more stable conditions redevelop on Tuesday as high pressure rebuilds across the islands.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.