West Kaua’i

Tonight: Mostly cloudy with isolated showers. Haze. Lows around 69 near the shore to around 59 above 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Haze through the day. Highs 81 to 86 near the shore to around 74 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy in the evening then becoming partly cloudy. Haze in the evening. Lows around 69 near the shore to around 59 above 3000 feet. Light winds.

South Kaua’i

Tonight: Mostly cloudy with isolated showers. Haze. Lows around 70. Light winds. Chance of rain 20 percent.

Sunday: Partly sunny. Isolated showers in the morning. Haze through the day. Highs 79 to 86. Northeast winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 20 percent.

Sunday Night: Mostly cloudy. Haze in the evening. Lows around 70. Light winds.

Kaua’i Mountains

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 61 to 67 in the valleys to around 57 above 4000 feet. Light winds. Chance of rain 30 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs 73 to 80 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 20 percent.

Sunday Night: Haze in the evening. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 61 to 67 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Tonight: Mostly cloudy with isolated showers. Haze. Lows 63 to 71. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Haze through the day. Highs 75 to 83. South winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy in the evening then becoming partly cloudy. Haze in the evening. Lows 62 to 71. Light winds.

East Kaua’i

Tonight: Mostly cloudy with isolated showers. Haze. Lows 62 to 73. Light winds. Chance of rain 20 percent.

Sunday: Partly sunny. Haze. Highs 73 to 84. West winds up to 10 mph shifting to the southeast in the afternoon.

Sunday Night: Mostly cloudy in the evening then becoming partly cloudy. Haze in the evening. Lows 61 to 73. Light winds.

Detailed Forecast

Synopsis

A stable southeasterly flow will continue to produce a land and sea breeze weather pattern with little rainfall through Tuesday. A weakening front may reach the western end of the island chain on Wednesday, followed by developing easterly trade winds late next week.

Discussion

Stable and mostly dry conditions persist under light winds. The subtropical ridge has been displaced southward to near Kauai, keeping southeast winds over most islands with a shift out of the south over the Garden Isle. As a result, most islands remain within a light flow in the downwind wake of the Big Island, allowing land and sea breezes to dominate. A ridge aloft parked overhead is maintaining a somewhat strong inversion around 6,500 feet, while precipitable water is largely below seasonal normal. These ingredients are producing scant rainfall, even as afternoon sea breezes generate clouds over interior terrain. The exception is on Kauai, where a shallow and diffuse area of moisture just to the south could produce a few brief showers over land. The southeasterly flow is also carrying some volcanic emissions from recent activity at Kilauea over most islands. While air quality sensors are not showing high concentrations and there is no significant restriction to visibility, a noticeable haze persists.
Expect little change through Tuesday. The subtropical ridge may briefly retreat slightly northward on Monday, but overall, the regional flow will remain southeasterly, with land and sea breezes dominating over land. The atmosphere will remain stable, and aside from a few lingering showers near Kauai and Niihau tonight, rainfall will continue to be minimal. Thin high clouds will periodically spread of the islands, and the widespread volcanic haze (vog) will likely stick around through Sunday, followed by an expected decrease in most areas on Monday.
A front could produce an increase in rainfall on the western end of the state on Wednesday, but confidence remains low as the GFS and ECMWF continue to disagree on how far the front will advance eastward. The latest runs of the GFS are keeping nearly all of the associated rainfall west of Kauai, while 12Z ECMWF depicts the front passing over Kauai before stalling just west of Oahu. Ensembles of both models do not show high probabilities of significant rainfall accumulation, with the wettest ECMWF scenario suggesting a couple of inches on northern slopes of Kauai.
Easterly trade winds will likely develop Thursday and Friday, bringing showers to windward slopes of all islands and pushing the stalled front west of Kauai.

Aviation

Surface observations from across the islands show light southeast background flow this afternoon. The light background winds have resulted in localized sea breezes and increased cloud cover over island interiors today. These interior clouds will clear once again overnight as land breezes resume.
Little change in the overall weather pattern is expected on Sunday, with daytime sea breezes and overnight land breezes. Stable conditions will limit rainfall potential throughout the rest of the weekend. VFR flight conditions will prevail at most locations.
There are currently no AIRMETs in effect, and none are anticipated at this time.

Marine

A ridge of high pressure will dominate over the Hawaiian Islands into early next week. Expect light to moderate southeast winds, with near shore sea breezes each day. An approaching cold front will stall just northwest of Kauai on Sunday, then a second cold front may approach the western islands on Wednesday. Current model guidance suggests this front will stall just W of Kauai before getting pushed back to the west by Thursday onward. An XL northwest swell will continue building into Hawaiian waters today, peaking Sunday, and slowly declining on Monday. Combined seas for Hawaiian Coastal Waters exposed to WNW swell will maintain above Small Craft Advisory levels (above 10 feet) through early next week.
An XL WNW swell will continue building into the region this afternoon through the evening. This swell will bring dangerous surf heights ranging from 25 to 45 feet along most N and W facing shores with larger waves over select outer reefs. This swell will peak Sunday morning, and slowly decline on Monday. A High Surf Warning remains in effect for the N and W facing shores of the smaller islands. And along the west facing shores of the Big Island, as warning level surf builds in rapidly tonight. Another moderate to large NW swell is possible for the second half of next week from another potential gale to storm force low that weather models are developing in the NW Pacific.
East shore surf will remain small through the weekend due to weak winds. Select south facing shores could experience westerly wrap from this weekend's large WNW swell passage.

Fire weather

Rather dry conditions are expected to persist through Tuesday. Winds will be light and variable under a stable land and sea breeze pattern, preventing critical fire weather thresholds from being approached. With the inversion holding around 6,500 ft, very dry conditions will persist on the upper elevations of the Big Island and Maui.

HFO Watches/Warnings/Advisories

High Surf Warning until noon 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.
High Surf Warning until noon HST Monday for Kona, Kohala.
Small Craft Advisory until noon HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.

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