West Side

Tonight: Partly cloudy. Breezy. Chance of showers in the evening, then slight chance of showers after midnight. Lows 66 to 73. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 77 to 83. East winds 10 to 20 mph.

Sunday Night: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 72. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

South Side

Tonight: Mostly clear. Breezy. Lows 64 to 75. Northeast winds 10 to 20 mph.

Sunday: Sunny and breezy. Highs around 87. Northeast winds 10 to 25 mph.

Sunday Night: Mostly clear. Lows 64 to 74. North winds 10 to 15 mph.

North Shore

Tonight: Mostly cloudy with showers likely. Lows around 68 near the shore to around 50 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday: Breezy. Mostly cloudy with showers likely in the morning, then mostly sunny with chance of showers in the afternoon. Highs 77 to 82 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday Night: Mostly cloudy with showers likely. Lows around 68 near the shore to around 50 near 5000 feet. East winds around 15 mph. Chance of rain 70 percent.

Central Maui

Tonight: Breezy. Partly cloudy with a 20 percent chance of showers. Lows around 67. Northeast winds 15 to 20 mph.

Sunday: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 80 to 87. East winds 15 to 25 mph.

Sunday Night: Partly cloudy with isolated showers. Lows around 66. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Tonight: Partly cloudy with a 50 percent chance of showers. Lows around 44 at the visitor center to around 48 at the summit. East winds 10 to 15 mph.

Sunday: Mostly sunny. Breezy. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs around 62 at the visitor center to around 58 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday Night: Breezy. Partly cloudy with scattered showers. Lows around 44 at the visitor center to around 47 at the summit. East winds 15 to 20 mph. Chance of rain 50 percent.

East Maui

Tonight: Mostly cloudy with showers likely. Lows around 68 near the shore to around 50 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday: Breezy. Mostly cloudy with showers likely in the morning, then mostly sunny with chance of showers in the afternoon. Highs 77 to 82 near the shore to around 66 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday Night: Mostly cloudy with showers likely. Lows around 68 near the shore to around 50 near 5000 feet. East winds around 15 mph. Chance of rain 70 percent.

Lanai City

Tonight: Mostly clear. Breezy. Lows around 64. Northeast winds 10 to 20 mph.

Sunday: Sunny and breezy. A 20 percent chance of showers in the afternoon. Highs 73 to 81. Northeast winds 10 to 20 mph.

Sunday Night: Mostly clear. Lows 61 to 66. Northeast winds 10 to 15 mph.

Kaunakakai

Tonight: Breezy. Partly cloudy with a 20 percent chance of showers. Lows 56 to 72. Northeast winds 10 to 20 mph.

Sunday: Breezy. Mostly sunny with a 20 percent chance of showers. Highs 69 to 86. East winds 10 to 20 mph.

Sunday Night: Breezy. Partly cloudy with isolated showers. Lows 56 to 72. East winds 15 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A series of high pressure systems building to the northwest and north of the state will keep trades blowing during the next 7 days. The trades will peak at breezy to windy levels on Sunday, then ease to moderate and locally breezy levels Monday through late next week. A band of moisture associated with an old front will keep showery conditions affecting Kauai tonight through Monday, while drier trade wind weather persists across the remainder of the state. The band of moisture will shift southward Monday night and Tuesday, then meander across the island through Thursday, bringing periods of showery weather to windward areas. The deepest moisture appears to lift back northward Friday and next Saturday, allowing a more typical and uniform distribution of showers to return to the island chain.

Discussion

Currently at the surface, a weakening stationary front is located just north of the state, while a 1034 mb high is centered around 1050 miles northwest of Honolulu. The resulting gradient is producing breezy to locally windy trades across the island chain this evening. Infrared satellite imagery shows variably cloudy skies in windward areas with clear to partly cloudy conditions in most leeward locales. Radar imagery shows isolated to scattered showers moving into windward areas, with a brief shower occasionally reaching leeward communities. Shower coverage is the highest on Kauai in closest proximity to the stationary front. Main short term focus revolves around rain chances and trade wind trends.
The strong high pressure system northwest of the state will peak out at around 1035 mb on Sunday. This in combination with inversion heights lowering to around 6 kft Sunday afternoon over the eastern end of the state, will likely bring advisory level winds to some of the windier areas of Maui and the Big Island. A Wind Advisory will likely be required for portions of Maui County and the Big Island with the morning forecast package.
The high will weaken slightly Sunday night and Monday, but the gradient locally will remain quite strong keeping breezy trades in place. A front passing by to the north of the state and a weak trough moving in from the east should weaken the gradient Tuesday into Wednesday, easing the trades to moderate levels. A new strong high building north of the islands Thursday into next weekend, could bring a return of breezy trades to the state.
As for the remaining weather details, the moisture associated with an old front will remain in close proximity to Kauai tonight through Monday, keeping shower coverage the highest here, while drier trade wind weather prevails over the remainder of the state. The frontal remnants appear to push southward Monday night and Tuesday, bringing an increase in shower coverage from Oahu to the Big Island, with little change in the weather across Kauai. The band of enhanced moisture will then meander over the islands Tuesday night through Thursday, bringing periods of showery weather mainly to windward areas although the trades will allow some showers to reach leeward communities at times as well. The deepest moisture appears to lift back northward Friday and next Saturday, allowing a more typical and uniform distribution of showers to return to the island chain.

Aviation

Breezy trade winds will persist through the weekend and into early next week with passing low clouds and showers favoring windward and mountain areas. Looking at current satellite imagery, most of the shower activity will be focused across Kauai tonight as upstream low clouds and showers continue to funnel across the westernmost end of the state. Periods of MVFR or even brief IFR conditions can be expected with this activity. As such, AIRMET Sierra remains in effect for mountain obscuration on Kauai.
AIRMET Tango is in effect for low level turbulence downwind of terrain due to the breezy trade winds across the state.

Marine

Rough marine conditions are expected over the weekend due to a combination of fresh to strong trade winds, rough seas, and an ongoing long period north swell. Small Craft Advisory conditions are expected across most Hawaiian waters and may persist into Monday before gradually improving. Trade winds are forecast to ease slightly on late Monday and Tuesday, then rebuild late Wednesday. Seas should also dip below advisory levels early next week as both the winds relax and the large weekend swell subsides.
Due to the strength and direction of this northerly swell (340-360 degrees), moderate to heavy harbor surges are anticipated to continue in north-facing harbors through the weekend. A marine weather statement remains posted for this hazard.
The ongoing XL northerly swell will also continue to bring warning level surf heights along north and exposed east-facing shores, with advisory- level surf for exposed west-facing shores through Sunday. A gradual decrease in surf is expected through the first half of next week as the swell eases.
Small surf will persist along south-facing shores through early Sunday. A series of small south swells may bring slight increases in surf late Sunday into Monday and again around midweek.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Sunday for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
High Surf Advisory until 6 PM HST Sunday for Kauai Leeward, Waianae Coast, Maui Leeward West, Molokai West.
Small Craft Advisory until 6 AM HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov