West Side

Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 73. East winds 10 to 15 mph. Chance of rain 20 percent.

Memorial Day: Mostly sunny with isolated showers. Highs 74 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 64 to 73. Northeast winds around 10 mph. Chance of rain 20 percent.

South Side

Tonight: Mostly clear. Lows around 68. Northeast winds 10 to 15 mph shifting to the north after midnight.

Memorial Day: Mostly sunny. Highs 77 to 88. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Monday Night: Mostly clear. Lows 66 to 71. Northeast winds 10 to 15 mph.

North Shore

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 53 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Memorial Day: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 53 near 5000 feet. East winds around 10 mph. Chance of rain 40 percent.

Central Maui

Tonight: Mostly clear. Lows around 68. Northeast winds 10 to 15 mph.

Memorial Day: Sunny. Isolated showers in the afternoon. Highs 81 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Lows around 67. East winds around 10 mph.

Upcountry

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 44 at the visitor center to around 40 at the summit. East winds up to 10 mph. Chance of rain 50 percent.

Memorial Day: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 52 to 68. East winds up to 10 mph in the morning becoming light. Chance of rain 40 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 44 at the visitor center to around 41 at the summit. Light winds. Chance of rain 20 percent.

East Maui

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 53 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Memorial Day: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Monday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 53 near 5000 feet. East winds around 10 mph. Chance of rain 40 percent.

Lanai City

Tonight: Mostly clear. Lows 59 to 66. Northeast winds 10 to 15 mph.

Memorial Day: Mostly sunny. Isolated showers in the afternoon. Highs 69 to 80. Northeast winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Mostly clear. Lows 59 to 66. Light winds.

Kaunakakai

Tonight: Partly cloudy. Lows 56 to 72. Northeast winds 10 to 15 mph.

Memorial Day: Sunny. Highs 68 to 87. East winds 10 to 15 mph.

Monday Night: Mostly clear. Lows 56 to 72. East winds 10 to 15 mph.

Detailed Forecast

Synopsis

The surface ridge north of Hawaii will weaken over the next couple of days, easing the trade winds down to more moderate levels through Friday. Drier conditions will persist this week with only brief passing showers in the forecast, mainly over windward and mountain areas during the overnight hours and some clouds over leeward terrain with afternoon sea breezes in the more wind-sheltered areas. Breezy trade winds return this weekend as the ridge builds north of the state.

Discussion

Current visible satellite imagery shows a weak front stretched out along 30N approximately 500 miles north of the state, acting to weaken the subtropical surface ridge. This will allow the trade winds to ease to moderate speeds over the islands through much of the coming week. Water vapor imagery shows ridging aloft over Hawaii between a couple of weak upper-level troughs to the north and the subtropical jet stream to the south. This pattern will remain largely unchanged through Friday, with a series of upper level troughs forming and dissipating north of the state. The stable downward motion/subsidence in over the islands will keep temperature inversion heights around the 4,000 to 6,000 foot level, limiting vertical cloud growth and shower activity through Friday. Brief passing showers remain in the forecast this week, though, favoring windward and mountain areas in the overnight to early morning time period, but are expected to remain mostly light with little rainfall accumulation.
The lighter overall wind flow will allow a hybrid sea breeze and trade wind weather pattern to develop from Monday through Friday. Surface heating will enhance the sea breezes along the wind sheltered leeward areas. This will result in cloud buildups along the leeward mountain slopes each afternoon, with perhaps a stray shower or two into the early evening hours. Otherwise, mostly stable conditions should prevail.
In the long-range forecast, some of the global models suggest a slight increase in shower trends. However, it will likely be subtle changes in the location and strength of some weak upper level lows that will drive our sensible weather for next weekend, so forecast confidence in shower activity is low this far out in time.

Aviation

Moderate to breezy trade winds will weaken slightly on Monday as clouds and showers favor windward and mauka areas. Expect mainly VFR conditions across the area, with isolated MVFR under passing showers.
AIRMET Sierra for tempo mountain obscuration remains in effect across windward Kauai as a band of moisture continues to move into the island. With drier air upstream expect conditions to improve tonight.
AIRMET Tango for moderate low level turbulence downwind of island terrain remains in effect over Kauai and Oahu. Expect conditions to improve this evening as winds across these areas weakens.

Marine

High pressure to the distant north-northwest of the main Hawaiian Islands will remain nearly stationary for the next several days as it gradually weakens. As this occurs, easterly trade winds will ease into the moderate to fresh range. The Small Craft Advisory that was previously in effect for leeward Kauai waters and waters and channels of Maui County and the Big Island has been cancelled.
The current small long period south-southwest swell will hold tonight and then gradually decline on Monday. However, a tiny long-period reinforcement will arrive late Monday followed by another long-period south-southwest swell Wednesday into Thursday. This mid-week swell will bring another boost to south shore surf.
East shore surf will gradually decline through mid-week as the trades weaken slightly. Surf along north facing shores will remain tiny through the next several days. Gale force winds associated with a surface low moving near the Aleutians this weekend are expected to send a small, medium period north- northwest swell towards the islands during the latter half of the week.
Through Wednesday, it is possible that higher than normal tides could lead to some coastal flooding during the peak of high tides in the early afternoon hours. However, since the elevated tides are generally expected between the peaks of the aforementioned south swells, this event should have minimal impacts.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov