West Side

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 78 to 83. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows 66 to 75. East winds up to 20 mph.

Saturday: Sunny. Highs 78 to 84. East winds up to 15 mph.

South Side

Today: Sunny and breezy. Highs around 84. North winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 68 to 74. North winds up to 20 mph.

Saturday: Sunny. Highs around 85. North winds up to 15 mph shifting to the northeast in the afternoon.

North Shore

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 79 to 85 near the shore to around 64 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 66 to 72 near the shore to around 46 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Central Maui

Today: Sunny and breezy. Highs 78 to 85. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Lows 67 to 72. East winds up to 15 mph.

Saturday: Mostly sunny. Breezy. Highs 79 to 86. East winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon.

Upcountry

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 60 at the visitor center to around 65 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 39 to 51. East winds up to 10 mph. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers. Highs around 60 at the visitor center to around 65 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

East Maui

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 79 to 85 near the shore to around 64 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 66 to 72 near the shore to around 46 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 71 to 79. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 62 to 68. Northeast winds 10 to 20 mph decreasing to up to 10 mph after midnight.

Saturday: Mostly sunny. Highs 71 to 79. Northeast winds up to 15 mph.

Kaunakakai

Today: Sunny and breezy. Highs 69 to 85. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 56 to 74. East winds 10 to 20 mph.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 71 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trades will gradually weaken through the weekend as a stout low pressure system developing to the far north disrupts the surface ridge extending over the islands. Clouds and showers will favor windward and mauka areas through Friday, then focus shifts to sea breezes each afternoon over the weekend. Early next week, increasing moisture will move up the island chain from the southeast, increasing rain chances for the eastern end of the state Monday and Tuesday. Moderate to locally breezy trades are expected to return shortly thereafter for the remainder of the forecast period.

Discussion

A strong surface ridge positioned north of the state will remain the primary driver of weather conditions across the Hawaiian Islands today. This pattern will continue to support moderate to locally breezy trades and maintains periodic shower activity mainly focused over windward and mauka areas. In addition, a weak upper-level trough quickly moving west to east across the state this morning will temporarily weaken the low-level inversion, allowing for a slight increase in moisture, cloud cover, and shower activity through the morning hours.
Trades will begin to weaken shortly thereafter as a broad area of low pressure develops southward from the Aleutian Islands. This system will erode the surface ridge and weaken the local pressure gradient, leading to lighter winds and the potential for localized land and sea breeze development through the weekend and into early next week. As a result, interior and leeward areas may experience increased afternoon cloud and shower development, followed by overnight clearing.
Model guidance indicate that moisture levels will gradually increase between Monday night and Wednesday as a large plume of tropical moisture lifts northwestward across the island chain from the southeast. Meanwhile, ridging will begin to rebuild over the region as the low pressure system lifts northward into the Gulf of Alaska, allowing trades to strengthen once again. This return to a more typical trade pattern will favor isolated to locally scattered showers, mainly favoring windward and mauka areas, through the remainder of the forecast period.

Aviation

Moderate to breezy trades through today then decreasing this weekend. Low cigs and SHRA along windward and mauka locations. MVFR conds possible in SHRA otherwise VFR prevails.
AIRMET Sierra is in effect for mtn obsc for Kauai, Oahu and windward Big Island. Conds should improve later this morning.
AIRMET Tango is in effect for mod turb across all islands downwind of terrain.

Marine

Fresh to strong trade winds will persist today as the subtropical ridge remains strong north of the state. This will support an extension of the Small Craft Advisory through this afternoon for the windier waters around Maui and the Big Island. Thereafter, guidance depicts the ridge beginning to weaken in response to broad low pressure developing roughly 1,500 nautical miles to the north near the Aleutian Islands this weekend through early next week. This will translate to local trades easing into the light to moderate range, likely giving way to localized land and sea breezes near the coasts late this weekend through early next week. A return of moderate to fresh easterly trades is likely by midweek as the ridge strengthens.
An active pattern is in store for surf along south-facing shores as we head into June due to a series of recent gale- to storm- force lows passing through our swell window near New Zealand over the past week. Expect surf to gradually build today as forerunners from a long-period south-southwest swell arrive while the current medium-period south swell fades out. Our buoys are already reflecting this new source with energy registering in the 20-23 second bands this morning. Surf heights will likely reach the advisory level by tonight, with the swell becoming fully established by Saturday. Heights will hover near the advisory level through the weekend. As the swell gradually begins to ease early next week, long-period forerunners from the next south- southwest swell are expected to arrive. Heights may briefly dip below the advisory level Monday night, but as the next swell fills in, surf will likely return to the advisory level Tuesday through midweek as it peaks. A gradual downward trend is then expected through the second half of next week.
A combination of advisory-level surf this weekend and water levels hovering above predicted levels could lead to some wave runup issues, with water sweeping across areas of beaches that typically remain dry. Water levels will steadily lower each day early next week as the next large south swell arrives.
The current small northwest swell will slowly lower through Saturday before fading on Sunday. A small north swell will likely produce surf near seasonal averages along north-facing shores from late Tuesday or Wednesday into Thursday.
Expect surf along east-facing shores to remain near seasonal averages today, then gradually decline through early next week as trade winds ease. A slight increase is possible Tuesday and Wednesday due to a combination of rebuilding trade winds and a wrapping north swell.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov