Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 90. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 68 to 73. Northeast winds around 10 mph.

Monday: Mostly sunny with isolated showers. Highs 79 to 90. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Highs around 89. North winds around 10 mph.

Tonight: Clear. Lows 67 to 73. North winds 10 to 15 mph shifting to the northeast after midnight.

Monday: Sunny. Isolated showers in the afternoon. Highs around 89. North winds around 10 mph. Chance of rain 20 percent.

North Shore

Today: Partly sunny with scattered showers. Highs 77 to 84 near the shore to around 67 near 5000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 71 near the shore to 48 to 54 near 5000 feet. East winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs 77 to 84 near the shore to around 67 near 5000 feet. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Isolated showers in the afternoon. Highs 81 to 87. Northeast winds around 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 67 to 72. Northeast winds around 10 mph in the evening becoming light.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 81 to 88. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 63 at the visitor center to around 58 at the summit. East winds around 10 mph in the morning becoming light. Chance of rain 50 percent.

Tonight: Mostly clear with scattered showers. Lows around 45 at the visitor center to around 42 at the summit. Light winds. Chance of rain 50 percent.

Monday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 64 at the visitor center to around 59 at the summit. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Partly sunny with scattered showers. Highs 77 to 84 near the shore to around 67 near 5000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 71 near the shore to 48 to 54 near 5000 feet. East winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs 77 to 84 near the shore to around 67 near 5000 feet. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 82. Light winds. Chance of rain 20 percent.

Tonight: Clear. Lows 63 to 68. Northeast winds around 10 mph in the evening becoming light.

Monday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 82. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 30 percent.

Kaunakakai

Today: Mostly sunny with isolated showers. Highs 69 to 90. Light winds becoming northeast around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 58 to 73. East winds around 10 mph.

Monday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 90. Northeast winds around 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

A surface trough east of the Big Island is causing the trades to weaken through today. Further weakening of the trades is on tap Monday through Tuesday while a surface trough passes north of the islands. The weakness of the trades will lead to a daytime sea breeze, bringing a few more clouds and showers the interior and lee areas in the afternoons. Breezy trade winds return to the islands during the second half of the week. Some tropical moisture may graze the Big Island and Maui Wednesday through Thursday.

Discussion

A gradual trending down of the trade winds from light to moderate will continue into Monday, where once it is done, a background light easterly wind flow will prevail through Tuesday. This is brought upon by a surface trough that is currently east of the Big Island. This trough, although it will pass north of the islands between Monday and late Tuesday night, will be sufficient in weakening the trades further. A light to moderate east-southeast wind flow follows immediately east of the trough that will linger over the area through Wednesday morning before easing to easterly trades Wednesday afternoon. Trades will strengthen to locally strong Wednesday night.
The light winds over land will favor an onshore sea breeze during the day, and a offshore land breeze at night. The onshore sea breeze will lead to some afternoon clouds and showers over the lee and interior areas of all islands. At night, the land breeze will clear most of the day time, heat driven clouds and showers, to off the island or to near the shoreline. In the mean time, a background light easterly flow will be bringing in a few loose showers into the windward areas.
The models are suggesting in a surface trough originating in the ITCZ southeast of the Big Island, scraping the Big Island and possibly Maui Wednesday afternoon and Wednesday night with an uptick in trade showers. Models, thus far, keep the brunt of the tropical moisture south of the remaining islands, although dense mid and high layered clouds will mask these islands. This tropical moisture is slated to clear Kauai Thursday morning.
A 1029 mb surface high north of the islands, will be generating moderate to strong breezy trades through the second half of the week.
Current weather radar is showing widely dispersed showers laced across the windward waters. These showers are favoring the windward and mountain areas of all islands exposed to this flow. There are some large patches of low clouds further upwind of Maui, but sufficient daytime mixing will burn off these patches before reaching these islands.

Aviation

Moderate trade winds will persist through the remainder of this morning, then weaken slightly by afternoon. Thus, expect scattered showers to mainly be confined to windward locations. Weak instability aloft will allow for some heavier showers with brief periods of MVFR ceilings and visibility. Otherwise, mainly VFR conditions will prevail elsewhere.
No AIRMETs are currently in effect.

Marine

A high pressure ridge far north of the state will interact with a surface trough northeast of the area. This trough will produce light background easterly trade winds across the region. Local scale land and sea breezes will develop into Tuesday near the islands. Moderate to breezy trades will likely return from late Wednesday into Thursday as the trough passes to the west and high pressure builds into the region.
A small south swell will likely peak later today then lower slowly into Tuesday. A series of small south and southeast swells will continue to keep south shore surf above flat levels through the end of the week.
Surf will continue to diminish along east facing shores with nearly flat conditions expected by Monday night. Surf along east facing shores will gradually increase later this week as trade winds strengthen. No other significant swells are expected.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov