Photo Credit: Jeni Ji Cousins

West Side

Today: Mostly sunny with isolated showers. Highs 77 to 83. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows 64 to 70. Northeast winds around 10 mph. Chance of rain 50 percent.

Washingtons Birthday: Mostly sunny with isolated showers. Highs 77 to 83. Northeast winds around 10 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny with isolated showers. Highs around 83. North winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 65. North winds 10 to 15 mph. Chance of rain 20 percent.

Washingtons Birthday: Mostly sunny with isolated showers. Highs around 83. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

North Shore

Today: Partly sunny with scattered showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with showers likely. Lows 62 to 68 near the shore to around 50 near 5000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

Washingtons Birthday: Partly sunny with scattered showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds around 10 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 84. North winds around 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with scattered showers. Lows 63 to 68. Northeast winds around 10 mph. Chance of rain 40 percent.

Washingtons Birthday: Mostly sunny with isolated showers. Highs 79 to 84. Northeast winds around 10 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 58 at the visitor center to around 54 at the summit. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 46 at the visitor center to around 41 at the summit. Southeast winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

Washingtons Birthday: Mostly sunny with scattered showers. Highs around 58 at the visitor center to around 54 at the summit. Light winds. Chance of rain 50 percent.

East Maui

Today: Partly sunny with scattered showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with showers likely. Lows 62 to 68 near the shore to around 50 near 5000 feet. Northeast winds around 10 mph. Chance of rain 70 percent.

Washingtons Birthday: Partly sunny with scattered showers. Highs 75 to 80 near the shore to around 63 near 5000 feet. East winds around 10 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 72 to 79. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 65. Northeast winds around 10 mph. Chance of rain 20 percent.

Washingtons Birthday: Partly sunny with scattered showers. Highs 73 to 80. Northeast winds around 10 mph. Chance of rain 40 percent.

Kaunakakai

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 70 to 80. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows 55 to 67. Northeast winds around 10 mph. Chance of rain 50 percent.

Washingtons Birthday: Mostly sunny with isolated showers. Highs 71 to 81. Northeast winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate trade winds will continue for the next few days, then strengthen during the upcoming work week. Clouds and showers will favor windward and mauka areas, while also developing across leeward sections during the afternoons this weekend.

Discussion

An upper low persists well north of the state, with an associated upper trough extending southward and passing just north of the islands. Troughing at the surface just east of the islands keeps winds light to moderate across local waters. Satellite loop shows deep moisture along the eastern flank of the upper trough remains east of the islands, characterized by a ragged 600 mile wide band of broken to overcast layered clouds.
Models show the surface trough will linger northeast of the state through Monday. Winds will weaken, with more northeasterly winds occurring across the west half and easterly winds across the east half. The gradient will be light enough for development of localized sea and land breezes. As a new high builds northwest of the state, drier air will move across Kauai and possibly toward Oahu. However, greater moisture and weaker/higher inversion heights will remain across Maui and the Big Island, leading to higher rainfall chances.
By Tuesday, a stronger high building north of the state will return us to a more typical trade wind pattern across the area, which is expected to continue through the coming work week. This will return us to a more typical trade wind rainfall pattern, with showers focused across windward and mauka areas mainly during the night and morning hours.

Aviation

Light to moderate northeast winds will continue over the islands today as a weak surface trough persists north of the islands. Localized land and sea breezes will interact with the trade winds enhancing clouds over island mountain and interior sections. Any showers that form will develop over these interior areas in the afternoon and early evening hours, or over windward and mountain areas in the overnight to early morning hours. VFR conditions will prevail for most locations.
No AIRMETs are in effect, and none are anticipated through the next 24 hours.

Marine

A weak surface trough lingering in the area through Monday will keep the moderate north-northeast winds over the Kauai and Oahu waters, with east to southeast trades holding over the eastern end of the state. A return of fresh to strong easterly trade winds is expected Monday night through Tuesday as high pressure builds north of the islands. Guidance shows this pattern holding through the second half of the week.
Surf along exposed north and west facing shores will remain up today as the northwest swell that peaked Saturday slowly eases. The downward trend will continue into the start of the week, with mainly a combo of small north-northwest and northwest swell energy moving through. A west-northwest swell associated with a large area of fresh- to near gale-force winds across the northwest Pacific will arrive by Tuesday, then linger through midweek. Guidance shows this source peaking below the high surf advisory levels Wednesday, then moving out by Thursday.
A more significant west-northwest swell is possible later in the week. Guidance shows a broad storm-force low emerging off the coast of Japan tonight into Monday, with a large area of storm- force winds expanding eastward toward the Date Line Monday through Tuesday – centered over the 295 to 315 degree directional bands relative to the islands. Wave guidance responds and depicts seas in this area climbing into the 30 to 40 ft range. If this evolves as predicted, surf will quickly build down the island chain through the day Thursday, with a peak likely exceeding warning levels Thursday night through Friday for exposed north and west facing shores.
Despite the light trades, recent fresh to strong easterly breezes upstream support the background easterly trade swell holding today before easing into the start of the week. PaciOOS buoy observations at Mokapu, Kaneohe, and Hilo reflect this easterly source holding above predicted this morning within the 8-10 second band. Increasing trades will lead to increasing short-period and choppy surf through the second half of the week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov