Photo Credit: Jeni Ji Cousins

West Side

Today: Sunny and breezy. Highs 74 to 83. East winds 10 to 20 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 63 to 70. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs 75 to 83. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

South Side

Today: Sunny. Highs 79 to 85. North winds 10 to 15 mph.

Tonight: Mostly clear. Lows 62 to 68. Northeast winds up to 15 mph.

Monday: Sunny and breezy. Isolated showers in the afternoon. Highs 79 to 85. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

North Shore

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 81 near the shore to around 69 near 5000 feet. Southeast winds 10 to 20 mph shifting to the east up to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 67 near the shore to 48 to 53 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Breezy. Numerous showers in the morning, then occasional showers in the afternoon. Highs 74 to 81 near the shore to around 70 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Central Maui

Today: Sunny and breezy. Highs 80 to 85. East winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows around 65. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs 79 to 85. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny with isolated showers. Highs around 61 at the visitor center to around 57 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 48 at the visitor center to around 43 at the summit. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Monday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 63 at the visitor center to around 57 at the summit. East winds 10 to 20 mph becoming up to 25 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 81 near the shore to around 69 near 5000 feet. Southeast winds 10 to 20 mph shifting to the east up to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 67 near the shore to 48 to 53 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Breezy. Numerous showers in the morning, then occasional showers in the afternoon. Highs 74 to 81 near the shore to around 70 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Lanai City

Today: Breezy. Mostly sunny with isolated showers. Highs 70 to 78. Northeast winds 10 to 15 mph becoming up to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 59 to 64. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 71 to 79. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Kaunakakai

Today: Sunny and breezy. Highs 65 to 84. Northeast winds 10 to 20 mph.

Tonight: Breezy. Mostly clear with isolated showers. Lows 54 to 68. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 65 to 83. East winds 10 to 25 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Moderate trade winds will continue through today, before gradually strengthening through the first half of the week. Trades will likely become strong by the middle of the week, then remain strong into next weekend. Passing clouds and showers will favor windward areas, with shower coverage increasing Monday, and potentially persisting through much of the week.

Discussion

A 1031 mb surface high far NE of the islands will support a moderate trade wind flow through today. Radar shows scattered showers moving along windward areas with a few showers spilling over to leeward areas of the small islands. Clouds and showers are expected to become more sporadic this afternoon as the atmosphere dries out slightly. Winds will ease slightly today as a front approaches from the northwest then stalls. Seabreezes could develop this afternoon, resulting in an increase in clouds and possible isolated showers along shelter leeward and interior locations.
The approaching front will stall and weaken to a trough several hundred miles NW of the islands Monday and Tuesday, but trade winds will gradually strengthen as the high to the NW tightens the local gradient. The island atmosphere will remain relatively stable, but a showery cloud band seen on satellite (a frontal remnant extending through 23N154W to 21N150W) will arrive Monday. This boundary will bring increased showers, especially windward, through at least Tuesday night.
By late Tuesday into Wednesday, a longwave trough aloft will develop W of the islands, with several impulses aloft diving into the trough. This is expected to lead to the development of a mid- level cutoff low to the NW, thereby initiating surface cyclogenesis along the stalled trough. The low is expected to develop about 500 miles NW of Kauai on Wednesday, then move W through Friday as the high passes N and NE of the islands.
Strong E to ESE winds will develop over the islands Wednesday, easing ever so slightly Thursday and Friday. The longwave trough and cutoff low may develop close enough to the islands to the destabilize the atmosphere and combine with the lingering moisture to bring some locally heavy showers, mainly to Kauai around Wednesday. Otherwise, it appears that a wet trade wind weather pattern will prevail as the mid-levels remain cool through the week.

Aviation

A high pressure system currently far northeast of the state will continue to slowly weaken and drift eastward away from the island chain as a cold front approaches the Hawaii region from the northwest. Trade winds will decrease slightly by this afternoon. Expect periods of showers mainly over windward and mountain areas as two cloud bands move over the islands through Monday. These additional clouds and showers will produce brief periods of MVFR conditions over windward airfields favoring the overnight to early morning hours. Mostly VFR conditions will prevail.
AIRMET Sierra for mountain obscuration remains in effect for north through east slopes of Kauai, Oahu, Molokai, Maui and the Big Island. This AIRMET will likely last through the early morning hours.

Marine

A cold front that is currently far northwest of the main Hawaiian Islands will push eastward over the next several days, displacing surface high pressure to the northeast. The short term trend will be toward weakening winds today. Trade winds will be just below the Small Craft Advisory (SCA) criteria today but may trend back up tonight for the typical windy waters around Maui County and the Big Island.
During the first half of the week, a surface trough is expected to develop between the coastal waters and the anomalously strong high pressure building in north of the islands. Typically with the high pressure we would anticipate strong to gale force winds, the surface trough will likely prevent trade winds from reaching their full potential across the coastal waters initially. Winds will build to fresh to strong speeds over Kauai and Oahu waters, and strong to locally near gale force over Maui County and the Big Island on Tuesday. By mid to late week, strong trades will become more widespread as a surface low forms northwest of the islands.
A small, medium period northwest swell is slowly filling in today for north and west facing shores keeping small surf. A series of small medium period reinforcements from the northwest will keep surf from going flat over north and west facing shores through the first half of the week. An upward trend is possible beginning Tuesday as a moderate sized, short- to medium- period north swell arrives from the low that is forecast to develop north-northwest of the islands.
Surf along east facing shores will ease a bit on today as trade winds ease. With the onset of strong trade winds on Tuesday, rough choppy surf is expected as a SCA is likely for seas 10 feet or greater Tuesday through the end of the week. Surf along south facing shores will remain small for the next several days. By the weekend, a small medium- to long- period south- southeast swell cannot be ruled out.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov