West Side

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 86. Light winds. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows 64 to 70. East winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 80 to 87. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 85. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 65. Light winds.

Saturday: Mostly sunny. Highs around 86. Northwest winds up to 15 mph.

North Shore

Today: Partly sunny with scattered showers. Highs 76 to 83 near the shore to around 64 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 68 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 77 to 84 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Central Maui

Today: Mostly sunny with isolated showers. Highs 81 to 86. South winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 68. Northeast winds up to 10 mph shifting to the southeast after midnight. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 82 to 87. East winds up to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny with scattered showers. Highs around 57 at the visitor center to around 54 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly clear with scattered showers. Lows around 44 at the visitor center to around 41 at the summit. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Saturday: Breezy. Sunny with isolated showers. Highs around 58 at the visitor center to around 55 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

East Maui

Today: Partly sunny with scattered showers. Highs 76 to 83 near the shore to around 64 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 68 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 77 to 84 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 with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 72 to 79. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 50 percent.

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

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 80. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 40 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 84. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 61 to 70. Light winds becoming east up to 10 mph after midnight. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 84. East winds up to 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

A weak surface trough north of the state will drift west today and tonight, bringing a return of light to moderate trades. Some moderate showers will affect windward and southeast facing slopes this morning, with scattered moderate showers affecting interior and leeward areas this afternoon. The trades will ease Saturday over the western islands and Sunday over the eastern end of the state. Drier and more stable conditions will decrease shower activity from Oahu to the Big Island, while moderate showers will continue to affect Kauai, particularly during the afternoon hours. A front will move into the islands from the northwest early next week, bringing a return of light to moderate trades. Some showery weather will likely accompany the front and stick with it as it stalls out over the island chain during the middle to latter part of next week, with windward slopes and coasts expected to see the brunt of the rainfall.

Discussion

Currently at the surface, a weak trough of low pressure is located just north of the state, while a surface ridge of high pressure is positioned around 300 miles north of Kauai. Light to locally moderate trade winds have developed in unsheltered areas overnight, although land breezes are present in the more sheltered locales. Infrared satellite imagery shows partly to mostly cloudy conditions across the state. Radar imagery shows scattered moderate showers moving into windward and southeast facing slopes of most islands, with dry conditions in most leeward locales. Main short term focus revolves around rain chances and wind trends.
The trough north the state will slowly drift west today and tonight as the ridge of high pressure builds north of the area. This will allow light to moderate trades to overspread the island chain. An approaching front will ease the winds over the western islands this weekend, with land and sea breezes common in most areas. Meanwhile, moderate trades will hold over the eastern end of the state through Saturday night before becoming light and variable with sea breezes common on Sunday. A weakening front will push southward into the islands early next week, ushering in a return of light to moderate trade winds which appear to linger through late in the work week.
As for the remaining weather details, lingering moisture associated with the trough, will shift westward over the islands today and tonight. This will bring some moderate showers to mainly windward and southeast facing slopes at night and during the early morning hours. Leeward areas should see drier conditions, although some moderate showers will likely develop this afternoon.
The higher precipitable water airmass appears to shift west of most of the islands except for perhaps Kauai over the weekend. This should decrease shower coverage from Oahu to the Big Island. A few showers will continue to move into windward and southeast facing slopes during the night and morning hours, and interior and leeward areas each afternoon, with shower coverage the greatest over Kauai.
The front moving in from the northwest should shift the higher PW airmass back over the entire state Sunday night and Monday. This should bring an increase in shower coverage, with showers favoring areas near the coast Sunday night and early Monday, and interior and leeward areas Monday afternoon. The front is then forecast to move into the islands Monday night and Tuesday, then stall out somewhere over the state during the middle to latter part of next week. Some showery weather will likely accompany the front and stick with it as it stalls out over the island chain, with windward slopes and coasts expected to see the brunt of the rainfall.

Aviation

Light to moderate east to southeast winds today will allow day time sea breezes and overnight land breezes to form over each island. Passing showers are forecast today as a weak trough drifts westward across the region. Brief MVFR conditions are possible with scattered showers.
AIRMET Sierra remains in effect for mountain obscurations over the north through east slopes of Kauai and Oahu, and east through southeast slopes of the Big Island this morning. These conditions will diminish in coverage around sunrise.

Marine

A trough north of the eastern Hawaiian Islands will slowly drift westward today as a ridge of high pressure builds north of the region. Expect light to moderate east to southeast winds to continue through Saturday. Moderate trades over the eastern end of the state on Saturday will slightly exceed Small Craft Advisory (SCA) wind thresholds over the windier waters and channels near Maui and the Big Island. An approaching cold front from the northwest will weaken the ridge north of the state on Sunday, decreasing wind trends from Saturday night through Monday. Light trade winds will return from Tuesday to Wednesday as a high pressure system builds in behind the weakening frontal passage.
The current short period west-northwest swell will gradually decline through Saturday. A new overlapping long period northwest swell is forecast to arrive by Saturday morning, build through the day, and then peak Saturday night into Sunday. A reinforcing medium period northwest swell will move in Sunday night, peak on Monday, then slowly lower through the middle of next week. Surf heights along north and west facing shores will show decreasing trends today and then increase into the weekend.
Surf along south facing shores will remain tiny today. A new long period south swell will arrive tonight, peak over the weekend near the summertime average, and then slowly decline through the middle of next week.
Surf along east facing shores will remain small through the middle of next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov