Photo Credit: Jeni Ji Cousins

West Side

Today: Mostly sunny with isolated showers. Highs 79 to 86. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 68 to 75. East winds up to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 80 to 87. East winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Highs 83 to 88. North winds up to 15 mph.

Tonight: Partly cloudy. Lows around 69. Northeast winds up to 15 mph.

Sunday: Mostly sunny. Highs 84 to 89. North winds up to 15 mph.

North Shore

Today: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then occasional showers after midnight. Lows 65 to 72 near the shore to around 55 near 5000 feet. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 80 percent.

Sunday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to around 69 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 86. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 73. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs around 87. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 64 at the visitor center to around 62 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 50 at the visitor center to around 47 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Sunday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 65 at the visitor center to around 63 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 78 to 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then occasional showers after midnight. Lows 65 to 72 near the shore to around 55 near 5000 feet. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 80 percent.

Sunday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to around 69 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly sunny. Breezy. Scattered showers in the afternoon. Highs 73 to 82. Light winds becoming northeast up to 20 mph in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows around 68. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs 74 to 83. Northeast winds up to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny with isolated showers. Highs 79 to 89. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 64 to 75. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 79 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate trades will prevail today, then strengthen to moderate and locally breezy levels Sunday through late next week. Showers will favor windward and mauka areas, with bands of moisture periodically moving through the islands and increasing the trade showers and sending a few into leeward communities as well.

Discussion

Currently at the surface, a 1029 mb high is centered around 1700 miles north-northeast of Honolulu, with a ridge extending southwest to a location around 400 miles northwest of Kauai. The resulting gradient is producing light to moderate trade winds across the island chain this morning. Infrared satellite imagery shows partly cloudy skies across much of the state, with a bit more cloud coverage over some windward areas as well as leeward sections of the Big Island. Radar imagery shows scattered showers moving into windward areas, with a few of these showers spilling leeward at times. Main short term focus revolves around trade wind trends and rain chances.
Moderate trades are expected to persist today as the surface ridge northwest of the islands remains nearly stationary. The ridge will shift northwest tonight and Sunday, strengthening the trades to moderate and locally breezy levels. Only minor fluctuations in trade wind strength are expected through late next week, with high pressure north of the state keeping moderate to locally breezy conditions in place.
As for the remaining weather details, typical summertime trade wind conditions are expected today, with showers favoring windward and mauka areas, while leeward areas remain mostly dry. We will likely see an increase in trade wind showers tonight through Sunday night as some enhanced moisture moves through. Showers will continue to favor windward and mauka areas, with a few more showers reaching leeward communities as well. Fairly typical trade wind weather will then prevail Monday and Tuesday, with the potential for another band of enhanced moisture to increase trade wind showers Tuesday night through Wednesday night, with drier trade wind weather to follow for the end of the upcoming work week.

Aviation

Moderate trades will continue with clouds and brief showers, favoring windward and mountain areas today. These moderate trade wind speeds will allow for some very localized daytime onshore sea breezes along terrain sheltered leeward slopes of each island today.
VFR conditions will prevail with brief periods of MVFR conditions possible mainly along windward and mountain slopes. A passing weak disturbance will produce increasing cloud and shower trends with MVFR conditions along windward and mountain slopes through the overnight hours.
No AIRMETs are in effect, and none are anticipated in the short term.

Marine

Moderate to locally fresh trades will hold through today before strengthening to moderate to locally strong trade winds tonight as a ridge of high pressure builds north of the state. A Small Craft Advisory has been issued for typical windy waters around Maui County and the Big Island beginning tonight. Winds may weaken slightly around the middle of next week as a weak trough moves over the state from the east. Otherwise, little variation is expected.
A small south southwest swell (14-15 seconds) will peak today slightly above the summer average. The swell will hold through Sunday before slowly subsiding early next week. Several small, south swells may move through the state next week, keeping small surf along south facing shores.
A tiny pulse from the north northwest is expected to fill in tonight, keeping tiny ripples along north facing shores through the rest of the weekend. Small, below average surf along east facing shores will persist through today. As trades build upstream and locally, expect east facing surf to gradually build Sunday into early next week. There is also a possibility of a small boost in east facing shore surf early next week from former Tropical Cyclone Emilia.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov