Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny with isolated showers. Highs 81 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 69. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 81 to 88. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Highs 85 to 90. North winds up to 15 mph.

Tonight: Mostly clear. Lows around 68. North winds up to 15 mph.

Saturday: Mostly sunny. Breezy. Highs 85 to 90. Northeast winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with isolated showers. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs around 88. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

Tonight: Partly cloudy with isolated showers. Lows 66 to 72. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 88. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Breezy. Mostly sunny with isolated showers. Highs around 63 at the visitor center to around 60 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 46 to 57. East winds up to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 66 at the visitor center to around 63 at the summit. East winds up to 25 mph. Chance of rain 20 percent.

East Maui

Today: Breezy. Partly sunny with isolated showers. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 81. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 66. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs 72 to 81. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 79 to 89. East winds 10 to 20 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 61 to 72. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 79 to 89. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The high pressure ridge north of the islands will strengthen from later tonight into the weekend, trade winds will remain in the moderate to breezy range from Saturday through the end of next week. Three upper level disturbances passing from east to west over the next seven days will lift the subsidence inversion heights enough for more typical windward and mountain shower activity. These periods of showers will favor the overnight to early morning hours along the eastern slopes of each island.

Discussion

Satellite imagery this morning shows a band of moderately unstable clouds just east of the Big Island and Maui drifting westward on the trade winds. These clouds are associated upward vertical motions along the eastern side of a weak upper level low drifting westward across the state. Expect increasing windward and mountain cloud and shower trends as this low slowly drifts across the state through Saturday morning. Local radar imagery shows isolated shower coverage this morning over windward and mountain slopes with increasing shower intensity along leeward convergence bands south and west of the state.
Moderate trade winds will continue today as a high pressure ridge remains in place north of the state. This ridge will strengthen from tonight into the weekend with trade wind speeds increasing into the moderate to breezy range, lasting from Saturday through the end of next week. A combination of stronger trade winds and three passing upper level lows, drifting in from east to west across the island chain, will produce periods of more normal windward and mountain showers. These passing upper lows will weaken the subsidence inversion aloft and allow cloud heights to deepen and produce increasing shower coverage over the state. Longer range models suggest a cloud band remnant from an old front will move into the region from the northeast on Wednesday. These passing showers will tend to favor the overnight to early morning hours with the arrival timing tied to each low passing over the islands, with basically two periods of wetter trades from today through Sunday, and from Tuesday night through Thursday.
The main changes in this mornings forecast were upgrading the precipitation chances and coverage with the highest trends favoring the overnight to early morning hours each day. Wind speeds were also increased over windier eastern waters and channels, and the mountain summits of Mauna Kea and Mauna Loa.

Aviation

With a surface ridge just north of the state, trade winds will remain in the light to moderate range. VFR will prevail over most areas most of the time through tonight, though brief periods of MVFR may occur across windward slopes as moisture embedded in the trades interacts with island terrain.
No AIRMETs are currently in effect, and none anticipated through tonight.

Marine

A weak ridge north of the islands will drive light to moderate east to east-southeast winds across local waters today. Winds will increase into the moderate to strong range tonight and Saturday as the ridge strengthens. A Small Craft Advisory (SCA) will be needed for the windier zones around Maui County and the Big Island over the weekend and early next week, and the SCA may need to include additional zones Sunday or Monday.
No significant swells are expected through the forecast period. A small northwest swell is due Sunday and Monday. Expect background summertime surf for south facing shores, though a small pulse from the southwest is possible during the middle of next week. Small, short-period surf along east facing shores will build to seasonal average over the weekend as trade winds strengthen, then hold into next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov