Weather Forecast

Maui Weather Forecast for September 11, 2021

September 11, 2021, 7:15 AM HST
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Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 90. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 75. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Sunday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 92. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

South Side

Today: Mostly sunny. Highs around 89. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Mostly clear. Lows 68 to 75. North winds up to 15 mph increasing to 10 to 15 mph after midnight.

ARTICLE CONTINUES BELOW AD

Sunday: Sunny and breezy. Highs around 90. North winds 10 to 20 mph.

North Shore

ARTICLE CONTINUES BELOW AD

Today: Showers in the morning, then scattered showers in the afternoon. Highs 76 to 87 near the shore to around 66 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 71 near the shore to 49 to 55 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday: Showers in the morning, then scattered showers in the afternoon. Highs 78 to 87 near the shore to around 67 near 5000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Central Maui

ARTICLE CONTINUES BELOW AD

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 83 to 90. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 73. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 84 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 61 at the visitor center to around 57 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 46 at the visitor center to around 43 at the summit. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 62 at the visitor center to around 58 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Showers in the morning, then scattered showers in the afternoon. Highs 76 to 87 near the shore to around 66 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 71 near the shore to 49 to 55 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday: Showers in the morning, then scattered showers in the afternoon. Highs 78 to 87 near the shore to around 67 near 5000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Lanai City

Today: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 82. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 66. Northeast winds 10 to 15 mph.

Sunday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 74 to 83. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the morning. Highs 68 to 89. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 58 to 75. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 68 to 90. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A weakened high pressure ridge north of the area and an upper level low roughly 1000 miles northeast of the islands will continue to keep the trade winds in the light to moderate range today. Trade winds will strengthen into the moderate to breezy range on Sunday and Monday as the ridge strengthens. This unstable upper low will slowly drift westward and weaken through early next week, passing just north of the Hawaiian Islands on Wednesday. Periods of enhanced rain showers are likely for all islands into Friday as this unstable system slowly passes through the region.

Discussion

The GOES water vapor satellite imagery this morning shows a narrow upper level trough just north of the state with an unstable upper low roughly 1000 miles northeast of the islands. A subtropical jet stream just south of the upper trough will continue to produce periods of high cirrus clouds, enhancing sunrise and sunset colors through Sunday. The infra-red satellite imagery shows moderately unstable cumulus clouds drifting in on the trade winds. A surface trough northeast of the islands, a reflection of the upper low, will help weaken the trade wind speeds across the region. This surface trough will tend to weaken as the low slowly drifts westward. Local radar imagery shows scattered showers riding in on the trade winds.
The high pressure ridge north of the state is split by a passing cold front moving through the eastern Pacific. The upper level low northeast of the islands continues to produce a surface trough northeast of the islands. Both trough features will reduce the strength of the trade winds today. Expect one more day of light to moderate trade winds across the region with weak daytime sea breezes limited to terrain sheltered areas along western slopes of each island. Trade winds are forecast to increase into the moderate to locally breezy range on Sunday and Monday. Trade wind speeds will decrease again into the light to moderate range from Tuesday onward as the upper low slowly passes by just north of the island chain.
On the rainfall side, enhanced showers are expected through the week for all islands as this upper low slowly passes by north of the state. Model cross sections show trade wind inversion heights around the 8000 foot level, which will produce deeper cloud heights and more shower coverage. All areas will see an increase in shower activity with the highest rainfall totals favoring the typical windward and mountain areas. However, leeward areas will also see periods of enhanced rainfall coverage through next Friday. Deeper moisture will be drawn up from the south on Wednesday and Thursday, producing higher shower coverage, as the upper low center passes by just north of the state. Rainfall coverage was increased in the morning forecast grids for this time period.

Aviation

High pressure north of the state will keep gentle to moderate trade winds in place through tonight. Clouds and showers will favor windward slopes and coasts, with a stray shower drifting into leeward communities from time to time. Brief MVFR cigs/vsbys will be possible in passing showers, mainly along windward slopes and coasts. Otherwise, predominantly VFR conditions will prevail during the next 24 hours.
AIRMET Sierra remains in effect for mountain obscuration across windward sections of Kauai. Conditions should improve here later this morning.

Marine

The weak surface trough northeast of the state resulting in recent light to moderate trades is washing out this morning. The pressure gradient from high pressure centered far north northeast of the state will become more dominant and produce a more healthy moderate to fresh trade wind regime late today through Monday. The only chance for winds reaching Small Craft Advisory thresholds this weekend will be over the east island channels and bays early Sunday, in particular the Alenuihaha Channel. Little change to the regional large scale pressure gradient equates to generally solid moderate northeast to east trades through the middle of the month.
A series of overlapping small, long period south southeast swells will hold slightly below average surf along south facing shores the next couple of days. A slightly larger swell, with more long period energy is passing over the Samoa buoy early this morning. This swell should reach the islands sometime Monday and pick south surf back up to near seasonable heights Tuesday and Wednesday. Recent observations have verified that more southern exposures along western shorelines have and will benefit from some of this south swell wrapping around to the west. Small wind wave swell from slightly stronger trades will maintain choppy surf along many east faces this weekend. A small, medium period northwest swell arriving Sunday may bring surf to just above flat into early next week for north facing shores.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov

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