Photo Credit: Tyler Rooke

West Side

Today: Isolated showers. Mostly sunny, with a high near 89. Calm wind becoming southwest around 5 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly clear, with a low around 69. East northeast wind 11 to 13 mph. Chance of precipitation is 20%.

Sunday: Isolated showers after noon. Increasing clouds, with a high near 88. Light and variable wind becoming south around 6 mph in the morning. Chance of precipitation is 20%.

South Side

Today: Isolated showers after 1pm. Mostly sunny, with a high near 90. Light and variable wind becoming southwest around 6 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers before 1am. Partly cloudy, with a low around 67. South wind around 6 mph becoming calm after midnight. Chance of precipitation is 20%.

Sunday: Increasing clouds, with a high near 89. Calm wind becoming southwest 5 to 7 mph.

North Shore

Today: Isolated showers. Mostly sunny, with a high near 88. Breezy, with an east northeast wind 13 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 68. East wind 9 to 13 mph. Chance of precipitation is 20%.

Sunday: Isolated showers. Mostly sunny, with a high near 87. Breezy, with an east northeast wind 11 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Central Maui

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 89. North northeast wind 9 to 13 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 67. North northeast wind 7 to 10 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Isolated showers before noon. Mostly sunny, with a high near 88. North northeast wind 9 to 13 mph. Chance of precipitation is 20%.

Upcountry

Today: Isolated showers after noon. Mostly sunny, with a high near 75. Light west wind increasing to 8 to 13 mph in the morning. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 55. Light and variable wind.

Sunday: Sunny, with a high near 74. West southwest wind 5 to 8 mph.

East Maui

Today: Scattered showers. Partly sunny, with a high near 83. East wind 7 to 10 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 68. East northeast wind 3 to 7 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers. Partly sunny, with a high near 82. East wind 3 to 7 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 79. Breezy, with an east northeast wind 7 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Isolated showers after midnight. Partly cloudy, with a low around 64. Breezy, with a northeast wind 9 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Sunday: Isolated showers after noon. Mostly sunny, with a high near 78. Northeast wind 10 to 13 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Isolated showers. Mostly sunny, with a high near 88. East wind 6 to 11 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 70. East wind 5 to 10 mph. Chance of precipitation is 20%.

Sunday: Isolated showers after noon. Increasing clouds, with a high near 87. East wind 6 to 9 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Moderate trade winds will continue today, then the trades will become light to moderate next week. An upper-level low just north of the islands may cause a few heavier showers to develop today. More stable atmospheric conditions are expected to result in a relatively dry trade wind weather pattern from Sunday through most of next week. The weaker background flow will also allow sea breezes to develop each afternoon, followed by land breezes at night.

Discussion

A 1030 mb surface high pressure system is centered near 39N 141W, or about 1600 miles northeast of Hilo. A surface ridge extends west-southwest from this high through a point about 620 miles north of Lihue. The pressure gradient south and southwest of these surface features is maintaining moderate trade winds across the state early this morning. Aloft, loops of water vapor satellite imagery show a broad upper-level cold core low pressure system is centered near 24.5N 157.5W, or about 225 miles north of Honolulu. The close proximity of the cold air aloft associated with this feature to the state is causing some atmospheric instability. Satellite imagery and radar reflectivity data show scattered low clouds with isolated embedded showers moving toward windward Oahu…Molokai…Maui and the Big Island. There are also a few clouds and showers moving toward windward Kauai. In addition to the low clouds, there are cirrus clouds moving up from the southwest over portions of the Big Island.
The moderate trade wind regime will persist into this evening. The upper-level low is expected to drift slowly eastward through this evening. This will keep slightly unstable conditions over the state. The instability will allow for some enhancement of the clouds and showers transported by the trades. There is also a chance of locally heavy downpours if towering cumulus clouds develop over some of the islands. In addition, there is a possibility of a few thunderstorms occurring over the upslope areas of Big Island this afternoon. By late tonight, the upper- level low is expected to lift out northeast away from the area. The forecast guidance indicates a ridge will build in aloft over the region from Sunday through most of next week, which will cause the atmosphere to become stable.
The forecast models keep light to moderate trade winds in the forecast from Sunday through the middle of next week. The relatively weak trade wind regime may allow alternating local afternoon sea breezes and nighttime land breezes to develop over each of the individual islands next week. The sea breezes could result in some clouds forming over leeward and interior sections of the islands each afternoon. However, the stable and dry atmospheric conditions will likely limit afternoon shower coverage. The land breezes, which will initially become established each evening, will tend to clear skies over most of the islands at night.

Aviation

A high far northeast of the area will sustain moderate trade winds through today and beyond. Any showers that develop will mainly affect windward and mauka sections, with a slight chance of a heavy shower or two, and even a thunderstorm, through the day as an upper air disturbance influences the local weather. Overall, VFR conditions will predominate across the island chain.
No AIRMETs are in effect, and none are anticipated through the next 24 hours.

Marine

A 1030 mb surface high is centered approximately 1,700 nm northeast of Honolulu with the associated upper ridge axis about 600 nm north of the state. As ridging holds its ground through the weekend, trade winds will generally remain moderate the next several days…locally stronger through the bays and channels through Sunday. A couple of northern Pacific cold fronts will pass over the ridge with one this weekend and a secondary front passage the middle of next week. These fronts may push the ridge closer to the islands and slightly weaken winds even further by Wednesday. Gentle to moderate trades will generally maintain seas in the 4 to 6 foot range through next week.
A series of long period south swells will be moving through into early next week and this will increase south facing shore surf heights. This surf may peak near High Surf Advisory levels Sunday, with a gradual fall from Monday into the middle of next week. North facing shore surf will remain nearly flat this weekend. A small bump in north and west facing shore surf is expected from Sunday night through mid-week as a small west northwest swell moves into the region. Weak trade winds will keep short period, wind wave heights small along eastern exposed shorelines through next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov