Photo Credit: Brittney Cruz

West Side

Today: Breezy. Partly sunny with scattered showers. Highs 75 to 86. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 66 to 73. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly cloudy with scattered showers. Highs 75 to 85. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

South Side

Today: Breezy. Partly sunny with scattered showers. Highs around 87. Northeast winds 15 to 20 mph. Gusts up to 40 mph in the afternoon. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 73. North winds 10 to 20 mph. Chance of rain 40 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs around 86. North winds 15 to 20 mph. Chance of rain 40 percent.

North Shore

Today: Cloudy and breezy. Numerous showers in the morning, then showers in the afternoon. Highs 74 to 82 near the shore to around 62 near 5000 feet. East winds 15 to 25 mph. Chance of rain 90 percent.

Tonight: Breezy. Cloudy with showers. Locally heavy rainfall possible. Lows around 68 near the shore to 47 to 52 near 5000 feet. East winds 15 to 25 mph. Chance of rain 90 percent.

Monday: Mostly cloudy. Breezy. Showers in the morning, then showers likely in the afternoon. Locally heavy rainfall possible. Highs 73 to 82 near the shore to around 62 near 5000 feet. East winds 15 to 20 mph. Chance of rain 90 percent.

Central Maui

Today: Breezy. Mostly cloudy with scattered showers. Highs 79 to 86. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 70. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly cloudy with scattered showers. Highs 79 to 86. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Upcountry

Today: Breezy. Mostly cloudy with scattered showers. Highs around 58 at the visitor center to around 54 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then isolated showers after midnight. Lows around 45 at the visitor center to around 42 at the summit. East winds 10 to 20 mph. Chance of rain 70 percent.

Monday: Partly sunny with scattered showers. Highs around 58 at the visitor center to around 54 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Cloudy and breezy. Numerous showers in the morning, then showers in the afternoon. Highs 74 to 82 near the shore to around 62 near 5000 feet. East winds 15 to 25 mph. Chance of rain 90 percent.

Tonight: Breezy. Cloudy with showers. Locally heavy rainfall possible. Lows around 68 near the shore to 47 to 52 near 5000 feet. East winds 15 to 25 mph. Chance of rain 90 percent.

Monday: Mostly cloudy. Breezy. Showers in the morning, then showers likely in the afternoon. Locally heavy rainfall possible. Highs 73 to 82 near the shore to around 62 near 5000 feet. East winds 15 to 20 mph. Chance of rain 90 percent.

Lanai City

Today: Breezy. Partly sunny with scattered showers. Highs 72 to 81. Northeast winds 15 to 25 mph. Chance of rain 30 percent.

Tonight: Windy. Partly cloudy with scattered showers. Lows 61 to 66. Northeast winds 15 to 30 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 72 to 80. Northeast winds 15 to 25 mph. Chance of rain 30 percent.

Kaunakakai

Today: Breezy. Partly sunny with scattered showers. Highs 65 to 85. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 56 to 72. East winds 10 to 25 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly cloudy with scattered showers. Highs 65 to 85. East winds 15 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Strong trade winds will decrease slightly by Tuesday but remain breezy through the rest of the week. An upper trough approaching from the west will destabilize our weather this afternoon through the rest of the forecast period. Showers will increase today into tonight, with wet and breezy trade wind weather expected through the first half of the new week. Locally heavy rainfall is possible over windward areas this evening through Monday.

Discussion

High clouds continue to stream northeastward across the main Hawaiian Islands, but have decreased in coverage since last evening when they completely blocked the view of lower clouds. Marking the eastern flank of an upper trough, high clouds will likely stick around into next week as the upper trough drifts eastward. Radar shows scattered to numerous showers embedded within strong trade wind flow, favoring windward areas.
An unstable pattern will develop as the approaching upper trough pinches into an upper low just north of the chain, then lingers nearby through much of the forecast period. Models show an area of enhanced low level moisture will be near the Big Island later this morning. This moisture will spread westward to the smaller islands by tonight. The combination of increased moisture and increased instability will enhance showers over windward areas with the potential for showers to anchor along terrain. Leeward areas should see scattered showers as well from time to time today.
The Big Island will have the greatest chance for heavy rainfall and isolated thunderstorms this afternoon through Monday, with this chance tapering off farther to the west. East Maui may also be affected. This setup may continue through the middle of the week as the upper low lingers in the area. The threat for heavy rain and isolated thunderstorms will depend on the location and strength of the forecast upper low. Models show the upper low lingering nearby through Thursday. There are still some uncertainties regarding the strength and position of the low but, with unstable conditions expected, we should see showery conditions this week, especially across windward areas.

Aviation

Moderate to locally strong trade winds will continue to settle in across the islands through the weekend, as a large area of high pressure builds north of the state. This pattern will concentrate a majority of clouds and showers along east/northeast facing windward slopes, coasts, and within channels between islands through the TAF period. However, expect increasing chances for some showers to be forced leeward later this afternoon and evening in response to strengthening winds. Additionally, weaker gradient flow near sheltered leeward areas, will allow for sea breeze clouds and isolated showers again this afternoon across interior sections of mainly the the Big Island. Expect mainly VFR conditions into the afternoon, with periodic MVFR cigs this morning increasing in areal coverage as conditions continue to deteriorate toward AIRMET Sierra criteria.
AIRMET Tango for low-level mechanical turbulence immediately south through west of higher terrain, remains in effect for all islands. Also, a period of light ice could potentially develop in a shallow layer between FL180/280 today, mainly stretching from Maui to the Big island, as mid and upper lvl moisture continues to lift up across the islands.

Marine

High pressure northeast of the area is producing breezy to locally windy trade winds across the area. A Small Craft Advisory (SCA) is expanded to included all Hawaiian Coastal Waters through Monday.
The current small, short period northwest swell will linger through tonight. A larger and longer period northwest swell is expected to arrive Monday. The swell will then get a reinforcement late Tuesday into Wednesday with surf heights possibly reaching low end advisory levels. This swell will then lower gradually through the remainder of the week.
Small, mainly background south swells are expected today. A slightly larger and long period south swell is then expected to arrive tonight and Monday, then linger on into Tuesday. An even larger south swell is then expected to arrive by Wednesday. Data from the Aunuu Buoy in American Samoa indicates that this well is running higher than model guidance. This swell may be large enough for surf heights to reach low end advisory levels during its peak late Wednesday and Thursday. This swell will then lower gradually through the remainder of the week.
Trade winds over and upwind of the state will continue to produce short period choppy surf along east facing shores through the weekend and on through all of next week. Surf heights are expected to remain below advisory levels.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for all Hawaiian waters,

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Data Courtesy of NOAA.gov