Photo Credit: Jeni Ji Cousins

West Side

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 81 to 87. Light winds becoming southeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 69 to 76. North winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs around 83. Southeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 30 percent.

South Side

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 85 to 90. Light winds becoming southwest around 10 mph in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers in the evening, then clear after midnight. Lows around 70. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny early in the morning, then isolated showers in the late morning and afternoon. Highs 84 to 89. Light winds. Chance of rain 20 percent.

North Shore

Today: Partly sunny with scattered showers. Highs around 81 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 73 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 78 to 83 near the shore to around 67 near 5000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Central Maui

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 90. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 67 to 75. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 84 to 89. Southeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 30 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 59 at the visitor center to around 57 at the summit. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly clear. Lows around 48 at the visitor center to around 45 at the summit. Light winds.

Friday: Sunny. Isolated showers in the late morning and afternoon. Highs 61 to 74. Southeast winds up to 10 mph. Chance of rain 20 percent.

East Maui

Today: Partly sunny with scattered showers. Highs around 81 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 73 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 78 to 83 near the shore to around 67 near 5000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Lanai City

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 75 to 82. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 66. South winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 76 to 81. Light winds. Chance of rain 40 percent.

Kaunakakai

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 88. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 61 to 72. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 75 to 85. West winds up to 10 mph. Chance of rain 30 percent.

Detailed Forecast

Synopsis

A large low pressure system far north of the Hawaiian Islands will continue to weaken the trade winds through the first half of next week. Local scale land and sea breezes will develop over each island in response to these light trades. This means the weather pattern will return to mountain and island interior sections with clouds and showers from afternoon to early evening due to converging sea breeze winds. More stable down sloping land breezes will lead to drier trends each night lasting through the early morning hours.

Discussion

A large low pressure system far north of the Hawaiian Islands will continue to weaken the high pressure ridge north of the state this week. Another trough associated with a dissipating cold front will move in north of the state this weekend keeping the ridge in a weakened state through next week Wednesday. Light to locally moderate trade winds remain in the forecast through the middle of next week. Local scale land and sea breezes will develop over each island in the absence of stronger large scale trade wind flow.
Weather wise, expect clouds and brief periods of showers over island mountain and interior sections each day due to converging sea breeze winds. Typically drier leeward areas will also see some measurable rainfall in this sea breeze pattern. An upper level trough shown on both water vapor satellite imagery and in the forecast guidance will likely expand rainfall coverage of these sea breeze showers through Friday afternoon. Down sloping land breezes will develop after sunset, produce more stable conditions and decrease shower activity over the islands in the overnight to early morning hours. Drier weather trends are forecast from late Friday into Saturday for most areas.
Weather trends from Sunday onward become more uncertain as large scale wind flow shifts to a more southeasterly direction with clouds passing more parallel to the island mountain ranges and keeping the smaller islands in a rain shadow just down stream of the Big Island. A low level trough, on a westward track, passes through the Big Island late Sunday into Monday. This low level trough may enhance shower activity over the slopes of the Big Island and Maui early next week.

Aviation

Light to locally moderate trade wind flow will continue to steer ragged bands stratocumulus off the Pacific towards the Islands. A weak eddy just west of the Big Island will keep the Kona coast shrouded in clouds through mid-morning. In the afternoon, localized sea breezes will focus daytime cumulus development over island interiors. Brief heavy showers are possible over the higher elevations of Maui and the Big Island later today.
No AIRMETs are in effect or anticipated at this time.

Marine

No Small Craft Advisory conditions are in the current forecast through Monday. The western end of a weak surface ridge is about 300 nm north of Lihue early this morning. Elsewhere, a 1007 mb surface low is near 35N 159W, or about 800 nm north of Lihue. A cold front trailing from this feature extends down to near 30N 163W. As this cold front advances toward the east-southeast at about 10 kt during the next 12 hours or so, it will cause the surface ridge to shift down closer to the islands. This will result in a continued easing of the background winds, which are forecast to veer out of the east to east-southeast through Friday. The front will eventually weaken to a surface trough, and shift westward from late Friday through this weekend. At the same, there will be a surface high far northeast of the islands. This will likely produce gentle to moderate easterly trade winds from this weekend into early next week.
The National Data Buoy Center buoys south of Hawaii, as well as the PacIOOS buoys in the nearshore waters, are showing increasing swell energy of 18 to 20 seconds from a south-southwest swell that is spreading up across the coastal waters early this morning. Since the swell height has been 1 to 2 feet above the wave model guidance, we have decided to issue a High Surf Advisory (HSA) for the south facing shores of all Hawaiian Islands. The HSA is currently in effect through this afternoon, but this may need to be extended into tonight if the observations show the swell does not begin to subside later today. This swell will slowly decline Friday, before the arrival of a reinforcing pulse of south swell energy on Saturday, which will likely maintain surf near the seasonal average along south facing shores this weekend. Surf will gradually lower along south facing shores early next week.
Surf will remain below the seasonal average along north facing shores through early next week. The current small northwest swell will fade late Friday. A small, short period north-northwest swell is possible during the weekend, followed by another small northwest swell next Tuesday. The weak trade winds over and upstream of the islands will maintain small surf along east facing shores through early next week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for all south facing shores.

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Data Courtesy of NOAA.gov