West Side

Today: Sunny. Highs 80 to 86. Northeast winds up to 15 mph.

Tonight: Mostly clear. Lows 69 to 76. East winds up to 15 mph.

Monday: Sunny. Highs 79 to 85. East winds up to 15 mph.

South Side

Today: Sunny and breezy. Highs around 88. North winds up to 20 mph increasing to 15 to 20 mph in the afternoon.

Tonight: Mostly clear. Breezy. Lows 67 to 77. North winds up to 20 mph decreasing to up to 10 mph after midnight.

Monday: Sunny. Highs around 87. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

North Shore

Today: Sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 72 near the shore to around 53 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Central Maui

Today: Sunny. Highs 80 to 88. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Mostly clear. Lows 67 to 72. Northeast winds up to 15 mph.

Monday: Sunny and breezy. Highs 80 to 88. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon.

Upcountry

Today: Mostly sunny with isolated showers. Highs around 62 at the visitor center to around 71 at the summit. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 48 at the visitor center to around 45 at the summit. Northeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the morning. Highs around 61 at the visitor center to around 68 at the summit. Northeast winds up to 10 mph. Chance of rain 20 percent.

East Maui

Today: Sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 72 near the shore to around 53 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Lanai City

Today: Sunny. Highs 72 to 81. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Mostly clear. Lows 65 to 70. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight.

Monday: Sunny. Highs 72 to 81. Northeast winds up to 15 mph.

Kaunakakai

Today: Sunny. Highs 70 to 88. Northeast winds up to 15 mph.

Tonight: Mostly clear. Lows 60 to 74. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight.

Monday: Sunny. Highs 70 to 88. Northeast winds up to 15 mph.

Detailed Forecast

Synopsis

Light to moderate east northeasterly flow will prevail today and bring scattered clouds and isolated showers to mainly windward areas. Localized afternoon sea breezes may help initiate a few showers over select leeward mountain slopes. Surface high pressure will build north of the area Monday through midweek and help strengthen trade winds to moderate to breezy levels. A weak surface trough is forecast to move through the area by midweek which could help enhance trade wind showers.

Discussion

GOES IR satellite imagery loop from this morning shows areas of scattered low clouds drifting towards the windward coasts, as well as the presence of cloud lines southwest of almost every island from leeside confluent boundaries. For the last several hours, isolated showers have been concentrated along the windward slopes with dry conditions elsewhere. Zooming out, a 1025 mb surface high remains parked well to the northeast of state and should help maintain light to moderate east northeasterly trades. By late this morning, sea breezes could form along select leeward locations thanks to this lighter flow pattern. Clouds and showers will be limited today as relatively dry and stable air dominates aloft. On the Big Island, however, hi- resolution model guidance depicts a slight uptick in shower activity this afternoon over the south slopes of Mauna Loa as sea breezes develop and push upslope.
By Monday, a strong surface high begins to expand north of our region and will further establish the moderate trade wind flow. Models advect a batch of low level moisture, caught in this flow, across the western most islands. As the moisture pushes through, expect brief period of increase shower activity. Time- height cross- sections show low level moisture deepening to around 10k feet. By late Monday, this round of moisture pushes west of the state and drier air briefly filters in.
Tuesday through early Thursday, a strong 1030 mb surface high builds well north of the state. In response, local pressure gradients will tighten and trades should increase to moderate to breezy levels. Meanwhile, both the GFS and ECMWF show a surface trough approaching the Big Island from the east, then slowly drifting across the remaining smaller islands. This feature would likely enhance any passing showers as the moisture levels deepen once again and the capping boundary layer temperature inversion weakens. Also during this period, an upper level low drops north of the state and begins to retrograde back to west or southwest. This feature could help enhance shower activity as well, depending how close it passes to the islands. All in all, confidence is increasing for a wetter and breezier period by midweek. For Friday into next weekend, a drier and more seasonable trade wind pattern returns.

Aviation

Light to moderate easterly trades will persist through Monday, with clouds and showers favoring windward and mauka locations through the early morning hours. Expect some cloud buildups over leeward and interior sections through the afternoon hours where localized sea breezes form. No AIRMETs are anticipated through the period, with only brief periods with MVFR CIGs/VSBYs possible in showers this morning.

Marine

A weak high pressure ridge north of the Hawaiian Islands will strengthen by the middle of this week, increasing trade winds and wind driven seas. A low level trough will move through the Hawaii region, from Tuesday through Wednesday, increasing shower activity from east to west.
Several overlapping small medium and long period south swells will continue to pass through the region this week. This south swell energy will keep south shore surf elevated into next weekend.
Surf along west, north and east shores will remain small due to lack of swell energy and lighter trade winds. Increasing trade winds later this week will raise surf heights slightly along all exposed east facing shores.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov