Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny with isolated showers. Highs 79 to 89. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 68 to 75. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 78 to 90. East winds around 10 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 88. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 67 to 75. North winds up to 15 mph.

Tuesday: Mostly sunny. Highs around 89. East winds 10 to 15 mph.

North Shore

Today: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 84 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows around 71 near the shore to 48 to 54 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 84 near the shore to around 67 near 5000 feet. East winds around 10 mph. Chance of rain 40 percent.

Central Maui

Today: Mostly sunny. Isolated showers in the afternoon. Highs 82 to 88. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 67 to 72. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs 82 to 88. East winds around 10 mph.

Upcountry

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 62 at the visitor center to around 58 at the summit. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 45 at the visitor center to around 42 at the summit. Light winds. Chance of rain 50 percent.

Tuesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 63 at the visitor center to around 58 at the summit. Light winds becoming east around 10 mph in the afternoon. Chance of rain 40 percent.

East Maui

Today: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 84 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows around 71 near the shore to 48 to 54 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 84 near the shore to around 67 near 5000 feet. East winds around 10 mph. Chance of rain 40 percent.

Lanai City

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 72 to 81. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Lows 63 to 68. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight.

Tuesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 82. Light winds. Chance of rain 30 percent.

Kaunakakai

Today: Mostly sunny. Isolated showers in the afternoon. Highs 69 to 89. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows 58 to 74. Northeast winds 10 to 15 mph shifting to the east after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 69 to 90. East winds around 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

A weak surface trough will move slowly over the islands from east to west, starting later today and continue through about Wednesday. The trough will weaken the trade winds and allow for localized daytime sea breezes and nighttime land breezes in some spots through about midweek. Showers will tend to favor windward and mauka areas during the nights and mornings, and interior and leeward locales during the afternoons and evenings. Relatively dry and breezy trade wind weather is expected to return for the latter portion of the new week.

Discussion

12z soundings continued to show a relatively weak and elevated subsidence inversion, about 8000 feet above Hilo and near 10000 feet over Lihue. Believe this is due to a weak 700 mb low developing near the islands. Even though precipitable water values are relatively modest…near 1.2-1.3 inches statewide, satellite and radar showing scattered showery clouds over and upwind from the islands from Kauai to Molokai. Some of these will likely fade after the sun comes up.
The tail end of a surface trough NE thru E of the islands approximately near 151W (based on satellite imagery and a partial evening ASCAT pass) will continue edging W, being reinforced by the mid-level low. This will lead to decreasing trades as the weak surface trough drags very slowly across the islands later today through about Wed. Today looks to be a hybrid pattern with light trades and a mix of some morning windward and mauka trade wind showers and a few afternoon leeward showers. Similar for Tue…although with even lighter winds, more of a trend toward afternoon interior showers. Although the mid-level low and surface trough will help to allow for taller showers, relatively meager precipitable water values should keep things from being too active.
The 00z ECMWF and it’s ensembles have backed off of the idea of bringing a slug of moisture up over the islands as the weak surface trough departs to our west. Thus Wed looks like a hybrid day as we transition back to trades pushing in from the east. The trades will increase and become locally windy by Friday, with drier air and warm temperatures aloft helping to keep shower activity rather sparse for the rest of the work week.
High level moisture streaming up from the southeast will lead to high clouds at times the next few days. Generally these will be thin, but they may thicken enough to lead to milky skies and dim sunshine for some areas starting near the Big Island on Wed and for the smaller islands Wed night and possibly into Thu morning before departing.

Aviation

Light trades and an elevated inversion are supporting a limited coverage of moderate to occasionally heavy showers focused over windward areas. This activity will diminish during mid-morning. By this afternoon, a modified sea breeze pattern will give rise to clouds and showers over favored leeward areas while windward showers decrease in coverage. Land breezes will bring clearing skies tonight.

Marine

No major changes to the marine forecast with the morning package. Light easterly flow will continue today and tomorrow with high pressure far to the north and a surface trough to the northeast. The trough is expected to move to the west heading into mid-week, allowing the pressure gradient over the region to strengthen again. This will bring moderate to locally breezy trade winds back for the second half of the week.
The current small south swell is slowly declining, with this trend expected to continue into Tuesday. A series of small south and southeast swells will continue to keep south shore surf from going flat through the end of the week. With the light winds, expect surf to continue to diminish along east facing shores with nearly flat conditions expected by tonight. During the second half of the week as trades strengthen, expect surf to gradually increase. No other significant swells are expected.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov