West Side

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 65 to 72. Northeast winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 82. East winds 10 to 15 mph. Chance of rain 40 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 65 to 72. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Tonight: Mostly clear. Breezy. Lows 64 to 74. Northeast winds 10 to 20 mph.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 86. North winds 10 to 15 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows 64 to 74. North winds 10 to 15 mph.

North Shore

Tonight: Breezy. Mostly cloudy with showers likely. Lows around 69 near the shore to around 50 near 5000 feet. East winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 70 percent.

Sunday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 77 to 82 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

Sunday Night: Breezy. Mostly cloudy with showers likely. Lows around 68 near the shore to around 50 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Central Maui

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 67. Northeast winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 79 to 86. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Sunday Night: Partly cloudy with isolated showers. Lows around 66. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Tonight: Breezy. Partly cloudy with scattered showers. Lows 42 to 53. East winds 10 to 25 mph. Chance of rain 50 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 61 at the visitor center to around 63 at the summit. East winds 10 to 25 mph. Chance of rain 50 percent.

Sunday Night: Breezy. Partly cloudy with scattered showers. Lows 43 to 53. East winds 10 to 25 mph. Chance of rain 50 percent.

East Maui

Tonight: Breezy. Mostly cloudy with showers likely. Lows around 69 near the shore to around 50 near 5000 feet. East winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 70 percent.

Sunday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 77 to 82 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

Sunday Night: Breezy. Mostly cloudy with showers likely. Lows around 68 near the shore to around 50 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Lanai City

Tonight: Mostly clear. Breezy. Lows around 64. Northeast winds 10 to 20 mph.

Sunday: Sunny. Isolated showers in the afternoon. Highs 72 to 80. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows around 64. Northeast winds 10 to 15 mph.

Kaunakakai

Tonight: Breezy. Partly cloudy with isolated showers. Lows 55 to 71. East winds 15 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 68 to 85. East winds 15 to 20 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 55 to 71. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trade winds will continue for the next several days, with passing clouds and showers favoring windward and mauka areas. Lighter winds are expected by the middle of next week, with fewer windward showers, and a greater chance for afternoon interior showers.

Discussion

A batch of moisture riding in on the breezy trades this evening is bringing scattered showers to windward and mauka areas across the island chain, with a few showers spilling over to leeward areas at times. As the night progresses, upstream moisture seen on satellite imagery is expected to focus over the eastern half of the state, with the southeast steering flow at 850mb backing to become more easterly and preventing the spread of that moisture up the island chain. Drier air will filter across the western end of the state, bringing clearer conditions across Oahu and Kauai by tomorrow morning.
Meanwhile, high pressure far northeast of the state will help to maintain breezy trade winds through the next couple of days. More batches of moisture caught up in these trades will periodically filter in across the island chain, with clouds and showers generally focusing across windward and mauka areas. An upper-level low will move over the state from the west starting late tomorrow and remain there through mid week, bringing some instability aloft, which may help to enhance windward showers at times.
A strong low pressure system to the far north will displace the ridge to bring it closer to, or over, the island chain by mid week. The proximity of this ridge and the approach of a front/trough from the northwest will bring lighter southeast winds across the area, allowing land and sea breezes to expand in coverage and dominate the local weather regime. This will lead to mostly clear nights and mornings giving way to afternoon clouds and showers over interior/leeward areas. An upper level trough will dive southeast across the Central Pacific and move overhead by Wednesday evening, bringing cooler temperatures aloft. The instability associated with this feature combined with pockets of moisture moving across the island chain on the southeast flow may lead to enhanced diurnal showers with brief heavy downpours over island interiors during the day, particularly on Thursday and Friday.

Aviation

Moderate to breezy trade winds will continue for the next few days. A strong trade wind inversion aloft will keep moisture trapped in the lower levels. Shower activity will be mostly light and intermittent. Clouds and showers will favor windward slopes and coasts and be most active in the late night and morning hours.
AIRMET Tango remains in effect for occasional moderate turbulence below 8000 feet over and to the lee of higher terrain due to moderate to strong winds at summit level.
AIRMET Sierra is now in effect for mountain obscuration along north and east facing slopes of Oahu, Molokai, and Maui. Sierra may need to be expanded later tonight to include portions of Kauai or Windward Big Island. Conditions are not likely improve until after sunrise Sunday.

Marine

High pressure northeast of the state will maintain moderate to strong trades through Monday. As a result, a Small Craft Advisory (SCA) remains in effect for the typically windy waters around Maui and the Big Island through 6 PM Monday. The trades will begin to ease Tuesday and become further disrupted Wednesday and Thursday as an approaching front induces surface troughing over the western end of the state. Winds will become light and variable over the western waters as a result, while winds over the eastern islands shift east-southeasterly at light to moderate speeds.
East shore surf will remain at or above normal levels through Tuesday, and will be rather rough due to the strong trades, particularly through Monday. As the trades diminish surf along east facing shores will drop below normal Wednesday through next Saturday.
North shore surf will remain very small through the weekend. A small northwest swell will give a boost to surf along north and west facing shores Monday and Tuesday, followed by a decline Wednesday and Thursday. A new moderate sized north-northwest swell will arrive late Thursday, potentially bringing advisory level surf to north and west facing shores Friday, then lowering through next weekend.
Surf along south facing shores will remain small and mostly at background levels through late next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov