West Side

Today: Mostly cloudy. A 20 percent chance of showers in the afternoon. Highs around 79. Northeast winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows 67 to 72. Southeast winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny in the morning then becoming partly sunny. A 20 percent chance of showers. Highs around 79. Northwest winds up to 10 mph.

South Side

Today: Mostly cloudy. Highs around 84. Northwest winds up to 10 mph.

Tonight: Mostly cloudy. Lows 67 to 75. Northwest winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny in the morning, then partly sunny with a 20 percent chance of showers in the afternoon. Highs around 83. Light winds.

North Shore

Today: Mostly cloudy with a 20 percent chance of showers. Highs around 80 near the shore to around 67 near 5000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows around 71 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph.

Monday: Partly sunny. Slight chance of showers in the morning, then chance of showers in the afternoon. Highs around 80 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Partly sunny in the morning then becoming cloudy. Highs 80 to 85. Northeast winds up to 15 mph.

Tonight: Mostly cloudy. A 20 percent chance of showers after midnight. Lows around 69. East winds up to 15 mph in the evening becoming light.

Monday: Mostly sunny in the morning then becoming partly sunny. A 20 percent chance of showers. Highs around 82. Light winds becoming northeast up to 10 mph in the afternoon.

Upcountry

Today: Mostly cloudy. A 20 percent chance of showers in the afternoon. Highs around 62 at the visitor center to around 67 at the summit. East winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows around 49 at the visitor center to around 44 at the summit. East winds up to 10 mph in the evening becoming light.

Monday: Partly sunny. Slight chance of showers in the morning, then chance of showers in the afternoon. Highs around 61 at the visitor center to around 66 at the summit. Light winds. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy with a 20 percent chance of showers. Highs around 80 near the shore to around 67 near 5000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows around 71 near the shore to around 54 near 5000 feet. Southeast winds up to 15 mph.

Monday: Partly sunny. Slight chance of showers in the morning, then chance of showers in the afternoon. Highs around 80 near the shore to around 66 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Partly sunny in the morning, then cloudy with a 20 percent chance of showers in the afternoon. Highs 72 to 78. East winds up to 10 mph shifting to the north in the afternoon.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows around 66. Northeast winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny with slight chance of showers in the morning, then partly sunny with chance of showers in the afternoon. Highs 71 to 77. Light winds. Chance of rain 30 percent.

Kaunakakai

Today: Partly sunny in the morning, then cloudy with a 20 percent chance of showers in the afternoon. Highs 69 to 85. East winds up to 15 mph.

Tonight: Mostly cloudy with a 20 percent chance of showers. Lows 58 to 72. East winds up to 15 mph in the evening becoming light.

Monday: Mostly sunny in the morning then becoming partly sunny. A 20 percent chance of showers. Highs 68 to 84. Light winds.

Detailed Forecast

Synopsis

An upper-level trough will will bring increased high clouds and renewed chances for isolated heavy showers and thunderstorms this afternoon and Monday. Light winds favor chances for mainly afternoon showers Tuesday and Wednesday, followed by rebuilding trade winds Thursday and Friday.

Discussion

Today and tomorrow, trades will weaken further and will shift out of the east-southeast across the western half of the island chain, while another upper-level trough brings instability, mainly tonight into Monday morning. For now, it appears that the deepest moisture and highest chances for widespread rainfall will remain along the surface trough northwest of Kauai, but isolated heavy showers or a thunderstorm remain possible around Kauai. Elsewhere, expect afternoon interior showers and possibly a thunderstorm on Big Island, and another item to monitor will be a chance for localized anchored heavy showers along the Koolau Mountains of Oahu tonight. Even though moisture does not appear to be significant on Oahu, the expected veering flow with height has a tendency to produce heavy rain events on the Koolau.
Chances for heavy rainfall look to diminish Tuesday and Wednesday. The upper level trough should move off to the east late Monday, allowing a weak ridge aloft to settle over the state. The GFS and ECMWF are hinting that the surface trough that had been lingering northwest of Kauai will be pushed over the western end of the island chain. This would favor light and variable winds over most areas with higher rainfall chances over island interiors during the late morning and afternoon hours. Trade winds are expected to rebuild Thursday and Friday.

Aviation

Predominately light northeasterly winds among some land-sea breezes will remain in place through the next several days under high pressure well northeast of the Hawaiian Islands and a surface trough lingering to the west. Some terminals may experience some mid- to high-clouds and embedded light showers, resulting in brief periods of MVFR conditions. Otherwise, expect VFR conditions to prevail across most terminals through the period.
No AIRMETs in effect.

Marine

A high pressure system far north of the state will slowly drift eastward this weekend. Easterly trade winds diminish tonight as a trough to the northwest of the islands develops into a weak low pressure system by Sunday. The resulting weakness in the ridge causes winds to veer southeasterly and diminish over the western Hawaii region from Sunday into early next week. By Thursday the high pressure ridge builds back in north of the state with fresh easterly trade winds returning to the region lasting through next weekend.
A small pulse of medium period swell energy from the northwest should produce a slight bump in north facing surf heights into the morning hours. Another small, medium period northwest swell will move into the region by Monday night and continue through Wednesday. A moderate, medium period northeast swell arrives Tuesday and peaks on Wednesday, bringing moderate surf to north- facing shores, before slowly declining through the end of the week.
A series of overlapping small south swells will move into the region this week keeping surf heights on the small side. Surf heights along east facing shores also remain small due to weaker trade winds until the arrival of the small medium period northeast swell building into the Hawaii region from Tuesday through Thursday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov