Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 73 near the shore to around 54 at 4000 feet. West winds up to 10 mph. Chance of rain 70 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 63 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 90 percent.

Kona

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 70 to 76 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 73 near the shore to 48 to 54 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Tonight: Mostly cloudy with scattered showers. Lows around 70 near the shore to 57 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 56 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy with scattered showers. Lows around 70 near the shore to 57 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs around 82 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 56 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 71 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 20 mph. Chance of rain 30 percent.

Monday Night: Mostly cloudy. Breezy. Isolated showers in the evening. Lows around 74 near the shore to around 52 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 73 near the shore to around 54 at 4000 feet. West winds up to 10 mph. Chance of rain 70 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 63 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 90 percent.

Waikoloa

Tonight: Partly cloudy with isolated showers. Lows 71 to 76 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 86 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Isolated showers in the evening. Lows around 74 near the shore to 51 to 56 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds will prevail through Monday as the surface ridge to the north briefly weakens. Rainfall will favor windward and mauka locations, but a few showers, some heavy, may develop across leeward areas as a disturbance aloft moves overhead. Locally breezy trades and more stable conditions will return on Tuesday and persist into next weekend.

Discussion

A surface ridge far north of the islands will drive moderate trade winds through tomorrow, and instability produced by an upper- level low will generate briefly heavy showers. The upper-level low remains centered just north of Kauai and Oahu this afternoon and will creep west slowly over the next couple of days. This feature has weakened and elevated the inversion over most of the island chain and is producing high lapse rates above 15,000 ft close to the core of the low. However, with no organized areas of moisture expected through Monday, an increase in widespread rainfall is unlikely. As a result, expect the locally scattered showers moving along the trades to be briefly heavy. Afternoon sea breezes in sheltered areas will generate spotty showers, some heavy, across leeward terrain, with some showers lingering into the evening. So far, rainfall has not been significant, but there is some potential for some minor flooding concerns over leeward Big Island each afternoon and evening.
A stronger and more stable trade wind flow will develop on Tuesday. The locally breezy trades will be driven by a tighter pressure gradient between the strengthening low-level ridge to the north and a pair of tropical disturbances passing several hundred miles south of the islands. The upper-level low will fill and drift away to the west, and a ridge aloft building in from the east will bring stability. Through the rest of the work week, expect typical windward rainfall for most islands, though windward Big Island may be brushed with some deeper tropical moisture Wednesday night through Thursday night.

Aviation

Moderate trades should continue through tomorrow. SHRA and low cigs should mostly be confined to windward and mauka locations. MVFR conds can be expected in SHRA, but otherwise VFR should prevail.
No AIRMETs are in effect.

Marine

Fresh trades ease slightly into Monday as the ridge north of the islands weakens. Locally strong trades then develop Monday night and persist for the remainder of the week. A Small Craft Advisory for the windier waters of Maui County and the Big Island will likely be needed by Tuesday or Tuesday night.
Surf along north and west facing shores will remain tiny through Monday. A moderate, long-period NW swell will arrive on Tuesday and push surf heights along north and west facing shores well above the seasonal average Tuesday night and Wednesday but will fall short of the High Surf Advisory threshold.
Surf along south facing shores will remain just below seasonal average levels as a SW swell advances through area waters. A reinforcing SW swell is expected late Monday into midweek. East shore surf remains small in response to declining trades with an upward trend anticipated beginning Monday night as trades restrengthen.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov