Hilo

Tonight: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 49 to 57 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 87 near the shore to 65 to 70 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 70 near the shore to 50 to 57 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 40 percent.

Kona

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

Tuesday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 68 near 5000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 73 near the shore to 48 to 53 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy with isolated showers. Lows 62 to 70 near the shore to 53 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 65 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 62 to 70 near the shore to 54 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy with isolated showers. Lows 62 to 70 near the shore to 53 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 65 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy with isolated showers. Lows 62 to 70 near the shore to 54 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Tonight: Breezy. Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows around 73 near the shore to around 54 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 83 to 88 near the shore to around 67 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Tuesday Night: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Lows around 73 near the shore to around 54 near 5000 feet. East winds up to 25 mph shifting to the northeast 10 to 20 mph after midnight.

Puna

Tonight: Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 49 to 57 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 87 near the shore to 65 to 70 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 70 near the shore to 50 to 57 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 40 percent.

Waikoloa

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 73 near the shore to 50 to 55 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to 65 to 74 above 4000 feet. Northeast winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Tuesday Night: Partly cloudy. Lows 71 to 76 near the shore to around 53 above 4000 feet. North winds up to 10 mph shifting to the east after midnight. Gusts up to 30 mph.

Detailed Forecast

Synopsis

Showers near Kauai and over the Kona slopes of the Big Island will diminish overnight as light to moderate trade winds bring a drier air mass over the island chain. For the remainder of the week, continued light to moderate trade winds and generally stable conditions will bring modest rainfall to windward areas. While most leeward areas will be rather dry, sea breezes will produce afternoon clouds and a few showers over terrain, especially on the Big Island.

Discussion

An area of moisture within a light to moderate trade wind flow has been producing some active showers over the western end of the island chain this afternoon. Aided by slight instability produced from a nearby upper-level low northwest of the state, a few showers briefly formed along the Waianae Mountains on leeward Oahu around midday, but as drier air pushed westward, this activity has largely moved over interior Kauai and waters just to the south. This moisture has also remained hung up on leeward Big Island and has fueled scattered showers, some briefly heavy, in and around Kailua-Kona. Expect shower activity on Kauai and leeward Big Island to linger into the evening then diminish overnight. Elsewhere, the stable trade wind flow will produce minimal windward rainfall and mostly dry conditions leeward.
A stable and somewhat dry light to moderate trade wind flow will become established on Tuesday. A weak surface ridge parked roughly 300 miles north of Kauai will maintain trades near current strength. The upper-level low will begin to creep northward and allow a strong mid-level ridge, already in place over the eastern half of the island chain, to bring increasingly stable conditions to the entire state. The moisture currently fueling showers around Kauai and over the Kona slopes will move west of the islands, and the incoming drier air mass will produce minimal showers over windward slopes. Most leeward areas will be rather dry, but sea breezes will produce afternoon clouds and a few showers, mainly on the Kona slopes of the Big Island. Little change is expected to the somewhat dry trade wind flow through the coming weekend.
The latest National Hurricane Center forecast has East Pacific Tropical Storm Kiko strengthening into a hurricane before crossing into the Central Pacific Friday or Saturday. It remains too early to tell what, if any, impacts this system might have on the local weather as it nears the islands early next week.

Aviation

Beneath a partial coverage of cirrus aloft, the trade wind inversion has trapped moisture in the 7-9kft layer which will continue supporting SCT-BKN VFR cigs through tonight mainly from Oahu to Kauai. Iso-sct aftn showers over select interior zones will dissipate with the loss of heating this evening followed by moderate trades that will deliver limited showers to windward and mauka zones overnight. Little to no change expected for tomorrow.

Marine

A ridge of high pressure north of the state will remain displaced to the south in response to large low far to the north. This will maintain moderate trades through most of the forecast period, with some localized sea breezes, especially across leeward waters.
Elevated surf will continue along north facing shores due to a short- to medium-period north swell. This swell will quickly be overshadowed by longer-period energy out of the northwest starting tonight. The northwest swell will peak Tuesday afternoon. A reinforcing pulse out of the north should arrive around the same time the northwest swell arrives. A mix of north and northwest swells are expected to continue thereafter, keeping north shore surf elevated, but slowly declining, through Thursday.
Surf along south facing shores will continue to decline through today as the south swell fades, despite a slight boost from short- period southeast energy. Below average surf is expected to continue along east facing shores persisting through early next week.
Peak monthly high tides, combined with water levels running higher than predicted, may lead to minor flooding along the shoreline and in low-lying coastal areas toward the end of next week. Coastal flooding may be possible around the daily afternoon peak tide.

Fire weather

Even as rather dry conditions return tonight and Tuesday, trade winds will remain in the light to moderate range and below the critical threshold this week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov