Hilo

Tonight: Cloudy. Isolated showers in the evening, then numerous showers after midnight. Lows 64 to 70 near the shore to 54 to 59 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Columbus Day: Cloudy with scattered showers. Highs 80 to 86 near the shore to 67 to 72 at 4000 feet. South winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Monday Night: Cloudy with numerous showers. Lows 65 to 71 near the shore to 54 to 59 at 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows around 73 near the shore to 48 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Columbus Day: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 87 near the shore to around 70 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Monday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 74 near the shore to 49 to 54 near 5000 feet. North winds up to 10 mph. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 71 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Columbus Day: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 67 to 85. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 65 to 72 near the shore to 57 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 71 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Columbus Day: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 67 to 85. East winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 65 to 72 near the shore to 57 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows around 74 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph.

Columbus Day: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 71 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday Night: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 75 near the shore to around 52 near 5000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

Puna

Tonight: Cloudy. Isolated showers in the evening, then numerous showers after midnight. Lows 64 to 70 near the shore to 54 to 59 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Columbus Day: Cloudy with scattered showers. Highs 80 to 86 near the shore to 67 to 72 at 4000 feet. South winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Monday Night: Cloudy with numerous showers. Lows 65 to 71 near the shore to 54 to 59 at 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows around 74 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Columbus Day: Mostly sunny in the morning then becoming partly sunny. Highs 84 to 90 near the shore to 66 to 74 above 4000 feet. Northeast winds up to 10 mph shifting to the northwest in the afternoon.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 75 near the shore to 51 to 56 above 4000 feet. Light winds becoming northeast up to 10 mph after midnight. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trades will deliver increased showers to windward and mauka areas tonight into early Monday. Trades then strengthen late Monday and persist through Thursday before diminishing for the latter portion of the week.

Discussion

Subsidence beneath upper ridging maintains high stability with partly cloudy conditions observed over most areas at press time. A narrow ribbon of moisture that has been the topic of discussion during the last couple of days extends southeastward from just east of Windward Big Island and will approach that area and Maui during the first half of the night, Oahu early tomorrow morning, and Kauai during midday Monday. The attendant weak surface trough presents as the lead edge of breezy trades and will tend to keep activity focused in a rather narrow band while these showers advance westward across the island chain. A slight uptick in windward clouds and showers can be expected with nothing more than a few light showers spreading leeward at times. Breezy trades gradually spread into the area in the wake of the trough as surface ridging anchored along 30N strengthens. Trades diminish this weekend, particularly across the western half of the state as mid-level height falls spread into the Central Pacific from the northwest.

Aviation

An area of low clouds and showers, currently just east of the Big Island, will move westward across the state tonight through Monday morning, resulting in enhanced windward showers. Periods of MVFR conditions are likely within the showers, potentially requiring AIRMET Sierra for mountain obscuration overnight. Otherwise, light to moderate trades will continue through Monday.

Marine

A front will weaken north of the state tonight allowing winds to strengthen Monday through Thursday followed by another slow down late in the week. A medium to long period north (350 degree) swell will build tonight into and produce advisory level surf along all exposed north facing shores Monday through Tuesday, then decline through the rest of the week. A small south swell will fade tonight and remain mostly background through the week. Surf along west facing shores will remain somewhat elevated due to the influence of the north swell wrap Monday into Tuesday before declining. East facing shore wind waves will remain relatively small under this recent weaker trade regime. East chop will pick back up through Tuesday in response to strengthening trades.

HFO Watches/Warnings/Advisories

High Surf Advisory from 6 AM Monday to 6 PM HST Tuesday for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.

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Data Courtesy of NOAA.gov