Hilo

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 58 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 82 to 87 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 71 near the shore to around 58 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Kona

Tonight: Mostly clear. Isolated showers in the evening. Lows 66 to 74 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the afternoon. Highs 85 to 92 near the shore to 68 to 73 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday Night: Mostly clear. Isolated showers in the evening. Lows 66 to 74 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 72 near the shore to 57 to 65 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Monday: Sunny. Isolated showers in the morning. Highs around 83 near the shore to 72 to 81 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy with scattered showers. Lows 64 to 73 near the shore to 58 to 66 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 64 to 72 near the shore to 57 to 65 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Monday: Sunny. Isolated showers in the morning. Highs around 83 near the shore to 72 to 81 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Monday Night: Partly cloudy with scattered showers. Lows 64 to 73 near the shore to 58 to 66 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly clear. Isolated showers in the evening. Lows around 75 near the shore to around 56 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the afternoon. Highs around 88 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Clear. Lows around 75 near the shore to around 57 near 5000 feet. Northeast winds up to 15 mph.

Puna

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 58 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers in the morning, then sunny in the afternoon. Highs 82 to 87 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 71 near the shore to around 58 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Tonight: Mostly clear. Lows 68 to 75 near the shore to 52 to 57 above 4000 feet. East winds up to 15 mph.

Monday: Sunny. Highs 87 to 92 near the shore to 68 to 75 above 4000 feet. Northeast winds up to 15 mph.

Monday Night: Clear. Lows 68 to 75 near the shore to 53 to 58 above 4000 feet. East winds up to 15 mph.

Detailed Forecast

Synopsis

Mostly dry and stable conditions with light to moderate trade winds will prevail through Tuesday, with clouds and mainly light showers favoring windward and mauka locations overnight through the early morning hours. A few cloud buildups and light showers are possible over leeward sections each afternoon where localized sea breezes form. A modest increase in moisture associated with a surface trough moving in from the east, combined with an upper- level disturbance, will support increasing rainfall chances from Tuesday into midweek. Trade winds will then strengthen into the breezy category by Wednesday as the trough and upper disturbance shift west of the area and the ridge strengthens north of the islands.

Discussion

A relatively dry and stable trade wind pattern will persist through Tuesday as a weak surface ridge remains positioned north of the islands. Light to moderate easterly trades will continue, with clouds and a few light showers primarily favoring windward and mauka areas overnight through the morning hours. Afternoon heating and localized sea breeze development may support a few cloud buildups and brief showers over leeward and interior sections each day, but rainfall amounts should remain limited through Tuesday.
Conditions will begin to change late Tuesday as a surface trough approaches from the east and moisture increases across the island chain. Guidance remains in good agreement showing precipitable water values rising to near 1.75 inches by Wednesday. At the same time, an upper-level shortwave trough is forecast to dig southward over the region, eventually cutting off and retrograding westward across the islands through the middle part of the week. The approach of this upper disturbance will lower mid- and upper- level heights while helping to weaken and elevate the inversion. The combination of slightly deeper moisture, reduced stability, and enhanced large-scale lift associated with the upper trough will support increasing shower coverage and rainfall potential from late Tuesday through Thursday, particularly over windward and mauka areas, though some showers may periodically spread into leeward locations on the trades.
By late week into next weekend, both the surface trough and upper-level disturbance are expected to shift west of the state. In their wake, a strengthening subtropical ridge north of the islands will support a return to a more typical breezy trade wind pattern. Upper heights will gradually rise, the trade wind inversion will strengthen and lower, and precipitable water values are expected to decrease back toward climatological levels. As a result, shower activity should trend downward, with rainfall becoming focused once again over windward and mauka areas within the prevailing trade flow.

Aviation

VFR conditions will prevail with limited showers through Monday. Trade winds increase in strength over the next few days, decreasing sea breeze coverage area. A passing low level trough will drift from east to west across the island chain, increasing shower trends from Tuesday afternoon through Wednesday.
No AIRMETs in effect.

Marine

A weak high pressure ridge will remain nearly stationary north of the waters maintaining gentle to locally fresh trade winds over the next several days. High pressure to the far north northeast will strengthen by midweek as easterly trade winds gradually strengthen. A low level trough moving in from the east Tuesday through Wednesday will bring an increase in shower activity.
A series of small to moderate medium to long period south swells will keep surf along south facing shores elevated through the forecast period. Surf along east facing shores will remain small due to the lack of trade winds energy upstream of the islands. Surf along north facing shores will remain flat to tiny through the forecast period with potentially tiny background energy midweek into Thursday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov