Hilo

Rest Of Tonight: Cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 67 near the shore to 47 to 54 at 4000 feet. Light winds. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs around 78 near the shore to around 64 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 60 to 68 near the shore to 48 to 55 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Kona

Rest Of Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 69 near the shore to 43 to 49 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs around 84 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 70 near the shore to 43 to 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Rest Of Tonight: Mostly cloudy. Isolated showers early in the evening, then scattered showers in the late evening and overnight. Lows 59 to 68 near the shore to 51 to 58 near 3000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 50 percent.

Sunday: Mostly cloudy with scattered showers. Highs around 77 near the shore to 68 to 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Kohala

Rest Of Tonight: Mostly cloudy. Isolated showers early in the evening, then scattered showers in the late evening and overnight. Lows 59 to 68 near the shore to 51 to 58 near 3000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 50 percent.

Sunday: Mostly cloudy with scattered showers. Highs around 77 near the shore to 68 to 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Rest Of Tonight: Partly cloudy with isolated showers. Lows around 71 near the shore to around 48 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny early in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 84 near the shore to around 66 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Sunday Night: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 71 near the shore to around 49 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Puna

Rest Of Tonight: Cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 67 near the shore to 47 to 54 at 4000 feet. Light winds. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs around 78 near the shore to around 64 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 60 to 68 near the shore to 48 to 55 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Rest Of Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Isolated showers early in the evening. Lows 67 to 72 near the shore to 46 to 52 above 4000 feet. Light winds becoming southeast up to 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 81 to 86 near the shore to 63 to 69 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 70 near the shore to 47 to 52 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trade winds will strengthen into Sunday, while a deep low pressure system to the west bring instability and enhancement to the incoming showers. Isolated thunderstorms and locally heavy rainfall will be possible statewide, but most of the widespread coverage will remain north of the state. Stability will return early next week with trade winds focusing showers windward and mauka.

Discussion

A deep low pressure system is positioned west northwest of the main Hawaiian islands this afternoon, and will be the cause of some active weather over the next few days. At the surface, high pressure north of the associated low is beginning to nose in from the east side of it and will allow trade winds to strengthen Sunday into next week as it sets up far northeast of the area. Winds will veer slightly southeasterly due to the low to the west northwest.
Moderate to locally heavy showers in a band connected to the surface low will linger just north of the state over the next few days, with showers and possible thunderstorms along the southern fringes of the band impacting the state at times through at least Sunday. The ingredients and the greatest focus just to the north of the islands do not push confidence high enough for the issuance of a Flood Watch, though the situation will need monitoring.
The GFS and ECMWF show the chances for rainfall declining by late Sunday or Monday. The upper low will weaken and broaden out and while the surface low weakens and tracks away to the west. Trade winds will push lingering and upstream moisture across the islands for the first half of the week resulting in lighter and less frequent showers focused windward and mauka showers. Trade winds and windward and mauka showers expected into the second half of the week as well.

Aviation

Light to moderate east southeast winds with localized land/sea breezes can be expected this weekend as a surface low and trough linger to the west of the Hawaiian Islands. There is also some marginal instability due to broad upper level troughing. Thus, expect isolated to scattered showers to affect mainly windward areas, with localized sea breezes leading to isolated to scattered showers over leeward locations as well. Brief MVFR ceilings and visibility will be possible in some of the heavier showers.
Enough instability will be present this evening and tonight to introduce a slight chance of thunderstorms to windward portions of the smaller islands.
AIRMET Sierra is in effect for mountain obscuration for northern and western portions of Kauai and Oahu and could be expanded to include other islands.

Marine

Fresh to moderate trades will veer slightly east-southeast over the western half of the state as an area of low pressure meanders northwest of the state into early next week. Isolated thunderstorms will be possible through Sunday night, mainly over the waters north of the islands, due to the proximity of the low. The low is expected to gradually weaken through early next week as a high passes north of state, which may generate fresh to locally strong easterly winds over the eastern half of the state, requiring a Small Craft Advisory (SCA), while the western half remains in moderate to locally fresh east-southeast flow. The low is expected gradually drift west and weaken further early next week, allowing winds to shift back to a more typical easterly direction and increase to fresh to locally speeds statewide by Tuesday night and hold through the second half of next week.
A moderate, west-northwest (300-320) swell will continue to trend down through the rest of the weekend. The High Surf Advisory has been cancelled as surf heights have dropped below advisory levels. A small to moderate, medium-period north-northwest swell (340-350) may overlap the fading west-northwest swell Sunday night into Wednesday. In the long range, a series of small, long-period northwest (320-330) swells look to keep surf from going flat through much of next week.
Rough choppy surf along east facing shores will drop a notch into early next week. As winds strengthen by midweek, expect east shore surf to pick back up. No significant south swells expected through next week.

HFO Watches/Warnings/Advisories

Wind Advisory until 8 AM HST Sunday for Big Island Summits.

Big Island Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Big Island Helicopter Tours today!

Data Courtesy of NOAA.gov