Hilo

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 near the shore to around 57 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 85 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 62 to 70 near the shore to around 55 at 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy with isolated showers. Lows around 74 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny 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. West winds up to 10 mph. Chance of rain 40 percent.

Saturday Night: Mostly cloudy with isolated showers. Lows around 73 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 65 to 85. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Saturday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 71 near the shore to 55 to 61 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 65 to 85. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Saturday Night: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 71 near the shore to 55 to 61 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 75 near the shore to around 54 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Saturday Night: Breezy. Mostly cloudy in the evening, then partly cloudy with isolated showers after midnight. Lows around 74 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with numerous showers. Lows 64 to 71 near the shore to around 57 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 85 near the shore to around 67 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Saturday Night: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 62 to 70 near the shore to around 55 at 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Waikoloa

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to around 55 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 90 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Saturday Night: Partly cloudy. Isolated showers after midnight. Lows around 74 near the shore to 51 to 57 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds will prevail through the weekend and much of next week. Trade wind showers will favor windward and mountain areas in the overnight to early morning hours, especially through tomorrow morning as a weak disturbance passes over the state. A slightly drier trade wind pattern is expected from Saturday afternoon through Monday, followed by wetter trends from Monday night into Wednesday.

Discussion

Local radar imagery this evening shows scattered to numerous showers moving through the windward and mountain slopes of each island on the easterly trade winds. This shower activity is enhanced by a weak disturbance aloft and these wet trends will continue into the early morning hours.
In the big picture, the high pressure ridge north of the Hawaiian Islands will begin to weaken slightly starting on Sunday as a cold frontal system passing through the Central Pacific basin. Moderate trade winds will continue to blow across the state through much of next week.
In the rainfall forecast, we continue to see subtle changes in the day to day shower activity over each island. A weak disturbance shown clearly on the 700 mb streamlines will continue to track westward over the islands tonight, keeping a slight increase in shower activity that favors the windward and mountain areas through the early morning hours. Brief drying trends will develop from Saturday afternoon through Monday. Additional bands of clouds, likely the remnants of an old East Pacific frontal boundary, will then drift into the state on the trade winds from Monday night into Wednesday; with increasing shower trends favoring the overnight through early morning hours.

Aviation

Moderate trades through the weekend. Windward and mauka SHRA can be expected with some spillover to leeward locations. Brief MVFR conds are possible in any SHRA, but VFR should generally prevail.
AIRMET Sierra is in effect for mtn obsc for windward portions of all islands. Conds expected to improve with sunrise.

Marine

Gentle to fresh trade winds will prevail through at least early next week as weak surface high pressure holds north of the island chain. Winds will be near the Small Craft Advisory (SCA) level at times around the Big Island and Maui through tomorrow, but an SCA is not anticipated. Winds may decline slightly Sunday and Monday as the surface ridge to the north is weakened, with a slight increase possible Tuesday or Wednesday.
The current small north-northwest swell will decline through tonight. A small, medium period north-northwest swell will build on Saturday and produce north shore surf near September average Saturday night and early Sunday. A small, medium period northwest will arrive on Tuesday, shift out of the north Wednesday and Thursday, and hold into Friday.
The current mix of small, long period south-southwest swell and short period southwest swell will decline tonight and Saturday. Another pulse of inconsistent southwest swell originating from the Tasman Sea will push south shore surf to near seasonal average late Sunday and Monday. A more consistent south-southwest swell is expected Tuesday and Wednesday.
East shore surf will remain well below normal through the week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov