Hilo

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

Friday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 86 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

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

Kona

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 74 near the shore to 51 to 56 near 5000 feet. Light winds. Chance of rain 40 percent.

Friday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 50 percent.

Friday Night: 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.

Waimea

Tonight: Mostly cloudy with scattered showers. Lows 65 to 72 near the shore to 57 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 66 to 85. East winds up to 15 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Mostly cloudy with scattered showers. Lows 65 to 72 near the shore to 57 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 66 to 85. East winds up to 15 mph. Chance of rain 50 percent.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 64 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Partly cloudy. Breezy. Lows around 75 near the shore to around 54 near 5000 feet. Northeast winds up to 20 mph.

Friday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 69 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Friday Night: 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. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

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

Friday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 79 to 86 near the shore to 65 to 70 at 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

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

Waikoloa

Tonight: Mostly cloudy in the evening then becoming mostly clear. Lows around 76 near the shore to 54 to 59 above 4000 feet. East winds up to 10 mph.

Friday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 84 to 90 near the shore to 67 to 74 above 4000 feet. North winds up to 15 mph. Chance of rain 20 percent.

Friday Night: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to around 55 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds will prevail through much of the week, focusing rainfall over windward slopes. With the exception of afternoon and evening showers over the Kona slopes of the Big Island, leeward areas will experience little rainfall.

Discussion

A stable, moderate trade wind flow remains in place. Surface high pressure centered about 700 miles north of the state is driving the trades, and a ridge aloft parked overhead is producing stable conditions with an inversion based around 6,500 feet. Random showers moving along the trade winds have produced modest rainfall along windward slopes today, mainly less than a tenth of an inch at most sites and over a quarter of an inch at a few of the wettest locations. SInce the trades down to moderate strength, sea breezes produced fairly extensive clouds along across sheltered leeward terrain, but with the exception of the Kona slopes of the Big Island, most leeward communities will experience little to no rainfall through the rest of the day.
Expect only subtle day to day changes through the week week, mainly due to small pockets of moisture moving through. One such area should provide an increase in windward showers Friday night and early Saturday, but drier conditions are expected for most of the weekend. Trades may decline slightly Sunday and Monday as surface high pressure to the north weakens. For midweek, the GFS and ECMWF models have been inconsistent about the strength of the trades, though winds are likely to be around moderate strength.

Aviation

Moderate to locally breezy trade winds will continue for the next several days. Incoming low clouds and showers will impact windward areas producing brief mountain obscurations along the eastern slopes of all islands through the evening. Possible AIRMET Sierra later tonight into Friday morning for windward areas as clouds and showers increase in coverage. Elsewhere, VFR conditions expected.

Marine

Weak high pressure north of the state will maintain moderate to locally fresh trade winds through the rest of the week. Guidance suggests that some zones could briefly reach Small Craft Advisory (SCA) criteria at times over the next couple of days, but these winds will likely not be persistent enough to warrant a SCA. Therefore, no headlines are in effect at this time. This weekend, a series of fronts approaching from the far northwest will weaken the high north of the state. In response, trades will ease even further on Sunday and hold at gentle to locally fresh levels through early next week.
The current moderate northwest swell (320 to 330 degrees) will continue to gradually decline through Friday. However, a new small, medium period north-northwest swell (330 to 340 degrees) will build in Friday night, providing a small, short lived boost to surf along north and select west facing shores this weekend.
A series of overlapping south and southwest swells will keep south shore surf slightly elevated into early next week. Although the current long period southwest swell and an overlapping tiny short period southwest swell will fade through tonight, a reinforcing, tiny long period southwest (220 degrees) swell will build on Friday, keeping small surf along south facing shores. The next small, long period south-southwest swell (200 degrees) is expected to fill in Monday and peak Tuesday into Wednesday. This could bring near to slightly above average surf along south facing shores.
East facing shores will remain small through early next week due to the lack of strong trades both locally and upstream.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov