Photo Credit: James Grenz

Hilo

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 67 near the shore to around 51 at 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 85 near the shore to around 65 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 72 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 85 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 30 percent.

Waimea

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to 65 to 75 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 40 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 64 near the shore to 52 to 59 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 80 near the shore to 65 to 75 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Kohala

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to 65 to 75 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 40 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 64 near the shore to 52 to 59 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 80 near the shore to 65 to 75 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 83 near the shore to around 69 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 66 near the shore to around 51 near 5000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Saturday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 83 near the shore to around 69 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 67 near the shore to around 51 at 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 81 near the shore to 65 to 70 at 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to 66 to 72 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 72 near the shore to 48 to 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 isolated showers in the afternoon. Highs around 84 near the shore to 66 to 72 above 4000 feet. North winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally breezy trades today will weaken to moderate levels this weekend before giving way to a land and sea breeze pattern early next week. Limited rainfall can be expected over windward areas through Sunday followed by increased potential for afternoon showers over interior and mauka locations Monday and Tuesday. Winds could tip to more southerly mid to late next week, potentially bringing some deeper moisture and increased rain chances to western portions of the state.

Discussion

Currently at the surface, a 1029 mb high is centered around 1600 miles northeast of Honolulu, while a front is located around 600 miles northwest of Kauai. The resulting gradient is producing moderate to locally breezy trade winds across the island chain early this morning. Infrared satellite imagery shows partly cloudy skies in most areas, with radar imagery showing a few light showers moving onshore with the trades. Main short term focus revolves around trade wind trends and rain chances during the next few days.
High pressure northeast of the state will gradually weaken as it settles slowly southward Friday through the weekend. The trades will remain locally breezy today, then ease to moderate levels tonight through the weekend. A front approaching from the northwest will shift winds around to the east-southeast on Monday, then off to the southeast and south Tuesday through Thursday. This will shelter the smaller islands allowing for land and sea breezes Monday and Tuesday. Moderate southerly winds could then develop over the western islands Wednesday and Thursday, with moderate southeasterly winds over the eastern end of the state.
As for the remaining weather details, a fairly dry trade wind pattern should hold in place through the weekend, with showers favoring windward and mauka areas and an occasional shower reaching leeward communities. A pattern shift appears likely Monday and Tuesday of next week, with land and sea breezes allowing for interior and mauka showers during the day and a few showers near the coast at night. With a further tip to the southeast and south mid to late next week, the potential exists for some deeper moisture to get drawn up from the south. The GFS is more aggressive with this idea, while the ECMWF keeps the brunt of the deep tropical moisture west of the state. Will follow a middle of the road solution for now until details become more clear.

Aviation

A high pressure ridge north of the islands will continue to produce mostly dry and breezy trade winds through Saturday. Brief passing showers and periods of broken MVFR ceilings will develop over windward and mountain slopes.
AIRMET Tango for moderate low-level turbulence over and immediately SW through NW of island mountains remains in effect, and will persist into early Saturday.

Marine

Fresh to strong easterly trade winds will continue into the weekend, then trend down and shift out of the south to southeast Sunday through Tuesday as a front sets up west of the state. The southerlies may reach moderate to fresh levels Tuesday through midweek if this scenario evolves. See the discussion section above regarding the potential for a wet pattern setting up over portions of the state.
Surf along east facing shores will remain rough into the weekend, then ease Sunday into early next week as the winds shift out of the south to southeast. Residual background easterly trade wind swell from the upstream trades, however, will support small surf continuing next week.
Surf along all other shores will remain small through the weekend with mainly background southerly energy moving through. The small northwest swell that arrived Thursday will linger today, then move out over the weekend. Surf along south facing shores will trend up Tuesday through midweek as a new, long-period, south swell arrives. Although confidence remains low due to significant model differences, a medium-period northwest swell from low pressure setting up around 1400 NM northwest of the state early next week can't be ruled out to arrive locally late next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov