Photo Credit: James Grenz

Hilo

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 85 near the shore to 70 to 75 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 68 near the shore to around 54 at 4000 feet. Northwest 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 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny with isolated showers. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 75 near the shore to around 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Today: Breezy. Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Kohala

Today: Breezy. Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

South Big Island

Today: Sunny and breezy. Isolated showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows around 70 near the shore to around 53 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Saturday: Sunny and breezy. Isolated showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 85 near the shore to 70 to 75 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 68 near the shore to around 54 at 4000 feet. Northwest 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 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny and breezy. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows 70 to 75 near the shore to 51 to 58 above 4000 feet. Southeast winds up to 20 mph.

Saturday: Sunny and breezy. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 20 mph.

Detailed Forecast

Synopsis

Trade winds will gradually strengthen through today and increased stability will prevail through the weekend, focusing modest rainfall over windward areas as well as across the Kona slopes of the Big Island each afternoon. Trade winds may ease early next week as another disturbance potentially brings an increase in shower activity.

Discussion

A ridge located north of the islands continues to drive strengthening trade winds across local waters this morning. Expect moderate to breezy trade winds through the weekend as models show the ridge holding to the north. Upper ridging will bring increased stability. No significant sources of moisture are noted in the trade wind flow, pointing toward modest rainfall over windward areas and a few showers over leeward Big Island slopes each afternoon. Other leeward areas will be mainly dry.
Trade winds will ease early next week as the ridge to the north erodes. An increase in showers is possible late Monday through Wednesday as upper troughing and associated moisture move in from the east. This could set up a period of increased humidity and daytime sea breezes, triggering afternoon clouds and a few showers over leeward areas.

Aviation

The trade winds will continue to gradually strengthen today. The moderate to locally strong trades will transport low clouds and some showers into windward facing sections through this evening. There may be brief periods of MVFR ceilings and visibilities along some windward facing slopes, but VFR conditions are expected to prevail over most areas today.
No AIRMETS are currently in effect. However, recent trends in atmospheric stability and observations from VAD wind profiles appear to indicate the trade wind flow may soon be strong enough to produce moderate low-level mechanical turbulence leeward of the higher terrain on the islands. Therefore, we will likely issue AIRMET Tango for these developing conditions starting later this morning. Once issued, this AIRMET would likely remain in effect into the upcoming weekend.

Marine

A ridge of high pressure north of the area will keep moderate to locally strong trade winds in place through the weekend. As a result, a Small Craft Advisory remains in effect for the typically windier waters around Maui and the Big Island through 6 pm Sunday. The ridge north of the islands will weaken as a front pushes southward towards the state early next week, easing the trade winds across the island chain.
A new long period south swell will begin to fill in late this afternoon and tonight, and is expected to be a rather long lived event. This swell is forecast to peak Sunday through Monday, with surf heights near or just below advisory levels, then gradually lower through the middle of next week. Only small surf is expected along south facing shores late next week. Short period choppy surf will hold steady through the weekend along east facing shores, then lower slightly early next week as the trades weaken. Surf along north facing shores will remain just above summertime flat levels through the weekend. A new long period northwest swell is forecast to move through during the first half of next week giving north shore surf a boost.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov