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. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows around 68 near the shore to around 54 at 4000 feet. Northeast winds up to 10 mph shifting to the northwest after midnight. Chance of rain 50 percent.

Sunday: 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. Northeast winds up to 10 mph. Chance of rain 40 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 69 to 75 near the shore to around 55 near 5000 feet. Northwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning, then partly sunny with 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: Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Breezy. Mostly sunny in the morning, then partly sunny with 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.

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 70 near the shore to around 53 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny in the morning, then partly sunny with 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. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows around 68 near the shore to around 54 at 4000 feet. Northeast winds up to 10 mph shifting to the northwest after midnight. Chance of rain 50 percent.

Sunday: 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. Northeast winds up to 10 mph. Chance of rain 40 percent.

Waikoloa

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 70 to 75 near the shore to 51 to 58 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. North winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds will continue across the islands through the weekend as high pressure remains anchored northwest of the state. The trades will strengthen Monday, and become breezy Tuesday through late next week as strong high pressure builds to the distant north and a potential tropical cyclone passes by well to the south of the island chain. Rather dry trade wind weather will prevail through the forecast period, with minimal shower activity confined to primarily windward slopes and coasts.

Discussion

Currently at the surface, a 1024 mb high is centered around 1050 miles northwest of Kauai, while a weak trough is positioned around 625 miles northeast of Honolulu. The gradient locally is producing moderate trade winds across the island chain early this morning. Infrared satellite imagery clear to partly cloudy conditions across the state, with a bit more extensive cloud cover over leeward Big Island. Radar imagery and rain gage observations indicate very dry conditions, with only a few sites on Kauai and the Big Island reporting measurable rainfall in the past few hours. Main short term focus revolves around rain chances and trade wind trends.
Very little change in the overall weather pattern is expected through the weekend, as a weak high remains northwest of the state and a weak trough holds in place to the north. This should keep trades at generally moderate levels. The trades are expected to begin strengthening early next week as the trough north of the islands washes out and high pressure strengthens to the distant northeast. The trades will then strengthen to breezy levels Tuesday through late next week as strong high pressure builds to the distant north and a potential tropical cyclone passes by well to the south of the island chain. This weather pattern is significantly different than what was experienced during Dora. The winds are expected to be not nearly as strong, as the high will be displaced much farther north and the potential tropical system not nearly as strong.
As for the remaining weather details, rather dry trade wind weather will prevail through much of the next 7 days, with minimal shower activity confined primarily to windward slopes and coasts during the late night and early morning hours. We could see a slight increase in shower coverage Monday night and Tuesday, particularly over windward portions of Maui and the Big Island as a band of moisture moves through.

Aviation

Moderate to locally fresh trade winds will drive scattered low clouds and a few light showers over windward and mountain areas through the weekend. VFR conditions will prevail with no AIRMET Sierra expected. Trade winds should stay just below speeds to generate moderate leeward turbulence, so expecting the light variety.

Marine

A surface ridge far north of the islands will continue to weaken, and shift slowly southward this weekend. This will likely maintain moderate trade wind speeds into early next week. A new surface high pressure system is forecast to build far northeast of the state by next Tuesday. In addition, a potential tropical cyclone may pass by well to the south of the island chain around mid-week. This may cause the trade winds to become locally strong with Small Craft Advisory (SCA) conditions likely developing across the typically windier waters adjacent to the islands of Maui County and the Big Island. There may be SCA conditions developing over additional waters Tuesday or Wednesday.
Surf along south facing shores associated with a medium-period south-southwest swell will gradually trend down this weekend. The current small to moderate, choppy surf along east facing shores will also steadily lower this weekend as the trades weaken locally, and upstream of the state. A small north-northwest swell may reach the islands early next week. If this swell does arrive, it may cause surf to trend up slightly above the typical summertime flat conditions along exposed north facing shores starting Monday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov