Hilo

Today: Partly sunny with scattered showers. Highs around 84 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly 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 west after midnight. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 40 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. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 30 percent.

Waimea

Today: Breezy. Partly sunny with scattered showers. Highs around 82 near the shore to 70 to 80 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Kohala

Today: Breezy. Partly sunny with scattered showers. Highs around 82 near the shore to 70 to 80 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 56 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 15 mph. Chance of rain 40 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: Partly cloudy. 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.

Sunday: Mostly sunny. 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: Partly sunny with scattered showers. Highs around 84 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly 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 west after midnight. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs around 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny in the morning, then partly sunny with scattered 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 40 percent.

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

Detailed Forecast

Synopsis

Moderate trade winds and fairly dry conditions should prevail through the weekend, with showers mainly focused over windward and mauka areas. The trades will ease through the first half of next week, allowing for land and sea breezes in many leeward areas. This pattern will keep showers focused over windward and mauka areas during the night and early morning hours, and over interior and leeward locales each afternoon and early evening, with a few downpours not out of the question Tuesday and Wednesday. A more typical moderate to locally breezy trade wind pattern with mainly windward and mauka showers should return late next week.

Discussion

Currently at the surface, a 1025 mb high is centered around 1450 miles northeast of Honolulu, and is delivering gentle to moderate trade winds to the island chain early this morning. Infrared satellite imagery shows partly cloudy conditions across the majority of the state, with a bit more cloud cover in some windward areas as well as portions of leeward Big Island. Radar imagery shows scattered showers moving into windward areas, with a few light showers or sprinkles reaching leeward locales. Main short term focus revolves around trade wind trends and rain chances.
High pressure northeast of the state will keep moderate trade winds in place through the weekend. The trades will ease through the first half of next week as the ridge north of the state weakens in response to a front pushing southward to near 30N. This should result in a light to locally moderate trade wind regime Monday through Wednesday, with sea breezes becoming common in the more sheltered leeward areas. Ridging is then forecast to re- strengthen north of the islands late next week, bringing a return of moderate to locally breezy trade winds.
As for the remaining weather details, a fairly dry trade wind pattern should prevail through the weekend, with showers favoring windward and mauka areas during the night and early morning hours. The winds may be light enough for some very localized sea breezes to allow for a few leeward showers each afternoon and early evening, with a stray spillover shower possible overnight. As the trades diminish Monday through Wednesday, we should see showers confined to windward areas during the night and early morning hours, with a transition to interior and leeward locales each afternoon and early evening. These afternoon/evening showers could produce a few downpours, particularly Tuesday and Wednesday, as troughing aloft remains over or just west of the state and some deeper moisture with precipitable water values above 1.5 inches moves into the region from the east. Stronger trades should bring a more typical windward and mauka focused shower pattern back to the islands late next week.

Aviation

A high pressure system northeast of the state will keep moderate trade winds in the forecast through Sunday. Clouds and brief passing showers will favor windward and mountain areas. VFR conditions will prevail with only brief MVFR conditions possible. No AIRMETS are currently in effect and none are expected.

Marine

The current forecast does not indicate Small Craft Advisory (SCA) conditions will occur over any of the coastal waters into the middle of next week. A surface ridge extends from a surface high pressure system centered far northeast of the islands to a point about 600 nm north of Lihue. The pressure gradient south of these features will likely maintain moderate to fresh trade winds through most of this weekend. A front moving down toward this ridge from the northwest early next week will cause it to erode. This is expected to cause the trade winds to ease to gentle to moderate speeds from Monday into Wednesday.
A small, medium period south swell combined with a small, short- period southeast swell may provide a slight boost to surf heights along most south facing shores this weekend. Surf is expected to be near, or just below the seasonal average along south facing shores early next week due to a combination of small south and southeast swells. Surf along east facing shores will gradually lower below the normal seasonal heights this weekend due to the weakening trade winds. A small, short-period north-northeast swell combined with the weak trade winds may keep tiny surf along exposed east facing shores early next week. Surf along north facing shores is expected to remain nearly flat through the middle of next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov