Hilo

Today: Partly sunny with scattered showers. Highs around 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 67 near the shore to around 53 at 4000 feet. Northeast winds up to 10 mph shifting to the west after midnight. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to 70 to 75 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Kona

Today: Mostly sunny with isolated showers 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 30 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 68 to 75 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: 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.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. 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 67 near the shore to 55 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered 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: Mostly sunny in the morning then becoming partly sunny. 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 67 near the shore to 55 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered 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 mostly cloudy 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 69 near the shore to around 52 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Monday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers. Highs around 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 67 near the shore to around 53 at 4000 feet. Northeast winds up to 10 mph shifting to the west after midnight. Chance of rain 50 percent.

Monday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to 70 to 75 at 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Waikoloa

Today: Mostly sunny in the morning, then partly sunny with 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 north in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 75 near the shore to 50 to 57 above 4000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: 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. West winds up to 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Moderate trade winds will prevail through the remainder of the weekend. Showers will remain focused over windward areas, and aside from afternoon showers over the Kona slopes of the Big Island, leeward areas will be rather dry. Trades will ease Monday through Wednesday, allowing daytime sea breezes to produce afternoon clouds and isolated showers over leeward terrain. Trade winds will strengthen late Wednesday and Thursday and will likely become breezy Friday into next weekend.

Discussion

Currently at the surface, a 1025 mb high is centered around 1600 miles northeast of Honolulu, and is producing moderate trade winds across the island chain early this morning. Infrared satellite imagery shows partly cloudy conditions across much of the state, with some pockets of more substantial cloud cover affecting mainly Kauai and the Big Island. Radar imagery shows scattered showers moving into windward areas, with a few showers or sprinkles making it into leeward locales at times. 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 remainder of the weekend. The trades will ease through the first half of the upcoming work 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 in the week, bringing a return of moderate to locally breezy trade winds Thursday, and breezy conditions Friday into next weekend.
As for the remaining weather details, a fairly dry trade wind pattern should prevail through the remainder of 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 again this afternoon to allow for the development of a few leeward showers which will diminish quickly in the evening. 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 Tuesday and Wednesday, as troughing aloft remains over or just west of the state and some deeper moisture 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 in the week, with more showery conditions expected on Thursday than on Friday and Saturday.

Aviation

A high pressure system far northeast of the islands will keep moderate trade winds blowing across the state. Clouds and brief passing showers will favor windward and mountain areas. VFR conditions will prevail with only brief MVFR conditions in showers. No AIRMETS are currently in effect and none are expected at this time.

Marine

An east-northeast to west-southwest oriented surface ridge about 550 nm north of Lihue will likely maintain moderate to fresh trade winds today. A front moving down toward the western end of this ridge tonight will cause it to erode, which will weaken the trade wind speeds to the gentle to moderate range from Monday through Tuesday. Heading into mid-week, the ridge builds back to the north of the islands, which will cause the trade winds to strengthen starting Wednesday. The latest forecast indicates the trades may reach the Small Craft Advisory criteria on Thursday over the typically windier waters adjacent to the islands of Maui County and the Big Island.
Surf is expected to remain below the seasonal average along most south facing through mid-week due to a combination of small background south and southeast swells. The forerunners from a new long-period south swell may spread across the area starting Friday night. If so, this might result in larger surf along south facing shores next weekend. Below normal surf heights will likely persist along east facing shores through mid-week due to the weakening trade winds. Surf along north facing shores is expected to remain nearly flat during the next couple of days. However, there are hints of very small, short-period north-northwest or north-northeast swells early this week. Even if these swells show up, they are unlikely to change the nearly flat conditions along most north facing shores during the foreseeable future.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov