Hilo

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 70 to 76 at 4000 feet. East winds up to 15 mph. Chance of rain 70 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. West winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs around 83 near the shore to 70 to 76 at 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 83 to 88 near the shore to 68 to 75 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 74 near the shore to 53 to 59 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 83 to 88 near the shore to 68 to 75 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to around 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to around 57 near 3000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 83 near the shore to around 75 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to around 75 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to around 57 near 3000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 83 near the shore to around 75 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Partly sunny with isolated showers. Highs around 86 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 69 near the shore to around 53 near 5000 feet. Northeast winds up to 15 mph.

Monday: Sunny. Isolated showers in the afternoon. Highs around 86 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 70 to 76 at 4000 feet. East winds up to 15 mph. Chance of rain 70 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. West winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs around 83 near the shore to 70 to 76 at 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 84 near the shore to 68 to 78 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 68 to 73 near the shore to 53 to 60 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to 68 to 78 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure ridge north of the Hawaiian Islands will keep light to moderate trade winds in the forecast through the week. Trade winds will remain light enough to allow local scale sea breezes to develop each day over western slopes of each island. The air mass is rather stable so just some brief passing light showers are expected mainly over windward and mountain areas with few interior showers possible each afternoon.

Discussion

The satellite imagery this morning continues to show a stable band of clouds hanging up over the Big Island and Maui County. Cloudy conditions will linger into the morning hours across the eastern islands before this cloud band begins to break up. Cirrus clouds are drifting up into the islands from the south today outlining a weak subtropical jet stream over the region. This jet stream sits at the southern edge of an upper level trough (also known as the TUTT), which remains anchored in place over the state through Tuesday.
A high pressure ridge just north of the state will keep trade winds in the light to moderate range through the week. Large scale trade winds will be light enough to keep local scale land and sea breezes in the forecast over terrain sheltered western slopes of each island. Strong subsidence (downward vertical motions) in the atmosphere under an upper trough (TUTT) axis and a nearby upper level ridge will continue to keep the air mass fairly dry and stable through Friday.
Global models continue to show subsidence inversion heights ranging from 5,000 to 7,000 feet, which matches the morning 12Z upper air balloon sounding inversion height range from Lihue and Hilo. Stable clouds that develop in this weather pattern will form over windward mountain areas, and over island interior sections in the afternoon hours from converging sea breeze winds. Shower activity will be severely limited this week due to the large scale stability and dry moisture levels. Overnight temperatures will feel a bit cooler in most areas due to the drier atmosphere.

Aviation

The persistent stratus deck in place over and around Maui County and the Big Island that has formed due to an increase in low- level moisture beneath a low inversion may linger well into Sunday before scattering out. As a result, AIRMET Sierra remains in effect for TEMPO IFR CIGS/VSBYS over windward sections of the Big Island (observations at Hilo have been reflecting IFR conditions most of the night and early this morning). CIGS over leeward Big Island and Maui County, however, have remained well above MVFR levels.
Elsewhere, light to moderate easterly trades will continue, with clouds and a few showers favoring windward and mauka locations through the morning periods. Although some leeward cloud development will occur through the afternoon hours where sea breezes form, the dry conditions will limit any rainfall chances. A band of mostly thin high clouds will continue to stream over portions of the state today before diminishing.

Marine

A ridge to the north will maintain light to locally moderate trade winds through the rest of the weekend with a slight strengthening Monday and Tuesday. Winds are expected to remain below Small Craft Advisory levels and will produce small surf along east facing shores this week.
A moderate south swell will maintain surf heights near the seasonal average before tapering off Monday and Tuesday. A small northwest swells will provide small surf along north and west facing shores through Monday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov