Hilo

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 68 near the shore to around 52 at 4000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Wednesday: Mostly cloudy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs around 82 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 63 to 68 near the shore to around 52 at 4000 feet. Light winds. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy with isolated showers. Haze. Lows 66 to 71 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Haze through the day. Isolated showers in the late morning and afternoon. Highs around 83 near the shore to around 64 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy with isolated showers. Haze. Lows 66 to 71 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy with isolated showers. Lows around 65 near the shore to 53 to 60 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy with isolated showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy with isolated showers. Lows around 65 near the shore to 53 to 60 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Kohala

Tonight: Mostly cloudy with isolated showers. Lows around 65 near the shore to 53 to 60 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy with isolated showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Wednesday Night: Mostly cloudy with isolated showers. Lows around 65 near the shore to 53 to 60 near 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly cloudy. Isolated showers in the evening. Haze through the night. Lows around 67 near the shore to around 52 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Haze. Highs around 82 near the shore to around 69 near 5000 feet. East winds up to 15 mph.

Wednesday Night: Mostly cloudy. Haze. Lows around 67 near the shore to around 52 near 5000 feet. Northeast winds around 10 mph.

Puna

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 68 near the shore to around 52 at 4000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Wednesday: Mostly cloudy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs around 82 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy with scattered showers. Lows 63 to 68 near the shore to around 52 at 4000 feet. Light winds. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly cloudy. Haze. Lows around 69 near the shore to 49 to 56 above 4000 feet. East winds up to 10 mph in the evening becoming light.

Wednesday: Partly sunny. Haze. Highs around 84 near the shore to 65 to 71 above 4000 feet. Northwest winds up to 10 mph.

Wednesday Night: Mostly cloudy. Haze. Lows around 69 near the shore to 49 to 56 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Gentle to moderate trade winds will continue through Thursday as a weak surface ridge sits about 300 miles north of Kauai. Stable and rather dry conditions will produce light showers over most windward slopes, though an upper-level disturbance may produce more rainfall on Kauai tonight and Wednesday. Trades will strengthen on Friday and Saturday.

Discussion

A gentle to moderate trade winds with stable and rather dry conditions are in place. A weak surface ridge stalled about 300 miles north of Kauai is driving the trades, which are light enough for sea breezes to form over sheltered leeward terrain this afternoon. Precipitable water within the trade wind flow over and upwind of the islands remains below seasonal normal, and mid-level ridging is producing a strong inversion based around 6,000 feet. As a result, rainfall has been limited to well below a tenth of an inch at nearly all windward gauges, and across leeward areas, scattered light showers have been confined to the South Kona and Kau slopes this afternoon.
The subtropical ridge will remain roughly stationary through Thursday, keeping trades in the gentle to locally moderate range, and most islands will continue to experience a somewhat dry conditions with limited rainfall. A shallow low aloft deepening just north of Kauai tonight may enhance a narrow band of moisture and produce an increase in shower activity on the Garden Isle tonight and Wednesday. The upper-level low will also send thin high clouds over the eastern end of the island chain and produce strong westerly winds on the high summits of the Big Island, where a Wind Advisory is in effect through at least Wednesday afternoon.
Trade winds should strengthen a notch Friday and Saturday as surface high pressure rebuilds far northeast of the state. The upper-level low will be pushed off to the east, and ridging aloft will move overhead, bringing stable and somewhat dry conditions.
Trade winds will become more easterly and may ease slightly Sunday and Monday due to a surface trough developing several hundred miles west of the islands. There is the potential for an increase in shower activity over the western end of the island chain as well.

Aviation

A drier trade wind pattern continues over the state today giving way to mostly VFR conditions and a great day for flying. Overnight, a brief shower over windward locations cannot be ruled out as an upper-level disturbance is nearby the western part of the state. However, current radar, satellite, and other observations continue to indicate that this trend will continue.
There are currently no AIRMETs in effect and none are anticipated today.

Marine

The ridge far north of the Hawaiian Islands will weaken into Friday in response to cold fronts passing by to the north. Trade winds will remain in the gentle to moderate range through Friday, then increase to fresh levels this weekend as the ridge strengthens.
Surf heights will remain tiny for most shores through Wednesday. Surf heights will increase along north and west facing shores Wednesday night through Thursday as a brief north-northwest (330-340 deg) swell moves through the region. A larger north- northwest (330-340 deg) swell will arrive in the islands by early Saturday morning, producing moderate surf heights along north and west facing shores, before rapidly declining Saturday night through Sunday.
A small background pulse of south swell will produce a slight bump to surf heights along south facing shores starting Wednesday afternoon, peaking by Friday, then slowly fading through the weekend.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST Wednesday for Big Island Summits.

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Data Courtesy of NOAA.gov