Hilo

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 63 to 71 near the shore to 49 to 56 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 20 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 87 near the shore to around 68 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 71 near the shore to 50 to 57 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Kona

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Haze through the night. Lows around 73 near the shore to 49 to 54 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Haze through the day. Highs 83 to 88 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 40 percent.

Wednesday Night: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Haze through the night. Lows around 73 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy with isolated showers. Lows 62 to 70 near the shore to 53 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 80 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy with isolated showers. Lows 62 to 71 near the shore to 54 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy with isolated showers. Lows 62 to 70 near the shore to 53 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 80 near the shore to 69 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday Night: Partly cloudy with isolated showers. Lows 62 to 71 near the shore to 54 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Tonight: Mostly clear. Breezy and haze. Lows around 73 near the shore to around 53 near 5000 feet. East winds up to 25 mph shifting to the northeast 10 to 20 mph after midnight.

Wednesday: Mostly sunny. Breezy. Haze through the day. Isolated showers in the afternoon. Highs around 86 near the shore to around 68 near 5000 feet. East winds around 10 mph becoming up to 20 mph in the afternoon. Chance of rain 20 percent.

Wednesday Night: Mostly clear. Breezy and haze. Lows around 74 near the shore to around 55 near 5000 feet. East winds up to 20 mph.

Puna

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 63 to 71 near the shore to 49 to 56 at 4000 feet. East winds up to 10 mph shifting to the west after midnight. Chance of rain 20 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 87 near the shore to around 68 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 64 to 71 near the shore to 50 to 57 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Waikoloa

Tonight: Mostly clear. Isolated showers in the evening. Lows around 73 near the shore to around 53 above 4000 feet. North winds up to 10 mph shifting to the east after midnight. Gusts up to 30 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 84 to 89 near the shore to 66 to 74 above 4000 feet. East winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Wednesday Night: Mostly clear. Lows around 73 near the shore to around 53 above 4000 feet. Northeast winds up to 10 mph.

Detailed Forecast

Synopsis

Stable, light to moderate trade winds will produce mainly light showers over windward areas into the weekend. Most leeward areas will continue to be rather dry, except the Kona slopes of the Big Island where scattered showers will develop each afternoon.

Discussion

A stable and somewhat dry light to moderate trade wind flow is in place this afternoon. Trade wind strength has changed little since yesterday, as a subtropical ridge sitting 200 to 300 miles north of the islands continues to be weakened by an area of low pressure farther to the north, and a robust ridge aloft is producing stable conditions. The trades have pushed away a diffuse area of moisture that triggered some heavy showers around Kailua-Kona yesterday afternoon, and precipitable water is now running about 25 percent below seasonal average. As a result of these stable and rather dry conditions, rainfall has been minimal across windward slopes, with only a few hundredths of an inch measured at a handful of stations. Most leeward areas have been dry, and in contrast to yesterday, the Kona slopes of the Big Island have received only a few light showers this afternoon.
Expect little change to the stable, light to moderate trade wind weather through Monday. The GFS and ECMWF have been hinting at a band of moisture moving through around Saturday night or Sunday, which could lead to a brief boost in mainly windward showers.
Heading into the middle of next week, forecast uncertainty increases considerably due to the passage of now Hurricane Kiko over the region. Given historical forecast errors in that time range, it remains too early to tell what, if any, impacts this system will have on local weather.

Aviation

Light to moderate trades are forecast into tomorrow with a brief shower possible especially on windward areas. Overall dry conditions should preclude any mountain obscurations tonight.
No AIRMETS are in effect or anticipated tonight.

Marine

A weak surface ridge to the north will remain nearly stationary through the forecast period. This will maintain moderate to locally fresh trade winds with some localized sea breezes, especially across leeward waters.
Elevated surf will continue along north facing shores with a mix of a short- to medium-period north swell, and a small medium- period northwest swell. These swells will peak this afternoon, then gradually decline through Thursday. Reinforcing small short- to medium-period north-northwest swells are expected through the week which will keep surf elevated.
Surf along south facing shores will continue to slowly subside this evening as the current south swell fades. Background medium- to long-period energy will hold through the week before a small to moderate long-period south-southwest swell fills in over the weekend.
Below average surf is expected to continue along east facing shores through the week.
Peak monthly high tides, combined with water levels running higher than predicted, may lead to minor flooding along the shoreline and in low-lying coastal areas Wednesday through the end of the week. Coastal flooding will mainly be focused around the daily afternoon high tide.

Fire weather

Light to moderate trade winds will remain below the critical fire weather threshold through at least the weekend. Dry and stable will prevail, with afternoon relative humidity dropping to around 45 percent each afternoon through Saturday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov