Hilo

Rest Of Tonight: Cloudy with showers. Lows 62 to 68 near the shore to 47 to 54 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 90 percent.

Wednesday: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 81 near the shore to around 64 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Cloudy with numerous showers. Lows 62 to 68 near the shore to 48 to 54 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Kona

Rest Of Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows around 70 near the shore to 44 to 52 near 5000 feet. Light winds. Chance of rain 50 percent.

Wednesday: Cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs around 83 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows around 70 near the shore to 45 to 52 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Rest Of Tonight: Breezy. Cloudy with scattered showers. Lows 61 to 69 near the shore to 51 to 59 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Cloudy with scattered showers. Highs 72 to 79 near the shore to 68 to 76 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Wednesday Night: Breezy. Cloudy with scattered showers. Lows 61 to 69 near the shore to 53 to 59 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Kohala

Rest Of Tonight: Breezy. Cloudy with scattered showers. Lows 61 to 69 near the shore to 51 to 59 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Cloudy with scattered showers. Highs 72 to 79 near the shore to 68 to 76 near 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Wednesday Night: Breezy. Cloudy with scattered showers. Lows 61 to 69 near the shore to 53 to 59 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Big Island

Rest Of Tonight: Breezy. Mostly cloudy with isolated showers. Haze. Lows around 71 near the shore to around 48 near 5000 feet. Northeast winds up to 20 mph becoming 10 to 15 mph after midnight. Chance of rain 20 percent.

Wednesday: Cloudy and breezy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs around 83 near the shore to around 64 near 5000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Wednesday Night: Breezy. Cloudy with isolated showers. Haze. Lows around 71 near the shore to around 48 near 5000 feet. Northeast winds 10 to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Puna

Rest Of Tonight: Cloudy with showers. Lows 62 to 68 near the shore to 47 to 54 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 90 percent.

Wednesday: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 81 near the shore to around 64 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday Night: Cloudy with numerous showers. Lows 62 to 68 near the shore to 48 to 54 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Rest Of Tonight: Mostly cloudy with isolated showers. Haze through the night. Lows around 70 near the shore to 48 to 54 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Haze through the day. Scattered showers in the afternoon. Highs 81 to 86 near the shore to 64 to 70 above 4000 feet. North winds up to 15 mph. Chance of rain 40 percent.

Wednesday Night: Cloudy with isolated showers. Haze. Lows around 71 near the shore to 48 to 55 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trades will build tonight and bring enhanced windward showers through the second half of the week due to an upper trough moving across the area. Conditions are expected to stabilize Saturday. A weak cold front will approach from the west Sunday, reach Kauai Monday and stall near Big Island midweek.

Discussion

An upper low to the west of Hawaii will weaken and broaden as it moves over the islands over the next several days. At the surface, high pressure far to the northeast will drive a slightly modified east southeast flow through the early evening that will strengthen to moderate to fresh trades by morning and continue through the second half of the week. Radar shows heavy showers briefly formed due to the daytime heating and instability over Kauai, Oahu and leeward Big Island this afternoon and are expected to fade through sunset.
Easterly trades will begin to focus more of the clouds and showers moving in from upstream across windward and mauka areas beginning tonight. Some enhancement of the trade wind showers will be possible as the aforementioned upper trough moves eastward across the state through the end of the week. Conditions should dry and stabilize by Saturday. On Sunday, winds will weaken and veer southeasterly in response to an approaching cold front that should reach Kauai Sunday night or Monday. GFS coming into line with the ECMWF in the long range showing the front stalling near or past the Big Island midweek.

Aviation

Light to moderate trade winds will gradually fill in from east to west tonight, and could become locally breezy tomorrow through midweek. Stability will marginally increase as drier air moves in, however upper level conditions could still be unstable enough to allow some of the trade wind showers to be on the heavier side. Overall clouds and showers will favor windward and mauka locations throughout the forecast period and VFR conditions should prevail. The exception being the Big Island windward areas, where enhanced moisture could move in tomorrow morning and bring MVFR ceilings and visibilities.
AIRMET Tango is in effect for moderate upper level turbulence over and west of Maui due to an upper level jet. This will likely linger through tomorrow. AIRMET Sierra is in effect for mountain obscuration over Kauai due to some leeward cloud buildups. Conditions should improve after sunset.

Marine

A surface trough, located approximately 525 nautical miles west of Kauai, is helping to maintain gentle easterlies over the western half of the state, while moderate to fresh east- southeast winds continue over the eastern half. An upper low near the same location will weaken and wash out through the middle of the week as surface high pressure north of the state becomes the dominant Central Pacific feature. Easterly trades will strengthen to moderate to fresh speeds tonight. A Small Craft Advisory has been issued for the typically windy waters around Maui County and the Big Island through Thursday afternoon. Winds will gradually weaken and shift southeasterly into the weekend, becoming light and variable statewide by Sunday as a front approaches the state from the northwest.
A series of small, medium-period northwest (310-320 degree) swells will pass through tonight through Saturday. These swells will maintain solid head-high surf along most north-facing shores and waist to head high surf along the better-exposed west shores. A significant northwest swell may reach the islands early next week.
East shore surf will likely pick up a bit through the middle of the week as easterlies increase over and upstream of the state. South shore surf will stay around the seasonal average, as a couple of small, long-period south swells move through the local waters this week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov