Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84 near the shore to around 72 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 69 near the shore to around 59 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 83 near the shore to around 71 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 80. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 60 to 65 in the valleys to around 54 above 4000 feet. East winds up to 20 mph. Chance of rain 80 percent.

Wednesday: Mostly cloudy. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 70 to 77 in the valleys to around 61 above 4000 feet. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 80 percent.

North Kaua’i

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 84. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 70. East winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers. Highs 73 to 83. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 74 to 84. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 72. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 82. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy easterly trade winds will continue through midweek, then ease slightly late Thursday into the weekend as the ridge weakens north of the area and an upper disturbance moves in. Showers will favor windward and mauka locations, especially overnight through the early mornings as pockets of moisture move through. As the upper disturbances moves southward into the region, there is a possibility of increasing shower coverage, with some potentially becoming locally heavy. A more stable trade wind pattern is possible over the weekend as the upper disturbances moves away.

Discussion

Short-term guidance remains in good agreement and depicts the breezy easterly trades holding through midweek as the ridge remains anchored to the north. An area of low clouds and enhanced moisture moving through will continue to support better windward shower coverage today, mainly over the western end of the state. Stable conditions associated with an upper ridge and plenty of mid-level dry air, however, will limit rainfall amounts. Mostly dry conditions will prevail over the leeward areas of the smaller islands.
Trade winds may weaken slightly late Thursday into the weekend as an upper trough drops south into the area and a weakness forms in the ridge to the north. Added instability accompanying the upper trough will support a few locally heavier showers Thursday through Friday night if this scenario materializes, especially over the eastern end of the state where more instability will be. A more stable trade wind pattern will likely return over the weekend as the upper trough shifts east of the area.

Aviation

Moderate to locally breezy trade winds will steer bands of showers off the Pacific towards the Hawaiian Islands. Showers will impact mainly windward slopes and coasts and be most active in the late night and morning hours. Brief MVFR ceilings and visibilities are likely in quick-moving showers. Otherwise, VFR conditions will prevail statewide.
Regarding Leeward Big Island, a weak eddy just west of the island will keep the Kona coast shrouded in clouds through the morning hours. In the afternoon, local sea breezes will encourage inland showers that will linger through most of the evening.
The locally breezy trade winds will continue the need for AIRMET Tango due to moderate low-level turbulence downwind of terrain, especially across the eastern half of the state.

Marine

A high pressure ridge north of the area will continue to strengthen through tomorrow as trade winds become fresh to locally strong with near gales in the windier zones around Maui county and the Big Island. Trade wind intensities are expected to weaken slightly toward the end of the week. The SCA is in effect through 6 PM HST Wednesday and may need to be extended for typical windy zones Thursday.
A small long period southwest swell will hold slightly above summer time averages through this afternoon. A series of small south and southwest swells will keep small surf along south facing shores into the weekend. There are no significant swells forecast to affect the north and west facing shores through the week. East shore surf is expected to be rough and choppy as the trades strengthen today, then hold into the second half before gradually easing into the weekend.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Wednesday for Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov