Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 72 near the shore to around 58 above 3000 feet. Light winds. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs around 88 near the shore to around 76 above 3000 feet. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs around 84. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 65 to 71. Northeast winds around 10 mph. Chance of rain 30 percent.

Saturday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 85. East winds around 10 mph. Chance of rain 30 percent.

Kaua’i Mountains

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 81 in the valleys to around 65 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with scattered showers. Lows 58 to 63 in the valleys to around 53 above 4000 feet. Light winds. Chance of rain 40 percent.

Saturday: Partly sunny with scattered showers. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 86. East winds up to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 61 to 71. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Saturday: Partly sunny with scattered showers. Highs 78 to 87. East winds up to 10 mph. Chance of rain 40 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 77 to 85. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 73. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Saturday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 86. East winds up to 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Light to moderate trades will persist through Saturday, with light showers favoring windward areas at night and interior and leeward areas in the afternoon. The trades will ramp back up to moderate and breezy levels Sunday through Thursday, with rather dry conditions Sunday and Monday, trending a bit more showery by the middle of next week.

Discussion

Currently at the surface, a ridge of high pressure located around 175 miles north of Kauai is producing light to moderate trade winds across the island chain. Infrared satellite imagery shows partly cloudy skies over the western islands, with mostly cloudy conditions over the eastern end of the state. Radar imagery and rain gauge observations indicate scattered light showers affecting windward Maui and both windward and leeward sections of the Big Island. Elsewhere, mostly dry conditions prevail with only a few light windward showers moving onshore from time to time. Main short term focus revolves around trade wind trends and rain chances during the next couple days.
The ridge of high pressure north of the islands will remain nearly stationary through tonight, keeping light to moderate trades in place and allowing some sea breeze development in leeward areas. The ridge will lift northward this weekend, allowing the trades to gradually increase to moderate and breezy levels Sunday, and hold at these levels through much of next week.
As for the remaining weather details, during the next couple of days in the weakened trade wind pattern, light showers will favor windward slopes and coasts during the night and early morning hours, with a few showers developing each afternoon over interior and leeward areas. Rather dry conditions will persist Sunday and Monday, with mid-level ridging and stronger trades keeping light showers confined primarily to windward and mauka areas. Mid-level ridging begins to break down Tuesday through Thursday, which should bring an increase in trade wind showers to the island chain.

Aviation

A mostly dry and stable air mass over the islands will limit cloud and shower development into the weekend. Light to moderate trade winds will continue and daytime sea breezes will strengthen over each island through Saturday. Expect VFR conditions at the TAF sites.
No AIRMETs are in effect and none are expected.

Marine

Light to locally fresh trades will continue into Saturday, then return to moderate to locally strong levels over the weekend as the surface ridge strengthens to the north. As the winds increase, expect Small Craft Advisory conditions to return over the windier waters and channels around Maui County and the Big Island beginning as early as late Saturday. Guidance shows this trend persisting through the first half of next week.
Surf along south-facing shores will continue to trend up today as a fresh south-southwest swell fills in. The offshore buoys reflect this upward trend in the 14 and 15-second bands this morning. The surf should peak below advisory levels later today through the weekend, then ease late Sunday through early next week. Guidance depicts a decent-sized area of south-southwest winds nosing northward within our swell window east of New Zealand today through Saturday, with seas responding and climbing into the 25 to 30 ft range. This could result in our next south- southwest swell arriving next weekend (8/9-8/10).
Surf along north and west-facing shores will trend up through the day Monday as an out-of-season, small north-northwest swell arrives. This trend with small north-northwest pulses could persist through a good portion of the upcoming week due to broad low pressure setting up far north of the state near the Aleutians.
Surf along east-facing shores will remain small due to the lack of strong trades locally and upstream. A slight increase is possible later this weekend through early next week as the trades pick up.
Higher-than-predicted water levels combined with near-peak monthly tides and a decent south swell moving through could lead to minor coastal flooding through the weekend. The best chance for coastal impacts will occur in the afternoon hours around the peak daily high tide cycle in the typical vulnerable low-lying coastal areas.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov