Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 71 to 76 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny with isolated showers. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 85. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 69 to 75. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 85. East winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then occasional showers after midnight. Lows 62 to 67 in the valleys to around 57 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 80 percent.

Sunday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny with scattered showers. Highs 78 to 87. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 75. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 78 to 87. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 78 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Light to moderate trades will prevail today, then strengthen to moderate and locally breezy levels Sunday through late next week. Showers will favor windward and mauka areas, with bands of moisture periodically moving through the islands and increasing the trade showers and sending a few into leeward communities as well.

Discussion

Currently at the surface, a 1029 mb high is centered around 1700 miles north-northeast of Honolulu, with a ridge extending southwest to a location around 400 miles northwest of Kauai. The resulting gradient is producing light to moderate trade winds across the island chain this morning. Infrared satellite imagery shows partly cloudy skies across much of the state, with a bit more cloud coverage over some windward areas as well as leeward sections of the Big Island. Radar imagery shows scattered showers moving into windward areas, with a few of these showers spilling leeward at times. Main short term focus revolves around trade wind trends and rain chances.
Moderate trades are expected to persist today as the surface ridge northwest of the islands remains nearly stationary. The ridge will shift northwest tonight and Sunday, strengthening the trades to moderate and locally breezy levels. Only minor fluctuations in trade wind strength are expected through late next week, with high pressure north of the state keeping moderate to locally breezy conditions in place.
As for the remaining weather details, typical summertime trade wind conditions are expected today, with showers favoring windward and mauka areas, while leeward areas remain mostly dry. We will likely see an increase in trade wind showers tonight through Sunday night as some enhanced moisture moves through. Showers will continue to favor windward and mauka areas, with a few more showers reaching leeward communities as well. Fairly typical trade wind weather will then prevail Monday and Tuesday, with the potential for another band of enhanced moisture to increase trade wind showers Tuesday night through Wednesday night, with drier trade wind weather to follow for the end of the upcoming work week.

Aviation

Moderate trades will continue with clouds and brief showers, favoring windward and mountain areas today. These moderate trade wind speeds will allow for some very localized daytime onshore sea breezes along terrain sheltered leeward slopes of each island today.
VFR conditions will prevail with brief periods of MVFR conditions possible mainly along windward and mountain slopes. A passing weak disturbance will produce increasing cloud and shower trends with MVFR conditions along windward and mountain slopes through the overnight hours.
No AIRMETs are in effect, and none are anticipated in the short term.

Marine

Moderate to locally fresh trades will hold through today before strengthening to moderate to locally strong trade winds tonight as a ridge of high pressure builds north of the state. A Small Craft Advisory has been issued for typical windy waters around Maui County and the Big Island beginning tonight. Winds may weaken slightly around the middle of next week as a weak trough moves over the state from the east. Otherwise, little variation is expected.
A small south southwest swell (14-15 seconds) will peak today slightly above the summer average. The swell will hold through Sunday before slowly subsiding early next week. Several small, south swells may move through the state next week, keeping small surf along south facing shores.
A tiny pulse from the north northwest is expected to fill in tonight, keeping tiny ripples along north facing shores through the rest of the weekend. Small, below average surf along east facing shores will persist through today. As trades build upstream and locally, expect east facing surf to gradually build Sunday into early next week. There is also a possibility of a small boost in east facing shore surf early next week from former Tropical Cyclone Emilia.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 PM this evening to 6 AM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov