Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 83 near the shore to around 71 above 3000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 71 near the shore to around 58 above 3000 feet. Light winds becoming northeast around 10 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the morning. Highs around 84 near the shore to around 72 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 80 to 86. Southwest winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67. Northeast winds around 10 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the morning. Highs 81 to 87. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 73 to 79 in the valleys to around 64 above 4000 feet. Southwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 59 to 65 in the valleys to around 55 above 4000 feet. Northwest winds around 10 mph shifting to the northeast after midnight. Chance of rain 20 percent.

Friday: Mostly sunny with isolated showers. Highs 73 to 79 in the valleys to around 64 above 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 73 to 83. Southwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 61 to 70. Northwest winds up to 10 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the morning. Highs 75 to 83. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 73 to 83. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 60 to 72. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the morning. Highs 73 to 83. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A surface high pressure ridge positioned just north of the Hawaiian Islands will be weakened by two passing cold fronts over the next seven days. Expect light to moderate winds with shifting background wind directions from east to southeast into early next week as the pressure pattern changes north of the state. A ridge aloft will limit shower potential as dry and stable trends continue into early next week.

Discussion

A high pressure center northeast of the Hawaiian Islands and an approaching cold front northwest of the state continues to produce light large scale east to southeasterly winds across the region. Local doppler radar shows fairly dry conditions across the state with isolated to scattered showers forming along southeastern slopes of the Big Island and East Maui this morning. Regional satellite imagery shows a rather large area of stable stratocumulus clouds upstream of the island chain.
The surface high pressure ridge will remain just north of the state over the next seven days with progressive eastward moving high pressure centers split by two approaching cold frontal troughs. The close proximity of the ridge relative to the Hawaiian Islands and the passing of two frontal troughs will keep winds speeds in the light to moderate range into early next week with a background east to southeast wind direction with periods of land and sea breezes over each island, especially along terrain sheltered western slopes. One exception to this wind forecast may develop on Tuesday as both the American (GFS) and the European (ECMWF) show a fairly 'dry cold front' moving down the island chain. This cold frontal passage will be felt more as a moderate to locally breezy northeast wind shift with slightly cooler temperatures based on the latest model consensus.
Forecast guidance continues to show a dry and stable weather pattern with this east to southeasterly wind pattern as the upper level ridge will remain directly over the islands into next week. Downward vertical motions (subsidence) under this ridge will produce warm and dry conditions aloft, keeping the trade wind temperature inversion heights in the 5,000 to 7,000 foot range through the next seven days. One exception to this precipitation forecast may develop on Tuesday as a fairly stable 'dry cold front' moves down the island chain. Only a slight increase in precipitation coverage is possible with this system mainly over the western islands of Niihau, Kauai and Oahu as the upper level ridge continues to limit instability. Any rainfall amounts are forecast to remain on the light side through Wednesday.

Aviation

As a surface ridge settles near the islands, winds will be light through the day and into tonight. Nighttime land breezes will give way to daytime sea breezes in many locales. And VFR conditions will prevail over most areas most of the time.
No AIRMETs are currently in effect.

Marine

Southeast winds trend towards light and variable through the day today. After a brief return to moderate east southeast trades on Friday, winds again veer and weaken becoming gentle to moderate southeasterly through the weekend.
West northwest swell moving through area waters will hold steady through the day today before a larger medium period west northwest swell (300-310) arrives later today bringing a high likelihood of advisory level surf to north and west facing shores of Kauai and Oahu and north shores of Maui tonight through Friday. In addition, due to the westerly angle of the swell, shadowing over north facing shores of Oahu and Maui are expected from Kauai. Also, there is medium confidence that surf will reach the advisory threshold of 8 feet for west facing shores of the Big Island late tonight into Friday.
A strong low developing east of Japan looks to merge with a large complex system that could generate a long period and larger NW (300-320) swell. It is expected to reach the islands late Sunday into Monday. Current indications are that warning level surf will be possible during this time.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov