Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 88 near the shore to around 74 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers and isolated thunderstorms after midnight. Lows around 69 near the shore to around 60 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny. Scattered showers and isolated thunderstorms in the morning, then isolated showers and thunderstorms in the afternoon. Highs around 87 near the shore to around 73 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 87. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then scattered showers and isolated thunderstorms after midnight. Lows around 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers and isolated thunderstorms. Highs 80 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Cloudy with showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 86 in the valleys to around 65 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers and isolated thunderstorms after midnight. Lows 63 to 69 in the valleys to around 57 above 4000 feet. East winds up to 15 mph. Chance of rain 60 percent.

Sunday: Mostly cloudy. Scattered showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs 74 to 85 in the valleys to around 65 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 77 to 88. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then scattered showers and isolated thunderstorms after midnight. Lows 63 to 73. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers and isolated thunderstorms. Highs 78 to 88. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 74 to 84. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers and isolated thunderstorms after midnight. Lows 63 to 74. East winds up to 15 mph. Chance of rain 60 percent.

Sunday: Mostly cloudy with scattered showers and isolated thunderstorms. Highs 74 to 85. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A high pressure ridge will remain in place north of Hawaii into next week, producing moderate trade winds through Sunday, and then strengthening into the moderate to breezy range from Monday onward. Passing showers are expected to mainly affect windward and mountain areas, favoring the overnight to early morning hours. An upper level low will continue to drift from east to west over the islands this weekend, likely increasing shower activity as it passes through the state. Isolated thunderstorms are possible over the interior Big Island this afternoon, and near Kauai through Sunday.

Discussion

An upper level low shown on satellite water vapor imagery around 400 miles northeast of Hilo, Hawaii will continue to drift west through the weekend. This system continues to enhance showers and produce a few thunderstorms over the coastal waters west of the Big Island and over portions of the Alenuihaha Channel this morning. This upper low will enhance showers over each island through Sunday, then weaken and drift northward away from the state on Monday. Isolated thunderstorms are possible this afternoon over the interior sections of the Big Island, and then near Kauai tonight through Sunday.
The subtropical ridge will remain in place north of the state into much of next week keeping easterly trade winds in the forecast for most days. The upper low will continue moving westward across the state of Hawaii over the next few days. A weak low level trough associated with the upper low will keep the pressure gradient on the weaker side, keeping trade winds at moderate levels through Sunday. By Monday expect the ridge to build in over the islands as the upper low departs the pattern, with trade winds increasing into the moderate to breezy range through much of next week. A stronger high pressure ridge will also produce more stable conditions with increasing subsidence over the state next week with decreasing shower trends. Trade wind thermal inversion heights will range from 5,000 to 6,500 feet keeping brief passing showers in the forecast over windward and mountain areas, trending higher in the overnight to early morning hours.

Aviation

Moderate trades are expected to continue across the island chain through the weekend. SHRA and low cigs embedded in the trades will bring brief periods of MVFR conds over windward and mauka locations. Otherwise, VFR conditions should prevail.
An upper-level low is forecast to move over the islands this weekend. This will likely cause increased SHRA coverage and require AIRMET Sierra periodically throughout the weekend, especially during the overnight and early morning hours.

Marine

High pressure north of the state will maintain moderate to fresh trade winds through the weekend. The trades are expected to strengthen back to fresh and strong levels early next week, and a Small Craft Advisory will likely be required for the typically windy waters around Maui and the Big Island by Monday. An upper level low passing nearby will bring a slight chance of thunderstorms around Kauai tonight and Sunday.
A series of south swells will keep south shore surf near the summertime average through Saturday. Surf will lower below normal levels much of next week. A small background south swell could give south shore surf a slight bump around the middle of next week.
Typical mostly flat summertime conditions will continue along north facing shores through next week.
East shore surf will remain well below normal through the weekend, then trend up and closer to seasonal levels next week as the trades strengthen over and upstream of the islands.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov