Photo Credit: Jason Weingardt

West Kaua’i

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 89 near the shore to around 78 above 3000 feet. Northeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 70 near the shore to around 61 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the afternoon. Highs around 89 near the shore to around 79 above 3000 feet. Northeast winds around 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Sunny. Highs around 89. North winds 10 to 15 mph shifting to the east in the afternoon.

Tonight: Partly cloudy with isolated showers. Lows 70 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs around 88. North winds around 10 mph shifting to the southeast in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 87 in the valleys to around 69 above 4000 feet. South winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 65 to 70 in the valleys to around 59 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 76 to 86 in the valleys to around 69 above 4000 feet. Southwest winds around 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

North Kaua’i

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 89. Southeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 65 to 74. East winds up to 15 mph becoming around 10 mph after midnight. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 89. South winds around 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs 78 to 90. Northwest winds around 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 78. Northeast winds around 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs 77 to 89. Northwest winds around 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Two upper lows will linger just north of the Hawaii Region, producing trough reflections at the surface. These surface troughs will continue to weaken the ridge farther north of the state, keeping light to moderate trade winds in the forecast at least through Friday. High pressure will build in from the northwest this weekend and will strengthen trade wind speeds into the moderate to locally breezy range from Sunday onward. Passing shower activity will return to windward and mountain areas, favoring the overnight to early morning hours.

Discussion

Satellite water vapor imagery this morning continues to show two upper level lows spinning just northwest and north of the Hawaii Region. These upper level lows are strong enough to produce trough reflections in the surface pressure gradient north of the island chain, weakening the ridge farther north of the state through Friday. A subtropical jet stream over the region will continue to spread high level cirrus and middle level clouds across the state for the foreseeable future, enhancing sunrise and sunset colors in most areas. Isolated thunderstorms are possible for the higher elevation slopes of Mauna Kea and Mauna Loa.
A local scale land and sea breeze weather pattern will continue through Friday for most areas in a light large scale trade wind weather pattern. Trade wind temperature inversion heights from the 12Z (2 AM HST) morning balloon soundings from Lihue and Hilo range from 4,000 to 5,000 feet. Boundary layer moisture levels are fairly dry and a lack of instability will limit rainfall amounts today. Clouds and moisture under the subtropical jet steam does not seem to have a good surface connection to produce any shower enhancement over the Big Island or Maui at this time. One exception mights be the higher elevation slopes on the Big Island where if enough moisture moves in then isolated thunderstorms may develop during maximum heating in the afternoon hours.
The weather pattern changes on Saturday as the high pressure ridge north of the region builds back in from the northwest. Strengthening trade winds will produce brief passing showers along windward and mountain slopes, favoring the overnight to early morning hours. Trade wind temperature inversion heights during this time will range from 6,000 to 8,000 feet elevation as the trade winds return favoring a scattered to occasionally numerous overnight shower pattern.

Aviation

A light trade wind flow will continue, which will allow daytime sea breezes and nighttime land breezes to develop. Limited low clouds and showers will favor interior and leeward areas during the afternoon through the early evening, then windward areas overnight through early morning. VFR conditions will prevail, with ISOL MVFR VIS/CIG in SHRA. Increased moisture moving over the Big Island today may fuel an isolated thunderstorm over the slopes this afternoon.
AIRMET TANGO for moderate turbulence between FL300 and FL450 will be dropped this morning as the potential for turbulence is diminishing.

Marine

A few surface troughs between the islands and surface high pressure northeast of the state will keep gentle to locally fresh easterly trade winds through Thursday. Surface high pressure far northwest of the state will push southeast near 170W, as a ridge builds north of the state. This will reinforce the local pressure gradient as moderate to locally fresh trades look to hold through the weekend.
A long period south swell has filled in across the state as surf along south- facing shores reach near High Surf Advisory levels through today. The swell will gradually decline Thursday and Friday.
No other significant swells are expected through the week. A tiny northwest swell will keep north facing shores above summer time averages. East facing shores will remain small, as trade remain relatively light. Long range forecasts indicate the potential for a moderate, long period easterly swell from rapidly intensifying Hurricane Jova in the east pacific arriving early next week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov