Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Highs around 83 near the shore to around 71 above 3000 feet. Northwest winds up to 10 mph shifting to the west in the afternoon.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 69 near the shore to around 58 above 3000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to around 72 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 80. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 70. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny with isolated showers. Highs around 81. Northeast winds around 10 mph shifting to the southeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 70 to 77 in the valleys to around 61 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 58 to 63 in the valleys to around 51 above 4000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 73 to 83. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 61 to 69. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Thursday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 84. East winds up to 10 mph shifting to the north around 10 mph in the afternoon. Chance of rain 40 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 73 to 82. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 58 to 71. North winds up to 10 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 83. East winds up to 10 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

The high pressure ridge north of the Hawaiian Islands will continue to weaken and drift closer to the state as a weak cold front approaches from the north. Trade wind speeds will show a weakening trend into the moderate range today. Winds over each island will become light and variable with cooling land and warming sea breezes from Thursday through Saturday. Clouds will build over island mountain and interior sections during this period of lighter winds. Northeasterly trade winds will return from Saturday night to Sunday morning as the dissipating cold front slowly drifts into the northwestern Hawaiian Islands. Clouds and brief showers will favor windward and mountain sections as the trade winds return to all islands through the first half of next week.

Discussion

Corrected aviation section.
In the larger weather pattern as shown on satellite imagery this morning we see stable cumulus clouds moving into the islands on the weakening trade winds. An upper level subtropical jet will stream high level cirrus clouds over the islands today. These ice crystal clouds will enhance island sunrise and sunset colors. Moderate trade winds today will produce a more typical weather conditions with clouds and brief passing showers favoring the windward and mountain areas in the overnight to early morning hours.
A cold front roughly 800 miles north of Oahu will continue to slowly approach the islands over the next several days and weaken the ridge north of the state through Saturday. This means moderate trade winds today will weaken and transition to light and variable winds from Thursday through Saturday. These lighter large scale winds will allow day time island heating to produce warmer sea breezes, and night time island cooling to produce cooler land breezes. The weather pattern will also shift with the changing winds as converging sea breezes build clouds and a few showers over island mountain and interior sections during the day, while diverging land breezes will clear out most of the cloud cover a few hours after sunset. Temperature inversion heights will range from around 7,000 to 9,000 feet during this time period, supporting scattered afternoon showers over each island.
A cloud band associated with this weak cold front will begin to drift through the northwest islands of Kauai, Niihau and Oahu from Saturday night through Sunday morning. Northeasterly moderate trade winds will return as this band passes through each island. Cloud and shower trends will increase along the remnant frontal band and favoring the typical windward and mountain areas. The forward motion of this cloud band will stall as the front dissipates near Maui and the Big Island from Sunday to Monday. Moderate trade winds will continue through Tuesday as wind directions veer from a northeasterly to a more easterly direction.

Aviation

Weak surface high pressure to the northeast of the state will allow for relatively dry moderate trades to persist through this afternoon. Thus, isolated showers will mainly affect windward portions of the islands. Brief periods MVFR ceilings and visibility may occur with any of the more robust showers.
No AIRMETS are currently in effect.

Marine

A ridge of high pressure will settle east-southward during the next few days as a cold front approaches from the northwest. Moderate to locally strong trades will hold in place today, and a Small Craft Advisory is now in effect for the typically windy waters around Maui and the Big Island through 6 PM this evening. The trades will gradually ease tonight and Thursday, with winds becoming light over all waters by Friday. Light to moderate trades will begin to develop again late Saturday as the front moves into the northwest islands, with moderate trades then filling back in statewide Sunday through early next week as the decaying front shifts down the island chain.
A combination of small medium-long period south and small period southeast swells will keep small surf in place along south facing shores through early next week.
Surf along north facing shores will likely remain small through Wednesday. A small medium period north-northwest swell will build Wednesday night and Thursday, giving north shore surf a noticeable boost by late Thursday. A re-inforcing medium period north- northwest swell will arrive late Friday and Friday night, boosting north shore surf up close to advisory levels this weekend. This swell will slowly lower and become more northerly early next week.
East shore surf will gradually lower during the next couple days, with minimal surf expected Friday through early next week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov