Photo Credit: Brendan Stephen

West Kaua’i

Today: Partly sunny with isolated showers. Highs around 78 near the shore to around 66 above 3000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows around 62 near the shore to around 51 above 3000 feet. Light winds. Chance of rain 20 percent.

Thursday: Sunny. Highs around 80 near the shore to around 68 above 3000 feet. Light winds.

South Kaua’i

Today: Partly sunny with scattered showers. Highs around 77. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 58 to 63. Northeast winds around 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs around 79. Northeast winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 65 to 73 in the valleys to around 60 above 4000 feet. Light winds. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 51 to 56 in the valleys to around 45 above 4000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny. Highs 67 to 75 in the valleys to around 62 above 4000 feet. Light winds.

North Kaua’i

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 70 to 77. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 54 to 63. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny. Highs 72 to 79. South winds up to 10 mph shifting to the northeast around 10 mph in the afternoon.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 70 to 77. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 52 to 64. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs 72 to 79. North winds up to 10 mph shifting to the northeast around 10 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A weakening front will edge a bit further south this morning, stall out over the eastern end of the state this afternoon and tonight, then dissipate on Thursday. The front will bring some showery weather to windward areas along with some leeward spillover. Moderate trade winds early this morning will gradually ease this afternoon and tonight. The front will dissipate on Thursday, with much drier and stable conditions overspreading the entire state. Light to moderate trades and minimal shower activity are then expected Friday through early next week, with many areas not seeing any rain at all.

Discussion

Currently at the surface, a weakening cold front is nearly stationary over Maui County early this morning. Meanwhile, a weak 1021 mb high is centered around 550 miles north of Kauai, and has brought a return of moderate trade winds to unsheltered areas across the island chain early this morning. Infrared satellite imagery shows mostly cloudy skies over Kauai and Oahu, with partly to mostly cloudy conditions across the remainder of the state, with cloud coverage the greatest in windward locales. Radar imagery shows numerous showers moving into windward sections of Kauai, Oahu, and Molokai, with lesser shower coverage over Maui and the Big Island. Main short term focus revolves around rain chances and trade wind trends.
The front may edge a bit further southward this morning, before stalling out over the eastern end of the state this afternoon and tonight, then dissipating on Thursday. Meanwhile, the ridge of high pressure north of the state will gradually settle southward and closer to the island chain. Moderate trade winds early this morning, will weaken and shift more northeasterly later today, with light to moderate trades then prevailing through Thursday. The ridge will remain nearly stationary north of the islands Friday through the weekend, maintaining light to moderate trades with only minor fluctuations in strength from day to day. The ridge axis will get shoved south and over the islands early next week, easing the trades enough to allow for daytime sea breezes and overnight land breezes in many areas.
As for the remaining weather details, with the front pushing slowly southward through the islands today, showery conditions can be expected for windward areas of the smaller islands along with some leeward spillover. The front appears to stay north of the Big Island, so shower coverage here will be much less. The deepest moisture associated with the stalled weakening front will shift south of Kauai tonight, while continuing to focus over Oahu and Maui County where shower coverage is expected to be the highest.
The front will dissipate on Thursday and the associated moisture will get dispersed, as mid and upper level ridging builds eastward and over the state. This will lead to an extended period of dry and stable weather with limited shower activity as inversion heights drop down to around 5,000 feet or less. A few light showers may affect Maui County and the Big Island Thursday through Friday, while very little if any shower activity is expected on Oahu and Kauai. Even drier conditions are then expected Friday night through early next week, with very little if any shower activity expected statewide.

Aviation

Gentle to moderate northeasterly winds this morning will relax today, as a weakening front stalls out across the central smaller islands. A mix of VFR/MVFR conditions are expected across most leeward areas through tonight. However, northeast flow will enhance shower chances across windward and mountain areas, with periods of MVFR conditions continuing. This will maintain the need of AIRMET Sierra for tempo mountain obscuration across most windward locations at times through today.

Marine

A decaying cold front looks to stall out over the eastern end of the state later today, with moderate to fresh trade winds easing into the light to moderate range this afternoon. Light to moderate trades will then prevail through Thursday, then briefly return to moderate and fresh levels late Thursday night through Friday night as high pressure passes to the north. A weakness in the ridge will form over the weekend as another front passes to the north, which will give way to light to gentle east trades over the weekend.
A medium period north (340-350) swell has begun to rise over the offshore buoy (51000) overnight as its expected to reach shorelines this morning. A High Surf Advisory (HSA) remains in effect for most north facing shores through 6 PM this evening. The subsiding west-northwest swell will ease through the day as west facing shores decline slowly. Surf along east facing shores will remain below average through Thursday except for areas exposed to the north swell. A trend up is expected Friday into Saturday as a small northeast swell arrives. Surf along south facing shores remain slightly elevated through Thursday before the south-southwest swell declines.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Oahu North Shore, Maui Windward West, Kauai North, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala.

Data Courtesy of NOAA.gov