Photo Credit: Braden Jarvis

West Kaua’i

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to around 69 above 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Lows around 66 near the shore to around 55 above 3000 feet. Northeast winds around 10 mph in the evening becoming light.

Sunday: Mostly sunny. Isolated showers in the late morning and afternoon. Highs around 81 near the shore to around 68 above 3000 feet. West winds around 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 83. East winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly clear with isolated showers. Lows around 64. North winds around 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 78 to 83. West winds around 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 73 to 80 in the valleys to around 63 above 4000 feet. East winds up to 10 mph. Chance of rain 60 percent.

Tonight: Mostly clear with isolated showers. Lows 56 to 63 in the valleys to around 53 above 4000 feet. Light winds. Chance of rain 20 percent.

Sunday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 73 to 78 in the valleys to around 62 above 4000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 40 percent.

North Kaua’i

Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 72 to 82. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 60 percent.

Tonight: Partly cloudy with isolated showers. Lows 58 to 67. South winds around 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 71 to 81. Light winds. Chance of rain 20 percent.

East Kaua’i

Today: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 72 to 81. East winds up to 10 mph. Chance of rain 60 percent.

Tonight: Mostly clear with isolated showers. Lows 57 to 69. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 72 to 81. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A developing light wind pattern will ensure that nights and mornings are mostly dry after this morning's cloudiness and windward showers. Interior and upslope clouds may develop in the afternoons and evenings, potentially dropping a few showers. Light winds will continue early next week, favoring a west to northwesterly direction as a weak front brings increased clouds and showers Monday night and Tuesday. A stronger front will bring increasing southwest winds Wednesday, and a period of clouds and showers Wednesday night and Thursday. Trade winds are expected by the end of next week.

Discussion

Despite low PWAT near 1″ and a strong subsidence inversion based around 7000-8000', clouds and showers associated with a weak low- level trough have continued to be fairly persistent near Kauai and Oahu overnight. Light to moderate E-SE flow is bringing a few of these showers ashore on windward Maui and Big Island, although land breezes have been able to keep some of the showers offshore elsewhere, with a narrow line of moderate showers noted over Oahu's nearshore windward waters.
Light winds will favor a E-SE direction today, then become variable tonight and Sunday as an approaching front weakens the ridge and shunts it E. Land and sea breezes will modulate island weather, with mostly clear/partly cloudy nights and mornings (after today), and partly to mostly cloudy skies over interior and upslope areas in the afternoons and evenings, with the potential for a few showers. Light winds will favor a W to NW direction early next week as a weak front moves through Monday night and Tuesday, becoming light and variable again late Tuesday. Increasing SW winds are expected Wednesday as a stronger front approaches, bringing a period of clouds and showers Wednesday night and Thursday. Trade winds are expected by the end of next week as high pressure builds N of the area.

Aviation

A weak disturbance passing through the western islands this morning continues to enhance cloud and shower coverage from Oahu to Kauai. Expect brief MVFR conditions within some of these showers over these Western islands through the morning hours. This disturbance will continue drifting slowly westward away from the state today with decreasing shower trends in the afternoon forecast.
In the larger scale, a low pressure trough approaching the islands from the northwest will continue to break down the high pressure ridge north of the islands, weakening the wind speeds across the Hawaii region. These lighter large scale winds will allow land and sea breezes to expand in coverage across all islands through this weekend. Clouds will build over island interiors each day in sea breeze winds, and then clear out each night in stable land breezes. Shower activity will be limited in this weather pattern with isolated to scattered coverage.
AIRMET Sierra remains in effect for mountain obscuration over Kauai and Oahu. This AIRMET will likely be cancelled later this morning.

Marine

A surface ridge just north of the islands will weaken as a couple of fronts pass north of the area through early next week. Light to moderate ESE winds will diminish, with light and variable winds over most of the state by tonight, continuing through early next week. Light winds will favor a west to northwest direction early next week as a weak front moves through, becoming light and variable again late Tuesday. Increasing SW winds are expected Wednesday as a stronger front approaches, and could reach SCA speeds around Kauai and Oahu.
A medium to long-period NW swell will peak today, based on observations from NDBC buoys 51001/51101 located northwest of the islands, and a High Surf Advisory is in effect for select north and west facing shores today. The swell is forecast to peak late today before becoming increasingly northerly and steadily declining through early next week. A small short-period NW swell is possible on Tuesday. A powerful, extra-large, long-period northwest swell is expected to arrive Thursday, likely resulting in surf well above warning levels along most north and west facing shores through Friday.
A couple of small, long-period south-southwest swells with Tasman Sea origins will provide small surf to south facing south shores for the next couple of days.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for North and West facing shores of Niihau Kauai Oahu Molokai and for North facing shores of Maui.

Data Courtesy of NOAA.gov