West Kaua’i

Tonight: Partly cloudy. Lows around 74 near the shore to around 64 above 3000 feet. Northeast winds up to 10 mph.

Saturday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 84 to 90 near the shore to around 77 above 3000 feet. Northeast winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Saturday Night: Partly cloudy. Lows around 73 near the shore to around 63 above 3000 feet. Northeast winds up to 10 mph.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 69 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 79 to 89. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 69 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with isolated showers. Lows 66 to 71 in the valleys to around 60 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs 70 to 83. East winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Mostly cloudy with isolated showers. Lows 65 to 70 in the valleys to around 60 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 65 to 75. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 72 to 88. East winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 65 to 74. Southeast winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 66 to 76. Northeast winds around 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 78 to 86. Northeast winds around 10 mph. Chance of rain 20 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 65 to 76. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Drier trade winds will prevail into early next week with light showers on the windward side of the islands. A weak disturbance will lift out of the deep tropics towards the middle of next week bringing a slight uptick in trades, increased humidity, and a better chance for showers.

Discussion

Evening satellite water vapor imagery shows a large upper level low well northeast of the state and generally dry northwest flow aloft as a weak short wave moves southeast over the area. A band of showers that developed in remnant moisture west of the Big Island is slowly progressing eastward, but is forecast to dissipate overnight as the moisture fizzles out.
Drier air in prevailing trade winds will continue through the weekend. Low-elevation dew points have already fallen into the mid to upper 60s across most of the islands. Typical trades weather is expected over the next few days with occasional light showers across the windward side of the islands each day.
A tropical disturbance currently several hundred miles southeast of Hilo will move northwestward over the next several days. NHC forecast holds at a 20% chance of development into a tropical cyclone over the next 7 days. Most likely scenario is for this feature to help pull tropical moisture into the area, though how much and when will depend on its track. For now expect dew points to increase once again with a small increase in trade winds and higher precipitation chances towards the middle of next week.
Tropical Storm Norbert is currently around 1900 miles ESE of Hilo, moving west-northwest at 12 mph. Any potential arrival in the vicinity of the Hawaiian Islands is at least 10 days away. Forecast uncertainty is characteristically high at that lead time and it will be several days before confidence in impacts, or lack thereof, improves.

Aviation

Lower to mid level low pressure centered approximately 1,100 miles northeast of the islands is disrupting the downstream pressure gradient. This has resulted in light to moderate trades that will persist through the weekend. Relatively drier air working its way in across the state from the north northwest will keep infrequent light showers away from many terminals. Lingering moisture sticking over the eastern half of the island chain will keep rain chances higher over HTO. Tempo MVFR categories will occur within lowering decks as more organized rain clusters pass across from the northeast. Winds may become light enough within more wind-protected leeward areas to initiate local land and sea breezes.
AIRMET Sierra remains in effect for tempo mountain obscuration on Big Island through this evening, Sierra may need to be extended as moisture lingers over that island Saturday morning.

Marine

Moderate to locally fresh northeast to east trade winds will continue through the forecast period. A tropical disturbance moving in from the trade winds may bring an increase of showers to the coastal waters by next week Tuesday into Wednesday.
Surf along south facing shores will gradually decline through the weekend as the small medium to long period energy slowly fades. Currently a low in the south pacific near Australia and New Zealand will bring the potential for a moderate long period swell for Hawaii late next week.
East facing shores will also remain at small to moderate through the forecast period due to the fresh to locally strong trade winds. Flat to tiny surf along north facing shores is expected through the forecast period.

Fire weather

Fire weather risk will remain low the next several days due light to moderate winds and the effects of recent rainfall, even as afternoon relative humidity falls below 50 percent over many leeward areas. Inversion heights are expected to remain elevated or weak through Monday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov