West Kaua’i

Tonight: Mostly clear. Lows around 74 near the shore to around 64 above 3000 feet. Northeast winds up to 10 mph in the evening becoming light.

Sunday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 84 to 89 near the shore to around 75 above 3000 feet. Northwest winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Sunday Night: Partly cloudy. Lows around 73 near the shore to around 63 above 3000 feet. Light winds.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 69 to 77. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 78 to 88. Northeast winds around 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 68 to 76. Northeast winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Tonight: Partly cloudy with scattered showers. Lows around 68 in the valleys to around 60 above 4000 feet. Light winds. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 74 to 82 in the valleys to around 67 above 4000 feet. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 65 to 70 in the valleys to around 60 above 4000 feet. East winds around 10 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 64 to 75. Southeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs 71 to 86. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 64 to 74. East winds around 10 mph. Chance of rain 20 percent.

East Kaua’i

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

Sunday: Mostly sunny with isolated showers. Highs 78 to 86. East winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 65 to 76. Northeast winds around 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. Low level convergence along a surface trough will bring a modest increase in clouds and showers late Monday into Tuesday. More rain is expected through the second half of the week as remnants of Tropical Storm Norbert pass by.

Discussion

High pressure far to the north is driving gentle trade winds across Hawaii today, weakened by surface troughs to the northeast and east of the area. Visible satellite this afternoon shows partly to mostly cloudy skies across the islands mainly due to the localized sea breezes. Radar shows very little rainfall across the area this afternoon. Light trade winds and isolated showers will continue through the rest of the weekend.
The trough mentioned to the east is forecast to track westward over the next several days. Low level convergence along this feature will bring a modest increase in clouds and showers late Monday into Tuesday, initially reaching the Big Island with showers becoming more diffuse as the trough moves west.
Tropical Storm Norbert is currently around 1675 miles east of Hilo, moving west-northwest at 12 mph. Recent advisory updates from the National Hurricane Center show this system becoming post-tropical on Tuesday while turning slightly west southwest as the motion become dictated by the low level trade winds. Trade winds will strengthen statewide as the gradient tightens around what is left over of Norbert, likely a trough by Thursday and Friday. Rainfall will also increase east to west across the state from Wednesday night through Friday night. A surface and upper trough over the area, with precipitable water values over 2 inches will likely be enough to produce some flooding across the state. Strengthening trade winds will keep showers moving along and focused windward, but leeward sides will also see a fair share of rain. Still a bit far out in the forecast to get too detailed for now, but a definitely a time period to focus on.

Aviation

A large upper level low well northeast of the islands is weakening the pressure gradient and therefore the trade winds near Hawaii. These weak to moderate trades will continue through Sunday. Winds may become light enough within more wind-protected leeward areas to initiate local topographically-driven breezes. These trades are also relatively dry, and will limit shower activity.

Marine

Moderate to locally fresh trades will continue through early next week before gradually strengthening through the latter half of the week. Moisture associated with a weak trough moving in on the trade wind flow may bring a slight uptick in shower activity to the coastal waters Tuesday into Wednesday. While the current forecast has Tropical Storm Norbert dissipating before it nears the Hawaiian coastal waters from the east, remnant moisture from this system is expected to arrive late next week, likely bringing more showers.
Surf along south-facing shores will gradually decline through the weekend as the small, medium- to long-period energy slowly fades. A moderate, long-period swell generated by a low that passed near Australia and New Zealand is forecast to arrive mid to late week next week and bring a bump to south shore surf.
Surf along east-facing shores will remain small to moderate through early next week, then build slightly over the latter half of the week as the trade winds strengthen and some easterly swell from Norbert potentially moves in. 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. Inversion heights are expected to remain elevated or weak through Monday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov