Photo Credit: Jason Weingardt

West Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 85 to 90 near the shore to around 75 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 70 near the shore to around 59 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers. Highs 84 to 89 near the shore to around 74 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 88. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 87. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 71 to 81 in the valleys to around 64 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows around 66 in the valleys to around 57 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 70 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 71 to 81 in the valleys to around 63 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 88. Northeast winds up to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 72. East winds up to 20 mph. Chance of rain 50 percent.

Thursday: Mostly sunny with scattered showers. Highs 74 to 86. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 72 to 85. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 73. North winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 71 to 84. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

With the surface trough weakening and pushing off to the west, a return to a more typical trade wind pattern is bringing showers to windward and mauka areas early this morning. A cold front approaching from the northwest will stall and dissipate across the islands later today. This will bring breezy trades with periodically wet conditions into the weekend, with clouds and showers favoring windward and mauka areas.

Discussion

Shower and thunderstorm activity near the surface trough have diminished overnight as the trough continues to weaken and gradually pushes off to the west of Kauai. In its wake, the local weather pattern is already transitioning to be dominated by the northeasterly trades, which are currently ushering scattered showers into windward and mountain areas, with a few showers making it over to leeward sections at times.
A cold front about 200 miles northwest of Lihue as of 2 AM HST this morning will continue to push southeast and stall somewhere near Maui County later today before dissipating. High pressure building in behind this front will strengthen the northeasterly trade winds and bring breezy conditions across the region. Breezy trades will continue through the rest of the week and into the weekend as high pressure remains anchored to the northwest and batches of moisture will filter in on the trades, periodically bringing showers to windward and mountain areas.
Models are coming into slightly better agreement on the development and progression of an upper level low that is projected to dig over and southeast of the Big Island late this week and into the weekend. However, there is still some variance in the strength and positioning of this upper level feature, as well as in the available atmospheric moisture. As of now, the latter looks to be the limiting factor in shower development Friday into Saturday, but an uptick in moisture Saturday night into Sunday combined with the instability aloft due to the proximity of the upper level low may help to enhance trade wind showers for the second half of the weekend into early next week.

Aviation

Gusty northeast winds will continue to fill in ahead of an approaching cold front this morning, with clouds and showers favoring north through east facing slopes. The front will advance down the island chain beginning later today, then stall over or around Maui County tonight into Thursday. Expect periods with MVFR CIGS/VSBYs in showers moving through.
AIRMET Sierra is in effect for Tempo Mountain Obscuration over N through E facing slopes of Kauai, Oahu, and Molokai at elevations above 2,000 ft. This may need to be expanded down the island chain later today as the front draws closer and begins to move into the area.

Marine

A cold front will move into the islands late today, then stall out and gradually weaken across the central islands Thursday and Friday. Strong high pressure will build in from the northwest behind the front. Trade winds have already ramped up across the coastal waters early this morning, and will hold at fresh to strong levels today through early next week. A Small Craft Advisory remains in effect for a good chunk of the marine area through 6 PM Thursday, and this will likely need to be extended in time.
Surf along north and west-facing shores will trend up this afternoon, with a pair of overlapping moderate sized medium- period north-northwest swells keeping surf up through the weekend. This, combined with strong northeast winds, will create rough conditions for most north-facing shores beginning today. A pair of moderate sized long-period northwest swells could move through during the early to middle part of next week, potentially bringing a more sizable boost to north and west facing shores.
Surf along east-facing shores will trend up today, then hold relatively steady through early next week.
Surf along south-facing shores will remain small and near the seasonal average through the middle of next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Thursday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Kaiwi Channel, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov