West Kaua’i

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 60 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 83 to 89 near the shore to around 75 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 61 above 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

South Kaua’i

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 71. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Thursday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 87. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows around 71. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 62 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 70 percent.

Thursday: Breezy. Mostly cloudy with frequent showers. Highs 73 to 81 in the valleys to around 64 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 90 percent.

Thursday Night: Breezy. Mostly cloudy with numerous showers. Lows 62 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 72. East winds up to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy with numerous showers. Highs 75 to 86. East winds up to 15 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy with scattered showers. Lows 64 to 72. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 75. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 72 to 84. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Thursday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate to breezy trades will continue to focus showers over windward and mauka areas through next week. A developing low aloft could increase trade wind showers this weekend into early next week.

Discussion

Current radar and satellite imagery show isolated to scattered showers moving into windward areas on the breezy trades this afternoon, along with some high clouds streaming over the area from the west. These high clouds are associated with the subtropical jet to our south and are expected to stream across portions of the island chain through tomorrow before gradually clearing out this weekend as the subtropical jet shifts eastward.
High pressure currently centered about 1500 miles northeast of the state will gradually sag a bit south this weekend as a series of lows traverse across the northern Pacific. The movement of this feature will have little affect on the local weather as moderate to breezy trade winds are expected to persist across the area. However, one of those northern Pacific lows will drag a front that will stall well to the northwest of Kauai and turn into a trough early next week. Model guidance suggests that the interaction of this distant front/trough with the surface high to our northeast will weaken the local pressure gradient and reduce trade wind speeds slightly on Sunday into early next week.
Pockets of moisture caught up in the trades will bring periodic clouds and showers into windward and mauka areas throughout the forecast period. As a developing lower latitude upper level trough/low develops and moves over the state tomorrow into early next week, it will lower temperatures aloft slightly and increase the temperature inversion heights. While the overall instability isn't expected to be impressive, the raised inversions will likely allow for some enhancement of trade wind showers over the weekend and into early next week as those pockets of moisture roll through.

Aviation

Moderate to breezy trade winds continue to prevail across the island chain through at least Thursday afternoon, steered by high pressure centered far northeast of the main Hawaiian Islands. Showers and occasional low clouds embedded within the trades will favor north through east sections of the islands throughout this period, especially during the overnight to early morning hours. While VFR flight conditions will prevail at most locations, periods of MVFR conditions will be possible within any showers that occur.
AIRMET Tango remains in effect for moderate low-level turbulence downwind of island terrain. This AIRMET will likely be needed through at least Thursday. Additionally, mountain obscuration could become an issue across windward sides of the islands again later this evening and tonight.

Marine

A strong high will remain far northeast of the state through the week and continue to bring fresh to locally strong trade winds to all local waters. A Small Craft Advisory (SCA) for the windier waters around Maui County and the Big Island remains in effect through Thursday. Winds may ease slightly and veer toward the east-southeast over the weekend due to a weak front far northwest of the state.
The current moderate period south-southwest swell will continue to decline through tonight. Expect mainly background energy along south-facing shores on Thursday. A tiny long-period south- southwest swell is possible this weekend. Otherwise, expect mainly background energy through the middle of next week.
Surf along east-facing shores will remain rough and choppy the next several days due to the fresh to locally strong trades. Surf along north-facing shores will remain small with some background northwest energy moving through throughout the week and into the weekend.

HFO Watches/Warnings/Advisories

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

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