Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly cloudy in the morning then becoming mostly sunny. Highs 86 to 91 near the shore to around 77 above 3000 feet. North winds up to 10 mph shifting to the southwest in the afternoon.

Tonight: Partly cloudy. Lows around 71 near the shore to around 61 above 3000 feet. Light winds.

Thursday: Sunny. Highs 86 to 92 near the shore to around 78 above 3000 feet. Northeast winds up to 10 mph.

South Kaua’i

Today: Mostly cloudy in the morning then becoming mostly sunny. Highs 84 to 91. Northeast winds 10 to 15 mph.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs 85 to 92. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with isolated showers. Highs 75 to 84 in the valleys to around 68 above 4000 feet. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with isolated showers after midnight. Lows 65 to 70 in the valleys to around 59 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers. Highs 77 to 86 in the valleys to around 68 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

North Kaua’i

Today: Mostly cloudy in the morning then becoming mostly sunny. Isolated showers. Highs 77 to 88. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 74. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the morning. Highs 79 to 88. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with isolated showers. Highs 76 to 88. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 64 to 77. Northeast winds up to 10 mph. Chance of rain 20 percent.

Thursday: Partly sunny with isolated showers in the morning, then sunny in the afternoon. Highs 77 to 88. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Stable, moderate trades will focus limited showers over windward and mauka slopes through Thursday. A land and sea breeze pattern emerges from Friday onward in response to further weakening of the trades.

Discussion

Moderate trades and high stability prevail over the islands this morning, a trend that will continue for the balance of the forecast period. Southerly flow aloft associated with a weak upper jet will funnel high clouds across area skies, especially today, which may take the edge off of afternoon heat at times. Otherwise, moderate trades will focus limited/light clouds and showers over windward and mauka zones through Thursday. From Friday onward, the large scale pattern will be dominated by an eastward extension of the Pacific jet. This will force rather flat but very broad ridging to build into the Central Pacific from the west resulting in a trend toward even greater stability as the weekend progresses. Meanwhile, trade winds at the surface will further weaken as they are suppressed south of the area. This leaves the islands in a rather non-descript area of the regional MSLP field characterized by weak ridging at the surface and light to variable winds. Afternoon sea breezes and overnight land breezes will dominate during this time, but inland shower development is likely to be sparse at best given the dearth of moisture and steadily increasing stability.

Aviation

A weak high pressure ridge far north of the Hawaiian Islands will produce light to moderate trade winds through Thursday. Brief showers are possible mainly over windward and mountain areas.
No AIRMETs are currently in effect.

Marine

The western end of a surface ridge about 400 nm north of Honolulu is expected to maintain moderate to locally fresh trade winds over the state today. A new surface high pressure system is expected to move to a position far northwest of the state tonight and Thursday. This feature will move slowly south as a front pushes down from the north-northwest, which will force a weak surface ridge to the east of the surface high to eventually move down closer to the islands. This will result in the trade winds gradually weakening to light to moderate speeds from late Thursday through Friday. By this weekend, expect light and variable winds in the vicinity of the western islands, while weak trade winds may linger near the eastern end of the island chain.
The current small, medium-period northwest (310-320 degrees) swell will continue to produce small surf along exposed north and west facing shores today. A slightly larger, medium-period northwest (310-320 degrees) swell will likely boost surf along exposed north and west facing shores from later tonight through Friday. A moderate, long-period north-northwest (320-330 degrees) swell arriving Saturday is expected to produce moderate surf along exposed north and west facing shores from late Saturday into early next week.
Modest surf is expected to persist along south facing shores this week due to a series of medium- to long-period south to south- southwest (190-200 degrees) swells moving through the area. A fetch of gale force winds southeast of New Zealand is expected to produce a new, long-period south-southwest (200-210 degrees) swell that may arrive Sunday. This may result in above the seasonal average surf along south facing shores from late this weekend into early next week. Elsewhere, the weakening trade winds will result in diminishing surf along east facing shores later this week, with nearly flat conditions possible along most east facing shores by late this weekend.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov