Photo Credit: Jason Weingardt

West Kaua’i

Today: Sunny with isolated showers. Highs 85 to 91 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows around 72 near the shore to around 61 above 3000 feet. Northeast winds around 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs 86 to 91 near the shore to around 76 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 81 to 89. Northeast winds 15 to 20 mph. Gusts up to 40 mph in the afternoon. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 72. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 81 to 89. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Mostly cloudy with numerous showers. Highs 74 to 85 in the valleys to around 65 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 63 to 70 in the valleys to around 58 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy with numerous showers. Highs 74 to 85 in the valleys to around 66 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Partly sunny with numerous showers. Highs 76 to 88. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 65 to 73. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 60 percent.

Thursday: Partly sunny with numerous showers. Highs 76 to 88. East winds 10 to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 74 to 86. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 65 to 76. 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 74 to 86. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate northeast trades will weaken during the second half of the week in response to a couple fronts north of the islands disrupting the trade wind flow. A trough moving in from the east will increase clouds and showers Wednesday afternoon into Friday. Some stregthening of the trades is expected early next week.

Discussion

As expected, no significant changes to the forecast with the morning package.
A surface trough, with the southern end about 290 miles northeast of the Big Island overnight, will continue to slowly advance towards the islands over the next couple of days, even as it weakens. The trough will continue to disrupt the trade wind flow, and will bring some clouds and showers mainly to windward portions of the islands as early as tonight. The southern end of the trough is expected to reach the Big Island late today into tonight, while the northern portion of the trough will be slower to reach the smaller islands, and may dissipate before reaching the smaller islands. However even if the trough weakens, left over moisture will be carried in on the background flow to mostly impact the windward sides of the islands tonight on into Friday.
Water vapor imagery shows the upper level trough digging southward towards the islands, in line with the latest GFS and ECMWF deterministic model runs. An upper level low is still expected to form to the west of the islands along the upper level trough later today. The upper level trough lingering over the islands could help to enhance the showers associated with the above mentioned surface trough, but overall its impact is expected to be minimal.
Even as the surface trough weakens Thursday and into the weekend, a couple of fronts passing north of the islands will maintain a light wind pattern over the islands. By Friday, an upper level ridge building over the islands will help to stabilize the airmass, helping to limit shower activity over the islands.

Aviation

Moderate to locally breezy trades expected through the rest of the week. SHRA and low cigs will bring brief MVFR conds to windward and mauka areas. VFR should prevail elsewhere.
No AIRMETs are currently in effect.

Marine

A surface high pressure cell remains stagnant today far northwest of the state. This feature will move little the next couple of days and help maintain moderate to locally fresh trades across the local waters. Winds should stay below Small Craft Advisory. A cold front approaching from the west will break down the aforementioned surface high Friday through this weekend, weaken pressure gradients across the region, and ease trades to gentle to locally moderate.
This morning, a 4 to 5 foot, 13-second, north northwest (330-340 degree) swell could be noted on both the Hanalei and Waimea buoys. The swell will to be on a very slow decline today, but continue to produce small surf, especially along the best targeted reefs with northerly exposure. The next significant north northwesterly swell will likely arrive late Sunday into early next week may be large enough to push for surf a High Surf Advisory along north facing shores.
Nearshore buoys along the southern shores continue to show the presence of a 2 to 3 foot, 13-second, south southwest (180-190 degree) swell, which is slightly above forecast guidance. As this swell holds through tomorrow, expect small surf along south facing beaches. The next long period south swell is poised to arrive mid-day Thursday and will reinforce this ongoing background swell. Surf along west-facing shores will be influenced by a mixture of both north and south swells. Thus, expect western exposures to remain slightly elevated as well. East- facing shore chop over the next several days will be near normal, then steadily decline as wind waves subside through late week in response to lighter trade flow.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov