Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 82 near the shore to around 68 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 66 near the shore to around 56 above 3000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs around 82 near the shore to around 69 above 3000 feet. Northeast winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 83. East winds 10 to 15 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 65. Northeast winds around 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 83. Northeast winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 40 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 73 to 78 in the valleys to around 62 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 57 to 64 in the valleys to around 54 above 4000 feet. Light winds. Chance of rain 70 percent.

Saturday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 80 in the valleys to around 63 above 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 71 to 81. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 67. Southeast winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs 72 to 82. Southeast winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 72 to 81. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 70. East winds up to 15 mph. Chance of rain 70 percent.

Saturday: Partly sunny with scattered showers. Highs 72 to 81. East winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Easterly trade winds will gradually ease through Saturday as a surface ridge to the north weakens. Showers will favor windward and mauka slopes, while most leeward areas remain dry. Trade winds will break down late Saturday through Sunday, leading to a land and sea breeze pattern with limited showers. A shallow dissipating front is expected drift over Kauai and Oahu Monday night and Tuesday under light northerly winds. Southwesterly winds are expected to develop around Wednesday as a stronger front approaches.

Discussion

Guidance remains in good agreement through the weekend and shows a weakness forming in the surface ridge as a couple of fronts pass north of the area. The low-level flow will gradually ease and shift out of the east-southeast, likely enough for a land and sea breeze regime to begin for most areas as early as Saturday night. Shower coverage will remain limited to windward areas through Saturday, with mostly dry and stable conditions holding over leeward areas.
The tail-end of the second front passing north of the area will begin to approach Sunday. A combination of the approaching boundary, lowering upper heights as a weak pulse aloft moves through, and daytime heating should be enough to trigger a few showers where sea breezes form Sunday. Otherwise, limited moisture in the area will support mostly dry conditions persisting.
A rather dry and light northwesterly flow on Monday will give way to northerly winds that should push the dissipating and shallow front down to Kauai or Oahu on Tuesday. These islands will likely experience some light shower activity, but little rainfall is expected elsewhere.
Southwesterly winds are expected to develop around Wednesday and could become gusty as a stronger front approaches. Timing on this frontal passage is uncertain but favors next Thursday.

Aviation

A low pressure trough approaching the islands from the northwest direction will break down the ridge north of the Hawaii region and decrease wind speeds into the light to locally moderate range through the weekend. In the absence of large scale winds, local scale land and sea breezes will continue to expand in coverage over each island. Clouds will build over island interiors each day in sea breeze winds, and then clear out each night in stable land breezes. Shower activity will be limited in this weather pattern with isolated to scattered coverage.
AIRMET Tango remains in effect for tempo moderate turb between FL180 and FL420. This AIRMET will likely be cancelled by the 16Z update.

Marine

High pressure system far northeast of the state will continue to drift eastward away from the islands today as the surface ridge to the north weakens through early next week. Trade wind speeds will continue to weaken into the weekend, with light to moderate winds forecast over the western islands starting today, then the entire state by Sunday. Eastern islands will remain moderate to locally fresh over the typical windy waters around Maui County and the Big Island but below Small Craft Advisory (SCA) through Saturday.
Surf heights along north and west facing shores will see a steady rise as a moderate medium to long period swell is expected to build through the day, peak Saturday near High Surf Advisory (HSA) levels before steadily declining through early next week. Wave guidance is indicating the potential for an extra large long-period northwest (320 deg) swell arriving around next Thursday, with the potential for surf well above warning levels in the extra-large to giant range along exposed north and west facing shores. This situation will be closely monitored over the next several days.
Expect small background south swell pulses to continue through the middle of next week. A small, long-period south (200-220 deg) swell with Tasman Sea origins will produce a slight bump in south shore surf today through Sunday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov