Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 85 to 91 near the shore to around 76 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly clear. 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. Chance of rain 50 percent.

Friday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 88 near the shore to around 75 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 83 to 90. East winds around 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 68 to 73. Northeast winds around 15 mph. Chance of rain 70 percent.

Friday: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 82 to 89. East winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Cloudy with occasional showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 75 to 84 in the valleys to around 67 above 4000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 64 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 74 to 83 in the valleys to around 66 above 4000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs 78 to 87. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 65 to 72. East winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with occasional showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 75 to 86. East winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 64 to 76. East winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy with showers likely in the morning, then mostly sunny with scattered showers in the afternoon. Highs 74 to 86. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will focus low clouds and brief showers over windward and mauka areas, especially during nights and mornings. Except for a few sprinkles, leeward communities will be mostly dry, but afternoon clouds and a few showers will develop over leeward portions of the Big Island. An increase in showers is possible early next week.

Discussion

Morning soundings show just a subtle change over the past 24 hours, with the subsidence inversion now based around 8 thousand feet, and PWAT still near 1.2″. This slight increase in inversion height has led to increased shower coverage, but it's continued presence is generally limiting rainfall intensity. Scattered to locally broken stable and showery low clouds extend well upstream of the islands, streaming westward at 15-20 mph within a locally breezy trade wind flow supported by a surface high to the distant NE. Thinning high clouds are moving ENE over the islands from Oahu to Molokai, associated with a persistent TUTT (tropical upper-tropospheric trough) NW of Kauai.
Little significant change to the current pattern is anticipated into next week, except for potentially a modest increase in trade wind speeds this weekend as the surface high re-organizes to a position N of the islands. A strong mid-level ridge will remain over the islands, keeping the subsidence inversion low and strong. Brief showers will favor windward areas, especially during nights and mornings, with sensible weather highly dependent on the arrival of difficult-to-anticipate low cloud clusters. We do expect that an area of increased low-level moisture associated with the remnants of former Hurricane Adrian (now near 21N 134W) will bring increased showers Monday into Tuesday. Leeward areas may receive an occasional sprinkle, except for the typical afternoon clouds and showers on the Big Island's leeward slopes.
The TUTT NW of Kauai will pass over the islands today, with little effect on island weather, except the high clouds will dissipate. A new low aloft will develop within a revived TUTT NW of the islands this weekend, likely sending more high clouds over the area.

Aviation

Moderate to locally breezy trade winds will continue to steer bands of light showers off the Pacific towards the Hawaiian islands. Mountain obscuration may briefly become an issue for windward locations this morning. In the afternoon, showers will diminish and become focused over island interiors.
On the Big Island, lee-side sea breezes will develop in the early afternoon then taper off after sunset. Overnight land breezes should yield mostly clear skies across leeward slopes and coasts in the late night and morning hours.
Early morning soundings reveal a strong trade wind inversion at around 08 kft. This, combined with increasing winds at summit level, could result in moderate low level turbulence over and downstream of higher terrain later today.

Marine

A high pressure ridge will remain locked in place far north of the Hawaii region, producing moderate to locally strong trade winds over and upstream of the Hawaiian Islands lasting into early next week. A Small Craft Advisory (SCA) was extended in time through Friday night for the typically windier waters around Maui County and the Big Island. This SCA will likely continue through the weekend.
Surf along all shores are expected to remain small through Friday. In the long range, a series of moderate period south- southeast (150 degree) to south (190-200 degree) swells are expected starting this weekend producing a good boost to south shore surf heights. Another long period south (180-190 degree) swell will move into the region from Monday to Tuesday of next week. North facing shores may see a slight pulses out of the north-northwest (330 degree) through the weekend keeping surf above flat levels starting on Friday.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov