Photo Credit: Braden Jarvis

West Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs 82 to 87 near the shore to around 73 above 3000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 68 near the shore to around 58 above 3000 feet. Northeast winds up to 10 mph.

Friday: Mostly sunny early in the morning, then isolated showers in the late morning and afternoon. Highs 81 to 86 near the shore to around 73 above 3000 feet. Northeast winds around 10 mph shifting to the southwest up to 10 mph in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 86. Northeast winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 69. North winds around 10 mph. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 78 to 86. North winds around 10 mph shifting to the southeast in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 72 to 80 in the valleys to around 64 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 59 to 66 in the valleys to around 55 above 4000 feet. East winds around 10 mph shifting to the southwest after midnight. Chance of rain 40 percent.

Friday: Mostly sunny with isolated showers early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 71 to 80 in the valleys to around 64 above 4000 feet. Southwest winds around 10 mph shifting to the northeast in the afternoon. Chance of rain 30 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 85. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 70. East winds around 10 mph shifting to the south after midnight. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 74 to 84. South winds around 10 mph shifting to the northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 71 to 83. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 61 to 73. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 71 to 83. West winds around 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Gradually diminishing trade winds will deliver just a few light showers to windward areas of the smaller islands today, while windward Big Island will continue to receive passing showers. Light and variable winds and mostly dry weather are expected statewide from tonight into Sunday. A weak front may move over the islands from the northwest late this weekend. This front is expected to bring little in the way of rainfall, however, and winds will remain light through much of next week.

Discussion

Early this morning, weakening high pressure is located about 300 miles north of Honolulu, which is promoting light to moderate trade winds over the islands. Dry air and stable conditions are prevailing over most of the state, with the 12z Lihue sounding showing stable conditions and a strong inversion near 5,000 feet. CIMSS MIMIC Layer Precipitable Water (PW) imagery depicts values between roughly 0.75 and 1 inch nudging over the smaller islands from the east. Radar imagery also shows minimal shower activity over much of the state early this morning, with the the exception of windward Big Island where deeper mixing and lingering moisture upstream continue to produce scattered to numerous showers.
Gradually diminishing trade winds will deliver little in the way of rainfall to windward areas of the smaller islands today, while windward Big Island will continue to receive passing showers. Shower coverage and frequency over windward Big Island should taper off by tonight, however, as background trade winds weaken further and a land and sea breeze pattern develops statewide. This will occur as the high pressure north of the state moves south and dissipates, leaving a surface ridge near/over the islands. Light winds and mostly dry conditions will persist into at least Sunday, after which forecast details become a bit uncertain.
Late Sunday into Monday, a weak front is expected to approach from the northwest, and deterministic model guidance continues to offer inconsistent solutions for the prognosis of this feature and the evolution of the weather pattern early next week. Ensemble guidance, however, indicates that we can be confident that winds remain light and precipitation totals associated with the potential frontal passage will remain fairly low. A relatively dry post-frontal weather pattern should persist well into next week as we head into the Thanksgiving holiday.

Aviation

Trades will decrease gradually through Friday. Expect showery weather for windward Big Island through today, with periods of MVFR conditions. Some of the heavier showers may produce brief IFR conditions. Elsewhere, expect fair trade wind weather with a few light showers possible over windward and mauka areas.
AIRMET SIERRA is in effect for northeast through southeast slopes of the Big Island due to mountain obscuration above 2500 feet. This AIRMET will likely remain in effect through today as a persistent band of showery low clouds extending east from the Big Island continues to supply low clouds and showers to that island. No other AIRMETS are in effect or are expected.

Marine

Weak surface high pressure will settle in over the far north offshore waters today. This will create and maintain primarily gentle to locally moderate trades winds through the rest of the week. The west-to-east orientated ridge axis will reach the northern coastal waters by Friday. This will result in continued light to gentle east to variable breezes, with slightly stronger winds in the Alenuihaha Channel and south of Big Island. Light winds are favored ahead of the approach of a weak front nearing Kauai on Sunday. This shallow frontal passage will disrupt trade flow as early week gentle easterly breezes veer northwest then northeast.
No significant swells are expected through early Friday as trade wind waves continue to gradually subside and result in a more calm sea state. Nearshore windward buoys are observing a 4 to 5 foot trade wind swell that will further decline throughout the remainder of the week as a result of light trades.
A series of northwest and north-northeast swells are due within a couple of days. A tiny 1 to 2 foot, 15 second period northwest (320 degree) swell is being observed at the nearshore CDIP buoys as it moves around the islands early this morning. This swell will level out around 2 feet today and then hang in through Friday. A larger 3 to 6 foot northwest (310-320 degree) medium period swell developing from a pair of lows far northwest of the islands is scheduled to travel through this weekend and peak Sunday. A smaller reinforcing northwest pulse (320 degree) is due Monday and Tuesday.
A small, short to medium period north (010-020 degree) swell will slowly build in today and hold at 4 to 5 feet Friday and Saturday. A very large, powerful storm force low churning off the U.S. Pacific Northwest coast will send an overlapping north-northeast (010-030 degree) swell across the islands late tonight or early Friday, peaking Sunday into Monday and then fading Tuesday.
While none of these swells are expected to produce advisory level surf, the potential for high surf along north and east-facing shores will need to be monitored, especially as combining north northeast swells peak Saturday through Monday.

Fire weather

KBDI values remain high across the state and an overall dry weather pattern is expected for the next several days. With this dry air moving overhead, relative humidity values will have the potential to reach the critical 45% threshold from late morning through the afternoon each day through Sunday. Fortunately, however, weak trade winds will mitigate fire weather concerns through the rest of this week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov