Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph.

Tonight: Partly cloudy. Lows 70 to 75 near the shore to around 61 above 3000 feet. East winds around 10 mph.

Friday: Mostly sunny with isolated showers. Highs around 89 near the shore to around 77 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 68 to 74. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs around 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with isolated showers. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Breezy. Partly sunny with isolated showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds 10 to 20 mph. Chance of rain 30 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 88. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with isolated showers. Highs 79 to 87. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 62 to 76. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 87. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Expect moderate to locally breezy trades and a relatively dry weather pattern into early next week. Tropical Storm Calvin, currently in the eastern Pacific, continues to intensify and is expected to move in the central Pacific basin late Sunday. Calvin will likely impact the state beginning next Tuesday, but it is too early for details.

Discussion

High pressure far north of the main Hawaiian Islands keeps moderate to breezy trade winds blowing across local waters this morning. Satellite loop shows scattered low clouds across most areas of the island, with patchy broken low clouds noted across windward waters. Overnight soundings show a dry and stable airmass, with about 1.2 inches of PW and positive lifted index values. A strong and low inversion, around 4100 feet, is noted in the Lihue sounding. The inversion above Hilo is a bit higher, near 5100 feet. Radar shows isolated light showers reaching windward areas of Maui and possibly the Big Island, but little or no activity elsewhere. Expect ample sunshine and light passing showers riding in on the breezy trades over the next few days.
Models show a slight moisture increase this weekend, ending the dry pattern we are in with a return of typical trade wind shower coverage. Scattered showers will favor windward areas, with isolated showers expected over leeward areas. Overall, it should be a fair weekend with moderate to locally breezy trade winds.
We continue to monitor the development of Tropical Storm Calvin in the eastern Pacific, which is expected to intensify to a hurricane later this morning. It is too early to specify details regarding Calvin impacts on the Hawaiian Islands, but the latest forecast from the National Hurricane Center has Calvin moving into the Central Pacific basin late Sunday as a weakening tropical storm. Calvin will likely impact the state in some sort of way, whether it is high surf, heavy rain, strong winds, or all of the above, it is yet to be determined. Although details are uncertain, we could begin to see impacts from Calvin as early as Tuesday, but more likely around Wednesday of next week.

Aviation

Moderate to breezy easterly trade winds will continue through the week. VFR conditions will prevail with brief MVFR possible in showers mainly over windward and mountain areas.
AIRMET Tango remains in effect for moderate turbulence over and in the lee of island mountains due to breezy trade winds. These conditions will continue through Friday morning.

Marine

Fresh to strong easterly trades may briefly lower Friday into the weekend due to a weakness in the ridge far to the north, but will likely surge back beginning around Sunday. For that reason, the Small Craft Advisory, currently in place for the windier waters and channels, will not be extended into the weekend at this time. Tropical Storm Calvin, located in the eastern Pacific, is forecast to enter the Central Pacific basin Sunday night as a Tropical Storm, then approach the Hawaiian waters Monday through Tuesday. Although confidence in any details is low being this far out in time, all interests should monitor the latest advisories issued by the National Hurricane Center in Miami, Florida under WMO header WTPZ33 KNHC.
Surf along south facing shores will remain up today as a south- southwest swell continues to move through. Offshore buoys reflect this where observations are hanging in there with the peak energy now centered around 14 seconds (~2 ft). A return of background level south-southwest and southeast swell energy moving through is anticipated Friday through early next week.
Surf along east facing shores will remain rough and choppy each day through the weekend. An upward trend is anticipated early next week due to a medium-period easterly swell arriving from Calvin. Details beyond this will highly depend on the exact track Calvin takes through/around the islands Tuesday through Wednesday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov