Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 77 near the shore to around 66 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 61 to 68 near the shore to around 51 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs around 77 near the shore to around 66 above 3000 feet. Northeast winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 74. Northeast winds 15 to 25 mph.

Tonight: Mostly cloudy. Breezy. Scattered showers after midnight. Lows 58 to 67. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs around 74. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Partly sunny with isolated showers. Highs 65 to 71 in the valleys to around 57 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then frequent showers after midnight. Lows 50 to 58 in the valleys to around 46 above 4000 feet. East winds up to 20 mph. Chance of rain 80 percent.

Friday: Mostly cloudy. Breezy. Frequent showers early in the morning, then scattered showers in the late morning and afternoon. Highs 65 to 71 in the valleys to around 57 above 4000 feet. East winds up to 20 mph becoming 10 to 15 mph in the afternoon. Chance of rain 80 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 67 to 77. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then numerous showers after midnight. Lows 55 to 66. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 70 percent.

Friday: Partly sunny. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 67 to 77. East winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 70 percent.

East Kaua’i

Today: Breezy. Partly sunny with isolated showers. Highs 66 to 76. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then numerous showers after midnight. Lows 51 to 69. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Friday: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 66 to 76. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy northeast trade winds will persist through early next week, with clouds and showers favoring windward and mauka locations as areas of moisture move through.

Discussion

Guidance has initialized well the current pattern and depicts the northeast trade winds increasing to breezy levels today and continuing through the weekend as high pressure strengthens north of the region. Showers will favor windward and mauka areas, which is the case early this morning over the eastern end of the state, where an area of moisture has moved in from the east. Despite this, rainfall accumulations have remained light due to the shallow nature of the low-level moisture and the presence of a strong mid-level ridge (subsidence inversion around 7 kft). Later tonight through Saturday, a weak pulse aloft and a shallow band of low-level moisture are forecasted to drop southward into the area, potentially leading to an uptick in shower coverage. Guidance indicates a trend towards increased moisture early next week, with precipitable water values rising to around 1.5 inches along with a mid-level trough moving in from the southeast. Should this scenario unfold, anticipate a more pronounced uptick in shower coverage over windward areas, while breezy trade winds persist.

Aviation

Moderate trade flow will prevail through today. Expect isolated showers along windward slopes this morning from Molokai eastward. An area of low clouds may spread additional showers across windward sections of Maui and the Big island later today. Brief periods of MVFR ceilings and visibilities may occur with some of the more robust showers. VFR conditions will dominate at the TAF sites.
No AIRMETs are in effect and none are expected through today.

Marine

Surface high pressure north of the state will slowly strengthen and drift east through Saturday. Trade winds will strengthen to moderate to locally strong today through the weekend. The Small Craft Advisory (SCA) is in effect for the typically windier waters near Maui County and the Big Island through Friday, with the potential for additional zones to be included as the stronger trades become more widespread Friday.
The current moderate, medium to long period northwest (310-320 degree) swell will keep surf elevated today but gradually decline through Friday. The High Surf Advisory (HSA) has been cancelled for all north and west facing shores. A new reinforcement small to moderate long period northwest (310-320 degree) swell, is expected to arrive late Friday with another slightly larger reinforcement from the same direction Sunday night and Monday. This late weekend swell will likely result HSA level criteria for exposed north and west facing shores.
Surf along south facing shores will return to background levels for the next several days. Short period trade wind swell will be below seasonal average through today and will likely pick up Friday through the weekend as trade winds increase.

HFO Watches/Warnings/Advisories

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