Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 79 near the shore to around 67 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to around 56 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs around 80 near the shore to around 68 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 78. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 68. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 79. East winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 66 to 74 in the valleys to around 61 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 56 to 61 in the valleys to around 50 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers. Highs 67 to 75 in the valleys to around 62 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 71 to 78. Southeast winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 68. Southeast winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 72 to 79. Southeast winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with scattered showers. Highs 71 to 78. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 57 to 69. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Highs 72 to 79. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy to windy easterly trade winds will gradually ease over the next several days becoming gentle to locally breezy Thursday into the weekend. Trade wind showers will mainly focus over coastal windward and mauka slopes with occasional showers spilling into leeward communities. An approaching front from the northwest will allow winds to ease to light to gentle wind speeds and veer out of the southeast over the weekend.

Discussion

A 1033 mb Surface high pressure around 1000 miles northeast of the islands continues to drive breezy to locally windy easterly trades. Latest wind observations show that winds have been more consistently below advisory levels for elevations lower than 6 kft thus the Wind Advisory has been cancelled. The 12Z soundings verify that the resident air mass remains dry and stable, with under one inch precipitable water vapor and a stout inversion around 6.5 to 8 kft, respectively. Satellite imagery continues to show very broad field of low level stratocumulus rotating in along the southern periphery of the surface high. Radar imagery depicts light to moderate scattered showers embedded in the trade flow, generally focusing in on east- facing coasts and slopes. Overnight rainfall totals range form 0.01 of an inch to just less than 1 inch for the typically wet areas such as Mount Waialeale.
The surface high will gradually weaken over the next couple of days, relaxing the pressure gradient. Wind speeds will respond by also gradually easing during this time becoming gentle to locally breezy by Thursday. Trade showers will continue to favor windward and higher elevations with the occasional cell reaching leeward areas. A couple fronts passing north then near the state late this week and early next week, will push this high pressure and trailing ridge east of the state allowing winds to become light to gentle over the weekend and veer out of the southeast. As trades fall off late this week and weekend, a hybrid pattern of windward and mauka trades showers along with afternoon interior/leeward showers may be more common as land/seabreezes take over.

Aviation

Gusty trades will prevail through the TAF period, with low clouds and isolated to scattered showers favoring windward and mauka areas. Cloud and shower coverage will be greatest through the early morning hours, with some light showers spilling over into leeward areas of the smaller islands. Expect mainly VFR conditions with brief MVFR possible under passing showers.
AIRMET Sierra for tempo mountain obscuration remains in effect for windward Kauai due to persistent low clouds, with little change expected through the morning hours.
AIRMET Tango for moderate lee turbulence below 8,000 ft remains in effect for areas over and downwind of all island terrain for the foreseeable future.

Marine

High pressure northeast of the state continues to produce strong winds across the coastal waters this morning, but have veered to straight easterlies overnight. Maalaea Bay is now sheltered from these strong winds enough to warrant dropping the Small Craft Advisory (SCA) there. The SCA has been extended for all other Hawaiian waters through 6 am Wednesday for strong winds and elevated combined seas. The strong trade winds will gradually weaken through Thursday as the high weakens and eventually shifts east- southeast.
Though rough conditions persist, surf along exposed north and west facing shores have decreased below High Surf Advisory (HSA) threshold this morning. This advisory has been dropped for those shores with this morning's forecast package. However, thanks to continued elevated easterly wind waves and a mix of a medium- period northeast (020-040 deg) and a long period northwest (310 deg) swells, surf heights along east facing shores will continue to reach HSA threshold. The HSA has been extended only for east facing shores through this afternoon. The northeast and northwest swells will slowly decline over the next couple of days as wind waves also ease.
Models show the next significant northwest swell will move into the region Friday into the weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for east facing shores of Kauai Oahu Molokai Maui and the Big Island.
Small Craft Advisory until 6 AM HST Wednesday for all Hawaiian waters except Maalaea Bay,

Data Courtesy of NOAA.gov