Photo Credit: Brendan Stephen

West Kaua’i

Today: Partly sunny. Highs around 90 near the shore to around 76 above 3000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy. Lows around 72 near the shore to around 62 above 3000 feet. Northeast winds up to 15 mph.

Tuesday: Partly sunny. Highs around 89 near the shore to around 76 above 3000 feet. Northeast winds up to 15 mph.

South Kaua’i

Today: Mostly cloudy. Breezy. Isolated showers in the morning. Highs 81 to 88. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 72. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Tuesday: Mostly cloudy. Breezy. Isolated showers in the morning. Highs 80 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 88 in the valleys to 63 to 68 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Cloudy with scattered showers. Lows 66 to 72 in the valleys to around 58 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 74 to 88 in the valleys to 62 to 68 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

North Kaua’i

Today: Mostly cloudy with isolated showers. Highs 78 to 90. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Cloudy with scattered showers. Lows 66 to 74. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 40 percent.

Tuesday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 90. East winds up to 15 mph. Chance of rain 30 percent.

East Kaua’i

Today: Mostly cloudy with isolated showers. Highs 75 to 86. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Cloudy with scattered showers. Lows 66 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 86. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

High pressure far north of the Hawaiian Islands will gradually weaken and slowly drift west over the next several days. Moderate to locally breezy trade winds will continue into Tuesday, then weaken slightly Wednesday through the rest of the week. Stable conditions across the region will focus showers mainly along windward and mauka areas, particularly during the overnight and early morning hours.

Discussion

Satellite imagery and radar imagery show clouds and showers have picked up overnight with the diurnal cycle. Expect typical summertime trade wind weather this week, with clouds and showers favoring windward and mauka areas during the overnight and early morning hours. Leewards areas will remain mostly dry, except the kona slopes on the Big Island could see some brief afternoon/evening sea breeze showers. Hi res models are hinting at a band of showers moving through the island chain along with breezy winds tonight that could provide a boost in showers mainly along windward and mauka areas. Guidance remains on track keeping the base of the inversion around 4,000-6,000 feet this week. This will help to limit vertical cloud development resulting in a decrease in clouds and showers across the state, especially during the second half of the week.
Latest model guidance maintains moderate to locally breezy trade winds through into Tuesday. A low pressure area is expected to develop far northeast of the state Tuesday which could weaken the gradient over the state, allowing for moderate trade winds to develop Wednesday through the rest of the week. May see breezy trade winds return late over the weekend and into early next week.

Aviation

Breezy trades are expected to continue today and tonight. Mostly dry conditions are expected today, with only a few showers affecting windward locales. We should see an increase in trade wind showers tonight as a band of enhanced moisture moves through. Predominantly VFR conditions should prevail today, with some MVFR cigs/vsbys becoming more likely tonight across windward areas as the band of enhanced moisture moves through.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue through the day.

Marine

Strong surface high pressure north of the state will maintain fresh to locally strong trades into the first half of this week. A Small Craft Advisory (SCA) was extended in time this morning to run through Tuesday afternoon for the typical windier areas around Maui and the Big Island. Trade winds will decrease into the gentle to fresh range by late Tuesday or by Wednesday as the the high center drifts farther west and a cut off low deepens far northeast of the state.
A small long period south-southwest swell (200 degrees) will arrive this afternoon, briefly bumping up south and west shore surf heights into Tuesday, and then surf heights will slowly decline with the swell through Wednesday.
Surf along east facing shores will remain choppy with short period wind waves before slowly declining with the trade winds through Wednesday. A tiny background west-northwest swell will arrive late Tuesday into Wednesday providing a small bump for north facing shores.

Fire weather

Locally breezy trade winds and low relative humidity will keep elevated fire weather concerns over leeward areas through Tuesday. Locations such as West Maui and leeward Kohala on the Big Island are of particular concern. Trade winds should weaken to moderate levels Wednesday as the pressure gradient relaxes over the state then hold through the rest of the week.
Most leeward areas will remain dry. Brief periods of showers may impact windward and mauka areas. Expect good to excellent overnight recoveries at lower elevations. The exception will continue to be near the inversion between 4,000-8,000 feet where periods of warmer temperatures with much drier conditions are possible through much of the upcoming week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov