West Kaua’i

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 85 to 92 near the shore to around 77 above 3000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 71 to 76 near the shore to around 63 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Partly sunny. Isolated showers in the afternoon. Highs 85 to 92 near the shore to around 77 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy with scattered showers. Highs 82 to 91. East winds 10 to 15 mph. Chance of rain 40 percent.

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

Tuesday: Partly sunny. Isolated showers in the morning. Highs 83 to 91. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy with scattered showers. Highs 76 to 84 in the valleys to around 66 above 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 65 to 71 in the valleys to around 60 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 86 in the valleys to around 68 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly cloudy with scattered showers. Highs 78 to 87. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 67 to 75. Southeast winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Partly sunny with isolated showers. Highs 79 to 88. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly cloudy with scattered showers. Highs 74 to 88. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 78. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Partly sunny with isolated showers. Highs 75 to 88. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The proximity of a mid-level low northwest of Kauai and lingering moisture over the western end of the state will enhance shower activity across this area today. Then as the low lifts and drier air filters in, drier, more stable conditions can be expected by Tuesday night, with moderate trades focusing light showers over windward and mauka areas.

Discussion

A mid-level low northwest of Kauai continues to draw up some mid- level moisture from the southwest and provide modest instability over the western end of the state today into Tuesday. Meanwhile, a weak surface trough embedded within the trade wind flow is aligned with a band of enhanced low-level moisture that is also moving across the western end of the state today. As a result, scattered showers, a few of which may be briefly heavy, will be possible mainly over Kauai and Oahu today. While the instability is expected to linger into tomorrow, the band of enhanced low- level moisture will be shifting west of the state, so drier conditions are expected as compared to today. Then by Tuesday night, the low begins to lift northwestward, allowing mid-level ridging to build back across the area. This will bring a transition to more stable conditions with decreasing shower coverage statewide.
At the surface, moderate trade winds will persist through most of the week as seasonably weak high pressure holds north of the islands. Compared to Sunday, slightly stronger trades will limit sea breeze development, though isolated leeward and interior build ups are still possible each afternoon. Overall, low clouds and showers will favor windward and mauka slopes, primarily overnight and during the early mornings, with drier conditions prevailing leeward. Late into the week and weekend, no significant changes are expected, with moderate trades and a fairly typical trade wind weather pattern continuing.
The National Hurricane Center is currently issuing advisories on Tropical Storm Kiko in the Eastern Pacific. According to their latest forecast, they have it strengthening into a hurricane as it continues on a mostly westward track over the next several days and crosses into the Central Pacific. At this time it's too early to tell what, if any, impacts this system might have on the local weather across the state.

Aviation

Light to moderate trade winds will allow localized sea breezes to develop in sheltered leeward locations today, bringing clouds and showers over some leeward and interior areas. Tropical moisture moving across the islands combined with some weak instability aloft may help to enhance today's shower activity, with periods of MVFR possible. Otherwise, VFR should prevail. Drier conditions are expected tomorrow as the area of tropical moisture pushes west of the state.
AIRMET Sierra for mountain obscuration is in effect for windward portions of Kauai and Oahu this morning.

Marine

A ridge of high pressure north of the state will remain displaced to the south in response to large low far to the north. This will maintain moderate trades through most of the forecast period, with some localized sea breezes, especially across leeward waters.
Surf along south facing shores will continue to decline through today as the swell fades, returning to background levels for most of the week. Surf along north facing shores will see a boost today due to a small, short-to medium-period swell. This swell will quickly be overshadowed by longer period energy out of the northwest starting this afternoon and peaking on Tuesday. Surf will increase again from the influence of this swell, but remain below advisory levels. A reinforcing pulse out of the north should arrive around the same time the northwest swell arrives. A mix of north and northwest swells are expected to continue through Thursday. Below average surf is expected to continue along east facing shores persisting through early next week.
Peak monthly high tides, combined with water levels running higher than predicted, may lead to minor flooding along the shoreline and in low-lying coastal areas toward the end of next week. Coastal flooding may be possible around the daily afternoon peak tide.

Fire weather

Moderate trades prevail for the remainder of week delivering limited showers windward and mauka. As the resident area of enhanced low-level moisture exits to the west of the state by Tuesday, dewpoints return to typical values in the upper 60s. Even with this drying trend, winds look to be the limiting factor, helping to keep the state from meeting critical fire weather thresholds.

HFO Watches/Warnings/Advisories

None.

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