West Kaua’i

Tonight: Breezy. Cloudy with scattered light showers. Haze. Lows 68 to 73 near the shore to around 61 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Cloudy and breezy. Scattered light showers in the morning, then numerous showers in the afternoon. Haze through the day. Highs 80 to 86 near the shore to around 73 above 3000 feet. Southeast winds up to 20 mph shifting to the south 10 to 20 mph in the afternoon. Chance of rain 60 percent.

Tuesday Night: Mostly cloudy with scattered light showers. Haze. Lows 68 to 73 near the shore to around 61 above 3000 feet. South winds 10 to 15 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Cloudy with scattered light showers. Haze. Lows around 72. South winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Cloudy with scattered light showers. Haze. Highs 79 to 86. South winds up to 15 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered light showers. Haze. Lows around 71. South winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Cloudy with scattered light showers. Haze. Lows 61 to 71 in the valleys to around 60 above 4000 feet. South winds up to 20 mph. Chance of rain 50 percent.

Tuesday: Cloudy and breezy. Scattered light showers in the morning, then numerous showers in the afternoon. Haze through the day. Highs 75 to 81 in the valleys to around 65 above 4000 feet. South winds up to 20 mph. Chance of rain 60 percent.

Tuesday Night: Mostly cloudy with scattered light showers. Haze. Lows 62 to 70 in the valleys to around 59 above 4000 feet. South winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Breezy. Cloudy with isolated showers. Haze. Lows 64 to 71. South winds up to 20 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered light showers in the afternoon. Haze through the day. Highs 76 to 83. South winds up to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered light showers. Haze. Lows 64 to 71. South winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Tonight: Breezy. Cloudy with scattered light showers. Haze. Lows 65 to 74. Southwest winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Breezy. Cloudy with scattered light showers. Haze. Highs 73 to 85. South winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy with scattered light showers. Haze. Lows 65 to 75. South winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Rain chances will steadily increase through the week as moderate southerly winds associated with an approaching cold front and upper-level disturbance draws moisture northward into the islands. The front may reach the western end of the state later this week, potentially leading to more widespread showers. Trade winds look to return by the weekend.

Discussion

The latest surface analysis shows a gale low approximately 900 nm northwest of the state moving slowly towards the southeast. Its associated cold front is approximately 400 nm northwest of Kauai this afternoon. Meanwhile, satellite imagery continues to show partly cloudy skies across the islands, with isolated showers streaming in from the south on east to southeasterly flow. In the near-term, the main impact will continue to be humid and voggy conditions due to the southerly winds.
Guidance continues to remain in good agreement through the first half of the week and shows the gale low and associated cold front slowly shifting southeast towards the state. As a result, winds look to become more southerly through Tuesday and strengthen to moderate speeds. Meanwhile, hi-res guidance continues to show an increase in moisture moving towards this islands over the next few days, with isolated to scattered showers likely over the western end of the state.
Winds look to gradually ease on Wednesday and Thursday as a deep moisture axis and frontal boundary approaches Kauai, then gradually stalls and weakens across the western end of the state through Friday. This moisture, combined with broad upper-level troughing and instability, will support more widespread showers later this week, especially across Kauai and Oahu. Trade winds look to fill in across the region by late Friday as the front dissipates, with breezy trade wind developing over the weekend. This should bring the return of clouds and showers to windward and mauka areas, with a few showers spilling over into leeward areas on occasion due to lingering instability.

Aviation

Southerly winds will continue to strengthen to moderate levels over Kauai and Oahu through Tuesday, in response to a frontal system approaching the island chain from the northwest, while moderate to breezy southeast winds continue over the remainder of the state. Expect increasing showers moving up from the south over the western end of the state through Tuesday as well, with mainly interior clouds and showers over Maui and the Big Island with afternoon sea breezes. Brief MVFR conditions are likely with any of the more robust showers.
No AIRMETs in effect nor expected through tonight, though AIRMET Sierra could be needed for mountain obscuration if showers become more widespread (highest chance being Kauai tonight).
For general awareness, all locations can expect to see some VOG with the degassing of Kilauea. It is not expected to impact visibility enough to warrant mention in the TAFs.

Marine

A storm system to the distant northwest, will strengthen winds and shift them around to the southeast and south this afternoon through Tuesday. Localized terrain enhancement around the Big Island and Kauai will likely result in advisory level winds, and a Small Craft Advisory (SCA) remains in effect for these areas through Tuesday 6 PM. The winds will gradually ease Wednesday and Thursday as a front approaches from the northwest, with moderate to locally strong northeast trades filling in behind the front for the end of the week.
A series of small overlapping north and northwest swells will keep some surf in place along exposed north and east facing shores through midweek. We should see the arrival of new north swell on Tuesday as well as some smaller northwest energy. A moderate north-northwest swell should arrive on Friday and could produce advisory level surf. A more significant north to north-northwest swell appears to arrive late in the week, and will likely produce warning level surf to north and possible west and east facing shores over the weekend.
Surf along south facing shores will gradually lower through the middle of the week with mainly background energy by the second half of the week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Big Island Windward Waters, Big Island Leeward Waters.

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