West Kaua’i

Today: Breezy. Mostly cloudy with numerous showers. Haze. Highs 80 to 86 near the shore to around 72 above 3000 feet. Southeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 60 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Haze. Lows 68 to 73 near the shore to around 61 above 3000 feet. Southeast winds 10 to 20 mph shifting to the east after midnight. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Isolated showers in the morning, then scattered 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 15 mph shifting to the south in the afternoon. Chance of rain 50 percent.

South Kaua’i

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 78 to 86. South winds 10 to 15 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy with isolated showers. Haze. Lows around 71. South winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 79 to 86. South winds up to 15 mph shifting to the southwest in the afternoon. Chance of rain 40 percent.

Kaua’i Mountains

Today: Breezy. Mostly cloudy with numerous showers. Haze. Highs 75 to 82 in the valleys to around 65 above 4000 feet. South winds up to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Haze. Lows 61 to 70 in the valleys to around 59 above 4000 feet. South winds up to 20 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Isolated showers in the morning, then scattered 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 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Haze. Highs 76 to 84. South winds up to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Haze. Lows 64 to 71. South winds 10 to 25 mph decreasing to up to 20 mph after midnight. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 75 to 83. South winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 73 to 85. South winds 10 to 25 mph. Chance of rain 60 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Haze. Lows 65 to 74. Southwest winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs 73 to 85. Southwest winds 10 to 15 mph shifting to the south in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Rain chances will steadily increase through the week as a cold front and upper-level disturbance draws moisture northward into the islands. The front is expected to move over Kauai late Wednesday into Thursday, before stalling near Oahu. A wet trade wind pattern looks to return by the weekend then dry out early next week.

Discussion

The latest surface analysis shows a gale low approximately 900 miles northwest of the state slowly moving east. An associated cold front is approximately 300 miles northwest of Kauai this morning. Meanwhile, satellite imagery shows a mix of upper and low level clouds streaming over the western end of the state with the eastern end of the state mostly clear. Radar shows some scattered light to moderate showers developing south of the central islands early this morning and can expect these showers to continue to move northward embedded in the southerly flow. Voggy conditions and dewpoints ranging in the upper 60s to low 70s will continue through much of the week.
The gale low is on track to move northeast and the associated cold front will slowly shift southeast towards the state. This setup is allowing for moderate southerly winds to hold through today. Winds look to gradually ease on Wednesday and Thursday as a deep moisture axis and frontal boundary approaches and moves over Kauai. The front is expected to stall and weaken across the western end of the state Friday. The moisture band ahead of the front, combined with broad upper- level troughing and instability, will support more widespread showers later this week, especially across Kauai and Oahu. Breezy trade winds look to fill in behind the front late Friday into the weekend as the front dissipates. Lingering moisture will keep chances of rainfall high mostly along windward and mauka areas, with a few showers spilling over into leeward areas on occasion. A drier, more typical breezy tradewinds pattern shall return next week.

Aviation

Southerly winds will continue to strengthen to moderate levels over the western side of the state due to a front approaching the island chain from the northwest. Over the eastern side of the state, moderate to breezy southeast winds will continue. Increasing SHRA expected over the western side of the state with sea breezes expected over Maui and the Big Island. Brief MVFR conds are likely within any heavier SHRA.
AIRMET Sierra is in effect for mtn obsc for all of Kauai and windward portions of Oahu.
All locations can expect to see some VOG with the ongoing eruption of Kilauea. It is not expected to impact vsbys enough to warrant mention in the TAFs.

Marine

A frontal system, slowly approaching the state from the distant northwest, will help maintain moderate to locally breezy southerly flow across the local waters today. Localized terrain enhancement around the Big Island and Kauai will continue to result in advisory level winds, and a Small Craft Advisory (SCA) remains in effect through this evening for waters around Kauai, and through Wednesday morning for waters around the Big Island. The winds will gradually ease Wednesday and Thursday as the aforementioned front weakens and nears the islands. As the front pushes southeast and dissipates across the smaller islands Friday through the weekend, moderate to locally strong northeast trades will begin to ramp up.
A series of small overlapping north and northwest swells will keep some surf in place along exposed north and east facing shores through late Wednesday. The presence of a small, medium period, northerly swell can already be noted on the near shore buoys this morning. Another small northwest swell of similar size and period will also affect the waters today. A moderate north- northwest (310-330) swell should arrive on Friday and could produce advisory level surf. A large to extra large, long period, north to north- north west (340-360) swell is forecast to arrive this weekend and would likely produce warning level surf along north and possibly west and east facing shores. This swell, aside from being hazardous to small craft, could generate harbor surges along north facing bays and inlets.
Surf along south facing shores will gradually lower over the next day or two with mainly background energy by the second half of the week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters.
Small Craft Advisory until 6 AM HST Wednesday for Big Island Windward Waters, Big Island Leeward Waters.