Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 86 to 91 near the shore to around 76 above 3000 feet. Light winds. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 73 near the shore to around 63 above 3000 feet. Light winds. Chance of rain 20 percent.

Sunday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 85 to 91 near the shore to around 76 above 3000 feet. Northwest winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 40 percent.

South Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 91. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Sunday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 83 to 91. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs 76 to 84 in the valleys to around 68 above 4000 feet. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 71 in the valleys to around 61 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 74 to 83 in the valleys to around 66 above 4000 feet. Light winds. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 88. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 74. East winds around 10 mph. Chance of rain 40 percent.

Sunday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 87. Northeast winds up to 15 mph. Chance of rain 40 percent.

East Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 77 to 88. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 77. Northeast winds around 10 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 75 to 87. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Gentle to locally breezy trade winds will continue to weaken today. Land and sea breezes pattern will become the dominate pattern for the next several days. Expect clouds and showers building over select leeward and interior areas each afternoon then clearing overnight and in the early morning hours. Some windward areas may still see limited clouds and showers, especially overnight and in the early morning hours. A shallow band of moisture will increase clouds and showers on Kauai today and spread to Oahu tonight and possibly Maui County Sunday. Expect slightly drier conditions Monday through mid-week.

Discussion

ASCAT overnight showed an area of light to gentle winds trades upstream of state generated from a high positioned 1100 nm northwest of Kauai. Satellite and radar imagery shows clouds and scattered showers have increased along windward areas. There is a band of low level clouds and increased moisture over Kauai due to remnant moisture from an old frontal boundary. The 12Z sounding from Lihue shows precipitable water vapor values have increased near normal since yesterday afternoon. Elsewhere clouds and showers have cleared over leeward areas.
The band moisture is expected to continue to move south today reaching Oahu late this evening, and possibly Maui County by Sunday, increasing clouds and shower potential. Overall, a sea breeze will develop this afternoon due to weak tradewinds, allowing clouds and showers develop over interior and leeward areas and along windward and mauka regions. A land breezes will develop at night lead to a few isolated showers over select windward areas with clouds and showers clearing for leeward areas.
During the first half of the week, a surface ridge will shift south just east of the state, maintaining light and variable winds with possible background wind flow shifting out of the southeast. The land/sea breeze pattern will continue with afternoon showers over interior and leeward areas that could briefly produce heavy showers as a weak upper level trough develops over the state. Land breezes will lead to a few isolated showers over select windward areas but generally drier conditions elsewhere at night as the remnant moisture dissipates.
By the second half of the week, model guidance shows the tail end of a front approaching the western half of the state. Depending on where this moisture ends up, we could possibly see a wetter pattern develop Thursday into Friday along with a brief return of moderate to breezy trades.

Aviation

Light trade winds will continue through the weekend allowing for the development of local land and sea breezes. Expect clouds and showers to develop over the interior during the afternoon, then dissipate shortly after sunset. Will see mainly VFR, with brief MVFR possible under passing showers.
No AIRMETs are currently in effect, nor expected through tonight.

Marine

Gentle to moderate trade winds will prevail through Monday as a surface ridge, currently about 375 nm north of Kauai, drifts southward. The ridge will be pushed near Kauai Tuesday into Wednesday, possibly disrupting the trade winds. Stronger surface high pressure passing far north of the state may drive increasing trade winds by Thursday and could push the tail end of a dissipating front near Kauai.
A series of North Pacific swells are due this week, likely leading to the first High Surf Warning event of the season. The current, declining north-northwest swell will be reinforced by the arrival of another north-northwest swell late this afternoon, leading to above October average north shore surf tonight into Monday. A deepening storm low that was West Pacific Typhoon Bolaven will send a large northwest swell toward the islands early next week. Low, long-period, westerly forerunners will arrive Monday and could produce High Surf Advisory level surf across west facing portions of the Big Island Monday night into Wednesday. Meanwhile, the larger, long-period northwest swell will build rapidly Monday night and Tuesday, and will likely produce High Surf Warning conditions for north and west facing shores from Kauai to Maui late Tuesday and Wednesday. In spite of the lighter winds, a Small Craft Advisory will likely be needed for seas in excess of 10 ft.
Along south facing shores, a series of south-southwest swells will keep surf around October average through much of the week. Due to the absence of significant upwind trades, minimal surf is due on east facing shores through at least Thursday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov