West Kaua’i

Today: Cloudy and breezy. Numerous showers in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 78 near the shore to around 64 above 3000 feet. Northeast winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Locally heavy rainfall possible. Lows around 65 near the shore to around 55 above 3000 feet. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Sunday: Windy. Cloudy with numerous showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs around 78 near the shore to around 64 above 3000 feet. Northeast winds 10 to 35 mph. Gusts up to 60 mph in the afternoon. Chance of rain 70 percent.

South Kaua’i

Today: Cloudy and breezy. Numerous showers in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 71 to 78. Northeast winds 20 to 25 mph. Chance of rain 60 percent.

Tonight: Breezy. Cloudy with numerous showers. Locally heavy rainfall possible. Lows around 64. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Sunday: Windy. Cloudy with numerous showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs 70 to 78. Northeast winds 20 to 30 mph. Gusts up to 50 mph in the afternoon. Chance of rain 70 percent.

Kaua’i Mountains

Today: Cloudy and breezy. Occasional showers in the morning, then numerous showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 64 to 70 in the valleys to around 56 above 4000 feet. Northeast winds 10 to 25 mph. Chance of rain 80 percent.

Tonight: Breezy. Cloudy with occasional showers. Locally heavy rainfall possible. Lows 55 to 62 in the valleys to around 52 above 4000 feet. Northeast winds 10 to 25 mph. Chance of rain 80 percent.

Sunday: Very windy. Cloudy with numerous showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs 65 to 72 in the valleys to around 56 above 4000 feet. East winds 10 to 30 mph with gusts to 50 mph shifting to the northeast 15 to 40 mph with gusts to 60 mph in the afternoon. Chance of rain 70 percent.

North Kaua’i

Today: Cloudy and breezy. Occasional showers in the morning, then numerous showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 67 to 76. Northeast winds 10 to 25 mph. Chance of rain 80 percent.

Tonight: Breezy. Cloudy with occasional showers. Locally heavy rainfall possible. Lows 58 to 66. East winds 10 to 20 mph. Gusts up to 40 mph in the evening. Chance of rain 80 percent.

Sunday: Windy. Cloudy with numerous showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs 68 to 77. East winds 10 to 30 mph. Gusts up to 45 mph increasing to 55 mph in the afternoon. Chance of rain 70 percent.

East Kaua’i

Today: Cloudy and breezy. Occasional showers in the morning, then numerous showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 63 to 75. Northeast winds 10 to 20 mph. Chance of rain 80 percent.

Tonight: Breezy. Cloudy with occasional showers. Locally heavy rainfall possible. Lows 57 to 68. Northeast winds 10 to 20 mph. Chance of rain 80 percent.

Sunday: Windy. Cloudy with showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs 64 to 75. Northeast winds 10 to 20 mph increasing to 15 to 30 mph in the afternoon. Chance of rain 80 percent.

Detailed Forecast

Synopsis

A cold front will move into Molokai this morning, then stall near Maui later today. This frontal boundary combined with increasing moisture and a disturbance aloft, will bring the potential for heavy rainfall, flash flooding, and a few rumbles of thunder through Monday. Breezy north to northeasterly winds will develop behind the front, with the trades then becoming very windy Sunday into Monday as strong high pressure builds north of the state. Conditions will gradually improve by mid to late next week, though breezy and showery trade wind weather is expected to persist.

Discussion

Currently at the surface, a slow moving cold front is located in the Kaiwi Channel just east of Oahu as of 3 am HST. Behind the front moderate to breezy north winds have filled in with frequent gusts of 35 to 40 mph observed across Kauai and Oahu. Ahead of the front light and variable winds prevail. Infrared satellite imagery depicts mostly cloudy to overcast conditions across the smaller islands, while clear to partly cloudy skies prevail over most of the Big Island. Radar imagery shows scattered to numerous showers across the smaller islands, with a few showers affecting east and southeast facing slopes of the Big Island. Main short term focus revolves around heavy rain and damaging wind potential over the weekend into early next week.
The cold front is expected to move into Molokai later this morning, then stall out over Maui later today. Low clouds and showers will continue to be most prevalent along and in close proximity to the front, with breezy north to northeast winds developing in its wake. The front will gradually weaken and dissipate during the next couple days, while strong high pressure builds north of the state. Abundant moisture will pool along the stalled front or its remnant moisture band through Monday, as a disturbance aloft moves overhead. This will maintain the threat for heavy rainfall and flash flooding across the area, with a couple rumbles of thunder not out of the question Sunday through Monday. As a result, a Flood Watch remains in effect from this afternoon through Monday afternoon.
In addition to the flooding threat, very windy conditions are forecast to develop this weekend and continue through early next week, as a strong area of high pressure builds north of the islands. A Wind Advisory will likely be required for the entire state Sunday through early Tuesday. Portions of the state could even see winds reach High Wind Warning levels. The strongest winds are expected in areas downslope of terrain, through valleys, and other local acceleration areas, and a High Wind Watch remains in effect for these locations Sunday through Monday.
Finally, the old temperatures aloft associated with the upper disturbance will support the potential for heavy snow on the Big Island summits as well. Dry mid-level air is expected over the summits today, with the arrival of deeper moisture expected sometime tonight. As a result, the timing of the Winter Storm Watch has been adjusted to begin tonight and run through Monday afternoon.
Conditions will gradually improve for the middle and latter portion of next week, although a somewhat showery and breezy trade wind pattern will likely persist.

Aviation

A strong cold front is moving through the island chain. The front is bringing low cigs, SHRA and strengthening north winds to Kauai, Oahu and Maui County this morning with the Big Island later this evening. IFR to MVFR conds expected, with localized LIFR conds, with FROPA.
AIRMET Sierra is in effect for mtn obsc from Kauai to Maui and will likely linger overnight. It will most likely be expanded to the Big Island later today. If conds deteriorate further Sierra may be needed for IFR conds.
AIRMET Tango for mod turb will likely become necessary this morning as winds increase.

Marine

A front is currently over the Kaiwi Channel and is expected to stall and dissipate over Maui County later today. ASCAT pass overnight showed widespread strong northerly winds behind the front, and these strong winds should fill in over Maui County behind the dissipating front. A Small Craft Advisory (SCA) remains in effect across the waters surrounding the smaller islands today. Over Big Island waters, gentle to moderate east to southeast winds will give way to strengthening easterly winds by tonight. Thus the Small Craft Advisory for Big Island waters start this evening.
As the high expands and strengthens on Sunday, trade winds will strengthen to near gale to gale force over most waters Sunday afternoon through Monday. Due to the strengthening trades, a Gale Watch has been issued starting Sunday for all Hawaiian waters. In addition, expect heavy showers over most waters Saturday through Monday with some isolated thunderstorms especially over select leeward waters Sunday through Monday. Winds are expected to ease some on Tuesday, but still remain in the strong range with some near gales over the windier waters through at least Wednesday.
A large west-northwest swell (295-310 degrees) has peaked overnight across most areas and will be trending lower throughout the day today. Recent observations at buoys 51001 and 51101 northwest of Kauai indicate a steady decline over the past 8 hours and we should see surf drop below High Surf Warning thresholds this afternoon. A High Surf Warning (HSW) remains in place for exposed north and west facing shores for today, but it should be downgraded to an advisory later this afternoon and drop below advisory thresholds by Sunday morning. Over on the Big Island, we should see a steady rise throughout the day today along west facing shores and a High Surf Advisory is in effect. Small to moderate north-northwest to northwest swells will prevail through the remainder of next week.
Surf along east facing shores will significantly ramp up Sunday into Monday as the trade winds strengthen, with surf heights exceeding the advisory level by Sunday night. Surf heights may potentially get close to warning levels along east facing shores of Kauai and Oahu on Monday. Large east shore surf will slowly decline Tuesday into Wednesday, but remain elevated through the remainder of the week. Surf along south facing shores will remain small with some small background south-southwest energy expected throughout the first half of next week. Select southern exposures exposed to the wind swell will likely see some larger waves.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Flood Watch from noon HST today through Monday afternoon for Niihau, Kauai Leeward, Kauai Mountains, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Haleakala Summit, Kona, Kohala, Big Island Interior, Kauai North, Kauai East, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Koolau Windward, Koolau Leeward, Molokai, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Big Island East, Big Island North.
High Wind Watch from Sunday morning through Monday afternoon for Kauai Leeward, Kauai Mountains, Waianae Coast, Central Oahu, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Leeward West, Kohala, Big Island Interior, Kauai South, Honolulu Metro, Ewa Plain, Koolau Leeward, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South.
High Surf Advisory until 6 PM HST this evening for Kona, Kohala.
Winter Storm Watch from this evening through Monday afternoon for Big Island Summits.
Small Craft Advisory until 6 AM HST Sunday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel.
Gale Watch from Sunday morning through Monday afternoon for all Hawaiian waters,
Small Craft Advisory from 6 PM this evening to 6 AM HST Sunday for Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Kaua‘i Helicopter Tours today!

Data Courtesy of NOAA.gov