Photo Credit: Braden Jarvis

West Kaua’i

Today: Breezy. Partly sunny with isolated showers. Highs around 77 near the shore to around 66 above 3000 feet. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 61 to 68 near the shore to around 51 above 3000 feet. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly cloudy with isolated showers. Highs around 77 near the shore to around 66 above 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy. Windy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs around 74. Northeast winds 20 to 30 mph. Chance of rain 60 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows 58 to 67. Northeast winds 20 to 30 mph. Chance of rain 50 percent.

Sunday: Mostly cloudy. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 74. Northeast winds 25 to 30 mph decreasing to 15 to 30 mph in the afternoon. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Frequent showers early in the morning, then scattered showers in the late morning and afternoon. Highs 65 to 71 in the valleys to around 57 above 4000 feet. East winds 10 to 25 mph. Chance of rain 60 percent.

Tonight: Cloudy and breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 50 to 58 in the valleys to around 46 above 4000 feet. East winds 10 to 25 mph. Chance of rain 80 percent.

Sunday: Cloudy and breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 65 to 71 in the valleys to around 57 above 4000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 80 percent.

North Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Highs 67 to 77. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 55 to 66. East winds 15 to 25 mph. Chance of rain 70 percent.

Sunday: Breezy. Mostly cloudy with scattered showers. Highs 67 to 77. East winds 10 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers early in the morning, then scattered showers in the late morning and afternoon. Highs 66 to 76. Northeast winds 15 to 25 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 51 to 69. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 66 to 76. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Strong and gusty easterly trade winds will continue into Monday, with showers favoring windward and mauka locations as pockets of moisture move through. Some showers will carry over into leeward areas of the smaller islands periodically with the strong winds in place, mostly overnight through the mornings. High clouds associated with an upper disturbance west of the state will support mostly cloudy conditions through the weekend. Trade winds will likely be disrupted Tuesday into midweek, followed by a cold front advancing down the island chain Wednesday through Thursday. Breezy northerly winds and drier conditions will follow the front.

Discussion

Guidance remains in good agreement through the weekend and depicts the gusty easterly trades persisting due to strong high pressure centered north of the islands. Winds up to 30 mph with gusts around 50 mph over and downwind of island terrain are expected in the windier locations of Maui County and the Big Island. As a result, a Wind Advisory is in effect and has been extended through Sunday. Showers will favor windward/mauka areas, especially overnight through the morning hours as areas of moisture move through. Water vapor imagery showed plenty of mid- to upper- level moisture pooling northward due to an upper low west-southwest of this state, which supports the high clouds streaming over the islands. Guidance has initialized well with this current pattern and shows no significant changes through the weekend.
The extended guidance remains in decent agreement and shows a pattern shift early next week, featuring a cold front approaching from the northwest and the aforementioned upper low to the west- southwest advancing eastward over the islands. Breezy easterly trades will hold Monday, then begin to ease and shift out of the southeast Monday night through Tuesday as the ridge weakens with the approaching cold front – likely enough for a land/sea breeze regime to become established briefly Tuesday night into Wednesday. Although the high clouds will begin to shift eastward Monday through Tuesday as the upper low drifts eastward into the area, increasing instability associated with it along with daytime heating and a sufficient amount of moisture may be enough to fuel locally heavy showers. As this upper low lifts out to the northeast and phases with the northern stream Wednesday, the rain chances will remain in forecast as the cold front and its attendant upper trough close in on the area from the northwest. Although uncertainty remains high this far out in the forecasts, guidance depicts this front advancing down the island chain with breezy northerly winds/drier air following it through the second half of the week.

Aviation

A high north of the state will drive strong and gusty east to northeast trades through Sunday. Showers embedded in this flow will bring periods of MVFR conditions, with brief IFR conditions possible in heavier downpours. Otherwise, VFR conditions will prevail at the TAF sites.
AIRMET Sierra for mountain obscuration remains in effect for north through east sections of Oahu, Molokai, Maui and the Big Island. This AIRMET will likely continue through Sunday.
AIRMET Tango for moderate to locally severe turbulence over and south through west of island mountains below 8000 feet remains in effect. This AIRMET will likely continue through Sunday.
AIRMET Tango for moderate turbulence between FL200 and FL450 remains in effect for all islands. This AIRMET will continue through today.
Severe turbulence is also forecast northeast of Kauai between FL240 and FL380 as a subtropical jet stream moves away from the region. See SIGMET November series.

Marine

A large area of strong high pressure centered northwest of the islands will steadily move east through Tuesday. The tight pressure gradient downstream of the high and across the islands will maintain fresh to strong trade winds through the weekend. The Gale Warning remains in effect for the channels surrounding Maui County and Big Island through Sunday as winds will frequently achieve gale force magnitudes. A Small Craft Advisory also remains in effect for the remaining waters through Sunday afternoon. Early week winds will gradually diminish and veer to the east southeast at mid week as the high moves east and a front approaches from the northwest. The front is timed to pass across the local waters from Wednesday through Thursday as moderate to fresh north to northeast winds fill in the front's wake.
Generally strong trades will continue to generate rough, choppy surf along east-facing shores through the weekend with a gradual early week decline as a result of weakening easterlies. A pre-dawn medium period spike in northwest swell is occurring at the far northwest buoys. Thus, north and west-facing shore surf will be on the rise today as this moderate size, medium period northwest (320-330 degree) swell arrives through late morning and peaks this afternoon into evening. Peak surf heights may approach High Surf Advisory levels along exposed north-facing shores today. A pair of moderate size, medium to long period north northwest swells are possible Tuesday into Wednesday and Thursday into Friday of next week. The early week northwest (320 degree) swell originating from a compact hurricane-force low east of Japan will begin filling in late Monday and peaking Tuesday. The later week north northwest (330-360 degree) swell coming from a broader area of gale force winds southwest of the Aleutian Islands may arrive and peak next Friday. While the first swell origin's source is a deeper low, it is farther away and swell size may be compromised by angular spreading along its long eastern journey. The late week swell fetch area's gales are more in-line with the Great Circle route aimed toward the islands. Thus, this may be the larger of the two swells, pushing surf to near High Surf Warning levels as it arrives from a more northerly direction. A small, long period southwest swell is possible Sunday into early next week.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST Sunday for Lanai Mauka, Kohala, Big Island Interior, Lanai Leeward, Lanai South, Maui Central Valley South, Kipahulu, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 PM 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, Big Island Windward Waters.
Gale Warning until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov