Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 67 to 73 near the shore to around 60 above 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 86. East winds 20 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 73. East winds 20 to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 78 to 86. East winds 20 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 71 to 81 in the valleys to around 63 above 4000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 72 to 83 in the valleys to around 64 above 4000 feet. East winds 15 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 73 to 87. East winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 80 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 73. East winds 10 to 20 mph. Chance of rain 40 percent.

Friday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny with numerous showers in the afternoon. Highs 75 to 87. East winds 15 to 20 mph. Chance of rain 60 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 69 to 84. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 76. East winds 15 to 25 mph. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 71 to 84. East winds 15 to 25 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Windy trade winds will persist into the weekend with bands of showers being carried in on the trade wind flow. Showers will be focused over windward and mauka areas, with some of the showers being carried over to leeward areas. A slot of drier air moving in on Friday could bring critical fire weather conditions to portions of the state. Additional moisture coming in Saturday will boost shower activity once again.

Discussion

No significant changes to the forecast this morning. Strong high pressure to the north of the islands continues to drive strong trade winds to the region. A Wind Advisory remains in place for parts of the lower elevations of Maui County and the Big Island, as well as for the Big Island summits. The Big Island summit winds are borderline advisory level, and are expected to remain hovering there through Thursday night. Meanwhile, winds at the lower elevations of Maui County and the Big Island will linger at high end advisory levels through Friday night. Winds are expected to weaken some on Saturday, with most areas falling below advisory levels. The winds for the Big Island summits remain a blend of the GFS and ECMWF, while the winds for the lower elevations have been nudged to the latest National Blend of Models, which should very little change.
A batch of showers is moving into Maui County and the Big Island during the pre-dawn hours today, focusing clouds and showers over the windward and mountain areas. Another band of showers will reach the smaller islands this morning, and could bring additional clouds and showers to Maui County and the Big Island later today. Behind that band of showers is a drier airmass that is expected to move over the islands Friday. That being said, the forecast was nudged to the National Blend of Models, which brings some showers back to the windward side of the Big Island by Friday afternoon. The drier air on Friday, combined with the strong winds, does raise some fire weather concerns. See more details below within the FIRE WEATHER section.
Remnant moisture from an old front is expected be carried on the trade winds, and arrive into the islands on Saturday. This will once again boost shower activity over the windward and mountain areas of the islands. An upper level trough moving in Saturday or Saturday night could help to enhance shower activity. The GFS would bring the instability to the islands Saturday and into Saturday night, while the ECMWF is a little slower, more Saturday night into Sunday. The combination of moisture and instability would once again be focused over windward Big Island and windward Maui on Saturday. A drier air mass should move in on Sunday, which should decrease shower coverage once again.
By early next week, a large low pressure will develop far north of the state and the trade winds should decrease to moderate speeds around Tuesday of next week. This could be short-lived though as a cold front approaches the state towards the middle of next week.

Aviation

Strong easterly trade winds will increase through the day and periodically deliver showery low cloud clusters that will focus over windward areas. Showers will also spread leeward at times, wetting some leeward runways, including PHNL. Expect periods of MVFR CIGS/VSBYS within passing showers.
AIRMET Sierra has been issued for mountain obscuration for north through east sections of Kauai, Oahu, Maui, Molokai, and the Big Island with conditions expected to continue through the morning hours.
AIRMET Tango for moderate low-level turbulence over and downwind of the mountains will remain posted until further notice.

Marine

A strong high pressure system will build in north of the Hawaiian Islands through Saturday. Strong and gusty trade winds are expected to blow through the weekend, peaking on Friday and Saturday. Strong trade winds will slowly decrease from Sunday onward as a low pressure system weakens the ridge north of the state. The Gale Watch was upgraded to a Gale Warning today through Friday for the windier waters and channels around Maui and the Big Island. The Small Craft Advisory remains in effect for all remaining coastal waters for the same time period. The SCA will likely be extended through Sunday.
The large, long-period northwest (320-330) swell will slowly trend down and shift from a more north-northwest (340-350) direction through Friday. Swell heights reported from coastal and offshore buoys this morning continue to show these downward trends. A High Surf Advisory remains in effect for north and west facing shores of Niihau, Kauai, Oahu, and Molokai, as well as north facing shores of Maui through this afternoon. Surf heights will slowly decrease into the low end advisory range by this afternoon, likely falling below advisory thresholds by tonight.
Rough and choppy surf along east facing shores will gradually become more elevated as the trade winds continue to strengthen. Surf heights along east facing shores will build to advisory levels today, and then hold into the weekend. A High Surf Advisory for exposed east facing shores was issued this morning due to the increasing strong wind driven wave heights.
Surf heights along south facing shores remains small through the period.
Peak monthly tides are forecast from Nov 15th to 18th. These high tides will combine with elevated seas due to strong trades and rising easterly seas, which may increase coastal inundation impacts for vulnerable locations during early morning high tides. Current water levels are not running as high above predictions as they have been, so inundation impacts do not appear likely until Friday.

Fire weather

Wind speeds will be at or near Red Flag thresholds with the windy trade winds expected through Saturday. The limiting factor remains the relative humidity levels across the state. Bands of moisture moving in on the trade wind flow today are expected to maintain higher relative humidity levels. However a slot of drier air moving in on Friday could bring lower relative humidity levels. This prompted the issuance of a Fire Weather Watch for the leeward areas of all islands Friday. Note, the winds do not look nearly as strong and humidities do not look as dry as the historical Aug 8th event. Nonetheless, critical fire weather conditions will still be possible on Friday. A broad band of moisture will move in on Saturday, which should decrease any fire weather concerns over the weekend.

HFO Watches/Warnings/Advisories

High Surf Advisory 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.
Fire Weather Watch from Friday morning through Friday afternoon for Niihau, Kauai South, Kauai Southwest, East Honolulu, Honolulu Metro, Ewa Plain, Waianae Coast, Oahu North Shore, Waianae Mountains, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Lanai South, Lanai Mauka, Maui Leeward West, Maui Central Valley North, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Kohala, Big Island Interior.
Wind Advisory until 6 AM HST Saturday for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Molokai North, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Wind Advisory until 6 AM HST Friday for Big Island Summits.
High Surf Advisory until 6 AM HST Saturday for Kauai East, Koolau Windward, Molokai Southeast, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Small Craft Advisory until 6 PM HST Friday 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 Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov