Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Sunny and breezy. Highs around 87 near the shore to around 74 above 3000 feet. East winds 15 to 20 mph.

Tonight: Breezy. Mostly clear with isolated showers. Lows 68 to 73 near the shore to around 60 above 3000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 86 near the shore to around 74 above 3000 feet. East winds 15 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 78 to 86. East winds 20 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows around 73. East winds 20 to 25 mph. Chance of rain 40 percent.

Saturday: Breezy. Mostly cloudy with scattered showers. Highs 79 to 87. East winds around 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 72 to 82 in the valleys to around 64 above 4000 feet. East winds 15 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 69 in the valleys to around 58 above 4000 feet. East winds 20 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Saturday: Breezy. Mostly cloudy with numerous showers. Highs 71 to 82 in the valleys to around 64 above 4000 feet. East winds 20 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 86. East winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 64 to 73. East winds 15 to 25 mph. Chance of rain 40 percent.

Saturday: Breezy. Mostly cloudy with numerous showers. Highs 75 to 87. East winds 15 to 25 mph. Chance of rain 60 percent.

East Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 71 to 84. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 76. East winds 20 to 25 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 71 to 84. East winds 20 to 25 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Windy trade winds will persist into the weekend, and then weaken a little heading into the new week. A slightly drier airmass over the islands will bring critical fire weather conditions to leeward areas today. Another band of moisture being carried in on the trades over the weekend will boost shower activity once again.

Discussion

No significant changes to the forecast this morning. Winds at the Big Island summits have weakened some as expected, and have been below advisory levels. Thus the Wind Advisory for the summits was recently cancelled. Winds remain gusty over portions of the lower elevations of Maui County and the Big Island. The Wind Advisory for those locations has been extend to Sunday morning with the models indicating many of those areas will remain at advisory levels.
The overnight sounding from Lihue saw precipitable water (PW) values drop to near 1 inch, which matches well with the satellite derived PW. PW values were higher at Hilo due to showers in the area. Satellite shows the low cloud band that brought showers to the Big Island is dissipating over the island, while another area of moisture is mostly passing south of the islands. Expecting that most areas will see limited clouds and showers through tonight.
Heading into Saturday, leftover moisture from a front will be carried in on the trade wind flow, once again increasing the shower activity around the state. With the trade wind flow, expect the clouds and showers to be focused over windward and mountain areas. The GFS and ECMWF models are coming into better agreement with the handling of an upper level trough moving over the islands this weekend, which could help to enhance some of the showers moving over the islands. The PoPs and associated grids have been nudged to the National Blend of Models, but there was little change in the overall forecast with that change.
By the end of the weekend, the high pressure far north of the islands will begin to weaken, which will weaken the trades over the first half of the new week. Drier conditions are once again expected, with a return to more typical trade wind showers.

Aviation

Strong easterly trade winds will continue through the day before decreasing slightly tonight. Strong trade winds will periodically deliver showery low cloud cloud clusters over windward areas. Showers will also spread leeward at times. Expect, occasional periods of MVFR CIGS/VIS within passing showers.
AIRMET Tango for moderate low-level turbulence over and downwind of the mountains will remain posted until further notice.
No other AIRMETS are currently in effect, although AIRMET Sierra may need to be updated in the morning for mountain obscuration around the Big Island as conditions warrant.

Marine

A strong high pressure system north of the islands will remain in place through the weekend. Strong and gusty trade winds will peak today through Saturday, and then slowly decrease into the new work week as low pressure system weakens the ridge north of the state. A Gale Warning remains in effect through Saturday night for the windier waters and channels around Maui and the Big Island. A Small Craft Advisory is also in effect for all remaining coastal waters for the same time frame. This advisory will likely be extended into Sunday.
The current long period northerly swell will continue to trend downward through the weekend. Some minor bumps are expected from small reinforcing northwest swells. A large, medium period northerly swell will build into the region by the second half of next week.
Along east facing shores a High Surf Advisory remains in effect through Saturday and may need to be extended into Sunday. Rough and choppy surf is expected through the weekend due to these strong trade winds. Surf heights along east facing shores will decrease early next week as trade wind speeds weaken.
Along south facing shores, expect surf to remain small through the forecast period.
Peak monthly tides are forecasted in the early morning hours each day through the 18th. These high tides combined with elevated seas from strong trade winds may increase coastal inundation impacts for vulnerable locations during the morning high tides. This has prompted a Coastal Flood Statement which will continue through early Monday morning.

Fire weather

A drier airmass will persist over the islands through much of today, which will allow late morning and afternoon relative humidity values to fall to around 45% or slightly lower in some leeward areas. Fuels remain dry, and when combined with the windy trades that are expected to continue, a Red Flag Warning is in effect for leeward areas today. There is a low probability for critical fire weather conditions to continue into early Saturday afternoon, however a band of showers expected on Saturday should end fire weather concerns by Saturday evening.

HFO Watches/Warnings/Advisories

Red Flag Warning from 10 AM this morning to 6 PM HST this evening 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.
High Surf Advisory until 6 AM HST Sunday for Olomana, Maui Windward West, Kauai East, Koolau Windward, Molokai Southeast, Windward Haleakala, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Wind Advisory until 6 AM HST Sunday 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.
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, Big Island Windward Waters.
Gale Warning until 6 AM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov