Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to around 70 above 3000 feet. East winds 10 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Scattered showers after midnight. Lows around 68 near the shore to around 57 above 3000 feet. East winds 10 to 25 mph with gusts to 50 mph. Chance of rain 40 percent.

Friday: Breezy. Mostly sunny with isolated showers. Highs around 81 near the shore to around 69 above 3000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 81. Northeast winds 20 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 69. East winds 20 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs around 80. East winds 20 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Windy. Partly sunny with scattered showers. Highs 69 to 77 in the valleys to around 64 above 4000 feet. East winds 15 to 30 mph. Chance of rain 50 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows 57 to 62 in the valleys to around 51 above 4000 feet. East winds 15 to 30 mph. Chance of rain 50 percent.

Friday: Mostly cloudy. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 68 to 76 in the valleys to around 63 above 4000 feet. East winds 20 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 74 to 81. East winds 15 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 60 to 69. East winds 10 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 73 to 80. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 74 to 81. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 58 to 70. East winds 15 to 25 mph. Chance of rain 50 percent.

Friday: Partly sunny. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 80. East winds 15 to 30 mph. Chance of rain 60 percent.

Detailed Forecast

Synopsis

A strong high pressure system passing north of the state will continue to produce windy conditions across the region through Friday. Breezy and gusty trade winds will continue through the weekend with a slight decrease in wind speeds. Periods of passing showers will mainly affect windward and mountain areas favoring overnight to early morning hours. East Maui and the Big Island will likely see the highest rainfall coverage. Two weak upper lows deepen over the state by early next week with shower activity remaining in the long range forecast.

Discussion

A strong high pressure system passing north of the Hawaiian Islands will continue to produce windy conditions with strong wind gusts across the region through Friday. Surface wind observations have shown sustained winds in some areas up to 40 mph with wind gusts as high as 65 mph. The strongest winds are currently blowing over the Kohala Mountains and Waimea areas on the Big Island where a High Wind Warning remains in effect. Most areas across the rest of the state will see Wind Advisory level conditions lasting through Friday afternoon. Strong and gusty trade winds may last into Saturday causing an extension in time for these Wind Advisory conditions.
The satellite imagery this morning shows bands of clouds moving from east to west across the state. Periods of showers are expected through the early morning hours, with decreasing shower trends in the afternoon. Strong trade winds will continue to lift Pacific moisture over the mountain slopes of each island through the weekend. Shower activity will favor the typical overnight to early morning hours with less coverage expected over the drier leeward sections of the island chain.
By early next week, the high pressure system northeast of the islands will lift north as two weak upper level low slowly deepen over the state. Trade wind speeds will decrease back into the moderate to breezy range from Monday onward. Long range forecast guidance continues to hint at wet weather solutions for most windward areas through much of next week. Rainfall amounts and thunderstorm potential will be highly dependent upon where these upper lows set up relative to each island and it remains too early to forecast island by island impacts. Stay tuned for weather updates as the forecast time period grows shorter.

Aviation

Strong and gusty trade winds will persist through Friday allowing for passing showers. The highest shower activity will occur during the overnight to early morning hours over windward and mountain areas.
AIRMET Tango for moderate to isolated severe low level turbulence over and downwind of terrain will remain in place. Brief MVFR conditions may occur in passing showers over windward areas, but otherwise VFR conditions will prevail.

Marine

Strong- to gale-force easterly trade winds will continue through the second half of the week as high pressure passes to the north. Gales are most likely over the typically windier waters and channels from Oahu to the Big Island. Seas have responded and expected to top out in the 10 to 15 ft range today through Friday. Although winds and seas should drop slightly over the upcoming weekend as a weakness in the ridge develops far north- northwest of the area, rough boating conditions will continue with Small Craft Advisory conditions expected for all waters.
Surf along north and west facing shores will briefly lower this morning as the swell that peaked over the past couple of days moves out. Recent observations reflect this at the nearshore and offshore buoys with the peak swell energy now down into the 12-13 second bands. As this swell moves out, a fresh north- northwest swell from a gale that developed west of the Date Line early this week will arrive and build down the island chain later today. Forerunners within the 19-21+ second bands have just started showing early this morning. This swell will peak by tonight, hold into Friday, then ease quickly into the weekend. A small long-period northwest swell from a hurricane-force low centered around 1900 nautical miles to the northwest is expected to fill in late Saturday and linger through the weekend.
Surf along east facing shores will quickly ramp up today as the strong trades expand over the state and upstream over the eastern Pacific. This will result in advisory-level surf for most easterly exposures through Friday.

HFO Watches/Warnings/Advisories

High Wind Warning until 6 PM HST Friday for Kohala, Big Island North.
Wind Advisory until 6 PM HST Friday for most of the Hawaiian Islands.
Gale Warning until 6 PM HST Friday for Kaiwi Channel, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST Friday for most Hawaiian coastal waters.
High Surf Advisory until 6 AM HST Saturday for east facing shores.

Data Courtesy of NOAA.gov