Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Scattered showers in the morning. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Lows 73 to 78 near the shore to around 64 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight.

Friday: Mostly sunny. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 15 mph.

South Kaua’i

Today: Partly sunny. Breezy. Scattered showers in the morning. Highs around 88. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows 71 to 77. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny. Isolated showers in the morning. Highs around 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Frequent showers early in the morning, then scattered showers late in the morning. Isolated showers in the afternoon. Highs 78 to 85 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 69 in the valleys to around 59 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 85 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny. Numerous showers early in the morning, then isolated showers in the late morning and afternoon. Highs 81 to 90. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with isolated showers. Lows 67 to 77. Southeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny with isolated showers. Highs 81 to 90. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny. Numerous showers early in the morning, then isolated showers in the late morning and afternoon. Highs 81 to 89. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with isolated showers. Lows 65 to 78. Northeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny with isolated showers. Highs 81 to 89. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy easterly trades will continue through Friday, then ease slightly over the weekend as the ridge to the north weakens and an upper disturbance moves over the region. Expect mostly dry conditions to prevail, with the best chance for showers overnight through the mornings across windward and mauka locations. A slight increase in windward shower coverage will be possible this weekend as the upper disturbance moves over the state.

Discussion

Guidance remains in good agreement and depicts the breezy easterly trades holding into Friday as high pressure remains anchored north-northeast of the area. Outside of a few pockets of low-level moisture moving through periodically enhancing overnight shower coverage, expect the stable and dry conditions to prevail. Most of the showers that do form will remain confined to windward/mauka locations, with very few expected to make it over our parched leeward locations. The exception will be over the typical leeward areas of the Big Island through the afternoon hours, where sea breezes may be enough to trigger a few showers.
A subtle transition is anticipated this weekend in response to a mid-to-upper trough moving into the area. This combined with a weakness forming within the surface ridge to the north will potentially support better windward shower coverage and lighter trades. A slight increase in the inversion height could allow a few of these showers to spread into leeward areas of the smaller islands during the overnight periods. Guidance depicts this pattern persisting into early next week, followed by a return of drier air associated with rising upper heights and breezy trades Tuesday through midweek.

Aviation

Breezy trade winds will continue through the next 24 hours. Doppler radar continues to show scattered showers moving into the windward portions of the Hawaiian Islands early this morning, with a few isolated showers making it over the mountain ridges into some leeward locations. Lower clouds and showers will continue to favor windward and mauka areas, particularly during the overnight to early morning hours. Expect mainly VFR conditions with brief MVFR conditions possible under passing showers.
AIRMET Tango will likely remain in effect for moderate lee turbulence through Friday. The potential for low-level turbulence will lower over the weekend as the trades weaken slightly.

Marine

High pressure north-northeast of the state will keep fresh to locally strong trade winds blowing through Friday, and a Small Craft Advisory (SCA) remains in effect for the typically windy waters around Maui and the Big Island. The trades may ease just below SCA thresholds Saturday through Monday as the high north- northeast of the state weakens. Long range guidance shows the high strengthening to the distant northeast Tuesday through the middle of next week, ramping trades back up into the fresh to locally strong range once again.
A medium period east swell generated by former tropical cyclone Hilary continues to move through islands early this morning, with energy centered around the 13 second band. This swell will gradually fade today through Friday, but when combined with the easterly trade wind swell, east shore surf should hold near or just below the summertime average. The easing trades over the weekend through Monday will lower surf along east facing shores below normal levels. East shore surf will then trend back up closer to the summertime average by the middle of next week as the trades strengthen once again.
Surf along south facing shores will remain small through Monday, with mainly background southerly swells moving through. A slight bump in south shore surf is possible Tuesday through the middle of next week, as a small medium period south swell moves through.
North shore surf will remain flat through the weekend. A small medium period northwest swell could give surf along north and west facing shores a slight boost Monday and Tuesday, before fading out during the middle of next week.

Fire weather

There remains an elevated fire danger threat today due to a combination of the very dry fuels and breezy trades. Although the winds are not expected to exceed the critical levels required for a warning, any fire that starts could become difficult to control. The threat should lower Friday through Monday as the winds ease slightly.

HFO Watches/Warnings/Advisories

Small Craft Advisory 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