Photo Credit: Brendan Stephen

West Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 83 near the shore to around 69 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy after midnight. Lows around 65 near the shore to around 56 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Partly sunny. Breezy. Highs around 84 near the shore to around 71 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

South Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 83. East winds 15 to 25 mph. Chance of rain 70 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows around 66. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Sunday: Partly sunny. Breezy. Scattered showers in the morning. Highs 77 to 83. East winds 15 to 20 mph. Chance of rain 30 percent.

Kaua’i Mountains

Today: Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 70 to 78 in the valleys to around 60 above 4000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows 58 to 64 in the valleys to around 53 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 83. East winds up to 20 mph. Chance of rain 90 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 59 to 69. East winds up to 20 mph. Chance of rain 50 percent.

Sunday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 73 to 83. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 30 percent.

East Kaua’i

Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 68 to 79. East winds 10 to 20 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 70. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 70 to 80. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy northeast trade winds will continue through next week focusing clouds and showers over windward and mauka areas, periodically reaching leeward areas.

Discussion

Water vapor imagery shows an upper level trough axis across the eastern part of the state with an upper level low developing southwest of the state. Meanwhile, a 1033 mb surface high centered around 900 miles to the northeast is driving breezy trade winds across the islands. Radar shows mostly light to moderate showers with a few heavier showers embedded moving mainly over the smaller islands. While the focus of these showers is along windward and mauka area, some showers are reaching leeward sides of the smaller islands due to the breezy winds.
The upper trough will slide east of the state while an the upper level low remains nearly stationary southwest of the state. The surface high will continue to strengthen slightly allowing wind speeds to gradually increase through today. A wind advisory has been issued for Big Island summits and some lower elevations regions near ridges and passes of the Kohala district and South Point Kau District through Sunday. Although a drying trend is expected through Sunday, the upper level low will aid in advecting moisture in the mid and high levels, increasing mid to high level cloud and possibly shower coverage over the state beginning with the Big Island today then reaching Kauai Monday and lingering through much of next week. Low clouds and showers will continue to track across the islands with the breezy winds, focusing along windward and mauka and occurring during the overnight and early morning hours. Leeward sides will also continue to see period showers at times.
The strong high pressure to the north will slowly drift east and weaken Tuesday, but will quickly be replaced by another high by Wednesday. Thus breezy trades will continue through much of next week, easing briefly Tuesday. Showers will continue to focus along windward and mauka areas with a few showers reaching leeward areas, especially early to mid week as moisture levels increase.

Aviation

High pressure to the northeast, with an associated ridge north of the state will maintain breezy trade winds through the weekend. Showers are expected to remain focused over windward and mountain areas in the trade wind flow. Brief MVFR conditions are possible in clouds and showers, mainly during the overnight and early morning hours.
AIRMET TANGO remains in effect for mechanical low-level turbulence over and downslope of the mountains. Expect this to remain in place through the weekend.
AIRMET SIERRA was recently issued for the east facing slopes of the Big Island as an area of clouds and showers has moved in. Anticipating conditions will improve later this morning, but additional clouds and showers could lead to additional AIRMETs.

Marine

Surface high pressure northeast of the state will gradually strengthen over the next couple of days, resulting in persistent strong trade winds this weekend. A brief decrease of winds is possible early next week, but another high will quickly build north of the state by the middle of next week. Trade winds should restrengthen by the middle of next week with strong to near gales expected during the second half of the week. A Small Craft Advisory remains in effect for all Hawaiian waters through Sunday afternoon.
A moderate long period northwest swell should steadily fill in across the smaller islands this morning and peak during the day today. Based on the latest buoy readings from buoy 51001 and 51101 northwest of Kauai, surf heights are expected to remain below High Surf Advisory (HSA) thresholds along north and west facing shores. However, a larger west-northwest to northwest swell will arrive Sunday, and will likely result in HSA level surf for exposed shores Sunday night into Monday. Due to the westerly component of this swell, surf heights may approach HSA thresholds for west facing shores of the Big Island on Monday.
Short period easterly wind wave swell will trend upward this weekend as trade winds gradually increase. As the trades strengthen even further later next week, we should see another uptick along east facing shores the second half of next week. South- facing shore surf will remain at background levels for the next several days.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST Sunday for Kohala, Big Island Interior, Big Island Summits, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST Sunday for all Hawaiian waters,

Data Courtesy of NOAA.gov