Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Partly sunny with scattered showers. Highs around 86 near the shore to around 74 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 72 near the shore to around 60 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 87 near the shore to around 75 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny with scattered showers. Highs around 83. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 68 to 73. Northeast winds around 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs around 84. Northeast winds around 10 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy with scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 60 to 65 in the valleys to around 55 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 76 to 85. East winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 72. East winds around 10 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers. Highs 77 to 86. East winds up to 10 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 76 to 84. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 61 to 75. Northeast winds around 10 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy with scattered showers. Highs 77 to 85. East winds around 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Expect moderate trade winds to continue through Monday. An upper level low over Maui and the Big Island will produce unstable weather conditions with periods of showers through Saturday night for all islands. The highest rainfall coverage will favor windward and mountain areas with some of the stronger showers drifting into leeward areas. Rainfall trends over the region will also increase during the overnight to early morning hours. Stable conditions will return on Sunday and Monday for the northwest islands with lingering unsettled weather over Maui and the Big Island through Tuesday. Trade winds strengthen into the moderate to breezy range by early next week.

Discussion

An upper level low settling in over Maui and the Big Island this morning is producing unstable conditions, and enhancing rain showers across the region. Expect isolated thunderstorms in this unstable environment mainly near the center and east flank of the upper low, over the Big Island waters, and over the Big Island slopes each afternoon through Saturday.
The high pressure ridge north of the islands will remain on the weaker side due to a combination of an approaching cold front and an upper level low over the region. Moderate trade winds will continue through Monday. The position of the low upstream of the islands will elevate the trade wind inversion heights statewide and allow numerous showers to develop for all islands through Saturday night. The windward Big Island and Maui may see continued periods of enhanced showers as a low level trough (850-700 MB) passes westward into the southeast islands on Monday and Tuesday.
A gradual transition to more stable conditions will start over the northwest islands on Sunday and Monday as the upper low departs to the northeast and a strong high pressure system builds in from the north. The high pressure ridge will build north of the islands from Tuesday through Thursday allowing the trade winds to strengthen into the moderate to breezy range.

Aviation

High pressure north-northeast of the area will maintain moderate trade winds across the state. Expect showers and accompanying MVFR conditions to increase later today, especially for windward and mauka areas. Instability could trigger brief thunderstorms over interior areas of the Big Island. AIRMET Tango remains in effect statewide between FL200 and FL400 due to TEMPO moderate turbulence. No other AIRMETS are in effect now, but AIRMET Sierra may be needed later today for mountain obscuration.

Marine

A southward moving cold front far north of the islands has weakened the surface ridge located far northeast of the state. In addition, an upper-level low is meandering near the Big Island early this morning. The disruption of the pressure gradient across the region due to these features will result in light to moderate trade winds. Therefore, no Small Craft Advisory (SCA) conditions are in the forecast through this weekend. Note that the instability due to the low aloft combined with abundant atmospheric moisture may trigger a few thunderstorms over the waters in the vicinity of the Big Island later today and tonight.
The trade winds will gradually strengthen early next week as a surface high pressure system builds far northeast of the state. The current forecast indicates SCA conditions may return over the typically windier waters adjacent to the islands of Maui County and the Big Island starting next Tuesday.
Relatively small, short-period north swells are expected through this weekend, which will maintain modest surf along most north facing shores. A small, medium-period north-northwest swell arriving Monday will likely provide a slight boost in surf heights along most north and west facing shores of the islands from late Monday into Tuesday. Small, medium-period south swells will continue to produce small surf along south facing shores through early next week. Surf along east facing shores will decline as the trade winds weaken through this weekend.. The strengthening trade winds are expected to provide a slight boost in choppy surf along east facing shores early next week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov