Photo Credit: Sebastien Gabriel

West Kaua’i

Rest Of Today: Mostly sunny with isolated showers. Highs around 83 near the shore to around 71 above 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 70 near the shore to around 59 above 3000 feet. East winds around 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Locally heavy rainfall possible in the afternoon. Highs around 84 near the shore to around 72 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Rest Of Today: Partly sunny with scattered showers. Highs around 80. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Highs around 81. East winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Rest Of Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 70 to 77 in the valleys to around 61 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 64 in the valleys to around 52 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Rest Of Today: Partly sunny with scattered showers. Highs 73 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 70. East winds around 10 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Locally heavy rainfall possible in the afternoon. Highs 74 to 84. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Rest Of Today: Partly sunny with scattered showers. Highs 73 to 82. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 72. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Highs 74 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate trades will focus isolated heavy showers over windward and mauka areas through the week. Afternoon showers will be common over portions of Leeward Maui and the Big Island each afternoon. Moderate trades will focus periodic showers over windward areas through the week.

Discussion

Have made a few changes through tomorrow. Winds have been trended up a bit based on the National Blend of Models (NBM), which helps to account for the high resolution models in the near term. PoPs have been lowered in some locations based in part to the high resolution models and the NBM. Based on the HREF data and the lack of a trade wind inversion, some areas of locally heavy rainfall have been added to the forecast. This is in line with our philosophy, so no major changes there.
High clouds have cleared the Big Island early this morning, but there still could be some high clouds passing overhead from time to time. The upper level trough to the north of the islands is expected to linger into the weekend, maintaining the upper level wind flow out of the southwest over the islands. The presence of this upper trough will help to prevent a trade wind inversion from setting back up, even though at the surface, trade winds will continue through the week. Precipitable water levels on the high end of normal will help to maintain shower activity, but the lack of a trade wind inversion means some of those showers could be a little heavier than normal. Models are in general agreement that the higher inversions will be over Maui County and the Big Island, so they are a little more likely to see some of those heavier showers. As mentioned above, have used HREF guidance to add mention of some locally heavy rainfall to the forecast. Those heavier showers are more likely to form during the afternoon hours and could impact leeward areas.
Heading into the weekend, the GFS and ECMWF develop a new upper level low along the trough to the northwest of the islands as a weakening front approaches from the northwest. Both of these models bring a much stronger upper level trough over the islands during the first few days of the new week. This will continue the lack of a trade wind inversion for the foreseeable future.

Aviation

Light to locally moderate trade winds will continue through twenty-four hours and beyond. Clouds and showers will generally favor windward coasts and slopes, especially in the late night and morning hours. In the afternoons, sea breezes will tend to focus shower activity over island interiors.
The airmass over the state remains moderately unstable, the result of a nearby trough of low pressure aloft. This will enhance afternoon shower development and intensity. Locally heavy downpours possible over island interiors today, especially the higher elevations of the Big Island.
Areas of mid to upper level layered clouds can be seen on late night IR satellite imagery. They are associated with the sub- tropical jet and will likely persist over the eastern half of the sate through at least midday. Occasional light rime icing above 13 kft can be expected in these higher layers.
No AIRMETs are in effect or anticipated at this time.

Marine

A high pressure ridge far north of the Hawaiian Islands will continue to produce moderate to locally fresh trade winds through the weekend. Wind speeds will likely remain below Small Craft Advisory thresholds for all coastal waters and channels through Sunday.
The current south-southwest (190-210 degree) swell will slowly decrease through Thursday. Another long period south-southwest (200-220 degree) swell will arrive by Saturday with small surf expected along south facing shores through the weekend and then slowly decreasing early next week.
Very small surf will continue along north and west facing shores through next week Tuesday. A small medium period northwest (320 degree) swell will build in by the middle of next week, associated with the remnants of Typhoon Mawar, producing fun sized waves along north and west facing shores.
East facing shores will remain small and choppy into the middle of next week due to the moderate trade winds blowing across the region.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov