Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 70 to 75 near the shore to around 61 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Today: Breezy. Partly sunny with isolated showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 86. East winds 15 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 74. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 85. East winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then frequent showers after midnight. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.

Monday: Mostly cloudy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.

North Kaua’i

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 88. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 74. East winds up to 15 mph. Chance of rain 70 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 87. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 75. East winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 86. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy easterly trade winds will persist through the first half of next week, before strengthening to breezy levels Thursday and Friday, then easing again next weekend. Pockets of moisture will continue to get caught up in the trades through the period, bringing some showery conditions to windward areas at times and sending a few showers into leeward communities as well.

Discussion

Currently at the surface, a trough of low pressure around 475 miles west of Kauai continues to push west at around 10 to 15 mph. Meanwhile, a 1027 mb high around 1200 miles north of Honolulu is shifting eastward at around 15 mph. The trades continue to blow at moderate to locally breezy levels this morning. Infrared satellite imagery shows mostly cloudy conditions over windward Maui and the Big Island, with mostly clear to partly cloudy skies elsewhere. Radar imagery shows scattered showers moving into windward sections of Maui and the Big Island, with nothing more than isolated showers from Molokai westward to Kauai. Main short term focus revolves around trade wind trends and rain chances.
High pressure north of the islands will shift eastward during the next several days, while the trough west of the islands continues westward and further away from the island chain. As a result, only minor fluctuations in trade wind strength are expected through the middle of next week, with trades holding at moderate to locally breezy levels. The trades may strengthen to breezy levels Thursday and Friday as a new strong high builds to the distant north-northwest. A cold front moving southward far to the north of the islands could bring a decrease in the trades next weekend.
As for the remaining weather details, a band of moisture moving into the eastern end of the state will keep some showery trade wind weather in place over windward sections of Maui and the Big Island this morning, with rather dry conditions prevailing over the remainder of the state. The deeper moisture will expand to the rest of the island chain this afternoon and tonight, then linger through Monday. This will keep showery conditions in place for windward areas, with leeward sections of the island seeing more showers as well. A drier more stable airmass should provide more typical trade wind weather Monday night through Wednesday, with showers favoring windward and mauka areas along with the stray leeward spillover. Troughing aloft building southward toward the islands could bring a period of wetter trades once again Thursday through next weekend.

Aviation

Moderate to locally breezy trades will persist today through early this week. Clouds and showers will continue to favor windward and mauka areas during the overnight to early morning hours, but a few showers may make it over to leeward areas at times. VFR conditions will generally prevail across most of the state, but brief MVFR conditions will be possible in any passing showers. However, with increased cloud cover and shower activity, windward portions of the Big Island may see more frequent periods of MVFR conditions this morning.
AIRMET Sierra for tempo mountain obscuration remains in effect for windward portions of the Big Island. These conditions will likely improve by mid morning today.

Marine

A high pressure ridge far north of the Hawaiian Islands will continue to produce moderate to locally strong trade winds. A Small Craft Advisory (SCA) remains in effect through Tuesday afternoon for the typical windier waters around Maui and the Big Island. This SCA will likely continue into next weekend.
A small, long to medium period south (170-180 degree) swell will peak today and produce up to head high surf along south facing shores. This swell energy will slowly decrease on Monday and Tuesday. Another long period south swell will arrive next weekend, boosting surf heights along south facing shores. Moderate trade winds will keep small east chop into next week. No significant swells are expected to reach north and west facing shores for the next seven days.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov