Photo Credit: Braden Jarvis

West Kaua’i

Today: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows 67 to 72 near the shore to around 58 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Thursday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. East winds around 10 mph. Chance of rain 40 percent.

South Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 83. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 65 to 71. Northeast winds around 10 mph. Chance of rain 30 percent.

Thursday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 84. East winds 10 to 15 mph. Chance of rain 30 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 58 to 63 in the valleys to around 53 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 76 to 85. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows 61 to 71. East winds around 10 mph. Chance of rain 40 percent.

Thursday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 86. East winds 10 to 15 mph. Chance of rain 40 percent.

East Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 84. East winds around 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 59 to 73. Northeast winds around 10 mph. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 85. East winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Update

Halemaumau Crater on the Kilauea Volcano Summit erupted at 4:44 AM HST this morning. This eruption was observed on infrared satellite imagery. Radar indicates winds will likely cause any ash emissions to drift towards the west-southwest direction this morning. A Special Weather Statement has been issued to cover the possibility of very light ashfall. We have also added haze (vog) to the forecast through this afternoon for the Puna, Kau and South Kona Districts on the Big Island.

Synopsis

A weak surface ridge north-northeast of the state will maintain light to moderate trade winds, with local sea and land breezes developing across sheltered areas of the islands into Thursday. Trade showers will favor windward facing slopes during the night and early morning hours, with showers forming over some interior and leeward sections each afternoon. Locally breezy trade winds will likely return from late Thursday and Friday into early next week. This will bring a return to a more typical trade wind weather pattern with brief showers focused mainly over windward areas by this weekend.

Discussion

The southern end of a weak surface front, which appears to be about 300 miles north of Lihue, is moving slowly toward the east- southeast. In addition, the western end of a weak surface ridge is about 300 miles north-northeast of Honolulu. The close proximity of these features to the state is keeping the pressure gradient relatively weak over the region early this morning. This is producing light to locally moderate trade winds across the island chain. The background flow have been light enough to allow local land breezes to become established over leeward and interior sections of each island overnight. The trade winds will continue to transport brief light showers into windward facing sections of some of the islands this morning. However, rainfall totals are expected to be meager over most areas due to the rather dry and stable atmospheric conditions.
The forecast guidance indicates the tail end of the front will continue to move slowly toward the east-southeast, and gradually dissipate through Thursday. The weak surface ridge will also remain north-northeast of the region, so the light to moderate trade winds will persist. In addition, dry and stable atmospheric conditions will likely continue. Therefore, expect the pattern of local afternoon sea breezes, followed by nighttime land breezes to dominate the weather pattern into Thursday. This scenario will keep showers focused over windward sections during the nights and early mornings. Then clouds and showers will develop over the interior and leeward sections of the islands each afternoon as the sea breezes become established, followed by clearing over these same areas as land breezes develop at night.
Once the front dissipates around late Thursday, a new surface high will likely build far northwest of the area. This will cause the pressure gradient to tighten across the islands, which will result in the trade winds strengthening from Thursday night into early next week. This will lead to a rather typical trade wind weather pattern with windward and mauka showers. The trade winds may be strong enough to allow a few showers to be transported to leeward sections of some of the smaller islands, especially at night. In addition, expect clouds and spotty showers to develop each afternoon over the upslope sections of the leeward Big Island.

Aviation

A frontal system passing to the north of the state will help keep the pressure gradient weak and generate mainly light trade winds across the islands through the forecast period. Thus, isolated to scattered showers will be mainly confined to windward locations this morning. Brief MVFR conditions may accompany any of the more robust showers.
By early this afternoon, sea breeze development could help initiate scattered showers along the leeward mountains and coasts.
No AIRMETs are currently in effect.

Marine

A cold front passing far north of the region will weaken the high pressure ridge far north of the state. Trade winds will remain in the light to fresh range today, and then strengthen from Thursday onward as high pressure builds back into the region.
Small surf will continue along south facing shores as a mix of background long period south and southwest (170-220 degrees) swells continue into next week.
Surf along exposed north and west facing shores will see an out of season west-northwest (300-310 degrees) swell, from former northwest Pacific Tropical Cyclone Mawar, will fill in later today. This swell will peak on Thursday, hold through Friday and then slowly subside through the weekend.
Surf along east facing shores will remain small into Thursday due to lower trade winds. A slight increasing trend will start Thursday night as trade winds strengthen.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov