Photo Credit: Sebastien Gabriel

West Kaua’i

Rest Of Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows around 72 near the shore to around 61 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 88 near the shore to around 75 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Rest Of Today: Mostly cloudy. Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 79 to 87. Northeast winds 15 to 25 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Occasional showers in the evening, then numerous showers after midnight. Lows around 73. Northeast winds 15 to 20 mph. Chance of rain 90 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 80 to 89. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Rest Of Today: Breezy. Occasional showers. Highs 74 to 84 in the valleys to around 64 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

Tonight: Breezy. Occasional showers. Lows 63 to 70 in the valleys to around 60 above 4000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Thursday: Breezy. Mostly cloudy with numerous showers. Highs 74 to 84 in the valleys to around 65 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Rest Of Today: Breezy. Mostly cloudy with occasional showers. Highs 75 to 88. East winds up to 20 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Occasional showers in the evening, then numerous showers after midnight. Lows 65 to 73. East winds 10 to 15 mph. Chance of rain 90 percent.

Thursday: Partly sunny with scattered showers. Highs 76 to 88. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

East Kaua’i

Rest Of Today: Mostly cloudy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 72 to 85. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Occasional showers in the evening, then numerous showers after midnight. Lows 65 to 77. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 72 to 85. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Update

The forecast has been updated in keeping with the latest trends in the high resolution models and the National Blend of Models. This increases the PoPs for the Big Island and Kauai for today, while slightly decreasing the PoPs for the islands of Maui County and Oahu today. Additionally, the HREF rainfall rate suggests some locally heavier showers are possible over windward Big Island tomorrow. That wording has been added to the forecast, but still not expecting any significant issues with these showers.

Synopsis

Expect breezy trade winds to continue today as the high pressure ridge strengthens north of the Hawaiian Islands. Passing showers will be focused over windward and mountain slopes, and favor the overnight to early morning hours. An increase in trade wind showers over the eastern islands later today will spread to the remaining islands Thursday into Friday. Weaker trades with more stable trends are forecast this weekend, followed by another round of wet weather much of next week as a tropical wave, and possible cold front move through the islands.

Aviation

Breezy trades will focus clouds and showers over windward and mauka areas through the forecast period. Brief passing showers are expected through the morning hours. Winds look to gradually decline into the moderate to breezy range today. This will ensure periods of MVFR windward, especially over the western half of the state.
AIRMET Sierra for mountain obscuration has been updated for N thru E sections of Maui, Molokai, Oahu and Kauai.
AIRMET Tango for moderate lee turb remains in effect.

Marine

Fresh to strong easterly trades will continue through Friday, then potentially ease over the weekend as a weakness forms in the ridge to the north. Expect the strongest winds and roughest conditions over the windier waters and channels from Oahu to the Big Island today, where a Small Craft Advisory is posted. The advisory may shift back to the typical windier zones and waters around Maui County and the Big Island from tonight through Friday.
Surf along north-facing shores will remain up at select locations that favor north-northeasterly swells today. Early morning observations at the buoys reflect this potential with a small north-northeast swell lingering in the 10-11 second bands. Guidance shows this holding today, but lowering Thursday into Friday.
An upward trend is expected this weekend due to a storm-force low centered over the far western Bering Sea. Earlier satellite data showed a large swath of storm-force winds aimed at Hawaii within the 310-330 degree directional bands, with altimeter data near the heart of the fetch showing heights of up to 36 ft (a few feet higher than model guidance is depicting). A SOFAR drifter buoy near the head of the fetch also is depicting a slightly underdone model forecast this morning. Expect small, long-period forerunners to arrive around sunset Friday evening from the north- northwest, then building over the weekend with a peak now anticipated on Sunday. Heights could approach advisory levels for exposed north- and west-facing shores during the peak, especially if the swell comes in higher than predicted.
Surf along east-facing shores will remain rough throughout the week due to the strong trades locally and upstream across the eastern Pacific. A downward trend is possible this weekend.
Surf along south-facing shores will remain small, with mainly a mix of short-period southeast and background long-period south swell energy.

Prev discussion

/ISSUED 357 AM HST Wed Oct 30 2024/
This mornings satellite imagery shows a few unsettled cloud bands riding into each island on the trade winds. Periods of light showers are showing up in the local radar imagery, mainly over windward and mountain areas. Upper air balloon soundings this morning at 2 AM HST (12Z) show subsidence temperature inversion heights in the 7,000 to 8,000 foot range. These inversion heights are slightly higher than expected and will support continued periods of showers through the morning hours, mainly along windward and mountain slopes.
Later this afternoon deeper tropical moisture and instability will move into the eastern islands, associated with the remnants of former Hurricane Kristy, affecting the windward slopes of the Big Island. This band of unstable tropical moisture will then spread numerous showers westward across the smaller islands through Friday. There remains a chance for a few heavy showers in this pattern, although not enough to support a Flood Watch at this time.
The forecast for this weekend continues to trend drier and light to moderate trade winds are favored due a weaker high pressure ridge to the north of the state. Lighter large scale winds will allow sea breezes to expand in coverage along western terrain sheltered slopes of each island.
The weather pattern changes towards the wet side early next week, starting on Monday as a easterly tropical wave brings unstable moisture and showers into the islands, enhanced showers will spread from east to west through Tuesday. By Wednesday a weakening cold front moves through the islands from the north. Both the American (GFS) and the European (ECMWF) operational models are in fair agreement with this weather story for the first half of next week.
Longer range forecast changes towards the end of next week are less certain as the GFS shows a strong surface low approaching the islands from the north, while the ECMWF holds a strong ridge north of the state with less rainfall and breezy trade winds.
AVIATION… Breezy trades will focus clouds and showers over windward and mauka areas through the forecast period. Brief passing showers are expected through the morning hours. Winds look to gradually decline into the moderate to breezy range today. This will ensure periods of MVFR windward, especially over the western half of the state.
AIRMET Sierra for mountain obscuration has been updated for N thru E sections of Maui, Molokai, Oahu and Kauai.
AIRMET Tango for moderate lee turb remains in effect.
MARINE… Fresh to strong easterly trades will continue through Friday, then potentially ease over the weekend as a weakness forms in the ridge to the north. Expect the strongest winds and roughest conditions over the windier waters and channels from Oahu to the Big Island today, where a Small Craft Advisory is posted. The advisory may shift back to the typical windier zones and waters around Maui County and the Big Island from tonight through Friday.
Surf along north-facing shores will remain up at select locations that favor north-northeasterly swells today. Early morning observations at the buoys reflect this potential with a small north-northeast swell lingering in the 10-11 second bands. Guidance shows this holding today, but lowering Thursday into Friday.
An upward trend is expected this weekend due to a storm-force low centered over the far western Bering Sea. Earlier satellite data showed a large swath of storm-force winds aimed at Hawaii within the 310-330 degree directional bands, with altimeter data near the heart of the fetch showing heights of up to 36 ft (a few feet higher than model guidance is depicting). A SOFAR drifter buoy near the head of the fetch also is depicting a slightly underdone model forecast this morning. Expect small, long-period forerunners to arrive around sunset Friday evening from the north- northwest, then building over the weekend with a peak now anticipated on Sunday. Heights could approach advisory levels for exposed north- and west-facing shores during the peak, especially if the swell comes in higher than predicted.
Surf along east-facing shores will remain rough throughout the week due to the strong trades locally and upstream across the eastern Pacific. A downward trend is possible this weekend.
Surf along south-facing shores will remain small, with mainly a mix of short-period southeast and background long-period south swell energy.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters.
Small Craft Advisory until 6 AM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov