Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny with scattered showers. Highs around 79 near the shore to around 66 above 3000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with scattered showers. Lows around 64 near the shore to around 54 above 3000 feet. Northwest winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny. Windy. Numerous showers in the morning, then occasional showers in the afternoon. Highs around 78 near the shore to around 64 above 3000 feet. Northwest winds 10 to 30 mph. Chance of rain 90 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 76 to 81. West winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows around 63. Northwest winds up to 15 mph. Chance of rain 30 percent.

Thursday: Partly sunny. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 74 to 80. Northwest winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 68 to 74 in the valleys to around 60 above 4000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 56 to 62 in the valleys to around 51 above 4000 feet. Light winds becoming west up to 15 mph after midnight. Chance of rain 50 percent.

Thursday: Mostly cloudy. Breezy. Numerous showers in the morning, then occasional showers in the afternoon. Highs 66 to 72 in the valleys to around 57 above 4000 feet. Northwest winds 10 to 25 mph. Chance of rain 90 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 69 to 79. West winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 57 to 66. West winds up to 10 mph. Chance of rain 50 percent.

Thursday: Partly sunny. Breezy. Numerous showers in the morning, then occasional showers in the afternoon. Highs 68 to 77. Northwest winds 10 to 25 mph. Chance of rain 90 percent.

East Kaua’i

Today: Mostly sunny with scattered showers. Highs 68 to 79. West winds up to 10 mph shifting to the north in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 56 to 68. Northwest winds up to 10 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Breezy. Scattered showers in the morning, then occasional showers in the afternoon. Highs 66 to 77. Northwest winds up to 25 mph. Chance of rain 90 percent.

Detailed Forecast

Synopsis

A weakening front will bring numerous showers to leeward Big Island today, with drier conditions expected across the smaller islands. The next front is forecast to deliver another round of gusty showers Thursday into Friday, with windy and much cooler weather filling in behind the front. Very pleasant conditions will prevail Friday night through Monday, with mainly dry weather statewide. Another round of showers could move through on Tuesday as yet another front approaches the island chain.

Discussion

Currently at the surface, a decaying front is moving into northern sections of the Big Island, while the next cold front is located around 800 miles west-northwest of Kauai. Moderate to locally breezy south winds prevail across the Big Island, with moderate west to southwest winds over the smaller islands. Infrared satellite imagery shows partly to mostly cloudy conditions across the state, with cloud coverage the highest over leeward Kauai and Big Island as well as eastern section of Maui. Radar imagery shows a line of showers approaching and moving into leeward Big Island, with isolated to scattered showers over the remainder of the state. Main short term focus now shifts toward the next cold front and potential impacts.
The front will move into the Big Island and dissipate today, while weak ridging builds in south of the state. West to southwest winds will ease into the light to moderate range over the smaller islands, while the winds shift more west-southwesterly and ease over the Big Island. Winds will begin to ramp up again out of the west late tonight and early Thursday as the next front approaches, then become very windy out of the northwest behind the front as it pushes down the island chain Thursday afternoon and Thursday night. The strong winds will continue through Friday while shifting more northerly, then ease to moderate level Friday night as a weak high settles southward and closer to the state. A Wind Advisory may be required for portions of the state Thursday afternoon and Thursday night, potentially lingering into Friday. The winds will become rather light Saturday through Sunday as the high builds over and eventually south of the state, allowing winds to clock around from northeasterly trades on Saturday to southwesterly winds on Sunday. Light southwesterly winds appear to hold through Monday as a front passes by north of the state, with the southwest winds ramping back up to moderate and breezy levels Tuesday as yet another front takes aim on the Aloha state.
As for the remaining weather details, isolated to scattered showers will continue over the smaller islands today, with the showers favoring leeward areas in the west-southwesterly flow. Over the Big Island, lingering deep moisture along the decaying front will keep showery conditions in place today in leeward areas, and allow for scattered shower development mainly this afternoon in windward locales. Isolated to scattered showers will continue to move into west and southwest slopes and coasts tonight and early Thursday, with a round of gusty showers expected Thursday afternoon and Thursday night as the next front pushes through the state, with some gusty showers continuing to move into northwest slopes and coasts into Friday behind the front. Much cooler weather will fill in behind the front as well with dewpoints lowering into the upper 40s and lower 50s. Very pleasant weather will then hold in place Friday night through Monday as high pressure slowly settles over and eventually south of the state, with mainly dry conditions expected. Showers could then increase in the southwesterly flow in advance of another cold front on Tuesday.

Aviation

A front is forecast to remain nearly stationary over the Big Island this morning and gradually dissipate by this afternoon. Thus, ahead of this front, lines of heavier showers will mainly affect leeward portions of Big Island. These showers may produce MVFR and brief periods of IFR ceilings and visibility. Isolated showers are expected elsewhere across the islands.
As the aforementioned front dissipates, weak to moderate westerly winds will dominate across the island chain.
AIRMET SIERRA for tempo mountain obscuration above 2500 feet remains in effect for Maui County and the Big Island.

Marine

Gentle to moderate westerly winds are expected between cold frontal systems through early Thursday across all Hawaiian waters. By Thursday from late morning to afternoon another cold front will move into the waters surrounding Kauai. This frontal band will swiftly move eastward across the state, shower activity will be focused along the front, reaching the Big Island by late Thursday night. Fresh to strong northerly winds will fill in behind the front as it passes through each island. A strong north to south oriented fetch on the west side of the surface low just north of the state will drive a large mid period north-northwest swell into the islands from Friday through the weekend. Decreasing wind speed trends are forecast from Saturday to Sunday. A Small Craft Advisory (SCA) remains in effect for most Hawaiian waters this evening due to lingering strong winds and high seas. The SCA will retreat to the waters surrounding Kauai and Oahu by Wednesday morning to account for the lingering northwest swell keeping seas above SCA thresholds.
A slowly declining medium period northwest (330 degree) swell continues to produce High Surf Advisory (HSA) level surf for the north and west-facing shores of Niihau, Kauai, and Oahu. The HSA appears to linger at low end advisory levels through Thursday.
On Thursday a gale force low deepening north of Hawaii will produce a north to south fetch aimed directly at the islands. The close proximity of this source will lead to a brief relatively large, medium period northwest swell (310-320 degrees) swell moving into the islands on Thursday. The swell direction will shift more northerly (350-010 degree) direction by Friday as the fetch area drifts slowly eastward with the parent low center. Another longer period northwest (320 degree) swell will overlap this medium period swell boosting surf heights along north and west facing shores above High Surf Warning thresholds from Thursday night through Friday. The surf along north and west facing shores will then decrease to HSA thresholds by Saturday as the swell energy declines. Small surf continues along south and east facing shores through the week.
High tides will peak over the next few days producing minor coastal flooding, however the large north swell run up on top of the winter peak high tides from 3 to 4 AM HST will produce additional impacts along north facing shores through Saturday morning, and the north swell will produce harbor surges in Kahului and Hilo Harbors from Friday through Saturday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Thursday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Kauai North, Kauai East.
Small Craft Advisory from 6 AM this morning to 6 AM HST Thursday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters.

Data Courtesy of NOAA.gov