Photo Credit: Tyler Rooke

West Side

Today: Scattered showers, mainly after 1pm. Mostly sunny, with a high near 84. South wind around 5 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before 1am. Mostly cloudy, with a low around 66. South southwest wind around 5 mph becoming light and variable in the evening. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers, mainly after 1pm. Mostly sunny, with a high near 85. Light and variable wind becoming west northwest 5 to 7 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

South Side

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 84. West wind 3 to 6 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before midnight. Partly cloudy, with a low around 63. Light and variable wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers after noon. Mostly sunny, with a high near 83. West wind 3 to 5 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

North Shore

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 82. Light east northeast wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before midnight. Partly cloudy, with a low around 64. Light east wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Sunny, with a high near 80. East northeast wind 6 to 8 mph.

Central Maui

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 82. Light and variable wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before midnight. Partly cloudy, with a low around 62. Light north northwest wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Isolated showers after noon. Mostly sunny, with a high near 81. North wind 3 to 7 mph. Chance of precipitation is 20%.

Upcountry

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 68. Southwest wind 6 to 10 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 52. South wind 3 to 5 mph. Chance of precipitation is 20%.

Thursday: Scattered showers after noon. Mostly sunny, with a high near 68. West wind 3 to 7 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

East Maui

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 80. Breezy, with a southeast wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 60. East southeast wind 11 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.

Thursday: Mostly sunny, with a high near 78. East southeast wind around 11 mph.

Lanai City

Today: Scattered showers. Partly sunny, with a high near 77. Breezy, with a south southwest wind around 17 mph, with gusts as high as 24 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. South southwest wind 6 to 11 mph becoming light and variable after midnight. Chance of precipitation is 50%. New precipitation amounts between a quarter and half of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 78. Northwest wind 3 to 6 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Kaunakakai

Today: Scattered showers. Partly sunny, with a high near 80. South wind around 10 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 66. South southeast wind around 5 mph becoming light and variable after midnight. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Mostly sunny, with a high near 80. West southwest wind 3 to 5 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

Winds have weakened and turned southerly ahead of an approaching cold front northwest of Kauai. Expect increasing showers to form along a cloud band, impacting mainly Oahu and Kauai through Thursday. The rest of the state will see passing showers with embedded brief downpours, mixed with periods of benign weather and clear skies.

Discussion

A front about 150 miles northwest of Kauai has turned island winds from the south. Convergence in the southerly flow has created a band of overcast skies over the Kauai Channel with scattered showers mainly impacting western Oahu. Small movement of this band to the east would bring large changes in the weather for Oahu in the form of clouds and widespread rain. The forecast for today increases showers over Oahu, with a focus on the western locations on the island. The Big Island Puna and Kau districts will see quick hitting showers through the morning as they ride the southeast flow into the Mauna Loa slopes. Some increased convection is expected on the Big Island lower slopes this afternoon with the potential for an isolated thunderstorm or two.
Satellite estimated precipitable water (PW) from CIMSS shows increasing PW moving over the eastern half of the state and reaching toward Oahu. This moisture paired with the low level convergence, and slight instability aloft should bring increasing rainfall along the convergence band. High resolution models depict this convergence band remaining in the vicinity of Oahu through Thursday as the front weakens to a trough as it reaches Kauai. Expect organized showers to form along the convergence band near Oahu, while the rest of the state sees scattered showers with embedded downpours. Away from the band there will also be plenty of periods of benign weather and clear skies.
Friday, high pressure to the northeast is expected to build in trade winds from east to west across the state. Current model solutions place a remnant trough near Oahu Thursday night that will push westward with the trades Friday. This scenario would bring increasing showers to Kauai, while the rest of the state transitions to a trade wind regime. Over the weekend, expect breezy trade winds and mainly windward showers.

Aviation

Light winds, ahead of a front approaching the islands from the northwest, will veer to southerly and southwesterly during the forecast period. This will focus clouds and showers over southern and mauka areas where isolated instances of MVFR are possible. Isolated thunderstorms are possible across the Big Island interior this afternoon. A prefrontal band of showery low clouds lies between Oahu and Kauai this morning. More organized shower activity and a greater probability of MVFR can be expected for the western islands through today.
No AIRMETs are in effect now, but may be needed later this morning as the showery cloud band in the Kauai Channel becomes more active and affects the nearby islands.

Marine

A cold front approaching will move over the Kauai and Oahu waters tonight into Thursday, then stall and diminish by Thursday night. Winds will vary from the south-southwest direction over the Kauai and Oahu waters to south-southeast over the Maui County and Big Island waters out ahead of the front. Pockets of fresh breezes can be expected within the southeast flow near South Point of the Big Island and over the Big Island windward waters along the Hamakua coast. Light and variable winds will be possible over the Kauai and Oahu waters tonight through Thursday as the front moves into the area. In addition to the winds, shower coverage along and ahead of the front will increase through the day, especially over the western end of the state (few storms can’t be ruled out today across the Kauai/Oahu waters). Fresh to locally strong easterly trade winds are expected to return Friday through the weekend as the trough shifts west of the area and the ridge builds to the north.
Surf along exposed north and west facing shores will trend up today and hold through Thursday as a moderate northwest (320 deg) swell builds down the island chain. Overnight observations from the offshore and nearshore buoys reflect this new energy increasing within the 14 to 15 second bands. Surf will near advisory levels at its peak this afternoon through Thursday for the smaller islands, then ease over the weekend. For the long range, guidance depicts a broad gale developing and lifting northward over the far northwest Pacific near the Kurils this weekend, which could send a small, long-period west-northwest swell into the area by Wednesday of next week (low confidence).
Surf along east facing shores will remain up just below the advisory level through Thursday due to a background easterly trade wind swell from a large area of fresh breezes upstream of the islands. A downward trend will be possible over the weekend.
Surf along south facing shores will trend up through the second half of the week and into the weekend as overlapping, long-period south- southwest swells move through from recent activity across the southern Pacific within Hawaii’s swell window.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov