Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny with isolated showers. Highs 75 to 83 near the shore to around 67 above 3000 feet. Northwest winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows 60 to 65 near the shore to around 53 above 3000 feet. North winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 83 near the shore to around 69 above 3000 feet. Northeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 30 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 75 to 82. Northwest winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 62. North winds around 10 mph. Chance of rain 20 percent.

Sunday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 82. Northeast winds up to 10 mph. Chance of rain 30 percent.

Kaua’i Mountains

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 68 to 75 in the valleys to around 60 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 53 to 62 in the valleys to around 51 above 4000 feet. North winds up to 10 mph. Chance of rain 30 percent.

Sunday: Partly sunny with scattered showers. Highs 68 to 75 in the valleys to around 61 above 4000 feet. North winds up to 15 mph. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 69 to 77. Northwest winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 56 to 65. Northwest winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 78. North winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 40 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 69 to 80. West winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 55 to 67. North winds around 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 69 to 80. North winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Residual moisture around a diminishing front in the vicinity of the central islands this morning has aided continued showers passing into leeward Maui County. A post-frontal drier pattern will commence statewide this weekend as northwesterly winds gradually veer more northerly. A typical trade wind regime is anticipated to return by Monday. Showers will favor more windward exposures and mauka slopes through the middle of next week. However, late week trades will weaken in response to a passing trough from the west.

Discussion

Latest satellite imagery continues to show a wave of showers persistently streaming in across the more leeward areas of Moloka'i and Maui from a diminishing front over the eastern half of the state. These areas has been monitored closely for flood advisories, but fortunately these showers have been progressively moving east as to preclude any localized flooding. Over a quarter of an inch of precipitation has fallen at Kahului Airport and Mahinahina, with just over three-quarters of an inch at Puu Kukui on Maui the last few hours. Showers are expected to continue through the morning hours before moving southeastward into Big Island. Elsewhere, conditions are relatively dry under this northwesterly flow pattern behind the front. Winds have significantly decreased over the summits of Mauna Kea and Mauna Loa, as well as Haleakala. Latest observations show sustained winds over Mauna Kea to have eased to below 20 mph with gusts below 30 mph. This has prompted the expiration of both the High Wind Warning and High Wind Advisory over the Big Island summits and Haleakala, respectively.
Behind the dissipating front, a more stable air mass and better established breezy northwesterlies will be the primary factor in determining today's precipitation. As winds veer more northerly through the afternoon, higher rain chances will stick on the windward northern exposures of the more eastern islands. Trades return on Monday courtesy of an area of Central Pacific high pressure building in from the west. Latest model guidance has hinted at the passage of a mid-level trough and associated weak surface front moving north of the islands Thursday. There remains a few discrepancies within the models with regards to timing, but they do indicate that there will be a brief disruption in late week trades. Other than winds becoming more light and variable, with a more pronounced land and sea breezes, there will be no significant weather associated with this weak frontal passage.

Aviation

A band of clouds and showers associated with a diminishing front will continue to impact portions of Maui County early this morning, then portions of the Big Island through the day as it drifts eastward. Showers will mostly favor SW thru N facing slopes, with the low-level flow gradually veering from the WSW to the N through the day. Elsewhere, expect VFR conditions through the day as drier air continues to fill in from W to E behind the front.
AIRMET Sierra for tempo mountain obscuration is in effect for SW thru N facing slopes of Maui County, which may persist through a good portion of the early morning before improving.

Marine

A strong low passing to the north of the state will continue its slow northeastward march. Its associated cold front is presently passing over Molokai and is expected to reach the Big Island this later today then move east of Hawaiian waters on Sunday. The air mass ahead of the front is moist and unstable. Radar indicates a band of moderate, possibly heavy, showers immediately preceding the front.
High pressure will build in northwest of the islands on Monday. Northerly winds will usher in drier, more stable air. Light trade wind flow will return later in the week.
The dominant north (010) swell has subsided, but multiple northwest and west swells will continue to impact the state through the remainder of the weekend. The Small Craft Advisory (SCA) for seas has been been extended for those marine zones directly exposed to north or northwest swells, but cancelled elsewhere.
The High Surf Advisory (HSA) for north facing shores of Niihau, Kauai, Oahu, Molokai, and Maui has been cancelled. Based on near shore buoy reports, surf heights fallen below advisory criteria. Locally generated wind waves out of the south and west will keep surf rough along west and southwest shores today.
A new north swell is expected to build in during the day Sunday. This swell could could generate advisory level surf Sunday night or Monday morning. The next northwest swell should arrive on Monday, peak on Tuesday, and linger through Wednesday, but should not produce high surf.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters.

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