West Side

Today: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Haze through the day. Highs around 78. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Haze. Lows 65 to 71. Light winds.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 79. North winds up to 10 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny in the morning then becoming partly sunny. Haze. Highs around 83. Light winds becoming southwest up to 10 mph in the afternoon.

Tonight: Partly cloudy. Haze. Lows 65 to 74. Light winds.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 83. Light winds becoming north 10 to 15 mph in the afternoon. Chance of rain 20 percent.

North Shore

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs around 79 near the shore to around 65 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Haze through the night. Lows around 69 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs around 80 near the shore to around 65 near 5000 feet. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Central Maui

Today: Mostly sunny in the morning then becoming partly sunny. Haze. Highs 79 to 84. Light winds.

Tonight: Partly cloudy. Haze. Lows around 67. Light winds.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 79 to 84. North winds up to 10 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 61 at the visitor center to around 70 at the summit. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Haze in the late evening and overnight. Lows around 46 at the visitor center to around 48 at the summit. Light winds.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs around 60 at the visitor center to around 58 at the summit. Northwest winds up to 10 mph. Chance of rain 20 percent.

East Maui

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs around 79 near the shore to around 65 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Haze through the night. Lows around 69 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs around 80 near the shore to around 65 near 5000 feet. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Lanai City

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs 70 to 77. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Haze through the night. Lows around 64. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 71 to 78. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Haze. Highs 68 to 83. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Haze through the night. Lows 56 to 71. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs 68 to 84. North winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A surface ridge will maintain light winds with land and sea breezes in most areas through tonight. Isolated showers will affect mainly coastal areas this morning, with a few showers also developing over the island interiors this afternoon. A weakening front is forecast to increase showers late tonight across Kauai, with the showers spreading southeastward to the other islands Friday through Saturday, with moderate to fresh north to northeast winds building in behind the front. Another stronger front is forecast to approach later in the weekend, bringing breezy southwesterly winds late Sunday through Monday. A band of heavier showers is expected to accompany the front as it moves through the islands late Monday through Tuesday, followed by breezy northwesterly winds.

Discussion

Currently at the surface, a 1027 mb high is centered to the distant northeast, with a ridge axis extending southwestward through the central islands. Meanwhile, a cold front is located about 170 miles northwest of Kauai. Light winds prevail across the state with land breezes present in most areas. Infrared satellite imagery shows a band of scattered to broken clouds over Oahu and Maui County, with mostly clear to partly cloudy conditions over Kauai and the Big Island. Dry conditions persist, with radar imagery showing a few very light showers or sprinkles drifting onshore along the immediate coasts of Oahu and Maui County. The main short term focus continued to revolve around an incoming front and its impacts on the islands late tonight through Saturday.
The ridge of high pressure over the central islands will shift slowly southeastward during the next day or so as a cold front approaches from the northwest. This will keep light winds in place across the state, with land and sea breezes present in most areas. Shower activity should remain minimal and light, with most showers remaining offshore or near the immediate coast this morning. Some deeper moisture will move in ahead of the front this afternoon, and this should allow for the development of a few more showers than what was seen yesterday over the island interiors, but once again rainfall amounts should be minimal.
Model guidance remains in good agreement showing a cold front moving into Kauai after midnight tonight, then decaying as it shifts southeastward through Oahu and into Maui County on Friday, before stalling out and gradually dissipating in the vicinity of Maui and the Big Island Friday night and Saturday. The front will bring an increase in clouds and showers as it moves through, followed by a period of moderate to fresh north to northeast winds. The best forcing will remain well to the north of the state as the front moves through, so we don't anticipate any significant rainfall or flooding concerns with this feature.
The remnant moisture from the old front is expected to gradually lift back north of the islands Saturday night and Sunday, as yet another front approaches from the northwest. This front appears stronger, with moderate to breezy southwesterly winds developing in advance of the feature late Sunday through Monday. The front appears to move through the state late Monday through Tuesday, accompanied by a line of heavier showers with potentially gusty winds, followed by breezy northwesterly winds.

Aviation

Light southeasterly background flow will give way to land and sea breeze pattern through this evening. This will provide the potential for low ceilings and interior clouds during the afternoon. An incoming weak front from the northwest will approach this evening and is expected to bring an increase in showers over Kauai late tonight and spread southeastward to the other islands by Friday. MVFR and lower ceilings are expected along the front over windward and northern terrain of Kauai and Oahu. Breezy north to northeast winds are expected behind the front. VFR conditions are expected to prevail before the frontal passage.
No AIRMETS are currently in effect.

Marine

A weak ridge over the islands today will keep light and variable winds in the forecast with near shore sea breezes during the day and land breezes overnight. A weak cold front moving in from the northwest on Friday will increase cloud cover and shower trends as it slowly drifts down the island chain through Saturday. Moderate to fresh northerly to northeasterly winds will gradually fill in behind the front as it passes each island. Light and variable winds return to Hawaiian waters Saturday night and early Sunday, with moderate to locally strong southwesterly winds developing ahead of the next cold frontal system approaching from the northwest late Sunday through Monday. This next cold front which will move into the islands from late Monday night into Tuesday appears stronger than the previous system, increasing chances for showers. Fresh to locally strong northwesterly winds will build in behind the front as it passes.
Two significant northwest (300-320 degree) swells are expected to impact the state over the next several days, originating from a broad and complex low that evolved over the far northwest Pacific over the past few days. The first moderate to large long period northwest (300-320 degree) swell will build down the island chain through the day today, while an overlapping stronger long period northwest (300-320 degree) swell will build in on Friday. The rising northwest swell today will build combined seas above our 10 foot Small Craft Advisory (SCA) thresholds for most of the coastal waters around Kauai and Oahu exposed to this northwest swell energy, and an SCA was issued for these affected waters. This swell energy will also produce High Surf Advisory (HSA) conditions today for north and west facing shores of Niihau, Kauai and Oahu. A HSA was issued this morning to cover the rapidly rising surf heights for these exposed shorelines. This will be a long duration event, with a peak centered around the Friday through Saturday time period. The rising swell will swiftly exceed warning levels from late Friday through Saturday for the same northwest islands, expect the HSA to expand in coverage to the islands of Molokai, Maui and west facing shores of the Big Island by Friday. This swell will then decline early next week before an even larger, extra large northwest (310-330 degree) swell arrives in the islands from Tuesday onward.
Impacts associated with the warning-level surf Friday through Saturday will likely lead to minor water inundation over vulnerable low lying roadways and infrastructure. This likelihood will especially increase if the peak surf coincides with the overnight high tide cycle from Friday night to Saturday morning.
Surf along east-facing shores will remain small due to the lack of trades locally and upstream of the state.
Surf along south-facing shores will gradually decline today as a small, long-period south-southwest swell gradually declines.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Friday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Kauai North.
Small Craft Advisory until 6 PM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters.

Data Courtesy of NOAA.gov