Photo Credit: Pamela Goguen Lynch

West Side

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs 79 to 86. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 65 to 72. East winds up to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny. Isolated showers early in the morning, then scattered showers in the late morning and afternoon. Highs 79 to 86. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 40 percent.

South Side

Today: Mostly sunny. Highs 83 to 88. Northwest winds up to 15 mph.

Tonight: Mostly clear. Lows around 66. North winds up to 15 mph.

Friday: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 83 to 88. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs 78 to 84 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to around 49 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 78 to 84 near the shore to around 65 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Partly sunny early in the morning then becoming mostly sunny. Breezy. Isolated showers in the morning. Highs around 86. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 64 to 69. East winds up to 15 mph shifting to the southwest after midnight. Chance of rain 20 percent.

Friday: Partly sunny with isolated showers. Highs around 86. Northeast winds up to 10 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs around 61 at the visitor center to around 58 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows around 45 at the visitor center to around 40 at the summit. East winds up to 10 mph. Chance of rain 50 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 61 at the visitor center to around 58 at the summit. East winds up to 10 mph in the morning becoming light. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs 78 to 84 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69 near the shore to around 49 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers. Highs 78 to 84 near the shore to around 65 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 72 to 81. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 64. Northeast winds up to 10 mph.

Friday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 72 to 81. Light winds. Chance of rain 50 percent.

Kaunakakai

Today: Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs 75 to 85. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 57 to 69. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny early in the morning then becoming partly sunny. Isolated showers early in the morning, then scattered showers in the late morning and afternoon. Highs 75 to 85. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Showery conditions will continue for windward and mauka areas of Oahu and Kauai this morning due to a lingering band of moisture. Although a drying trend is anticipated tonight through Saturday as the band of moisture moves out and our trades diminish, a few spotty interior and leeward afternoon showers associated with sea breezes are possible. A brief return of moderate to breezy trades is expected late Saturday through Monday as high pressure builds north of the area behind a passing front. Increasing moisture associated with low pressure forming west of the state could bring the rainfall chances and south-southeast winds back Tuesday through midweek.

Discussion

Early morning radar loop showed light to moderate showers continuing over windward Oahu and Kauai due to an area of moisture moving through and a band of low clouds associated with an old frontal boundary lingering in the area. The rainfall rates, however, have dropped quite a bit from what was observed earlier on Wednesday with peak overnight totals (through 2 AM HST) ranging from 0.5 to 2 inches. Streams on Oahu and Kauai have responded and steadily lowered through the night. Near-term guidance remains in decent agreement and shows a drying trend later today through Saturday as the moisture moves out and the upper ridge holds. Trades will persist today, then diminish and shift out of the southeast beginning tonight as the ridge shifts southward into the area. This light southeast background flow will allow land and sea breezes to form, which supports the best chance for spotty showers forming over our interior and leeward areas each afternoon.
Over the weekend, guidance reflects the progressive pattern continuing across the northern Pacific with another front passing to the north and an upper low closing off west of the state. While the moisture axis associated with the passing front is expected to remain north of the islands, a surface ridge quickly nosing eastward behind it will bring our moderate to breezy trades and windward showers back Saturday night through Monday.
Increasing moisture and instability associated with lowering upper heights as the previously mentioned upper low opens as it lifts northeast across the region will drive the the rain chances up for the state by Tuesday. Broad surface troughing near or west of the state could lead to the trades diminishing and shifting back out of the south to southeast by Tuesday. The probabilistic rainfall guidance supports this upward trend, especially over the western end of the state Tuesday through Wednesday.

Aviation

Light to moderate easterly flow, along with enhanced low level moisture, will allow for scattered showers to persist along windward locations through the day today. Periods of MVFR ceilings and visibility may accompany any of the more robust showers. Isolated showers may occasionally spill over the higher terrain and onto the leeward slopes.
AIRMET SIERRA remains in effect above 2000 feet for north through east sections of Kauai and Oahu due to tempo mountain obscuration from low clouds and showers.

Marine

Moderate to locally fresh east trade winds continue today and then veer to a more southeast direction as low pressure develops west of the Hawaiian Islands. Trades then quickly back to northeast as a cold front encroaches on the islands from the north late Saturday into Sunday. Locally strong winds can be expected behind the front, though its southward progress through the island chain remains uncertain. At this time, the strongest winds are most likely in the waters near and north of Kauai late Sunday night into Monday.
Long period energy associated from the northwest swell (320 degrees) has reached offshore buoys late last night as early forerunners are expected through the day. The initial surge of long period energy will fill in today before extra-large reinforcements will cause a sharp rise in the swell height tonight into early Friday morning. A High Surf Warning (HSW) is in effect from noon today through Friday for north and west facing shores most exposed to the swell. A High Surf Advisory (HSA) is possible for Big Island west facing shores as it builds down the island chain Friday. A Small Craft Advisory (SCA) has been issued for most waters for seas greater than 10 feet through Friday. Past events have suggested the potential for marginal to significant coastal impacts with periodic overtopping of the roadways late tonight into Friday morning due to the high tide and the peak of the swell.
Surf along east facing shores will remain rough and choppy for the next day or so, due to the combination of breezy trade winds and the decreasing north swell wrapping into exposed locations. Less choppy conditions are expected later in the week due to decreasing wind speeds, however locations exposed to northwest swell may still be impacted.
Surf along south facing shores will remain small through the rest of week. The next small, long-period south-southwest swell is expected to fill in over the weekend, keeping surf from going flat.

HFO Watches/Warnings/Advisories

High Surf Warning from noon today to 6 PM HST Friday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory from noon today to 6 PM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

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Data Courtesy of NOAA.gov