Photo Credit: Tyler Rooke

West Side

Today: Partly sunny. Isolated showers in the afternoon. Highs 76 to 89. Light winds becoming east up to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Cloudy with isolated showers. Lows 64 to 74. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly cloudy. Highs 75 to 88. East winds up to 15 mph in the morning becoming light.

South Side

Today: Mostly sunny in the morning then becoming partly sunny. Highs 78 to 88. Light winds becoming west up to 15 mph in the afternoon.

Tonight: Cloudy. Lows 66 to 71. North winds up to 15 mph.

Sunday: Partly sunny. Highs 77 to 88. Northwest winds up to 15 mph.

North Shore

Today: Breezy. Partly sunny with isolated showers. Highs 78 to 83 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 74 near the shore to around 54 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Sunday: Breezy. Mostly cloudy with isolated showers. Highs 76 to 82 near the shore to around 66 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Central Maui

Today: Mostly sunny in the morning then becoming partly sunny. Highs 82 to 88. East winds up to 15 mph.

Tonight: Breezy. Cloudy with isolated showers. Lows around 69. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly cloudy. Highs 80 to 87. Northeast winds up to 15 mph.

Upcountry

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 54 to 73. East winds up to 10 mph in the morning becoming light. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 48 at the visitor center to around 45 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly cloudy. Highs 52 to 70. Northeast winds up to 10 mph.

East Maui

Today: Breezy. Partly sunny with isolated showers. Highs 78 to 83 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 69 to 74 near the shore to around 54 near 5000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Sunday: Breezy. Mostly cloudy with isolated showers. Highs 76 to 82 near the shore to around 66 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Lanai City

Today: Partly sunny. Isolated showers in the afternoon. Highs 69 to 80. Light winds becoming north up to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Cloudy with isolated showers. Lows 60 to 67. Northeast winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly cloudy. Highs 68 to 78. East winds up to 10 mph.

Kaunakakai

Today: Partly sunny. Scattered showers in the afternoon. Highs 67 to 88. Light winds becoming northeast up to 15 mph in the afternoon. Chance of rain 30 percent.

Tonight: Cloudy with scattered showers. Lows 57 to 74. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Sunday: Mostly cloudy. Isolated showers in the morning. Highs 66 to 87. East winds up to 15 mph in the morning becoming light. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A kona low northwest of the state will continue drawing unstable tropical moisture northward over Kauai County through today. The kona low will begin slowly drift north and weaken over the next few days improving trends spreading from east to west, though enhanced rainfall may linger over Kauai and Niihau through tonight. By Monday all islands will see an improvement in weather conditions as easterly trade winds return.

Discussion

A kona low remains centered roughly 850 miles northwest of Kauai with a trough orientated northeast to southwest 150 miles west of Kauai. Radar and satellite imagery shows isolated thunderstorms embedded along the main line of convergence just east of the trough. Radar is now showing this main line of convergence nearing Kauai County from the west early this morning. The Flood Watch for Kauai remains in effect through tonight as current observations remains in line with hi- res model guidance showing rainfall activity picking up this morning. Although most showers will remain light to moderate a few heavy showers and isolated thunderstorms could still develop as the day progress, in addition to this band lingering over Kauai County during the most of the day. A few stray showers could also reach as far as Oahu today so have increased the pops slightly especially for the leeward and interior areas this morning.
A ridge of high pressure will slowly build in from east to west across the state today and Sunday as the kona shifts north and weakens. East southeast winds will keep winds light an variable along sheltered leeward locations down stream of the Big Island. This pattern could also be conducive for showers to develop along the Koolau range this afternoon and evening. Upper levels continue to show divergence aloft that will keep some instability over western end today. Expect more stabilizing trends with decreasing showers as east to southeast winds spread across the state. Likely by Sunday, the moderate to heavy rainfall threat will diminish over Kauai as more stable conditions fill in across the state.
Easterly trade winds will return across the state from Monday onward. Trade showers may be somewhat enhanced during the first half of next week due to lingering moisture and some upper level instability from a short wave trough during the first half of next week. The tongue of high precipitable water vapor should become more normal during the second half of next week allowing for a more typical trade wind pattern.

Aviation

An unstable tropical environment with a low level trough over Kauai will keep MVFR conditions with brief IFR conditions possible in moderate to locally heavy showers through tonight. Lingering instability near Oahu will keep periods of MVFR conditions in showers. Moderate turbulence may develop later this morning over all islands from FL280-400.
Most islands will see light large scale southeast to south winds interacting with overnight land and daytime sea breezes through the weekend. Clouds and showers will build over island mountain and interior sections during the day with some clearing at night for most islands. Kauai will be the exception to this rule as a low level trough will approach the island enhancing clouds and showers through tonight.
AIRMET Sierra in effect for mountain obscurations over all islands.
Occasional light rime icing is expected from Kauai to Oahu in layer 140-FL250.

Marine

Moderate to locally strong east to southeast winds associated with a kona low far north-northwest of the state will persist over the weekend. A shift out of a more typical easterly trade wind direction is expected early next week as it lifts northward and away from the region and the ridge builds to the north. A Small Craft Advisory is now in effect for the windier coastal waters around Maui County and the Big Island through Sunday.
Surf along south facing shores will remain up through early next week due to overlapping, long-period south-southwest swells. The first swell will hold around the advisory level today before briefly lowering Sunday. Offshore buoy observations are holding strong with the peak energy associated with this swell now into the 14-16 second bands. The short-period wind chop added from the southerly winds will linger today, then ease as we transition back to an east to southeast wind regime by early next week. A fresh, long-period south-southwest swell will fill in through the day Sunday, then peak slightly lower than the current swell early next week before easing Tuesday through midweek.
Surf along north facing shores will steadily lower through the weekend, with a return to a more typical pattern for this time of year next week.
Surf along east facing shores will remain well below average through the weekend. An upward trend is possible next week as the trades return locally and far upstream over the eastern Pacific.

HFO Watches/Warnings/Advisories

Flood Watch through late tonight for Niihau, Kauai,
High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Southeast, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 PM HST Sunday for Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters.

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Data Courtesy of NOAA.gov