Photo Credit: Tyler Rooke

West Side

Today: Partly sunny with scattered showers. Highs 76 to 84. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows 66 to 73. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 84. Light winds. Chance of rain 40 percent.

South Side

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 30 percent.

Tonight: Mostly clear with isolated showers. Lows 64 to 73. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86. Light winds. Chance of rain 30 percent.

North Shore

Today: Mostly cloudy. Numerous showers and slight chance of thunderstorms in the morning, then numerous showers in the afternoon. Highs 75 to 82 near the shore to around 65 near 5000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 69 near the shore to 48 to 54 near 5000 feet. Light winds. Chance of rain 60 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 76 to 82 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 86. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 70. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 86. Light winds. Chance of rain 50 percent.

Upcountry

Today: Breezy. Partly sunny with scattered showers. Highs around 60 at the visitor center to around 55 at the summit. East winds up to 20 mph shifting to the southeast up to 10 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows around 47 at the visitor center to around 44 at the summit. South winds around 10 mph. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming mostly cloudy. Scattered showers. Highs around 61 at the visitor center to around 57 at the summit. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Numerous showers and slight chance of thunderstorms in the morning, then numerous showers in the afternoon. Highs 75 to 82 near the shore to around 65 near 5000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 69 near the shore to 48 to 54 near 5000 feet. Light winds. Chance of rain 60 percent.

Thursday: Mostly cloudy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 76 to 82 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 70 percent.

Lanai City

Today: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 73 to 81. Light winds. Chance of rain 60 percent.

Tonight: Partly cloudy with isolated showers. Lows around 63. Light winds becoming southeast around 10 mph after midnight. Chance of rain 20 percent.

Thursday: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 73 to 80. South winds around 10 mph. Chance of rain 60 percent.

Kaunakakai

Today: Partly sunny with scattered showers. Highs 67 to 86. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 56 to 73. Light winds. Chance of rain 20 percent.

Thursday: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 68 to 86. Light winds. Chance of rain 60 percent.

Detailed Forecast

Synopsis

Unsettled weather will persist through the forecast period. Locally heavy rainfall and thunderstorms are possible for Maui and the Big Island through this morning. Breezy trades will turn southeasterly and diminish today and tonight. Gusty northerly winds will accompany a cold front that will push through the islands Thursday night through Friday. Heavy rainfall and flash flooding are possible from Friday into next week.

Discussion

A surface trough southeast of the Big Island will approach the islands today, then move up the chain tonight and Thursday. Winds will weaken and shift to southeasterlies as it passes. Associated clouds and showers will persist this morning. Localized heavy rainfall may occur at times. West of the surface trough, trade wind showers may be locally heavy, but will move fast enough to minimize flooding concerns this morning. However, as winds taper off later today and tonight, localized flooding could occur. Satellite loop shows an upper low just south of the Big Island this morning, providing enough instability to keep a slight chance of thunderstorms in the forecast for windward and southeast portions of Maui and the Big Island through this morning.
Models show a deep trough will develop over the central Pacific and drive a cold front through most or all of island chain Thursday night through Friday. As the deepening trough approaches from the north, the closed upper low near the Big Island will transition to an open wave and quickly move eastward. However, lingering moisture will be readily available for the incoming front. Heavy rainfall and potential flooding are possible as early as Friday morning over north-facing slopes of Kauai within post- frontal northerly flow. The flood threat would then quickly shift to the Big Island, where the front appears likely to stall Friday night through Saturday.
Sunday into early next week, a band of moist southerly flow will develop east of the upper trough axis as a deep low closes off near or west of Kauai. This moisture band will fuel the greatest potential for heavy rain and flash flooding. Models vary in their placement of this moisture band as it shifts across the islands, decreasing forecast confidence. However, it is becoming clear that active wet weather is in store for the state through the forecast period, especially from the weekend onward.

Aviation

Moderate to locally breezy easterly winds will push occasional showers, a few locally heavy, over windward and mauka sections of the smaller islands through the forecast period. Brief MVFR or IFR will be possible within heavier showers. Over the Big Island, thunderstorms over the southeast-facing slopes and adjacent waters have diminished, but steady moderate to locally heavy rain will continue through the predawn hours. Showers in this area are expected to diminish in coverage during the morning, but renewed diurnal development can be expected over the Big Island interior this afternoon.
AIRMET Sierra for mountain obscuration remains effect for the Big Island from Cape Kumukahi to Apua Point to South Cape.
AIRMET Tango remains in effect tempo moderate upper-level turbulence between FL250 AND FL400 over Maui and the Big Island. Conditions are expected to gradually improve through the morning.

Marine

An upper level low pressure system continues to produce isolated thunderstorms in the vicinity of the Big Island. The low is slowly weakening but should continue to support thunderstorm development near the Big Island and Maui through today. The locally strong trade winds over the nearshore waters of the Big Island and Maui is trending down to moderate speed. So the Small Craft Advisory (SCA) covering these waters is canceled. This weakening trend will continue through tonight.
A cold front is forecast to enter the far northwest offshore waters Thursday and move down the main Hawaiian Islands Thursday night and stall near the Big Island late Friday. Strong and gusty northerly winds and rough seas will follow in behind the front, along with an elevated north-northwest swell. A surface low is expected to move south to near Kauai on Saturday night and Sunday, and the stalled front will then move west as a trough, with southerly winds spreading west across the area.
A small to moderate northwest swell is slated to arrive today and hold through Thursday. A very large north-northwest swell arrives Friday, peak Saturday night, followed by a gradual decline through Sunday. This large swell is from a storm- force low forecast to develop about 1000 nm north of Kauai tonight and drift south through Thursday. A High Surf Warning is very likely for the north and west facing shores of most islands Friday and the weekend. For the other shores, the east facing shores will see surf trending down as the trade winds weaken. Surf along south facing shores may rise a foot or two late in the weekend due to winds blowing in from the south. Otherwise, surf will be flat or nearly flat.
The arrival the strong northerly winds and large north- northwest swell Thursday night through Friday will boost the seas to 10 feet or higher covering most Hawaiian waters, thus prompting a Small Craft Advisory.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov