West Side

Today: Mostly cloudy. Numerous showers and isolated thunderstorms in the morning, then scattered showers and isolated thunderstorms in the afternoon. Locally heavy rainfall possible in the morning. Highs 72 to 83. South winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 60 percent.

Tonight: Cloudy with scattered showers. Lows 65 to 73. South winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Cloudy with isolated showers. Highs 73 to 83. Light winds. Chance of rain 20 percent.

South Side

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 85. Southwest winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Cloudy. Isolated showers in the evening. Lows around 69. South winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Cloudy. Highs 74 to 85. Light winds.

North Shore

Today: Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 66 near 5000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Tonight: Cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 71 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 40 percent.

Monday: Cloudy with isolated showers. Highs 78 to 83 near the shore to around 65 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Central Maui

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 80 to 85. South winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 69. South winds around 10 mph in the evening becoming light. Chance of rain 40 percent.

Monday: Cloudy. Isolated showers in the morning. Highs 80 to 85. Light winds. Chance of rain 20 percent.

Upcountry

Today: Partly sunny with scattered showers. Highs 51 to 68. Southwest winds up to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 42 to 54. Southwest winds up to 10 mph. Chance of rain 40 percent.

Monday: Cloudy. Highs 50 to 68. Light winds becoming east up to 10 mph in the afternoon.

East Maui

Today: Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 66 near 5000 feet. South winds up to 10 mph. Chance of rain 50 percent.

Tonight: Cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 71 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 40 percent.

Monday: Cloudy with isolated showers. Highs 78 to 83 near the shore to around 65 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Lanai City

Today: Mostly cloudy with numerous showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 67 to 78. South winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy. Scattered showers and isolated thunderstorms in the evening, then scattered showers after midnight. Lows 60 to 67. South winds around 10 mph. Chance of rain 50 percent.

Monday: Cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 68 to 78. South winds up to 10 mph in the morning becoming light. Chance of rain 30 percent.

Kaunakakai

Today: Breezy. Cloudy with numerous showers and isolated thunderstorms. Locally heavy rainfall possible. Highs 66 to 84. South winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 70 percent.

Tonight: Cloudy with numerous showers and isolated thunderstorms. Locally heavy rainfall possible. Lows 57 to 72. South winds up to 10 mph. Chance of rain 70 percent.

Monday: Cloudy with scattered showers. Highs 68 to 85. South winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A light to moderate hybrid easterly to southerly weather pattern will continue for the next seven days across the Hawaiian Islands. This weather pattern will bring cloudy, unsettled wet weather conditions to the western islands, and a drier more stable easterly weather pattern to Maui and the Big Island of Hawaii. Two cold frontal systems will move into the western half of the state over the next five days, each front will then stall out and diminish into a trough before drifting westward. Overall expect periods of unsettled and wet weather conditions, including locally heavy showers and thunderstorms at times, across the western half of the state lasting into next weekend.

Discussion

A combination of the local radar and satellite imagery shows a cold front currently moving through the Kauai Channel towards Oahu. A prefrontal convergence band of showers is also riding into Oahu this morning, spreading numerous showers across island in advance of the weakening cold front. Expect periods of showers to continue over Oahu and possibly over the island of Molokai later this morning as the forward motion of the front stalls out. Isolated thunderstorms remain in the forecast mainly along the narrow frontal boundary.
The latest weather model consensus shows this fading frontal band will stall out near Oahu and Molokai later today, then weaken into a trough and then drift northwestward back over Kauai by early Monday morning. The highest shower amounts will develop along the frontal or trough axis. A Flood Watch remains in effect through Monday night for Niihau, Kauai and Oahu as locally heavy rainfall and isolated thunderstorms will elevate convective flash flooding risks.
Another cold low pressure system with a trailing cold front will move into the Hawaii region by Monday, this new cold front will absorb the trough on Tuesday, and then move back into the region as the next cold frontal system. Models show this next cold front stalling out and diminishing into a trough near Kauai and Oahu from Wednesday into Thursday, producing yet another round of numerous showers over both islands.
This unsettled light to moderate variable wind pattern will continue into next weekend as low pressure troughing lingers just north of Hawaii.

Aviation

A cold front pushed through Kauai overnight and is expected to reach Oahu later this morning. Ahead of this front, a band of showers is becoming better organized and moving into Oahu from the southwest. These two surface boundaries gradually move eastward and dissipate over the central islands later tonight. MVFR, or even IFR, conditions will be possible as these showers move through. Elsewhere, VFR conditions will prevail. Moderate southerly winds will prevail ahead of the front, with light and variable winds in its wake. Then moderate southerly winds will build back across the entire state tonight as the front dissipates.
AIRMET Sierra remains in effect for mountain obscuration for Kauai and Oahu. As conditions deteriorate this may become an IFR AIRMET.
AIRMET Tango is in effect for moderate low level turbulence across Kauai, Oahu and Molokai. This AIRMET may be cancelled later today as winds under the inversion decrease.

Marine

The front that moved through Kauai overnight will continue to push east through Oahu this morning with the potential for showers and isolated thunderstorms along the front. As the front stalls and weakens, the chance for isolated thunderstorms remains over the western coastal waters through Monday. Winds are expected to weaken behind the front before becoming locally fresh out of the south Monday through mid- week as another front approaches from the west. Gentle to locally moderate south to southwest winds are forecasted through the rest of the forecast period.
Long period forerunners from the west northwest have begun to fill into the nearshore waters as the new moderate medium to long period west northwest swell will build quickly throughout the day and peak this evening at High Surf Advisory levels for north and west facing shores before gradually declining Monday. A High Surf Advisory has been issued for select north and west facing shores starting at noon today as the swell rises through Monday. Due to travel time, western shores of the Big Island may need to be expanded for Monday. A Small Craft Advisory (SCA) has also been expanded to all waters around Kauai and Oahu windward waters due to the incoming swell and also the winds along the front through Monday too. A combination of moderate northwest and north swells will keep surf elevated through the week.
East facing shores will remain tiny to small given the lack of trade winds but shorelines exposed to the north swells may be slightly elevated through Wednesday. Surf along south facing shores will see an increase of short period wind wave chop mainly over the western islands associated with the passing front. A slight lull is expected today for zones behind the front, before the next front approaches and increases the wind waves coming from the south.

Fire weather

Weather conditions will remain below critical fire weather thresholds through the forecast period. Unsettled light to moderate southerly winds are forecast for the western half of the state, while more stable and drier easterly winds will continue over Maui and the Big Island. Periods of wet weather are forecast to last into next weekend for Niihau, Kauai, Oahu, Molokai and possibly Lanai; with much lower rainfall chances elsewhere. Temperature inversion heights near Maui and the Big Island will range from 7,000 to 8,000 feet today.

HFO Watches/Warnings/Advisories

Flood Watch through late Monday night for Niihau, Kauai and Oahu.
High Surf Advisory from noon today to 6 PM HST Monday 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 until 6 PM HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters.

Data Courtesy of NOAA.gov