Photo Credit: Jeni Ji Cousins

West Side

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 82. South winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 64 to 70. South winds up to 15 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 77 to 83. Northeast winds up to 20 mph. Chance of rain 50 percent.

South Side

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 86. Southwest winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 65. Southwest winds 10 to 15 mph shifting to the south after midnight. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs around 83. Northeast winds up to 15 mph shifting to the north in the afternoon. Chance of rain 50 percent.

North Shore

Today: Mostly sunny with isolated showers. Highs 78 to 83 near the shore to around 64 near 5000 feet. Southwest winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 68 near the shore to 49 to 54 near 5000 feet. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Partly sunny. Breezy. Isolated showers in the morning, then numerous showers in the afternoon. Highs 75 to 80 near the shore to around 61 near 5000 feet. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 82 to 87. Southwest winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows 63 to 68. South winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 40 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 79 to 84. Northeast winds up to 15 mph increasing to 15 to 20 mph in the afternoon. Chance of rain 50 percent.

Upcountry

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 60 at the visitor center to around 55 at the summit. Southwest winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows around 47 at the visitor center to around 42 at the summit. Light winds. Chance of rain 20 percent.

Monday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 55 at the visitor center to around 51 at the summit. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 40 percent.

East Maui

Today: Mostly sunny with isolated showers. Highs 78 to 83 near the shore to around 64 near 5000 feet. Southwest winds up to 15 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 68 near the shore to 49 to 54 near 5000 feet. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Partly sunny. Breezy. Isolated showers in the morning, then numerous showers in the afternoon. Highs 75 to 80 near the shore to around 61 near 5000 feet. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Lanai City

Today: Breezy. Partly sunny with scattered showers. Highs 71 to 78. Southwest winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 65. Southwest winds 10 to 15 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 70 to 77. East winds up to 20 mph increasing to northeast in the afternoon. Chance of rain 50 percent.

Kaunakakai

Today: Breezy. Partly sunny with scattered showers. Highs 74 to 84. South winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with numerous showers. Lows 58 to 70. South winds up to 15 mph. Chance of rain 70 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 71 to 81. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy south to southwest winds will overspread the state today as a cold front approaches from the northwest. Showers will be most prevalent on Kauai, where there will also be a slight chance for thunderstorms. The front will push through Oahu tonight, then stall out over Maui County on Monday. The front will bring some showery weather as it moves through, with winds shifting northeasterly and becoming breezy behind, with the shower focus shifting to windward slopes and coasts. The front will gradually dissipate Monday night and Tuesday, with light to moderate trades and fairly typical trade wind weather expected Tuesday through the end of the work week. Another front could shift winds southerly and bring an increase in showers next weekend.

Discussion

Currently at the surface, a cold front is located around 125 miles west-northwest of Kauai and is moving eastward at around 15 mph. Winds have responded and strengthened to breezy levels out of the south and southwest early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions across the state, with cloud coverage the highest over Kauai. Radar imagery shows frequent showers moving through Kauai, and scattered pre-frontal showers moving into leeward sections of the remaining smaller islands. Meanwhile, only a few light showers are seen moving into the southeast facing slopes of the Big Island. Main short term focus remains on the incoming front and the associated weather it will bring to the islands.
The latest model solutions continue to exhibit some differences, but have remained remarkably consistent from run to run. The GFS remains more progressive with the front, allowing it to reach Maui County, while the ECMWF hangs the front up over Oahu. The two models haven't changed much during the past 24 hours, and the current forecast appears in good shape reflecting a blend of these solutions.
Breezy south to southwest winds will continue today in advance of the approaching front. The front will push through Kauai later today, Oahu tonight, then stall out in the vicinity of Maui County on Monday. Moderate to locally breezy north to northeasterly winds are expected to fill in following the frontal passage. The front will gradually dissipate over the central islands Monday night and Tuesday, with a weak ridge building in north of the state. The northeasterly trades will ease back to moderate levels Monday night, with light to moderate trades then prevailing Tuesday through Friday. Winds could shift southerly next weekend in advance of the next approaching front.
As for the remaining weather details, increasing south to southwest flow will bring some pre-frontal showers into leeward areas of Oahu and Maui County today as the front approaches from the northwest. The more showery conditions are expected on Kauai, where there will be enough instability for some heavier showers and possibly a few thunderstorms as well. The most unstable airmass appears to lift northeast of the islands by tonight, but we will continue to monitor this closely. The front and its associated band of moisture will push through Oahu tonight then stall out across Maui County on Monday, bringing some showery weather with it. The front will become increasingly west to east oriented with time, so the showery conditions will continue behind the front particularly for windward locales. Both the GFS and ECMWF continue to show the deepest moisture associated with the front remaining to the north of the Big Island, so rather dry weather will prevail here through Monday.
The front will gradually dissipate across the central islands Monday night and Tuesday, bringing a return of more typical trade wind weather featuring mainly windward and mauka showers which should continue through the end of the work week. The next approaching front could bring an increase in showers next weekend.

Aviation

Breezy southerly winds will usher showers and pockets of MVFR over Kauai, Oahu, and adjacent waters for the next several hours while a greater coverage of showers advances toward Kauai from the west. AIRMET Sierra for mountain obscuration will likely remain in effect for Kauai until the front passes later today. Showers will then expand in coverage in the vicinity of Oahu as the decaying frontal boundary arrives favorably during the onset of nocturnal cooling. AIRMET Sierra may be needed for Oahu late this evening. Prevailing VFR is anticipated for the remainder of the island chain. Southerlies transition to gusty northeast trades in the wake of the front.
AIRMET Sierra for tempo mtn obsc is in effect for Kauai.

Marine

An approaching front just west of our waters will cause winds to strengthen into the moderate to locally strong range out of the south to southwest today, especially for waters around Kauai and Oahu. The front will push down the island chain this afternoon into Monday, producing numerous showers, and fresh to locally strong trade winds as the high pressure ridge builds in behind the front. A Small Craft Advisory (SCA) is in effect for western waters through the day. This SCA may need to be altered through tonight as conditions warrant, especially with frontal passage.
A small, medium period northwest swell will continue to provide a a slight boost to west facing shores today. However, a large, medium period, north- northwest (340-350 deg) swell should start to arrive late tonight, providing large level surf. A High Surf Advisory (HSA) is likely to be issued starting tonight into Monday for north and select west facing shores. If observations come above guidance, a High Surf Warning (HSW) may be issued for mainly north facing shores. This swell will hold as it transitions to a more northerly direction Tuesday, then slowly subside Wednesday into Thursday. This could lead to moderate surges in harbors such as Hilo and Kahului from the northerly swell component, so the buoys will be closely monitored as the event unfolds. In the long range forecast, another potential HSW northwest swell may develop late next week for north facing shores.
An out of season south swell will continue today near the summertime average, then decline over the next few days. Surf along east facing shores will remain rough and choppy as the trade winds build back this week. Although, east facing shores exposed to the north swell wrap will see a rise coinciding with the north swell.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters.

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Data Courtesy of NOAA.gov