Photo Credit: Jeni Ji Cousins

West Side

Today: Sunny. Isolated showers in the afternoon. Highs around 82. Light winds becoming southwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 63 to 69. South winds up to 10 mph increasing to 10 to 20 mph after midnight. Chance of rain 30 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs around 82. South winds 10 to 20 mph. Chance of rain 50 percent.

South Side

Today: Sunny. Highs around 86. Light winds becoming southwest up to 10 mph in the afternoon.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 64. South winds 10 to 15 mph. Chance of rain 30 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs around 86. South winds 10 to 25 mph. Chance of rain 50 percent.

North Shore

Today: Mostly sunny with isolated showers. Highs 78 to 83 near the shore to around 66 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows 61 to 67 near the shore to around 52 near 5000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 78 to 83 near the shore to around 64 near 5000 feet. Southwest winds up to 20 mph. Chance of rain 20 percent.

Central Maui

Today: Sunny. Highs 82 to 87. Light winds becoming west up to 10 mph in the afternoon.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 62 to 67. South winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 82 to 87. Southwest winds 10 to 25 mph. Chance of rain 40 percent.

Upcountry

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

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 48 at the visitor center to around 45 at the summit. Southwest winds up to 10 mph. Chance of rain 40 percent.

Sunday: Mostly sunny with scattered showers in the morning, then partly 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.

East Maui

Today: Mostly sunny with isolated showers. Highs 78 to 83 near the shore to around 66 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows 61 to 67 near the shore to around 52 near 5000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 30 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 78 to 83 near the shore to around 64 near 5000 feet. Southwest winds up to 20 mph. Chance of rain 20 percent.

Lanai City

Today: Mostly sunny. Isolated showers in the afternoon. Highs 72 to 79. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 65. South winds 10 to 15 mph increasing to 15 to 25 mph after midnight. Chance of rain 50 percent.

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

Kaunakakai

Today: Mostly sunny. Isolated showers in the afternoon. Highs 74 to 84. Light winds becoming southwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 57 to 69. South winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 30 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 74 to 84. South winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A cold front approaching from the northwest will shift winds around to the south today, with breezy conditions expected to develop tonight and continue through Sunday. Rather dry conditions will prevail today, with showers then increasing tonight and Sunday in advance of the front, with a thunderstorm possible Sunday on Kauai. The front will push into the central islands and stall out Sunday night and Monday bringing some showery weather with it and shifting winds northeasterly. The front will dissipate Monday night, with light to moderate trades and fairly typical trade wind weather then expected Tuesday through the end of the work week.

Discussion

Currently at the surface, a 1021 mb high is centered around 1250 miles northeast of Honolulu, while a cold front is located around 800 miles west-northwest of Kauai. The trade winds are breaking down, with winds shifting southeasterly and light to moderate levels early this morning. Infrared satellite imagery shows mostly clear to partly cloudy conditions in most areas, with a bit more cloud cover over east and southeast facing slopes of Kauai and the Big Island where radar imagery also shows a few showers. Main short term focus is on the upcoming front and the associated weather it will bring to the islands.
The latest model solutions continue to exhibit some differences, but the general trend has been for less of an eastward progression of the front into the island chain. This trend has been reflected in the latest forecast, which is roughly a blend of the previous forecast and the latest GFS and ECMWF solutions.
As a result, we expect the approaching front to shift winds southerly today, with winds becoming breezy out of the south and southwest tonight and Sunday. The front will push into the western islands late Sunday, then stall out in the vicinity of the central islands Sunday night and Monday, with moderate north to northeasterly winds expected following frontal passage. The front will dissipate Monday night, with a weak ridge north of the state keeping light to moderate trades in place Tuesday through the end of the work week.
As for the remaining weather details, rather dry weather will prevail today with limited shower activity statewide. Increasing south to southwest flow will bring increasing showers into leeward areas of the smaller islands tonight and Sunday as the front approaches from the northwest, with the most showery conditions on Kauai and Oahu. In fact, there might be enough instability for some heavier showers and a few thunderstorms along and ahead of the front over Kauai on Sunday. The most unstable airmass appears to lift northeast of the islands by Sunday night, but we will continue to monitor this closely. The front and its associated band of moisture will then push into the central islands and stall out Sunday night and Monday, bringing some showery weather with it. Meanwhile, the deepest moisture associated with the front will remain north of the Big Island, so rather dry weather will prevail here. In fact if trends continue, further downward adjustments to rain chances may be required for Maui County.
The front appears to dissipate Monday night, with the combination of its remnant moisture and an influx of moisture from the southeast bringing a return of a more typical trade wind pattern featuring mainly windward and mauka showers which should continue through the end of the week.

Aviation

High pressure far northeast of the islands will continue to drift eastward today, as a frontal system approaches the state from the northwest. Light winds will become southeasterly this morning, ahead of this feature, then veer southerly by late this afternoon or evening.
Relatively dry air in place will act to suppress shower activity through this morning. However, isolated showers are expected to develop over the islands and adjacent waters later in the day.
Southerly winds will become breezy by tonight, as the front approaches, and brings frequent showers to Kauai.
No AIRMETS are currently in effect.

Marine

Latest ASCAT pass shows winds have eased to the moderate to fresh range and will continue to ease today, thus the Small Craft Advisory has been cancelled. An approaching front will veer the wind out of the south to southeast today. Winds will then strengthen slightly to the moderate to locally strong range out of the south to southwest late tonight into Sunday, especially for the western half of the state. The cold front will march down the island chain Sunday afternoon into early next week producing numerous showers and winds out of the north and northeast in the moderate to fresh range or possible slightly stronger behind the front.
The High Surf Advisory for the east facing shores has been cancelled as conditions have dropped below advisory levels. Latest observations show that the northeast swell has dropped about a foot overnight. This trend is expected to continue through today which will translate to surf dropping quickly along east facing shores.
A mix of a small, long period northwest swell and the fading northeast swell mentioned above will provide a slight boost to west facing shores today and tomorrow and allow north facing shore surf to drop more steadily today into Sunday. A large, medium- period, north- northwest (340-350 deg) swell should arrive late Sunday, peak above the warning threshold on Monday. This swell will hold as it transitions to a more northerly direction Tuesday, before slowly subsiding Wednesday into Thursday. In the longer range forecast, an even larger northwest swell may develop late next week with surf heights possibly exceeding warning levels along north facing shores.
An out of season south swell will continue to build today, peak tonight into Sunday near summer average, before declining early next week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov