West Side

Today: Partly sunny. Isolated showers in the morning. Highs around 82. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 75. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Tuesday: Sunny with isolated showers. Highs 78 to 84. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny in the morning then becoming partly sunny. Highs around 87. Northwest winds up to 15 mph.

Tonight: Mostly clear. Lows 67 to 75. North winds up to 15 mph.

Tuesday: Sunny. Highs around 87. North winds up to 15 mph.

North Shore

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 71 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to around 64 near 5000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Central Maui

Today: Partly sunny with isolated showers. Highs 81 to 88. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows 68 to 73. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Sunny and breezy. Isolated showers in the morning. Highs 81 to 87. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Partly sunny. Isolated showers in the morning. Highs around 62 at the visitor center to around 69 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows 43 to 55. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Sunny with scattered showers. Highs around 61 at the visitor center to around 58 at the summit. East winds up to 10 mph. Chance of rain 50 percent.

East Maui

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 71 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to around 64 near 5000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Lanai City

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Kaunakakai

Today: Mostly cloudy. Isolated showers in the morning. Highs 71 to 88. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows 59 to 74. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Sunny. Isolated showers in the morning. Highs 71 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trades will gradually weaken over the next several days. An upper level low/trough will help bring increased instability to the western end of the state, enhancing the chance for heavier showers through Tuesday. A few thunderstorms are possible but expected to remain offshore.

Discussion

Satellite and radar imagery shows a large area of showers associated with an extensive cloud shield moving northward. While the cloud shield covers the whole state, shower are occurring over Kauai and Oahu with some windward and mauka locations also getting some showers riding in on the trades.
An upper level low 300 or so miles to our west has helped keep a few offshore thunderstorms going. This low will move NE through tonight and weaken into a trough. It will then become nearly stationary over the state, bringing enhanced instability to the region. There is a slight chance for thunderstorms over/near Kauai and Niihau over the next couple of days due to the cold air aloft associated with this trough. Models also indicate enough instability developing over the Kona side of the Big Island Wednesday afternoon to warrant a mention of thunderstorms.
Wednesday, the trough will form a new closed low to our southwest due to the influence of an upper ridge asserting itself eastward around 30 N. The low will move SW, away from the state. At the same time, a large central Pacific trough will move down the east side of the ridge, and may even push a boundary into or through the area late next weekend. Models have yet to come into agreement on the evolution of this system, and at this time range, that's to be expected.
At the surface, a series of high pressure centers to our north will move from west to east, keeping us in a trade wind pattern. Windward and mauka showers will be favored, with some limited spillover to leeward sides.

Aviation

Moderate to breezy trade winds will gradually ease through the week as a front far to the north weakens the high pressure. Showers from low clouds on the trade winds will mostly focus over windward and mountain areas, however a few brief light showers from mid and high level clouds are possible anywhere. Expect an increase in showers along windward and mauka regions tonight as a band of moisture associated with the front moves south near the western end of the state. Low ceilings and MVFR conds are possible in any heavier showers, otherwise VFR should prevail. In addition, an upper level low will open up to a trough today across the state into Tuesday which should continue drawing up mid and upper level clouds from the south through the forecast period as well as provide a slight chance of thunderstorms over the waters west of Kauai and Oahu.
AIRMET Zulu is in effect over the state for light icing btn 140 and FL210. Conditions should continue through the morning hours and could even be moderate icing at times.
AIRMET Tango is in effect for tempo moderate upper level turbulence between FL250 and FL380. This should continue through today.

Marine

Weak high pressure far northeast of the waters will remain stationary as a front stalls and weakens north of the area through midweek. Moderate to locally fresh trade winds will prevail through the forecast period as the Small Craft Advisory has been cancelled this morning. A weak ridge will nose into the northern offshore waters through the latter half of the week before another front approaches.
Surf along north facing shores should see a gradual increase today as a short to medium period north- northwest (330-340 degrees) swell fills in and peaks this afternoon before declining Tuesday. As this swell fades on Wednesday, a moderate short- period north swell will produce a brief boost in north shore surf. Since the storm generating the swell will be compact and fast- moving, there is some uncertainty as to the potential surf height. Model guidance for north swells have trended towards a low bias so surf heights may come in higher then projected. Stay tuned for more details. A new northwest swell will bring surf heights near advisory levels this weekend along exposed north and west facing shores.
Surf along east facing shores will remain small to moderate as the trade winds ease. Although, shorelines exposed to the north swell on Wednesday may see an increase in surf. South facing shores will experience mainly small background swell through the week.

Fire weather

Low-level moisture is expected to be high enough this week to keep RH values above critical levels. Trade winds will still be present, but weaker, in the coming days. Temperature inversion heights will range from 6,500 to 7,500 ft today.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov