Photo Credit: Travis Guthrie

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 80 to 89. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 70 to 77. Northeast winds 15 to 25 mph. Chance of rain 40 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 80 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 91. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 71 to 78. Northeast winds 10 to 20 mph.

Sunday: Mostly sunny. Breezy. Highs around 90. Northeast winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to around 70 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 73 near the shore to 50 to 57 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 69 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 81 to 90. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 73. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 81 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Breezy. Sunny with isolated showers. Highs around 70 at the visitor center to around 72 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly clear with scattered showers. Lows around 54 at the visitor center to around 50 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Sunday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 63 to 74. East winds up to 20 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to around 70 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 73 near the shore to 50 to 57 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 80 to 85 near the shore to around 69 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 75 to 83. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 68. Northeast winds 10 to 25 mph.

Sunday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 75 to 83. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 72 to 92. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 61 to 77. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs 71 to 92. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure system far north of the Hawaiian Islands will continue to keep moderate to breezy trade winds in the forecast through Wednesday. The high center will drift westward away from the islands as a cold front digs south from Alaska into the Eastern Pacific basin, weakening the ridge north of the island chain.. A weak disturbance passing from east to west through the state will produce a slight increase to shower activity across the Hawaii region from Sunday through Monday. Otherwise fairly stable trade wind weather will prevail for most areas through Wednesday.

Discussion

This mornings satellite imagery shows some unsettled clouds drifting into the windward and mountain areas of each island on the trade winds. Periods of light showers are possible through the early morning hours. This mornings upper air balloon observations from Lihue and Hilo show subsidence temperature inversion heights in the 5,000 to 7,000 foot range respectively. These fairly stable conditions will yield passing showers mainly over windward and mountain areas through the morning hours with decreasing trends by mid morning.
Sunday and Monday…The weather conditions will change a bit as a weak tropical wave in the easterly trade winds moves from east to west over the islands. Low level forcing from this passing easterly wave will lift temperature inversion heights into the 6,000 to 8,000 foot range, allowing for higher cloud heights and increasing shower trends. The best chances for shower activity will occur during the overnight to early morning diurnal rainfall peak, favoring the windward and mountain areas. Some of the stronger showers that develop will move into the typically drier leeward locations. A brief drop in the trade wind speeds remains in the forecast for Monday and Monday night.
From Tuesday onward…A fairly stable moderate to locally breezy trade wind weather pattern will continue through the first half of the week. However, there remains a larger degree of uncertainty in the wind and weather patterns towards the end of next week as Tropical Cyclone development may change the wind pattern and rainfall activity. Both the American GFS and the European ECMWF long range model guidance continues to suggest that we may see Tropical Cyclone development or movement near the Hawaii region. Therefore, the island by island weather forecast from Thursday onward will highly depend upon the potential for any Tropical Cyclones forming or moving of into the northern Central Pacific basin. Stay tuned for updates, as this long range weather forecast evolves over time.
Forecast guidance continues to show the potential for Tropical Cyclone formation in the north Central Pacific basin over the next seven days. Please see the latest Tropical Weather Outlook (TWOCP) for details at www.hurricanes.gov

Aviation

Moderate to breezy trades will bring low clouds and showers to windward and mauka areas for the next few days. MVFR conditions will be more likely during the overnight to early morning hours when better low cloud and shower coverage is expected. Otherwise, VFR conditions should generally prevail.
AIRMET Sierra is in effect for mountain obscuration for windward portions of Kauai, Oahu, Molokai, Maui and the Big Island. This will likely be needed through the early morning hours today.
AIRMET Tango for low level turbulence leeward of the terrain is in effect statewide due to the breezy trades and will likely last through the weekend.

Marine

High pressure far north of the area will continue to drive moderate to locally strong trade winds to the region into the early part of the new week. A Small Craft Advisory (SCA) is in effect for the typical windier waters around Maui County and the Big Island through Sunday afternoon. Conditions may linger in some areas a little longer.
The current small south swell is expected to continue to decline today. Lingering small background energy from the southeast will continue through tonight. A more significant south swell will arrive late Sunday and Sunday night, peaking above the summertime average Monday, and then slowly lower through the middle of next week. Seasonally flat to tiny surf is expected through early next week for north facing shores, with the possibility of the arrival of a swell midweek from Typhoon Ampil, currently near Japan. East shore surf will trend to seasonal averages through the next week.
The combination of the upcoming full moon and water levels running around 0.5 ft higher than predicted could produce minor coastal flooding during the afternoon high tides that will continue through at least Monday. A Coastal Flood Statement is in effect for all islands.
Some thunderstorms are possible over the offshore waters south of the islands Sunday night through Monday night, as an area of increased moisture and instability moving from east to west.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov