Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 92 near the shore to around 80 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 74 near the shore to around 64 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers. Highs around 91 near the shore to around 79 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 83 to 91. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 75. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Sunday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 84 to 91. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Partly sunny with scattered showers. Highs 76 to 89 in the valleys to around 68 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 73 in the valleys to around 61 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 88 in the valleys to around 68 above 4000 feet. East winds 10 to 15 mph. Chance of rain 60 percent.

North Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 92. East winds up to 20 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy with scattered showers. Lows 68 to 76. East winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 91. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 76 to 88. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 78. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 75 to 88. Northeast winds 10 to 15 mph. Chance of rain 50 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.

Data Courtesy of NOAA.gov