Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 89 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 69 to 74 near the shore to around 61 above 3000 feet. East winds up to 20 mph becoming 10 to 15 mph after midnight.

Monday: Mostly sunny in the morning then becoming partly sunny. Highs around 90 near the shore to around 76 above 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon.

South Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Highs 80 to 87. East winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 69 to 74. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Partly sunny. Isolated showers in the morning. Highs 81 to 88. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 87 in the valleys to 62 to 67 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 66 to 72 in the valleys to around 58 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Monday: Cloudy and breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 88 in the valleys to 63 to 68 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 90. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with isolated showers. Lows 65 to 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly cloudy with isolated showers. Highs 78 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 86. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with isolated showers. Lows 66 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly cloudy with isolated showers. Highs 75 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure system far north of the Hawaiian Islands will continue to gradually weaken and slowly drift west over the next several days. Trade winds will continue to blow at moderate to locally breezy levels today, and then decrease to more moderate wind speeds from Monday through Friday. A slight increase in cloud and shower trends remains in the forecast through the morning hours as a weak easterly wave continues to move through the islands. Otherwise, a high pressure ridge aloft will hover over the island chain this week, producing strong subsidence with stable conditions limiting shower activity.

Discussion

A weak easterly wave will slowly drift through the western islands this morning keeping a slight enhancement in the morning shower activity in the forecast. The trough will weaken and drift away from the state later this afternoon and evening as a more stable high pressure ridge build back in over the islands.
Expect more stable conditions under this ridge pattern with lower subsidence temperature inversion heights in the 4,000 to 6,000 foot range capping vertical cloud development and producing a sharp decrease in clouds and showers statewide. This drier weather pattern will continue through the week with only brief periods of showers over windward and mountain areas in the forecast, favoring the overnight to early morning hours. Upper level cirrus clouds associated with a subtropical jet stream will drift over the islands this week, enhancing sunrise and sunset colors.
The high pressure system far north of the islands will continue on its westward journey away from the state this week. Global models suggest a cut off low will embed itself in the broader ridge north of the state. This weaker ridge pattern will keep trade winds in the gentle to moderate range from Monday afternoon through Friday. In the extended range forecast, yet another high center builds in far northeast of the Hawaii region by Saturday with a slight increase to our trade wind speeds just in time for next weekend.

Aviation

Breezy trade winds will continue through tonight. Low clouds and showers will favor windward and mauka areas, particularly this morning, with a few showers spilling leeward at times. Conditions should improve in most areas by this afternoon.
AIRMET Sierra remains in effect for mountain obscuration over windward sections of Kauai Oahu Molokai and Maui. Condition should improve later this morning in most areas.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue through the day.

Marine

Strong surface high pressure north of the state will maintain fresh to locally strong trades through tonight. Thus, a Small Craft Advisory has been extended for the typical windier areas around Maui County and the Big Island through tonight. Trade wind speeds look to generally decrease into the gentle to fresh range by Monday as the aforementioned high drifts west.
A small, medium period south swell will continue to provide small surf along south facing shores today. A small long period south southwest swell (200 degrees) is forecast to arrive towards the middle of the week, which will bump up surf along south facing shores.
Surf along east facing shores will remain choppy with short period wind waves before slowly declining with the trade winds on Monday. Local wind swell may wrap into select north and south facing shores through the day. A tiny background west northwest swell could arrive late Tuesday into Wednesday providing a small bump for north facing shores.

Fire weather

Breezy trade winds and low relative humidity will keep elevated fire weather concerns over leeward areas today. Locations such as West Maui and leeward Kohala on the Big Island are of particular concern. Trade winds will remain in the moderate to breezy range today, and then trend down to more moderate levels from Monday through Friday as the pressure gradient over the state relaxes.
Most leeward areas will remain dry. Brief periods of showers will move into windward areas mainly in the overnight hours. Humidity levels will see good to excellent overnight recoveries. Exceptions to this humidity rule will be for elevations in the 4,000 to 8,000 foot range, which may see periods of warmer temperatures with much drier conditions, within and above the subsidence temperature inversion level.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov