Photo Credit: Braden Jarvis

West Kaua’i

Today: Sunny. Highs 87 to 93 near the shore to around 79 above 3000 feet. East winds up to 15 mph.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 73 near the shore to around 63 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Monday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 85 to 91 near the shore to around 76 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning. Highs 85 to 92. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows 71 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 84 to 91. East winds up to 10 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 86 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 71 in the valleys to around 60 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs 75 to 84 in the valleys to around 67 above 4000 feet. Light winds becoming northeast up to 15 mph in the afternoon. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 79 to 90. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 75. Southeast winds up to 15 mph. Chance of rain 30 percent.

Monday: Mostly sunny with isolated showers. Highs 78 to 88. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with scattered showers in the morning, then sunny with isolated showers in the afternoon. Highs 77 to 89. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows 65 to 78. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 40 percent.

Monday: Mostly sunny with scattered showers. Highs 76 to 88. East winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will deliver passing clouds and showers through today, mainly to windward and mauka areas. Winds will become light Monday through the week, with overall drier conditions and limited showers over interior areas during each afternoon.

Discussion

A high pressure ridge north and northeast of Hawaii will continue to drive breezy trades today. A fairly typical and relatively benign trade wind weather pattern remains in place today. This morning sounding looks relatively more stable than the sounding yesterday, and precipitable water measurements have also declined slightly more towards normal. Satellite imagery show isolated thunderstorms have stayed just northwest of the coastal water region overnight. Radar imagery show clouds and scattered showers embedded in the tradewind flow and focusing along windward and mauka areas with dry and mostly clear conditions along leeward areas.
Trade wind speeds will slowly diminish today and tonight as a surface low pressure system to the distant northwest moves east and weakens the ridge. A weakening front associated with the low will draw closer to the islands and the surface ridge will move over the islands. A mid- level ridge will also build over the area from the west starting Monday, further contributing to a mostly dry, light wind pattern through the first half of next week. Some interior and upslope clouds may develop in response to daytime heating, but little in the way of rainfall is expected, with mostly clear nights and mornings.
Depending on the evolution of the parent low north of the islands, the weakening front may move over the western portion of the state during the second half of the week. However, there is still considerable differences with timing with model guidance. Either way, the recent persistent trade wind flow will have an extended absence.

Aviation

Moderate to breezy trade winds will gradually trend weaker later today, but should stay predominate with land/sea breezes not expected until Monday or Tuesday. Clouds and showers will primarily focus on the windward and mountain areas, with the greatest coverage and intensity during the overnight through early morning hours. Brief periods of MVFR ceilings and visibility will be possible with any of the heavier showers.
AIRMET Tango remains in effect for tempo moderate turbulence below 9000 feet for areas downwind (south through west) of island terrain. This AIRMET will likely remain in effect through mid day and then conditions should begin to improve during the afternoon or evening hours.

Marine

A high far north-northeast of the main Hawaiian Islands will continue to drive moderate to locally strong trades across coastal waters through today. The Small Craft Advisory (SCA) for the typical windier waters near Maui County and the Big Island has been extended through tonight. By Monday, a low far to the northwest will push the ridge south, causing winds to weaken. Weaker winds will persist through much of the new week. An upper low continues to generate thunderstorms over the northern offshore waters which may recur over the next several days.
A medium period northwest swell is expected to arrive today, peak tonight and Monday, then slowly subside Tuesday. A slightly larger northwest medium period swell will arrive late Tuesday, then persist through Thursday. Trade winds near and upstream of the islands will continue to bring short period, choppy surf to east facing shores through today, but expect this to drop off Monday as winds weaken. A series of background southerly swells will continue over the next several days. A small long period south swell will arrive Monday night and linger into Thursday. Another small long period south swell will arrive Friday. A slightly larger medium period southeast swell arriving at the same time as the first long period south swell will help boost surf along south facing shores.

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