Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows 72 to 77 near the shore to around 63 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 89 near the shore to around 77 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs around 86. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 70 to 76. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 86. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.

Tonight: Occasional showers. Lows 63 to 68 in the valleys to around 58 above 4000 feet. East winds up to 15 mph. Chance of rain near 100 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 79 to 88. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 66 to 76. East winds up to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny with scattered showers. Highs 79 to 88. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with numerous showers. Highs 79 to 87. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with occasional showers. Lows 64 to 78. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 90 percent.

Tuesday: Partly sunny with scattered showers. Highs 79 to 87. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail across the islands through the work week and into the upcoming weekend. A slug of deep moisture will bring an increase in trade wind showers particularly to windward slopes and coasts as it moves from east to west across the islands today and tonight. Typical trade wind weather featuring mainly windward and mauka showers will return by Tuesday and continue through the upcoming weekend.

Discussion

Currently at the surface, a 1030 mb high is centered around 1500 miles north-northeast of Honolulu, and is driving moderate to locally breezy trade winds across the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions across the state, with cloud coverage the greatest in windward areas. Radar imagery shows numerous to widespread shower activity over windward areas from Oahu eastward, with scattered showers moving into windward Kauai. Main short term focus is on rain chances during the next couple days.
High pressure north-northeast of the state will drift westward to a location due north of the islands today, then remain nearly stationary through Thursday, keeping moderate to locally breezy trade winds in place. The high will shift eastward and weaken slightly Friday through the upcoming weekend, which could bring a slight easing in the trade wind speeds.
As for the remaining weather details, a mid-level trough will bring a slug of deeper moisture from east to west across the islands today and tonight. Showery weather can be expected in windward areas as this batch of deeper moisture moves through. We should see a return back to more typical trade wind weather beginning this afternoon over the Big Island and by Tuesday morning over Kauai. Typical trade wind weather featuring mainly windward and mauka showers and the occasional leeward spillover will then continue Tuesday through the upcoming weekend.

Aviation

High pressure centered far north of the state will maintain moderate to breezy trades over the next few days. A plume of deeper moisture is moving across the state this morning, affecting primarily windward portions of the islands, though the temperature inversion heights will remain elevated enough to allow occasional showers to pass over island terrain into some leeward areas. MVFR conditions, and isolated IFR, are expected in heavier showers through the morning. Elsewhere, VFR conditions are expected to prevail.
AIRMET Sierra is in effect this morning for mountain obscuration due to low clouds and showers for windward portions of the state except for Kauai, although it may need to be added later this morning. These conditions will persist through the morning and may improve by the afternoon.
With locally breezy trade winds prevailing across the state, AIRMET Tango remains in effect for low-level turbulence over and downwind of terrain. This AIRMET will likely continue through tonight.

Marine

Moderate to locally strong trade winds will hold through Thursday, as a strong surface high meanders far north of the islands. A Small Craft Advisory (SCA) has been expanded for all waters surrounding Maui County and the Big Island through tonight, and remains in effect for the typically windy waters around the Big Island and Maui County through Tuesday night. The SCA advisory may need to be extended through Thursday. The high will weaken and move eastward late Thursday and Friday, leading to a slight decline in the trades.
Surf across most shores will be below seasonal average through the week. Surf along east facing shores will remain choppy through Thursday due to persistent trades locally and upstream of the islands. A decrease in trade winds will cause east shore surf to decline Friday. South facing shores will continue to decline over the next few days. A small southwest pulse out of the Tasman Sea could produce a slight rise in surf Friday. Aside from trade wind wrap, surf along north facing shores will be minimal through Wednesday, and a tiny northwest swell will be possible Thursday or Friday.
The combination of seasonally high astronomical tides and water levels running around 6 inches higher than predicted will produce localized coastal inundation each afternoon through Tuesday. A Coastal Flood Statement has been issued to highlight these conditions.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Tuesday for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov