Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Sunny and breezy. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 69 to 74 near the shore to around 60 above 3000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Tuesday: Sunny. Isolated showers in the morning. Highs around 86 near the shore to around 74 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84. Northeast winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 67 to 73. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 83. East winds around 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 60 to 65 in the valleys to around 55 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 86. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 73. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 85. East winds 10 to 15 mph. 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 77 to 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 61 to 74. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 84. East winds around 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trade winds will continue this week with high pressure slowly tracking eastward. Scant trade showers will favor windward shores and slopes.

Discussion

High pressure to our north continues to rebound as troughing farther to the north lifts out. The pressure gradient remains steep enough to support breezy trade winds across local waters this morning. Ridging aloft keeps our airmass dry and stable, with overnight soundings showing strong inversions near 6300 feet along with PW around 1.2 inches and positive lifted index values. Satellite loop shows patchy broken to overcast low clouds across windward and mauka areas of Oahu and the islands of Maui County, with only scattered low clouds noted on Kauai. Cloud cover decreased significantly across the Big Island overnight, leaving patchy broken low clouds across windward shorelines and lower slopes. Radar shows only isolated light showers associated with this cloud cover.
Models show high pressure to our north will track eastward through the week, with a low shifting the high a bit southward by next weekend. Our weather pattern will change very little through the period, with minor fluctuations in wind speeds and mostly dry and stable conditions continuing. A few windward clouds and showers will occur at times, but no significant rainfall is expected through the week.

Aviation

High pressure and dry air is in place over the region. This should limit any SHRA activity to windward and mauka locations if at all. A strong inversion will keep cigs low allowing for periods of MVFR conds. VFR conds should reign supreme otherwise. Locally breezy trades will continue slightly increasing through the rest of today.
While conds are generally VFR across the area, AIRMET Sierra for mtn obsc may be needed.
AIRMET Tango is in effect for mod turb S and W of island terrain.

Marine

Fresh to strong easterly trades will continue through much of the week, as the surface ridge strengthens to the north. Guidance suggests a potential weakness forming in the ridge northwest of the state next weekend, which could lead to moderate to fresh east-southeast trades.
Surf along south-facing shores will hold around the advisory level today due to a long-period south-southwest swell moving through. No signs of any downward trend at the offshore buoys early this morning with the peak energy holding steady in the 15 to 17 second bands. As a result, the advisory may need to be extended through tonight. A downward trend is anticipated Tuesday through midweek, with mainly a mix of the fading south-southwest swell and a small, medium-period southeast swell. A similar long- period south swell is expected to arrive Thursday night into Friday, then peak late Friday into Saturday.
Surf along north-facing shores will remain up slightly through the first half of the week as small north to north-northwest pulses move through. The next north pulse should fill in today, with a small north-northwest swell arriving Tuesday into midweek. A return to summertime/flat conditions is likely later this week through next weekend.
Surf along east-facing shores should trend up later this week as the trades become established locally and upstream across the eastern Pacific.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai West, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov