Photo Credit: Braden Jarvis

West Kaua’i

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

Tonight: Partly cloudy with isolated showers. Lows around 73 near the shore to around 62 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 91 near the shore to around 78 above 3000 feet. East winds up to 10 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 83 to 91. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

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

Tuesday: Partly sunny with scattered showers. Highs 82 to 90. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy with occasional showers. Highs 75 to 88 in the valleys to around 68 above 4000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Occasional showers. Lows 65 to 72 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Tuesday: Occasional showers in the morning, then showers likely in the afternoon. Highs 75 to 87 in the valleys to around 67 above 4000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

North Kaua’i

Today: Partly sunny with showers likely. Highs 78 to 91. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with occasional showers. Lows 66 to 75. East winds 10 to 15 mph. Chance of rain 90 percent.

Tuesday: Partly sunny. Showers likely in the morning, then isolated showers in the afternoon. Highs 77 to 91. East winds 10 to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 75 to 87. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Tonight: Showers likely in the evening, then occasional showers after midnight. Lows 66 to 77. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Tuesday: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 87. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Persistent high pressure far north of the islands will support locally breezy trade winds this week. Passing trade showers are nearly a certainty for most windward areas as showery low cloud clusters periodically move quickly through, with some showers occasionally spreading leeward.

Discussion

Persistent surface high pressure far N of the islands will support locally breezy trade winds for the foreseeable future. A developing trough aloft just N of the islands will bring some mid-level cooling the next couple of days, then change little as the trough lingers. This will lead to some weakening of the subsidence inversion, allowing incoming clouds to grow to greater heights. Passing trade showers are nearly a certainty for most windward slopes and coasts this week as showery cloud clusters periodically move quickly through, with some showers occasionally spreading leeward. Additionally, daytime heating will lead to afternoon showers over the Kona slopes. Significant rain totals are not expected as showers will be relatively short-lived.
TAFB surface analysis shows a weak 1014 mb surface low, the remnants of what was once T.S. Emilia, centered about 1300 miles ENE of the islands. GOES ProxyVIS imagery helps to view the associated showery low cloud swirl, with a large area of broken to overcast closed-cell stable stratocumulus clouds between the islands and the low. As this stable cloud field edges closer to the islands, the clouds are thinning in coverage while becoming increasingly open-celled and showery. While a significant increase in PWAT is not anticipated the next couple of days, continuing values near 1.4″ will ensure that trade showers will be fairly active, especially night and morning.
Guidance indicates that the low will weaken to a trough today as it continues to track W in the trade flow, with the trough expected to dampen out as it nears the longitude of the islands Thursday and Friday. Its passage may bring minor fluctuations in trade wind speeds and direction. Guidance has been inconsistent as to whether or not associated increased PWAT will move over the islands.

Aviation

Moderate to locally breezy trades will remain in place through the new work week. Low cigs and SHRA should favor windward and mauka locations, with occasional spillover to leeward areas. Brief MVFR conds possible with SHRA but otherwise VFR should prevail.
While no AIRMETs are currently in effect, AIRMET Sierra may periodically be needed for mtn obsc due to low cigs and SHRA, particularly overnight and in the early morning hours over the course of this week.

Marine

An area of surface high pressure north-northeast of the state will remain relatively stagnant over the next several days. This feature will continue to produce moderate to locally strong trade winds across the local waters. A Small Craft Advisory has been extended through Wednesday morning for the typically windier waters around Maui County and the Big Island and will likely get extended through late this week.
A 2 to 3 foot south swell can still be observed this morning at the nearshore buoys, with most concentrated energy in the 12-14 second range. As a result, south shore surf will likely remain slightly elevated this morning, before gradually declining by this afternoon. The next small, long- period south swell is expected to arrive mid- day Tuesday and peak Wednesday into Thursday morning. This swell will produce another small boost in surf along south facing shores before declining through the rest of the week.
Nearly flat to tiny surf expected through this week for beaches along north facing shores, typical for this time of year. Nearshore buoys indicate swell energy out of the east in the 6-9 second range, due to increasing trades. Persistent moderate to locally strong trades will bring choppy east shore surf through much of the week.

HFO Watches/Warnings/Advisories

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