Photo Credit: Jason Weingardt

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 86 near the shore to around 74 above 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 70 to 75 near the shore to around 61 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 83. East winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 68 to 74. Northeast winds 15 to 20 mph. Chance of rain 70 percent.

Tuesday: Breezy. Cloudy with numerous showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 83. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Breezy. Mostly cloudy with scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Cloudy and breezy. Numerous showers in the evening, then showers after midnight. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds 10 to 20 mph. Chance of rain 80 percent.

Tuesday: Breezy. Cloudy with showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 20 mph. Chance of rain 80 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 76 to 85. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Cloudy in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 76 to 85. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 76 to 84. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 75. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Breezy. Cloudy with numerous showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 84. East winds 10 to 20 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

A high pressure system far to the north of the Hawaiian Islands will continue to produce moderate to locally breezy easterly winds across the region through Saturday. Expect typical trade wind weather with brief periods of showers favoring windward and mountain areas, mainly in the overnight to early morning hours. Isolated showers are possible over leeward locations. An upper level trough currently northwest of the islands will produce high clouds over the region through much of the week, enhancing sunrise and sunset colors.

Discussion

In the big weather picture around the islands a high pressure system positioned far to the north of the state will continue to drift slowly eastward. In the upper levels a weak ridge over the islands will limit shower activity today with trade wind inversion heights shown on the 2 AM HST morning soundings in the 5,000 ft (Lihue) to 7,000 ft (Hilo) range. An unsettled low level cloud band drifting in on the trades later today may bump up showers just a bit from the tonight through Tuesday morning time period. An upper level trough far northwest of the state shown on satellite water vapor imagery is interacting with a weak subtropical jet to spread high level cirrus (ice crystal) clouds across the region.
Expect a progressive west to east moving weather pattern far north of the islands, with high centers and cold fronts passing from west to east through the weekend. The current high pressure center far north of the islands this morning will continue to slowly drift eastward as a cold front also drifts eastward into the Central Pacific basin. The ridge over the state will move closer to the islands, briefly strengthening the trade winds today and Tuesday. Moderate to locally breezy trade winds will continue into the weekend as two additional high pressure system pass eastward, far north of the island chain. Trade winds will trend more east- northeasterly from Wednesday onward.
Weather-wise we will continue to see typical trade wind weather each day for the next seven with trade wind inversion heights ranging from 6,000 to 8,000 feet. An upper level trough, currently northwest of the state, will move over the islands from Tuesday to Wednesday with not much impacts for local area weather. Overall passing showers will remain in the forecast into the weekend, mainly affect windward and mountain areas with higher rainfall amounts in the overnight to early morning hours. Leeward areas will see drier conditions with only isolated showers in the forecast. One wrinkle in this weather forecast will occur from tonight into Tuesday morning as rainfall coverage will increase due to an unsettled low level cloud band drifting into the islands on the easterly trade winds.

Aviation

Moderate to locally breezy trades will prevail during the next 24 hours, strongest during the late morning and afternoon hours where some gustiness can be expected. Showers will favor windward slopes and coast, with a few showers reaching leeward communities at times. Brief MVFR cigs/vsbys will be possible in windward areas when showers move through, but predominantly VFR conditions are expected today. A band of enhanced moisture moving into the islands tonight could bring some more widespread MVFR conditions to windward locales.
AIRMET Tango remains in effect for low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue for the next couple days. AIRMET Sierra may be required for mountain obscuration tonight.

Marine

A strong surface high pressure system far north-northeast of the islands is maintaining a tight pressure gradient across the region, which is producing locally strong trade winds. Therefore, a Small Craft Advisory (SCA) remains in effect for the typically windier waters adjacent to the islands of Maui County and the Big Island through Tuesday afternoon. The SCA has just been added for the remaining waters adjacent to Maui County through Tuesday afternoon. The surface high that is currently far north-northeast of the islands will move slowly southeast to a position far northeast of the area during the next few days. A new surface high will move to a position far north of the state later this week, which will maintain the locally strong trade winds. The latest forecast indicates the SCA will continue to be needed over the typically windier waters near Maui County and the Big Island from Tuesday night into Friday.
The locally strong trade winds in the vicinity of, and upstream of the islands, will likely maintain slightly elevated, rough surf along east facing shores into mid-week. Surf heights may trend down along east facing shores later this week assuming there is a slight weakening of the trade winds.
The latest wave model guidance does not show any large north or northwest swells through Friday. Small, medium-period north- northeast swell energy may persist into Wednesday. A slightly larger, medium-period reinforcing north-northeast swell may arrive early Thursday, and could provide a modest boost in surf heights along most north facing shores from Thursday into Friday. Looking ahead to next weekend, a large northwest swell arriving late Friday night or early Saturday may cause surf to reach the High Surf Advisory criteria along most north and west facing shores of the smaller islands starting Saturday. Elsewhere, surf along south facing shores will gradually lower through the end of this week. A small, long-period south-southwest swell, which may arrive late Friday, could potentially provide a noticeable boost in surf heights along south facing shores next weekend.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov