Photo Credit: Braden Jarvis

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 71 near the shore to around 57 above 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 87 near the shore to around 75 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 85. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 70. Northeast winds around 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 84. Northeast winds around 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds 10 to 20 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 57 to 62 in the valleys to around 52 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 78 to 87. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with numerous showers after midnight. Lows 60 to 70. East winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 86. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 58 to 72. East winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 77 to 85. Northeast winds around 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Several high pressure systems passing far north of the islands will drift eastward through the week keeping moderate to locally breezy trade winds in the forecast through Saturday. Trade winds decrease from Sunday onward as a cold front approaches the islands from the north. A band of low level clouds drifting into the islands will increase shower coverage through the early morning hours. Otherwise typical trade wind shower activity will continue with drier trends each day and wetter trends through the overnight to early morning hours, favoring windward and mountain areas.

Discussion

A long band of unstable low clouds will continue to drift in on the trade winds this morning enhancing shower activity. Shower activity will trend lower later this morning. Subtropical jet stream cirrus is outlining a weak ridge over the state. An upper level trough lingers north of the islands. Another low level cloud band may enhance showers later tonight through early Wednesday morning.
in the large scale synoptic weather pattern we see progressive west to east moving weather systems far north of the islands. Two high pressure centers and cold fronts are passing far north of the island chain through the weekend. The ridge over the state will move closer to the islands and briefly strengthening the trade wind speeds today. Moderate to locally breezy trade winds will continue through Saturday as two additional high pressure systems pass by north of the state. Trade wind directions will shift to a more east-northeasterly direction from Wednesday onward. A cold front will approach the islands early next week. This frontal trough will weaken the ridge and moderate trade wind speeds from Sunday onward.
A typical trade wind weather pattern will continue for the next seven days 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 today through Wednesday with only slight increases to local rainfall coverage. 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.

Aviation

Moderate to locally breezy trade winds will continue during the next 24 hours, strongest during the late morning and afternoon hours when gustiness can be expected. A band of low clouds and showers will continue to affect the islands this morning. Periods of MVFR cigs/vsbys can be expected in windward areas with showers reaching leeward areas more frequently as well. Conditions should improve with prevailing VFR conditions statewide by late this morning or early this afternoon.
AIRMET Sierra remains in effect for mountain obscuration over windward sections of most islands. This AIRMET will likely continue through mid morning before conditions improve. AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely remain in place for the next few days.

Marine

High pressure ridging will remain north of the area into the weekend. Under this regime, trade winds will remain fresh to strong, with a Small Craft Advisory (SCA) continuing in effect for most waters around Maui County and the Big Island through Wednesday afternoon. However, the SCA will likely be extended beyond that time frame.
The 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.
A series of small to moderate north-northeast swells are expected through Friday. These swells were mostly aimed east of the state so there is a larger margin of error during the next several days. We should see a small, medium-period north-northeast swell begin to arrive later today, followed by a slightly larger pulse Thursday. These swells should provide a modest boost in surf heights along most north facing shores and select east facing shores from Wednesday through Friday. Looking ahead to the weekend, a large northwest swell arriving late Friday night will likely cause surf to reach the High Surf Advisory criteria along most north and west facing shores of the smaller islands starting Saturday. Exposed areas could also see seas reaching the Small Craft Advisory threshold of 10 feet during the peak of the swell sometime late Saturday through Saturday night.
Surf along south facing shores will remain small through most of this week with minimal background energy. A small, long-period south-southwest swell, which may arrive as early as Friday, could potentially provide a noticeable boost in surf heights along south facing shores this weekend.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov