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 shifting to the southwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 73 to 78 near the shore to around 64 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs around 90 near the shore to around 78 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with scattered showers. Highs around 88. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 71 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 87. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 85 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 69 in the valleys to around 59 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 84 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly sunny with scattered showers. Highs 81 to 90. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 77. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 80 to 89. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 81 to 89. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 78. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 80 to 88. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate trades will continue across the islands today as a ridge of high pressure remains anchored to the northwest of the state. Trades will become breezy Tuesday through Thursday as high pressure builds to the distant north and Tropical Storm Greg passes by to the south. The trades will ease into the light to moderate range Friday through the weekend. Rather dry trade wind weather will prevail through the forecast period. Shower activity will remain confined primarily to windward slopes and coasts, with a few showers reaching leeward communities at times.

Discussion

Currently at the surface, a 1024 mb high is centered around 850 miles northwest of Kauai, while a weak trough is positioned around 300 miles north of Honolulu. Meanwhile, Tropical Storm Greg is located around 1100 miles east-southeast of the Big Island. The gradient locally continues to drive moderate trade winds across the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions in windward and mauka areas, with mostly clear to partly cloudy skies in leeward locales. Radar imagery shows scattered showers moving into windward slopes and coasts, with a few showers spilling into leeward communities at times. Main forecast focus revolves around rain chances and trade wind trends during the next few days.
The overall weather pattern will change little today, with a weak high remaining northwest of the state and a weak trough holding in place to the north. This should keep trades at moderate strength. The trades are expected to strengthen to breezy levels Tuesday through Thursday as the pressure gradient tightens in response to a strengthening high north of the state and a Tropical Storm Greg passing westward well to the south of the island chain. This scenario continues to appear significantly different than what was experienced during Dora. The winds are expected to be much weaker as high pressure will be displaced much farther north, inversion heights not nearly as low, and the tropical cyclone not nearly as strong as Dora. The trades are forecast to ease back into the light to moderate range Friday through the weekend as the pressure gradient relaxes once again.
Rather dry trade wind weather will prevail through much of the next seven days. Shower activity will remain confined primarily to windward slopes and coasts during the late night and early morning hours, with a shower or two reaching leeward communities at times. A slight increase in shower coverage is expected tonight and Tuesday, particularly over windward portions of Maui and the Big Island as a band of moisture moves through. Another round of moisture associated with the remnants of Fernanda could increase trade wind showers late Sunday into early next week.

Aviation

Moderate to locally breezy easterly trade winds will continue through the 24-hr period, with clouds and a showers favoring windward and mauka locations, particularly at night and during the early morning hours. VFR conditions will prevail, with only brief periods of MVFR CIGS/VSBYS possible as showers pass through.
No AIRMETs are expected through the day.

Marine

A high pressure ridge north of the Hawaii region will keep moderate to fresh trade winds in the forecast for most areas today, with locally strong trades in the windier coastal waters and channels near Maui and the Big Island. The ridge will build far north of the region and produce moderate to strong trade winds from Tuesday through Thursday as tropical cyclone Greg passes well south of the island chain. Trades will trend lower from Friday into the weekend. A Small Craft Advisory was issued this morning for the windier waters and channels around Maui and the Big Island.
A lingering south-southwest swell will trend lower during the first half of the week. Small background south swell energy will keep surf heights small along south facing shores through the weekend. A small medium period north-northwest swell has reached buoy 51001 last night, the PACIOOS buoy at Hanalei, Kauai this morning, and is beginning to build at the Waimea buoy as of 3 AM HST. Surf heights along north facing shores will build today with some of this swell energy wrapping around into exposed west facing beaches of Kauai and Oahu. Surf heights along east facing shores will small and choppy due to increasing trade wind driven waves.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov