Photo Credit: Brendan Stephen

West Kaua’i

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 87 to 93 near the shore to around 78 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Lows around 72 near the shore to around 62 above 3000 feet. East winds up to 15 mph.

Tuesday: Sunny. Isolated showers in the morning. Highs 87 to 93 near the shore to around 78 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 86 to 92. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Partly cloudy with isolated showers. Lows around 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 85 to 92. East winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly cloudy with occasional showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 76 to 86 in the valleys to around 67 above 4000 feet. East winds up to 10 mph. Chance of rain 80 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows 66 to 72 in the valleys to around 60 above 4000 feet. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 75 to 87 in the valleys to around 68 above 4000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

North Kaua’i

Today: Partly sunny with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 89. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 75. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 90. East winds 10 to 15 mph. Chance of rain 30 percent.

East Kaua’i

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 89. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 79. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 89. East winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

Moderate and slightly unstable trades will bring locally heavy showers to windward and mauka areas through the morning. More stable trades take over later this evening, becoming breezy to locally strong Wednesday and Thursday. A return to more typical trade pattern is expected Friday through the coming weekend.

Discussion

Water vapor satellite imagery early this morning shows the upper level trough northeast of the state continuing to move away to the northeast. This will allow drier mid-level air to move in from the east and showers to trend down over the eastern half of the state later this morning.
At the surface, a hybrid trade and land/sea breeze pattern continues. Current infrared satellite imagery and radar show mostly clear conditions over leeward areas of Maui County and the Big Island due to localized land breezes. For the remainder of the state, a weak shortwave trough embedded in the trades is moving westward across Kauai and Oahu, bringing increased showers into windward areas, with some clouds and a few showers making it over to leeward areas at times. Expect a gradual decreasing trend to the showers through late morning, as the shortwave exits off to the west of the state.
Winds will transition to a more stable flavor of trades later this evening through the remainder of the week, as mid-level ridging builds back in over the region. Trades are forecast to become breezy to locally strong around mid-week, in response to lowering pressure just north of the equator and an expansive, 1031 mb high centered northeast of the state near 35N. A more typical moderate to locally breezy trade pattern is expected to return Friday through the upcoming weekend.

Aviation

High pressure far northeast of the state will maintain moderate trade winds through Monday. Clouds and showers will favor mainly windward and mauka areas through the early morning hours. Afternoon sea breezes are once again expected to develop today, with scattered showers possible over terrain sheltered areas. Will see predominately VFR conditions with brief MVFR under passing showers.
No AIRMETs are currently in effect.

Marine

Moderate to fresh easterly trades will increase into the fresh to strong category Tuesday through the rest of the week. Small Craft Advisory conditions will be likely for the typically windier channels and waters around Maui County and the Big Island Tuesday, then for most exposed waters Wednesday into the second half of the week.
Surf along exposed north and west facing shores have been trending up overnight as a small northwest swell builds down the island chain. Observations at the Hanalei and Waimea PacIOOS buoys reflect this trend with the peak energy centered around the 12 second band. Expect this trend to continue with a peak expected later today. Guidance shows the swell lingering Tuesday out of the north-northwest, then easing through midweek. For the upcoming weekend, a small west-northwest (300-310 degrees) swell arriving will be possible. This will be in response to Tropical Storm Damrey racing eastward toward the Date Line from Japan over the next couple of days.
Surf along south facing shores will remain small throughout the week. A modest increase is expected tonight into Tuesday as a small south-southwest swell moves through the state. Another tiny long-period southwest swell is possible Friday into the weekend.
Surf along east facing shores will remain small through the first half of the week, then trend up through the second half as the trades ramp up locally and upstream of the state. Additionally, expect some groundswell mixed in with 10 second periods next weekend from Tropical Storm Irwin tracking westward across the eastern Pacific.

Fire weather

Breezy to locally strong trade winds will develop Wednesday and continue through Thursday. An initially moist airmass on Wednesday will eventually give way to an influx of much drier air arriving from the east late Wednesday and Thursday. Red Flag conditions, characterized by sustained winds of 20 mph or greater and afternoon RH values below 45 percent, will be possible on Wednesday, but more likely Thursday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov