Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Highs around 79 near the shore to around 65 above 3000 feet. Northeast winds up to 15 mph.

Tonight: Partly cloudy. Lows around 63 near the shore to around 53 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight.

Sunday: Mostly sunny. Breezy. Highs around 78 near the shore to around 64 above 3000 feet. Northeast winds up to 20 mph.

South Kaua’i

Today: Mostly sunny. Breezy. Highs 75 to 80. Northeast winds 10 to 20 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 62. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Scattered showers in the morning. Highs 74 to 79. Northeast winds 15 to 25 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Partly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 68 to 74 in the valleys to around 58 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 30 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 55 to 61 in the valleys to around 51 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 67 to 74 in the valleys to around 57 above 4000 feet. Northeast winds up to 20 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 68 to 78. Northeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 56 to 65. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny. Breezy. Scattered showers in the morning. Highs 68 to 78. East winds 10 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Partly sunny in the morning, then mostly sunny with isolated showers in the afternoon. Highs 68 to 78. North winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 56 to 67. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Sunday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 67 to 77. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Lingering clouds and showers in the wake of a cold front will continue over portions of Maui County and the Big Island into Saturday. Cool,northerly winds will persist across the state through the weekend, and turn more easterly early next week.

Discussion

Breezy NNE trades have filled in behind the surface front which has advanced east of the islands. Deeper moisture, however, lags the surface portion of the front and is bringing overcast skies and showers to windward portions of Maui County and the Big Island. Meanwhile, much drier and cooler air is noted upstream over the smaller islands where dewpoints have fallen into the 50s and boundary layer cu is quite shallow beneath the strengthening inversion. Yesterday afternoon's and this morning's soundings out of Lihue and Hilo highlight this contrast in airmasses with high moisture content through 10kft noted at the latter while Lihue was well-mixed, dry, and stable in the post-frontal environment. Cool and breezy conditions will continue through the weekend, especially from Maui westward. High pressure will steadily build into the area during this time resulting in gradual strengthening of trades which may become locally strong tonight into Sunday. The building high will also serve to erode the lingering frontal moisture band from west to east with windward showers hanging on the longest (likely well into the daytime hours today) over windward sections of the Big Island. Elsewhere, mostly dry conditions will prevail through the weekend and any showers will tend to be very progressive and on the lighter side.
Early next week will be characterized by trade winds weakening and veering to a more easterly direction as mid-level ridging advances east and deamplifies. The attendant high at the surface will sag southward toward the islands and will likewise weaken considerably causing trades to settle in the moderate category for the Monday through Wednesday period. Strong consensus exists in the global models that trades restrengthen for the second half of next week.

Aviation

Breezy northerly winds will continue to fill in behind an exiting cold front. Bands of low topped clouds and isolated showers off the Pacific will impact mainly north and northwest facing slopes and coasts. AIRMET Sierra for occasional mountain obscuration across windward portions of the Big Island north of Cape Kumukahi. This AIRMET will likely be canceled later this morning as drier air moves in from the northwest.
AIRMET Tango remains in effect for the Big Island due to occasional moderate turbulence downwind of higher terrain. This AIRMET will likely need to be expanded to include some of the smaller islands later today due to increasing wind speeds aloft. Winds are expected to veer to the northeast late tonight, ushering in a more typical trade wind pattern for the remainder of the weekend.

Marine

The recent extra-large NW swell will continue to gradually diminish as it becomes increasingly N today. A new N swell will arrive tonight and Sunday, driving another increase in surf heights along N facing shores. Surf along W facing shores will gradually decline through the weekend. The High Surf Warning has been cancelled. A High Surf Advisory is now in effect for N facing shores of most islands, and for the W facing shores of the Big Island. See Coastal Hazard Message (CFWHFO) for additional details.
The medium-period to long-period N swell expected tonight and Sunday has been generated by a potent but fast-moving low that passed N of the islands over the past 24 hours. The peak of the swell (conservatively estimated to be near 12 feet 14 seconds) will be tonight and Sunday, with peak surf heights along N facing shores approaching High Surf Warning-level heights of 25 feet.
This swell will gradually diminish Monday and Tuesday as the associated period lowers to near 12 seconds. A hurricane-force low now in the distant NW Pacific will result in a moderate, long- period NW swell that will arrive Monday through Wednesday, with peak surf heights below HSA heights.
A Small Craft Advisory (SCA) remains posted for all waters for winds and/or seas through Sunday. Although seas may briefly drop below 10 feet in some areas today, seas are expected to increase again tonight and Sunday as the new N swell arrives. Additionally, surface high pressure centered NW of the islands will move slowly E through early next week, driving fresh to locally strong NE trade winds. Gradually veering winds are expected early next week, diminishing Tuesday as the high weakens NE of the islands. A new high building far N of the islands may bring increasing E trade winds by midweek. A stable trade wind weather pattern will prevail into next week, with limited windward showers.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 AM HST early this morning for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
Wind Advisory until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 AM HST Sunday for all Hawaiian waters,

Data Courtesy of NOAA.gov