Photo Credit: Jason Weingardt

West Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 65 to 70 near the shore to around 56 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Veterans Day: Sunny with isolated showers. Highs around 86 near the shore to around 74 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 83. Northeast winds around 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 63 to 69. Northeast winds around 15 mph. Chance of rain 50 percent.

Veterans Day: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 83. Northeast winds 15 to 20 mph. Chance of rain 40 percent.

Kaua’i Mountains

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

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 56 to 61 in the valleys to around 51 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 60 percent.

Veterans Day: Breezy. Partly sunny with scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 76 to 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 59 to 69. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Veterans Day: Breezy. Mostly sunny with scattered showers. Highs 76 to 85. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 76 to 84. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 57 to 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Veterans Day: Breezy. Partly sunny with scattered showers. Highs 76 to 84. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will focus passing band of low clouds and showers over windward and mountain locations. Expect more showers during the overnight and early morning hours. Winds will weaken some tonight, but increase again tomorrow.

Discussion

As anticipated, no major changes to the forecast with the morning package.
A 1027 mb high pressure system is far northeast of the islands early this morning and continues to move to the east. A gale force low is to the northwest of the islands, with a dissipating cold front extending southwest from the low. A north to south surface trough is to the east, associated with an upper level low. This upper level feature is expected to linger to the east of the islands over the next several days. A 1023 mb high far north- northeast of the region is moving to the east, and will be replaced by yet another high to the northwest of the islands tomorrow. The trough to the east of the islands is helping to turn the trades to a more northeasterly direction, and tightening the pressure gradient over the islands.
Expect winds to remain breezy today, but then relax a little overnight in many locations as the winds shift to a more northeast direction. Winds are expected to increase again tomorrow as the new high settles in north of the islands.
The overnight soundings show precipitable water (PW) values remaining near 1 inch, which is on the dry side of normal. The satellite derived PW shows drier air immediately upstream of the islands. An area of increased moisture upstream of the smaller islands will be carried in on the trades later tonight. An upper trough associated with the above mentioned gale low has sparked some thunderstorms over the offshore waters to the northeast of the islands overnight. That trough axis is expected to remain to the northeast, so not expected the instability from that to reach the islands. Despite the lower than normal PW values, clouds and showers will be carried in on the trades from time to time through the weekend. As is typical, expect more shower activity during the overnight and early morning hours.
Heading into Sunday, a cold front will begin to approach the islands from the northwest. As it does, we can expect the ridge to the north to weaken, resulting in a downward trend to our winds. The front will also bring an increase in low level moisture that will likely boost rainfall totals over the state from Sunday onward.

Aviation

Moderate to locally breezy trade winds will continue through today. This will maintain a typical trade wind weather pattern, focusing showers and lower clouds across windward areas. VFR conditions are expected across TAF locations through the period, however brief MVFR conditions are possible across some windward locations.
AIRMET Tango remains in effect for moderate low level turbulence below 8000 ft, over and downwind of terrain for all islands. This AIRMET will likely remain in place through today.
Additionally, there is an increasing trend toward a potential period of tempo moderate turb above FL340, in the vicinity of the Big Island, as upper dynamics increase across the eastern end of the island chain into this afternoon.

Marine

High pressure passing far north of the state will maintain fresh to strong trade winds through Friday afternoon. A Small Craft Advisory (SCA) thus remains in effect through that time frame for the typically windier waters around Maui County and the Big Island. A surface low developing far northeast of the islands and building high pressure to the northwest has been causing winds to back toward the northeast. Winds will then veer slightly toward a more typical trade wind direction and slowly ease Saturday through Monday as the surface ridge drifts closer to the state from the north.
Pulses of small to moderate north-northeast swell will continue during the next few days, with the larger portion of the swell and north shore surf expected to favor the Big Island during the next couple of days, followed by a pair of northwest swells this weekend and the middle of next week. A larger, shorter-period north-northeast swell, originating from the surface low northeast of the islands, will arrive tonight and continue through Saturday. The first sizable northwest swell of the season is expected this weekend. Surf may reach the High Surf Advisory criteria along most north and west facing shores of the smaller islands Saturday night and Sunday. Another northwest swell is due during the middle of next week.
Fresh trade winds upstream of the state are generating rough seas along east facing shores, though expect this wind wave energy to drop through the day. At the same time, east shores exposed to the north-northeast swell will experience little change in surf. A small south-southwest swell will arrive Friday night and may produce south shore surf a notch above seasonal average late Saturday and Sunday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov