Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Breezy. Highs around 83 near the shore to around 70 above 3000 feet. East winds up to 20 mph.

Tonight: Partly cloudy. Lows around 67 near the shore to around 58 above 3000 feet. East winds up to 15 mph.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 83 near the shore to around 70 above 3000 feet. East winds up to 20 mph.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 78 to 84. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 68. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tuesday: Partly sunny. Breezy. Isolated showers in the morning. Highs 78 to 83. East winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny. Isolated showers early in the morning, then scattered showers late in the morning. Isolated showers in the afternoon. Highs 69 to 76 in the valleys to around 62 above 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 70 to 77 in the valleys to around 62 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 72 to 82. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 61 to 70. East winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Breezy. Partly sunny with isolated showers. Highs 73 to 83. Southeast winds up to 20 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with isolated showers. Highs 70 to 80. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 61 to 72. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy with isolated showers. Highs 70 to 81. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy trades and typical trade wind weather will return today and persist through at least Wednesday, followed by the potential for increased showers later in the week.

Discussion

Satellite imagery and the latest surface analysis showed a weakness in the surface ridge north of the state due to a passing cold front. With the tail-end of this front stalling nearby to the northwest, a weak surface trough has formed around Oahu/Maui County. This pattern has disrupted the trades locally, which has led to light winds with northerly background flow setting up over the western end of the state and southeast flow over the eastern end. The recent upper air profiles at Lihue and Hilo reflected dry and stable conditions in place with a strong subsidence inversion, which has limited cloud and shower coverage.
Guidance shows the winds shifting out of the east through the day as high pressure builds to the north and the weak trough shifts west of the area. A weak shortwave trough passing through combined with a slight increase in moisture could be enough to trigger a few light windward showers this morning, especially for Kauai closer to the moisture axis/front and the central islands near the weak trough drifting westward. Otherwise, pleasant trade wind conditions are anticipated.
Upper heights will rise Tuesday through midweek as the upper trough exits to the east. This combined with the moderate to breezy easterly trades will support a more typical trade wind pattern continuing, with showers favoring windward and mauka locations overnight through the early mornings.
Trade winds may veer out of the southeast and ease slightly, and showers may increase as a mid-to upper-level trough approaches on Thursday and passes over the state on Friday. An increase in high clouds will likely accompany this feature.

Aviation

Light to moderate northerly winds will veer and strengthen to become moderate to breezy northeasterlies later this morning. With a relatively dry and stable airmass in place, shower activity will be limited through the period. However, a weak surface trough near Maui County and remnant moisture from an approaching and dissipating cold front may be enough to help support light showers across mainly windward areas today. In addition, smoke from New Year's Eve fireworks has temporarily dropped visibilities into the MVFR range or lower for a few areas, but these conditions will improve later this morning. Otherwise, VFR conditions will generally prevail, except for in any passing showers.
No AIRMETs are in effect and none are expected.

Marine

A weakening cold front will stall and dissipate just north of Kauai today. A high pressure system will build in north of the state through much of next week with moderate to breezy trade winds in the forecast each day through Tuesday. A Small Craft Advisory was issued this morning for the typical windier zones near Maui and the Big Island lasting through Tuesday. Winds will weaken slightly and shift from a more east to southeast direction with hybrid land and sea breeze elements from Wednesday through Sunday.
The current long period northwest swell will remain steady today and tonight, hovering near low end High Surf Advisory (HSA) thresholds. The current HSA was extended in time through this afternoon for most north and west facing shores of the smaller islands. Surf heights are forecast to fall just below advisory thresholds by this evening as the swell period continues to decline. A small north swell will also linger through the day today before fading by tonight. A series of reinforcing long period northwest swells will arrive this week, likely bringing north and west shore surf back into advisory levels Thursday through Friday.
South shore surf will remain on the small side over the next 7 days. East shore surf will remain small today, then build from Tuesday into next weekend as trade winds strengthen over and upstream of the island chain.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov