Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Highs 82 to 87 near the shore to around 73 above 3000 feet. Southeast winds up to 10 mph.

Tonight: Partly cloudy. Lows 65 to 71 near the shore to around 57 above 3000 feet. East winds up to 10 mph in the evening becoming light.

Thursday: Mostly sunny. Isolated showers in the late morning and afternoon. Highs around 83 near the shore to around 71 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 81 to 87. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows around 66. Light winds.

Thursday: Partly sunny early in the morning, then mostly sunny with isolated showers in the late morning and afternoon. Highs 80 to 86. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 74 to 80 in the valleys to around 65 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 59 to 64 in the valleys to around 55 above 4000 feet. Light winds. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the late morning and afternoon. Highs 72 to 78 in the valleys to around 63 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 75 to 84. Southeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 61 to 69. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Mostly sunny. Isolated showers in the late morning and afternoon. Highs 73 to 83. Light winds. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 73 to 84. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 59 to 71. Light winds. Chance of rain 20 percent.

Thursday: Partly sunny early in the morning, then mostly sunny with isolated showers in the late morning and afternoon. Highs 72 to 83. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate trades will trend southeasterly and weaken tonight. A land and sea breeze pattern will become established during the latter half of this week. Rainfall will be limited as dry and stable conditions continue into next week.

Discussion

Current radar trends show the areal coverage of showers has increased slightly early this morning, as an area of moisture moves into the region underneath the low level inversion in place (12z sounding data HTO/HLI) across the islands. This moisture has helped increase the shower coverage in the vicinity of the Big Island and Maui County this morning. Overall, expect some showers to continue around the islands this morning as the area of moisture moves through. However, Satellite imagery continues to show dry air (PW values ~1.00 inch) streaming in from the east, which matches well with 12z sounding data from HTO, showing PW values around 0.90″. Light to moderate easterly trades will focus clouds and showers across mainly windward and mauka areas into tonight.
The pattern remains persistent this week, with surface and upper level ridging anchored over the islands continuing deep layer subsidence. This pattern will maintain dry and stable conditions across the islands this week, with moisture depths ranging from 4-6k ft. A cold front will approach the area from the northwest Thursday and disrupt the trade wind flow across the islands. The front will weaken and quickly exit northeast, allowing light to locally moderate ESE trade wind background flow to redevelop across the state Friday through the weekend. The light background wind field, will allow for the development of a hybrid trade wind and sea breeze pattern. This pattern will promote afternoon sea breeze clouds along with isolated showers, across sheltered leeward and interior areas, especially across the western and central islands. However any afternoon clouds or showers that do develop, will quickly clear during the diurnal transition toward evening land breezes.
Next week…the airmass remains stable and mainly dry through the first half of next week. However, forecast moisture depths will increase slightly across the western end of the state in advance of another cold front approaching Kauai from the northwest. This may help increase the chance for showers, though precipitation will remain limited as stable and dry conditions continue.

Aviation

Light to moderate east to east-southeasterly flow will persist across the islands this morning as a ridge of high pressure remains anchored northeast of the state. A relatively dry atmosphere will prevent much in the way of precipitation. Thus, expect mainly partly cloudy skies with isolated light showers along the windward coasts and slopes. Dry weather with VFR conditions elsewhere.
No AIRMETs are currently in effect.

Marine

Moderate to locally fresh easterly trade winds will occur through the day as the region falls about 200 miles south of surface ridging. Trades will gradually ease and veer more southeasterly going into tomorrow (Thursday) as the ridge weakens from the west. The ridge axis will be pushed toward the islands by an approaching cold front northwest of the area Thursday. This will cause Thursday's winds to further drop off and become variable, especially over the western end of the state. The weakened front will pass across the far northern offshore waters Friday as high pressure moves north of the area. This will introduce a brief period of strengthened trades Friday. A surface ridge trailing the high will be pushed toward the islands New Years weekend. This will result in gentle to moderate east to southeast breezes.
The current west northwest swell will be holding steady through the morning. A pair of increasingly larger west northwest swells will pass around the islands the remainder of the week and into the beginning of the new year. The first of these west northwest (300-310 degree) swells will be arriving through the day and is just showing up at the far offshore northwest buoys. This swell will lift surf through this afternoon into evening and produce High Surf Advisory level surf along many north and west-facing Kauai-to-Maui shorelines Thursday and Friday. This moderate size, medium period swell may have just enough of a westerly component to sneak higher swell into Big Island's leeward waters and generate elevated west-facing shore surf later today and Thursday. A larger northwest (310-320 degree) swell is expected to build in New Year's Day and peak next Monday. East-facing shore surf will experience a small bump through the day in response to slightly increased trade flow.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov