Photo Credit: Brendan Stephen

West Kaua’i

Today: Partly sunny with isolated showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 84 near the shore to around 74 above 3000 feet. Light winds. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Lows 69 to 74 near the shore to around 60 above 3000 feet. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to around 74 above 3000 feet. Northeast winds up to 10 mph shifting to the south in the afternoon. Chance of rain 30 percent.

South Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 83. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows 69 to 74. Northeast winds around 10 mph. Chance of rain 40 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 83. East winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 72 to 78 in the valleys to around 67 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Lows around 64 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 40 percent.

Thursday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 72 to 78 in the valleys to around 67 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Partly sunny with isolated showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 74 to 83. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers early in the evening, then isolated showers in the late evening and overnight. Lows 64 to 72. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 74 to 83. East winds up to 15 mph. Chance of rain 30 percent.

East Kaua’i

Today: Mostly cloudy in the morning then becoming mostly sunny. Scattered showers. Highs 74 to 84. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 74. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 84. Northeast winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Light trade winds will prevail during the next few days, keeping showers confined to windward slopes and coasts at night, while a few showers develop over interior and leeward areas each afternoon. The trades will gradually strengthen and more showery conditions will develop over the weekend. The breezy and showery trade wind weather is then expected to continue through the middle of next week.

Discussion

Currently at the surface, a front is located around 350 miles north of Honolulu, with a weak ridge in between the front and the islands. This is resulting in light to locally moderate trades across the island chain early this morning, with land breezes present in some areas as well. Infrared satellite imagery shows mostly cloudy conditions across the state resulting from a combination of low clouds moving along with the trades and high clouds passing overhead. Radar imagery shows scattered showers moving into windward slopes and coasts with mainly dry conditions in leeward locales. Main short term focus revolves around rain chances and trade winds trends during the next few days.
A front north of the islands will shift slowly southward during the next few days, before stalling out near or just north of Kauai this weekend. The gradient will remain rather weak through Friday, with light to locally moderate trade winds prevailing. The winds will likely be light enough during this time for localized land and sea breezes to develop across the state. High pressure building to the distant north will gradually strengthen the trades over the weekend, with breezy to locally windy conditions expected by late Sunday and continuing through the middle of next week.
As for the remaining weather details, relatively dry conditions will prevail through the remainder of the work week. Light showers will favor windward slopes and coasts at night and during the early morning hours, with a few showers developing over interior and leeward areas each afternoon. The exception could be Thursday night and Friday as some frontal moisture may graze Kauai and some deeper tropical moisture may try to work into the Big Island bringing an increase in showers. Details are less clear over the weekend, the vast majority of the ECMWF ensembles favor a solution close to the parent ECMWF, which appears more reasonable than the GFS and will lean the forecast in this direction. Friday night and Saturday could remain relatively dry over the western islands, with some deeper moisture keeping some more showers in place over the eastern end of the state. Eventually, a front or its remnants appear to get caught up in the trades, which should bring some wetter trade wind weather to the entire island chain Saturday night and Sunday, with rather wet trade wind weather continuing through the middle of next week as a mid-level low passes westward just to the south of the state.

Aviation

A cold front far north of the state will slowly drift south and keep light winds in the forecast through at least Thursday. Lighter large scale winds will allow afternoon sea breezes and overnight land breezes to develop over all islands. This will result in some cloud build-ups over island interiors each afternoon, then clearing overnight. A weak ridge aloft will also produce stable conditions across the state with limited clouds and only a few showers possible.
No AIRMETs in effect and none are expected.

Marine

A surface ridge to the north will remain weak for the next several days as broad low pressure meanders well northwest of the state. Expect land and sea breeze conditions near the coasts, with diurnally driven accelerations potentially leading to fresh breezes during the afternoons. Moderate to locally strong trade winds will build over the state as the ridge strengthens to the north towards the end of the work week. Early next week, widespread fresh to strong easterly trade winds are expected and Small Craft Advisories (SCA) will be possible for many coastal zones.
North and east facing shores will trend up slowly late this evening as a short- to medium- period north-northeast swell builds in with reinforcing pulses out of the north- northeast keeping surf elevated through early next week. Guidance indicates this first pulse may bring surf to near High Surf Advisory (HSA) levels for east-facing shores (10 ft faces) as early as Thursday. Reinforcements Friday into Saturday will likely bring surf to HSA criteria for east shores while north- facing exposures are expected to remain below advisory levels (15 ft faces). An SCA will be likely also be issued for windward waters due to seas above 10 feet during the peak of the swell.
For the long-range, guidance shows a gale- to storm- force low tracking eastward from the Bering Sea to the Gulf of Alaska late tonight through Friday. If this materializes, a small long- period northerly swell could arrive late Sunday into early next week from this feature.
Surf along south facing shores will remain small, with predominantly a mix of short- to medium-period southeast and long- period south to south-southwest swells. A tiny to small long-period swell from the south- southwest, will hold today before declining Thursday. A slightly larger south swell is possible this weekend.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov