Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 73 above 3000 feet. Light winds. Chance of rain 30 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 65 to 70 near the shore to around 56 above 3000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 73 above 3000 feet. Light winds. Chance of rain 30 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs around 82. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 69. Northeast winds around 10 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs around 82. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 72 to 79 in the valleys to around 63 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 56 to 61 in the valleys to around 51 above 4000 feet. Light winds. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers. Highs 72 to 79 in the valleys to around 63 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 84. Southeast winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 30 percent.

Tonight: Partly cloudy with scattered showers. Lows 59 to 69. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 84. East winds up to 10 mph. Chance of rain 40 percent.

East Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 83. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 57 to 70. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 83. East winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

The presence of weak ridging to the north will keep light to moderate trades in place, with localized land and sea breezes expected in the more sheltered areas through the middle of next week. Showers will favor windward slopes and coasts at night and interior and leeward areas each afternoon. A return to more typical trade wind weather featuring mainly windward showers and a few leeward spillovers is expected Thursday through next weekend, with trades possibly strengthening to moderate and breezy levels from Friday onward.

Discussion

Currently at the surface, a weak cold front is located around 500 miles north of Kauai, while a weak surface ridge is positioned around 250 miles north of Honolulu. The resulting gradient is producing light to locally moderate trade winds, strongest over the eastern end of the state, with land breezes present on Kauai and in leeward sections of the other islands. Infrared satellite imagery shows considerable high cloud cover resulting in mostly cloudy conditions over Oahu and Maui County, while partly cloudy skies prevail over Kauai and the Big Island. Radar imagery shows isolated to scattered showers moving into windward slopes and coasts, along with a few showers drifting leeward on Oahu. Elsewhere, mostly dry conditions prevail. Main short term focus revolves around rain chances and trade wind trends.
A series of weak fronts several hundred miles north of the state will shift east-southeast during the next couple days, weakening the ridge and displacing it southward and closer to the state. The trades will remain light to locally moderate through Monday, with overnight land breezes and daytime sea breezes expected in many leeward areas and even some windward sections over the western end of the state. The ridge to the north will strengthen slightly and lift northward Monday night and Tuesday, then hold steady through Wednesday. This should give trades a slight boost back to mostly moderate levels, although the gradient will likely remain loose enough to allow for localized sea and land breezes in the more sheltered leeward areas. The ridge will strengthen and lift northward Thursday, with trades possibly reaching moderate to breezy levels Friday through next weekend.
As for the remaining weather details, scattered morning showers mainly affecting windward areas should diminish and transition over to leeward areas this afternoon. Not much change in the forecast is then expected tonight through Wednesday, with showers favoring windward areas at night and interior and leeward areas each afternoon, although a bit higher shower coverage is possible Wednesday and Wednesday night as some deeper moisture moves in from the east. A return to more typical trade wind weather featuring windward showers and the occasional leeward spillover is expected Thursday through next weekend.
Periods of scattered to broken high cloud cover will continue to move overhead at times. The latest model guidance shows the high clouds thinning out today, then thickening up again tonight but refocusing over the eastern half of the state. Most of the high clouds should mostly dissipate Wednesday and Thursday, with some more high clouds possible at times Friday through next weekend.

Aviation

Gentle to locally moderate trade winds will continue for the remainder of the weekend. This pattern will maintain showers across windward areas. Light background winds will also allow for afternoon sea breeze clouds, along with an isolated shower, across sheltered leeward areas this afternoon. Mainly VFR conditions are expected through tonight, however brief MVFR conditions will continue this morning across some windward locations in heavier showers.
AIRMET Tango remains in effect for tempo moderate turbulence statewide between FL250 and FL350 due to upper level jet dynamics over the islands. The jet will linger around the state today, maintaining high clouds over the area.

Marine

Light to moderate easterly trade winds will continue through midweek as a weakness in the ridge to the north lingers. Despite the lighter winds, expect localized pockets of fresh breezes to develop near the coasts and over the windier locations, especially during the late morning and afternoon hours due to a combination of the orientation of the terrain, wind direction, and heating. Guidance shows a return of fresh to strong easterly trades by the end of the week.
Surf along south facing shores will remain small through the week with mainly a mix of background long-period south-southwest and south-southeast swells rolling through. As these sources fade by Thursday, another small background south-southwest swell is expected by Friday into next weekend.
Surf along north facing shores will remain near the seasonal average each day through the first half of the week. Although guidance does show a decent out of season northwest swell arriving late Wednesday, confidence is low at this point due to the source quickly lifting north-northeast over the far northwest Pacific later today through tonight.
Surf along east facing shores will remain small through the week due to the light trades locally and far upstream over the eastern Pacific.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov