Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 88 near the shore to around 76 above 3000 feet. Light winds. Chance of rain 20 percent.

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

Wednesday: Mostly cloudy. Breezy. Occasional showers in the morning, then showers likely in the afternoon. Highs around 85 near the shore to around 73 above 3000 feet. North winds up to 20 mph. Chance of rain 90 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs around 85. North winds up to 10 mph in the morning becoming light. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 69. Light winds. Chance of rain 20 percent.

Wednesday: Breezy. Mostly cloudy with showers likely. Highs around 82. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly sunny with isolated showers. Highs 75 to 82 in the valleys to around 66 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 56 to 61 in the valleys to around 51 above 4000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Breezy. Mostly cloudy with occasional showers. Highs 72 to 79 in the valleys to around 63 above 4000 feet. North winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 90 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 87. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 59 to 69. Southwest winds up to 10 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly cloudy with occasional showers. Highs 75 to 84. North winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 90 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 86. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 57 to 71. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 20 percent.

Wednesday: Mostly cloudy. Breezy. Occasional showers in the morning, then showers likely in the afternoon. Highs 75 to 83. North winds up to 20 mph increasing to 15 to 20 mph in the afternoon. Chance of rain 90 percent.

Detailed Forecast

Synopsis

Light winds and mostly dry weather will continue through today, with afternoon sea breezes bringing some clouds and a few showers to interior and upslope areas. A cold front is expected to move over the western islands on Wednesday, bringing a period of strong north winds and an increase in showers on Kauai and Oahu. The front will weaken into a trough and slowly shift westward Thursday through Friday, with showers favoring the western end of the state. Moderate to locally breezy trade winds and more typical windward and mauka focused showers will return over the weekend and hold in place through early next week.

Discussion

Currently at the surface, a cold front is located around 450 miles northwest of Kauai, while a 1020 mb high is centered around 1550 miles northeast of Honolulu with a ridge extending southwest to a position around 100 miles north of the Garden Isle. Observations indicate the presence of land breezes across the entire state early this morning. Infrared satellite imagery shows clear to partly cloudy conditions across most of the state, with a bit more cloud cover over portions of Kauai and the Big Island. Radar imagery shows rather dry weather with only a few showers brushing the windward coasts. Main short term concern revolves around the incoming cold front during the middle of the week.
Model guidance remains in good agreement showing the cold front approaching the state from the northwest today and tonight. The front is then forecast to push through Kauai Wednesday morning, Oahu Wednesday afternoon, then stall out and weaken over Maui County Wednesday night. Light winds will continue ahead of the front, with land and sea breezes dominant. Behind the front moderate to breezy trade winds will prevail. The front will weaken into a trough Thursday morning, then retrograde westward Thursday afternoon through Friday. Light winds will prevail Thursday with seas breezes developing in many areas. Moderate southerly flow is then forecast to develop Thursday night, tip southeasterly with trades gradually filling in across the eastern islands Friday and Friday night, with the trades then returning the western end of the state on Saturday. High pressure building north-northeast of the islands will then keep moderate to locally breezy trade winds in place Saturday afternoon through early next week.
As for the remaining weather details, rather dry conditions will prevail today. A few showers may move onshore into windward areas this morning, and a few may develop over the island interiors this afternoon. Dry conditions should continue tonight, with any shower activity remaining near the coast.
The cold front is forecast to bring some showery weather to Kauai Wednesday morning and Oahu by late Wednesday afternoon. Elsewhere, isolated to scattered sea breeze driven showers can be expected over Maui County and the Big Island Wednesday afternoon. Showers associated with the weakening front are expected to move into Maui County Wednesday night. As the front weakens into a trough and shifts westward Thursday through Friday, the shower coverage should be highest over the western half of the state, with drier conditions over the eastern islands. The pattern should transition over to a typical trade wind set up Friday night through early next week, with showers favoring windward slopes and coasts.

Aviation

A weak surface ridge located just north of Kauai, which is moving slowly southward, has caused the background trade wind flow to weaken. This light wind regime will continue through this evening, and will allow local nighttime land breezes and afternoon sea breezes to form over each of the individual islands. The atmosphere will also remain relatively dry and stable today.
The weak trade wind flow will transport some low clouds and brief trade showers into windward facing sections of some of the islands this morning. This may result in brief periods of MVFR conditions along windward facing slopes, but VFR will likely prevail across most of the state. By this afternoon, the sea breezes may produce increasing cloud cover over many leeward and interior sections of the island chain. However, shower activity is expected to be limited over most of the state.
No AIRMETs are currently in effect, and none are expected through this evening.
Looking ahead to early Wednesday morning, a front moving toward Kauai from the northwest will produce strengthening north winds over the far western end of the state. At the same time, the coverage of low clouds and showers may start to increase ahead of this front over portions of Kauai County and the adjacent waters.

Marine

Winds will be light to locally moderate through today as a weak surface ridge approaches the islands from the north. A front is then expected to reach Kauai by early tomorrow morning and Oahu tomorrow afternoon. Gusty north winds will fill in behind the front according to the most recent guidance, which will likely require a Small Craft Advisory (SCA). The front will weaken to a trough, and retreat west Thursday through Friday. Southerly winds will fill in behind the trough. A high will build far north- northeast of the islands over the weekend ushering the return of typical trade wind pattern.
The current northwest swell has subsided below High Surf Advisory thus the HSA has been cancelled. A larger, but shorter- period, north swell is expected to arrive tomorrow and may bring low-end advisory level surf to north facing shores tomorrow night and Thursday, before lowering Thursday night through Saturday. It will also likely bring SCA- level seas to exposed waters.
Small background south swells are expected through today, with a series of slightly larger, longer-period south swells expected tomorrow through Saturday. With no significant trade wind flow over and upwind of the state, most surf along east facing shores will be from north swell wrap through the week and slowly trend up over the weekend as trades return.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov