Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly cloudy. Scattered showers in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy with showers likely and slight chance of thunderstorms. Lows 65 to 70 near the shore to around 56 above 3000 feet. Light winds. Chance of rain 70 percent.

Wednesday: Mostly cloudy with showers likely and slight chance of thunderstorms. Highs around 84 near the shore to around 73 above 3000 feet. Light winds. Chance of rain 70 percent.

South Kaua’i

Today: Mostly cloudy. Scattered showers in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Highs around 84. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy with showers likely and slight chance of thunderstorms. Lows 63 to 69. Light winds. Chance of rain 70 percent.

Wednesday: Cloudy with showers likely and slight chance of thunderstorms. Highs around 82. Light winds. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Isolated showers in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Highs 74 to 81 in the valleys to around 65 above 4000 feet. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy with showers likely and slight chance of thunderstorms. Lows 56 to 61 in the valleys to around 51 above 4000 feet. Light winds. Chance of rain 70 percent.

Wednesday: Mostly cloudy with showers likely and slight chance of thunderstorms. Highs 72 to 79 in the valleys to around 63 above 4000 feet. Light winds. Chance of rain 70 percent.

North Kaua’i

Today: Mostly cloudy. Isolated showers in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Highs 77 to 86. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy with showers likely and slight chance of thunderstorms. Lows 59 to 69. Light winds. Chance of rain 70 percent.

Wednesday: Mostly cloudy with showers likely and slight chance of thunderstorms. Highs 75 to 84. Light winds. Chance of rain 70 percent.

East Kaua’i

Today: Mostly cloudy. Scattered showers in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Highs 77 to 85. Light winds. Chance of rain 70 percent.

Tonight: Mostly cloudy with showers likely and slight chance of thunderstorms. Lows 57 to 71. Light winds. Chance of rain 70 percent.

Wednesday: Cloudy with showers likely and slight chance of thunderstorms. Highs 75 to 83. Light winds. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Humid conditions along with daytime sea breezes and nighttime land breezes can be expected during the next several days as a weak front remains in the vicinity of the western islands. A wetter weather pattern is expected during the next few days due to this front, with the potential for a few thunderstorms at times as well. A new cold front is forecast to move into the state Friday and Saturday, then stall out and dissipate over the central or eastern islands Sunday into early next week. The front is expected to bring a return of moderate trade winds and more typical trade wind weather back to the island chain.

Discussion

Currently at the surface, a 998 mb low is located around 975 miles north of Honolulu. This feature has eroded the ridging to the south, and is maintaining a light wind regime with land breezes prevailing in most areas early this morning. Infrared satellite imagery shows mostly cloudy conditions over the smaller islands, with partly cloudy skies over the Big Island. Meanwhile, radar imagery shows some light showers moving through Oahu and Kauai, with very little shower activity elsewhere. Main forecast concerns revolve around the potential for some more widespread rainfall and thunderstorms through Thursday.
A weak front is expected to gradually develop in the vicinity of the western islands today, then remain nearly stationary through Wednesday, before slowly edging eastward and dissipating Wednesday night and Thursday. A cold front is forecast to move southward into the state Friday and Saturday, before stalling out and dissipating somewhere over the central or eastern islands Sunday into early next week. Overall this pattern is expected to produce light winds for the next several days, with land and sea breezes common in most areas through Thursday. Trade winds could begin to fill in Thursday night, then strengthen to moderate levels late Friday through the weekend. The trades may then ease up again early next week.
As for the remaining weather details, the closed upper low north of the state will open up and lift northeastward today, but will quickly be replaced by a potent shortwave trough closing off into another slow moving closed low north of the islands on Wednesday, then shifting eastward Thursday and Friday. This will keep a steady influx of deep tropical moisture into the islands with precipitable water values in excess of 2 inches for the next couple days. Shower coverage should remain the highest over the western islands during the next couple days in closest proximity to the weak front, although daytime heating will allow for scattered shower coverage over the other islands as well. Additionally, a few infrequent rumbles of thunder will be possible over portions of the state at times through Thursday. The deeper moisture should begin to exit the region to the northeast on Thursday, with a new cold front forecast to bring a more typical trade wind weather pattern back to the islands Friday through next weekend.

Aviation

A light wind weather pattern will continue with deeper tropical moisture riding up from the southwest over the state enhancing clouds and showers across the island chain through Thursday. Local scale sea breezes will develop over each island a few hours after sunrise each day. Cloud trends will increase over mountains and island interior sections during the day, with additional cloud and shower bands drifting up from the south and southwest in the overnight to early morning time periods. Isolated thunderstorms may develop across the region.
All airfields will see brief periods of MVFR conditions as showers drift through the islands over the next few days. Lanai airport will also see brief periods of ceilings between 008 and 015 at times as low level clouds and showers move over the island. AIRMET Sierra remains posted for tempo mountain obscuration over all islands of Kauai, Oahu, Molokai and Lanai. Other islands may be added as to this AIRMET as local weather conditions could change rapidly today and tonight.

Marine

Low pressure north of the islands will result in continued light to gentle trade winds. As this low slowly moves north northeast the next couple of days, the weak pressure gradient to its south will maintain regionally light to gentle breezes through Thursday. While there will be little to no wind waves under this light wind regime, the passage of moderate size north swell through the day and again late this week will support more elevated seas.
The ongoing moderate size, medium period north swell will be trending down through the day as will north-facing shore surf. A late week north moderate, medium period swell will likely increase surf along north-facing shores to near or slightly above High Surf Advisory levels. Today's south shore surf will waver little under a very small, long period background south swell. A slightly larger, long period south swell arriving Wednesday will bump south-facing shore surf up by another foot or two during the second half of the week. Eastern shore chop will remain very small due to a lack of trades. East-facing shores better exposed to north swell wrap may experience a minor increase in surf today from a fading north swell and then again from a new north swell Friday and Saturday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov