Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly cloudy. Scattered showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs around 85 near the shore to around 75 above 3000 feet. Southeast winds up to 15 mph shifting to the south in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers and slight chance of thunderstorms. Lows 69 to 74 near the shore to around 60 above 3000 feet. South winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy with numerous showers. Highs around 84 near the shore to around 74 above 3000 feet. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

South Kaua’i

Today: Partly sunny. Scattered showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs around 84. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers and slight chance of thunderstorms. Lows 69 to 75. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Breezy. Mostly cloudy with numerous showers. Highs around 83. Southwest winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Numerous showers and slight chance of thunderstorms in the afternoon. Highs 73 to 79 in the valleys to around 68 above 4000 feet. Southwest winds up to 10 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers and slight chance of thunderstorms. Lows around 64 in the valleys to around 56 above 4000 feet. South winds up to 20 mph. Chance of rain 70 percent.

Monday: Breezy. Mostly cloudy with numerous showers. Highs 72 to 78 in the valleys to around 67 above 4000 feet. Southwest winds 10 to 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny. Numerous showers and slight chance of thunderstorms in the afternoon. Highs 75 to 84. South winds up to 15 mph shifting to the north in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers and slight chance of thunderstorms. Lows 64 to 72. South winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy with numerous showers. Highs 74 to 83. South winds up to 15 mph shifting to the southwest in the afternoon. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny. Isolated showers in the morning, then numerous showers and slight chance of thunderstorms in the afternoon. Highs 75 to 85. Southwest winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers and slight chance of thunderstorms. Lows 62 to 75. Southwest winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 70 percent.

Monday: Breezy. Mostly cloudy with numerous showers. Highs 74 to 84. Southwest winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Winds will pick up out of the south and southwest in advance of an approaching front today, with moderate south to southwest winds prevailing this afternoon through Monday night. Winds will diminish Tuesday and Tuesday night as the front stalls and fizzles out over the western or central islands. An increase in rainfall will be possible over the Big Island and Kauai from late Sunday night through Tuesday as a couple bands of moisture move into these islands, while drier conditions persist over Oahu and Maui County. A return to a land and sea breeze pattern is expected Wednesday through Friday, with showers possible near the coast at night and over the island interiors each afternoon. A new cold front could bring another round of showers and moderate northerly winds to the islands Friday night into next weekend.

Discussion

Currently at the surface, a weakening cold front is located around 250 miles northwest of Kauai, while a surface ridge is positioned over the Big Island. Light land breezes prevail across the entire state. Infrared satellite imagery shows partly to mostly cloudy conditions, with cloud coverage the highest over Kauai and the Big Island. Radar imagery shows scattered showers moving onshore over south Kauai, with the showers remaining generally off the coast of the other isles. Main short term focus revolves around wind trends and rain chances/thunder potential associated with an approaching front.
Winds will begin to pick up this morning as a front approaches from the northwest, with moderate south to southwest winds then prevailing this afternoon through Monday night. The front will stall and fizzle out over the western or central islands Tuesday and Tuesday night with surface ridging then building over or just north of the state Wednesday through Friday. This will bring a return of light winds with land and sea breezes dominant from Tuesday afternoon through Friday in most areas. A new cold front may push southward through the islands Friday night into next weekend, bringing a push of moderate northerly winds following its passage.
As for the remaining weather details, a few showers will continue to move onshore over Kauai this morning, and may move into the southern coasts of the other isles. Daytime heating should then drive another round of showers over the island interiors this afternoon, with coverage highest over Kauai as some deeper moisture overspreads the island in advance of the approaching front. In fact we will need to include a slight chance of thunderstorms on Kauai this afternoon do to a more unstable airmass moving overhead here.
The deepest moisture and greatest instability in association with the approaching front appears to remain north and west of the state tonight through early next week. Rain chances appear highest over Kauai during this time, and there remains a slight chance of a thunderstorm here Sunday night. Some deeper moisture may try to sneak northward into the Big Island Monday through Tuesday as well, bringing a bit higher shower coverage here along with the potential for an isolated thunderstorm each afternoon. Over Maui County, and to a lesser extent Oahu, drier conditions are expected during this time as these islands will remain in the dry slot between deeper moisture to the east and west.
A sea breeze/land breeze pattern appears to become re-established Tuesday night through Friday, with showers possible near the island coasts at night and over the island interiors each afternoon. A cold front could push southward through the islands Friday night into next weekend bringing a round of showers with it as it moves through.

Aviation

Light and variable winds this morning will become south southwesterly by mid-day ahead of an approaching frontal system. Weak instability aloft ahead of this feature, along with increasing moisture, will allow for scattered to numerous showers to develop over Kauai late this afternoon through tonight. There may be periods of MVFR ceilings and visibility associated with this activity. Isolated showers expected elsewhere across the state.
No AIRMETs are currently in effect.

Marine

Expect southerly winds to pick up today ahead of an approaching cold front. Moderate southwesterly winds will develop near Kauai and Oahu this afternoon and continue through Monday night as the weakening cold front stalls out over the western or central islands. A slight chance of thunderstorms remains in the forecast along the frontal boundary near Kauai through tonight. The front will weaken through Tuesday and a weak ridge will build just north of the state from Wednesday through Friday, bringing a return to light to locally moderate trade winds with some afternoon sea breezes along the near shore coastal waters.
Surf along exposed north facing shores will lower through this afternoon as a north swell eases. A new northwest (320 degree) swell will build in later tonight into Tuesday, then linger through Wednesday. Surf heights along both west and north facing shores are forecast to peak near or slightly below the High Surf Advisory thresholds on Monday and Tuesday.
Background surf expected along south facing shores until Monday morning when a long period south swell moves in and lingers through the rest of the week. Surf heights along east facing shores will remain small through much of next week due to light winds across the Hawaii Region.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov