Photo Credit: Jason Weingardt

West Kaua’i

Today: Partly sunny. Isolated showers in the late morning and afternoon. Highs around 81 near the shore to around 68 above 3000 feet. Northwest winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 65 near the shore to around 55 above 3000 feet. Light winds becoming north up to 20 mph after midnight. Chance of rain 50 percent.

Friday: Breezy. Mostly cloudy with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 78 near the shore to around 63 above 3000 feet. North winds up to 25 mph shifting to the northeast 10 to 25 mph in the afternoon. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny with isolated showers. Highs around 80. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 63. Light winds becoming north up to 15 mph after midnight. Chance of rain 50 percent.

Friday: Windy. Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 79. Northeast winds up to 25 mph increasing to 15 to 30 mph in the afternoon. Chance of rain 60 percent.

Kaua’i Mountains

Today: Mostly cloudy. Scattered showers in the late morning and afternoon. Highs 72 to 78 in the valleys to around 63 above 4000 feet. Light winds. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 56 to 63 in the valleys to around 53 above 4000 feet. Light winds becoming north up to 20 mph after midnight. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 66 to 72 in the valleys to around 57 above 4000 feet. North winds 10 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 71 to 80. Light winds. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 57 to 65. Light winds becoming northwest up to 20 mph after midnight. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 67 to 77. North winds 10 to 25 mph. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny with isolated showers. Highs 73 to 81. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 58 to 67. North winds up to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny. Breezy. Numerous showers in the morning, then isolated showers in the afternoon. Highs 66 to 77. North winds 10 to 25 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

The winds will shift out of the north and remain light today, then increase as strong high pressure builds eastward behind a cold front expected tonight through Friday night. Showers will favor northern facing slopes along and head of the front moving through. Strong and gusty northerly winds will usher in much drier and cooler conditions behind the front Friday into the weekend. The winds will gradually shift out of the northeast on Saturday, then out of the east Sunday through early next week.

Discussion

Satellite imagery showed a moisture axis extending southward over the western end of the state this morning from a weak front passing to the north. Guidance has initialized well with this feature and shows it moving eastward through Oahu today, then to Maui County tonight. This weak boundary moving through combined with a shortwave trough and a developing cold front quickly approaching from the west will be enough to keep the rainfall chances in the forecast through tonight. The low-level flow will veer out of the north and remain light enough for late morning and afternoon sea breezes to form today.
Guidance depicts a dramatic change in conditions Friday through the weekend compared to what has been observed through the month of January. Gusty northerly winds ushering in drier and cooler air is anticipated through the day Friday as the aforementioned cold front advances eastward through the area and strong high pressure builds to the north. Dewpoints will dip well into the 50s late Friday, then remain in place through the weekend as the northerly winds gradually veer out of the northeast Saturday, then out of the east through the day Sunday.
A more typical breezy easterly trade wind pattern is expected through the first half of next week. The cool and dry air mass will steadily modify and moisten as the winds shift out of the east early next week, which supports increasing windward and mauka showers returning to the forecast.

Aviation

A surface trough ahead of a developing cold front will maintain increased cloud cover and isolated to scattered showers across the western end of the state early this morning. As the weak front develops and begins to progress down the island chain later today into tonight, clouds and showers will follow in its vicinity. Periods of MVFR conditions will be possible with this activity, especially this evening, but VFR conditions are expected to be predominate during the day. Winds will remain light this morning, become light to moderate during the day, then a surge of northerly winds will fill in tonight into Friday morning.
No AIRMETs are currently in effect. Depending on how widespread the showers and lower clouds become later today and tonight, AIRMET Sierra for mountain obscuration may be needed for portions of the western end of the state. AIRMET Tango for low level turbulence to the south and west of island terrain may be needed just beyond the forecast period when the northerly winds pick up.

Marine

A weak ridge over the islands and a trough near Oahu will keep background winds light across the coastal waters through the morning hours. Shower activity will pick up over the western islands later this morning with shower activity increasing statewide from tonight into Friday as the next front sweeps through the Hawaiian Islands. A strong high pressure system will build as it passes north of the islands, resulting in strong to gale force trade winds returning to the island chain this weekend. The strongest winds will be over the eastern channels, Maalaea Bay, and waters south of the Big Island. Small Craft Advisories will be issued statewide on Friday, and Gale Warnings may be needed by this weekend for the windiest waters.
A large, medium period northwest swell is declining below High Surf Advisory (HSA) thresholds this morning. Surf heights will briefly remain below HSA levels through tonight. Two overlapping north to north-northeast swells will move into the Hawaii region starting later today and lasting through this weekend. The larger north-northeast swell originating from a storm force low near the Gulf of Alaska will become the dominant swell from tonight into the weekend. This swell will likely produce advisory to warning level surf along all exposed north facing shores. Given the strong trade winds and the rising large north-northeast swell direction. Impacts are also likely for exposed northern harbors, including harbor surges at Hilo and Kahului.
Surf along east facing shores will remain small through today due to the lack of trade wind flow and smaller swell heights. Rapidly building surf is forecast along east facing shores from tonight into next week as the north-northeast swell builds and strong trades return. Surf heights will also reach solid HSA levels along exposed east facing shores from Friday to Sunday. South shore surf will remain small through early next week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov