Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 83 near the shore to around 70 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then scattered showers after midnight. Lows around 67 near the shore to around 56 above 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs around 81 near the shore to around 69 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 83. East winds 10 to 20 mph. Chance of rain 60 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then occasional showers after midnight. Lows around 67. East winds 15 to 20 mph. Chance of rain 90 percent.

Saturday: Mostly cloudy. Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 76 to 81. East winds 15 to 20 mph. Chance of rain 90 percent.

Kaua’i Mountains

Today: Occasional showers in the morning, then showers likely in the afternoon. Highs 73 to 79 in the valleys to around 62 above 4000 feet. Southeast winds up to 15 mph. Chance of rain near 100 percent.

Tonight: Breezy. Occasional showers. Lows 59 to 65 in the valleys to around 54 above 4000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Saturday: Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 68 to 76 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 73 to 82. Southeast winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then occasional showers after midnight. Lows 59 to 69. East winds up to 20 mph. Chance of rain 90 percent.

Saturday: Mostly cloudy. Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 71 to 82. East winds up to 20 mph. Chance of rain 90 percent.

East Kaua’i

Today: Breezy. Partly sunny with numerous showers. Highs 71 to 81. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Occasional showers. Lows 60 to 71. East winds 10 to 20 mph. Chance of rain near 100 percent.

Saturday: Breezy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 68 to 79. East winds 10 to 20 mph. Chance of rain near 100 percent.

Detailed Forecast

Synopsis

Trade winds will prevail into next week, favoring an east-southeast direction through Friday. Winds will strengthen over the weekend, then remain breezy next week. Clouds and showers will favor windward areas, but some will occasionally spread to leeward areas of the smaller islands.

Discussion

A dry and stable mid-level airmass is entrenched over the islands at press time. This airmass is supported by a mid-level ridge that will gradually erode during the next 24 hours or so as a zonally oriented 90 kt jet snakes its way eastward. In the meantime, high stability characterized by a strong subsidence inversion anchored around 7.5kft will prevail. Rather moist ESE boundary layer winds with surface dewpoints in the mid 60s will facilitate a healthy shower coverage over windward and mauka zones, but high stability will maintain a firm cap on shower depth and intensity.
A couple bands of showers positioned east of the islands, one associated with a remnant cold frontal boundary, will sweep through the area Friday evening through Saturday. This will bring an increase in shower coverage to windward, mauka, and possibly even some leeward areas mainly overnight and during the early morning. Weakly cyclonic flow along the northern periphery of the resident upper jet will maintain weakly stable conditions heading into next week. A somewhat drier airmass will fill in behind the aforementioned remnant frontal zone on Saturday (dewpoints around 60). Nonetheless, cooler temperatures aloft (around 850mb) will foster relatively steep boundary layer lapse rates conducive for shallow shower production. Such showers will be modulated by the typical diurnal trend and will be embedded within continued widespread breezy trade winds at the surface. Breezy trades are then modeled to continue for the balance of next week.

Aviation

Locally breezy trade winds are expected today and throughout the next several days. Latest infrared satellite imagery shows that broken to overcast stratocumulus clouds continue to stream across portions of the state, particularly the western islands. A few light trade wind showers will be possible along coasts throughout the next 24 hours and beyond. Meanwhile, leeward sea breezes will support cumulus development along west facing slopes and coasts in the afternoon and evening hours. A strong inversion aloft will inhibit vertical cloud development, however, so any showers that do develop should be light in intensity.
Isolated MVFR conditions will be possible at times within showers, but in general, VFR flight conditions are expected to prevail at most locations. The current AIRMET Sierra for mountain obscuration along windward sections of the Big Island will likely be able to be dropped later this morning. AIRMET Tango may be needed for moderate low-level turbulence later today as surface wind speeds increase a bit.

Marine

Fresh to strong east-southeast trades will continue today, then shift out of the east and become strong for most waters over the weekend through early next week. The Small Craft Advisory has been expanded to most Hawaiian waters, which will continue through the weekend.
Surf along north and west facing shores will gradually ease today as a medium-period northwest swell begins to move out. An upward trend is expected over the weekend as a fresh, long- period north-northwest swell arrives late tonight, then builds down the island chain through the day Saturday. This swell will peak late Saturday through Saturday night, likely driving the surf along exposed coasts to the advisory thresholds. A slow downward trend is expected by late Sunday.
Surf along exposed north and east facing shores will trend up early next week as a medium-period north-northeast swell arrives. Surf heights will likely reach the advisory levels as this swell peaks Monday through Tuesday (potentially near the warning level for east facing shores). Otherwise, short-period/rough surf is anticipated along exposed eastern shores due to the strong trades locally and upstream.
Surf along south facing shores will potentially trend up late next week as we move into March due to a long-period south swell arriving.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Maui County Windward Waters, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov