Photo Credit: Jason Weingardt

West Kaua’i

Rest Of Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 82 near the shore to around 71 above 3000 feet. Southwest winds around 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows around 67 near the shore to around 58 above 3000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Sunday: Sunny with isolated showers. Highs around 80 near the shore to around 69 above 3000 feet. North winds around 10 mph. Chance of rain 20 percent.

South Kaua’i

Rest Of Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 79 to 84. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows around 67. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 77 to 83. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Kaua’i Mountains

Rest Of Today: Sunny in the morning, then mostly cloudy with showers likely in the afternoon. Highs 71 to 77 in the valleys to around 63 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 60 to 65 in the valleys to around 55 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 90 percent.

Sunday: Partly sunny with scattered showers. Highs 69 to 76 in the valleys to around 61 above 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Rest Of Today: Breezy. Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 82. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 61 to 68. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 71 to 81. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

East Kaua’i

Rest Of Today: Breezy. Sunny in the morning, then mostly cloudy with showers likely in the afternoon. Highs 72 to 82. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows 61 to 71. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 68 to 80. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

A trend toward locally breezy northeasterly trade winds can be expected tonight and Sunday, with moisture associated with a dissipating front fueling increased showers, mainly windward. Trade winds will trend lighter early next week, likely bringing fewer showers.

Discussion

In summary, high pressure to the NW of the islands will move slowly E the next couple of days, bringing strengthening NE trade winds this afternoon through Sunday. The high will also push remnants of a front over the islands, with this increased low-level moisture expected to fuel scattered to numerous windward showers. The high will weaken slowly early next week, with lighter winds likely bringing fewer showers by Tuesday/Wednesday. Long range guidance depicts a somewhat unseasonable trend toward a light and increasingly moist SE flow by the end of the week as low pressure develops W of the islands.
Latest satellite and radar images indicate a cluster of broken to overcast stable and showery low clouds from just E of Kauai to Molokai this morning, associated with an area of increased low-level convergence. Light to moderate NE winds prevail at cloud level over these islands, but scattered to numerous showers have been mainly staying offshore Oahu and Molokai since around midnight, as the lighter winds have allowed land breezes to develop. Kauai and surrounding waters have almost completely cleared overnight. Light and variable winds over Maui County and the Big Island have allowed land breezes to bring overnight clearing as well. A diffuse area of broken to overcast stable and showery low clouds over Offshore waters just N of the islands is associated with a weakening front.
Winds will likely remain sufficiently light over Maui County and the Big Island to allow afternoon sea breezes to develop again today, with mostly sunny morning skies giving way to afternoon clouds over the slopes, with a few showers possible. This may occur to a lesser degree on Kauai and Oahu, but the building trade winds are expected to low clouds and showers to windward areas. The NE trade wind flow will spread E tonight and Sunday, delivering stable and showery low clouds to windward areas of all islands. As the increased moisture associated with the dissipated front gradually diminishes and dew points lower in the wake of its passage, fewer showers are expected on Monday. The high will weaken Tuesday/Wednesday, with easing trade winds delivering just a few showers.
Longer range guidance is indicating a low aloft W of the islands leading to lowering surface pressures toward the end of the week that could lead to a moist and unstable SE flow, potentially leading to locally heavy rainfall. Limited confidence in this somewhat unseasonable evolution of our weather pattern, but large-scale conditions may become more favorable for precipitation formation over the central Pacific as the Madden-Julian Oscillation (MJO) is forecast to be in phase 7 next week.

Aviation

Land breezes will keep showers offshore over the coastal waters through mid morning. An area of clouds and showers left over from a dissipated trough will linger near Oahu. Northeasterly trades will strengthen through the day focusing showers over windward and northern portions of the islands. No AIRMETs are in effect at this time, but AIRMET Sierra may be possible by the end of the day as the trades push the remnant moisture onto windward slopes.

Marine

A weak front will dissipate across the islands this weekend. Moisture associated with the dissipating front will support a slight uptick in showers, mainly along the windward areas this weekend. High pressure to the distant NNW will build in behind the front as moderate NE trades will begin to fill in around Kauai this morning and slowly fill in across the state as the front dissipates. The typically windier waters around Maui County and the Big Island will likely see a Small Craft Advisory (SCA) for winds by Sunday morning. A typical trade wind pattern is expected for the beginning of the week.
Several pulses of medium-period NNW and N swells are expected to arrive through the weekend, with the swell gradually shifting to the NNE (010 degrees) early next week. A High Surf Advisory for the N facing shores of Niihau, Kauai, Oahu, Molokai, and Maui is in effect from 6 AM HST this morning through Sunday afternoon. Wave height observations are rising on nearshore buoys right now and should peak late today. Due to the direction of the swell, north facing shores of the Big Island may need to be added as the swell. Combined seas may also near the SCA threshold (10 ft) for windward waters around the smaller islands during the peak. This will be a long lived event with elevated surf along N facing shores into next week.
Relatively small but persistent medium to long-period S (170-180 deg) and SSE (140-160 deg) swells will continue for at least the next couple of days, keeping surf near seasonal averages along S facing shores.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Sunday for north facing shores of Niihau, Kauai, Oahu, Molokai, and Maui.

Data Courtesy of NOAA.gov