Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Sunny in the morning, then partly sunny with a 50 percent chance of showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. Northeast winds around 10 mph shifting to the south in the afternoon.

Tonight: Mostly clear with isolated showers. Lows 68 to 73 near the shore to around 59 above 3000 feet. Northeast winds around 10 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with a 20 percent chance of showers. Highs around 83. North winds around 10 mph shifting to the east in the afternoon.

Tonight: Partly cloudy. Scattered showers in the evening. Lows 66 to 72. Northeast winds around 10 mph. Chance of rain 40 percent.

Wednesday: Partly sunny with scattered showers. Highs around 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny in the morning then becoming mostly sunny. A 50 percent chance of showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds around 10 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 59 to 64 in the valleys to around 54 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

Wednesday: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 60 percent.

North Kaua’i

Today: Mostly sunny with a 50 percent chance of showers. Highs 76 to 85. South winds 10 to 15 mph shifting to the east in the afternoon.

Tonight: Partly cloudy with scattered showers. Lows 62 to 72. East winds around 10 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny with scattered showers. Highs 76 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with a 50 percent chance of showers in the morning, then sunny in the afternoon. Highs 76 to 84. Northwest winds around 10 mph shifting to the east in the afternoon.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 60 to 73. East winds around 10 mph. Chance of rain 40 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 84. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Today's light to moderate trade winds will strengthen on Wednesday, with breezy conditions continuing through the weekend into next week. Windward showers will be brief, favoring nights and mornings. A few leeward showers are expected this afternoon.

Discussion

Persistent high pressure NE of the islands will ensure that trade winds prevail through the forecast period. Wind speeds will be on the lighter side today before strengthening Wednesday and Thursday, and will then remain breezy through the weekend into next week.
The island atmosphere will become increasingly stable as a low aloft just N of the islands gradually moves N and a mid-level ridge builds over the area. Any showers that arrive on the trade flow will favor windward areas during nights and mornings, with little in the way of total accumulation. Leeward Big Island will see typical afternoon clouds and showers that linger well into the night, while leeward areas of the other islands could see some afternoon clouds/showers today as the lighter trades allow sea breezes to develop.

Aviation

Light to moderate trade winds will steer bands of showers off the Pacific towards east facing slopes and coasts. In the afternoon, local sea breezes will drive shower development along south and west facing slopes of the Big Island.
An upper level low passing just north of the state is contributing to mild air mass instability. Late night upper air soundings confirm little or no trade wind version aloft at either Lihue or Hilo. The air mass over the state, however, is relatively dry so shower activity will remain modest.
As of 2 am Tuesday, radar indicated mostly clear skies statewide except for isolated light to moderate showers dotted across the smaller islands and windward Big Island. More frequent showers are expected in the afternoon, especially over the higher elevations of the Big Island. No AIRMETs are in effect or anticipated at this time.

Marine

Moderate to locally fresh trades will continue today, then surge back into the fresh to strong category Wednesday as the ridge strengthens to the north. Seas will quickly respond and become rough over the exposed waters, especially over the windier waters and channels. Expect this trend to continue through the upcoming weekend, when the winds potentially reach or near strong levels for most waters as high pressure sets up north of the state. Expect Small Craft Advisory conditions beginning Wednesday for the typically windier waters and channels between Molokai and the Big Island, then potentially expanding to most waters this weekend.
Surf along exposed north and west facing shores peaked earlier Monday as a west-northwest swell from former Typhoon Guchol arrived. Early morning observations from the offshore buoys northwest of Kauai continue to reflect this source holding out of the west- northwest (290-315 deg) with a spectral peak now down to around 10- 11 seconds. As a result, this swell will linger today, then fade through midweek. There was a compact low that trailed this system east of Japan a few days ago, which could be enough to keep the surf from going completely flat Wednesday through Thursday, with a small swell holding out of the same west-northwest direction. Otherwise, back to summertime conditions with the best chance of surf coming from the short period trade wind generated waves wrapping in to select spots. For the long-range, guidance does show low pressure evolving over the far northwest Pacific Wednesday through Thursday, which could generate a small northwest (320-330 deg) swell early next week (low confidence).
Surf along east facing shores will remain small through Wednesday, then trend up through the weekend as the local and upstream trades return to fresh/strong levels.
Surf along south facing shores will remain small each day with mainly background south-southwest to south-southeast swell energy moving through. Although high pressure is currently parked in our typical swell window southeast of New Zealand, a powerful gale- to storm-force low that has been pulsing over the past few days far south of the Tuamotus and Tahiti will generate a long-period south- southeast (165-175 deg) swell, that should arrive Friday night and be fully filled in by the end of Saturday driving surf heights above the summertime average.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov