Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 76 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows around 72 near the shore to around 62 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Friday: Breezy. Sunny with isolated showers. Highs around 87 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 83 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 72. East winds 10 to 15 mph. Chance of rain 40 percent.

Friday: Breezy. Mostly sunny with isolated showers. Highs around 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 75 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 65 to 70 in the valleys to around 60 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 75 to 84 in the valleys to around 67 above 4000 feet. East winds up to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 88. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers. Lows 66 to 74. Southeast winds up to 15 mph. Chance of rain 30 percent.

Friday: Mostly sunny with isolated showers. Highs 78 to 88. Southeast winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 75 to 86. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 77. East winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate east to southeast winds will continue today. Modest showers will remain largely confined to windward slopes, while clouds and a few showers will develop over interior and leeward areas mainly in the afternoon. Trade winds will shift out of a more typical easterly direction on Friday and hold into the weekend. Trades will strengthen Sunday and early next week.

Discussion

The combination of broad high pressure far north of the state and a surface trough located roughly 500 miles northwest of Kauai will maintain moderate east to east-southeast winds today. Under this flow Kauai, Oahu, and Molokai will remain somewhat blocked from the prevailing winds by the Big Island and Maui, resulting in a more widespread afternoon sea breezes across the western half of the island chain. Moisture will remain somewhat limited, and ridging aloft will keep stable conditions in place. Modest rainfall will be focused along windward slopes, and the combination of sea breezes and convergent plumes will generate clouds and a few showers over leeward areas.
Winds will shift back to a more typical easterly direction on Friday as the nearby surface trough moves away from the islands and broad high pressure holds north of the state. A pocket of moisture is expected to move in on the trades as early as Friday night and pass over the western end of the island chain Saturday, bringing an increase in mainly windward showers. A weak shortwave aloft will move over the state during this time and could trigger a few heavy showers, especially over windward Oahu and Kauai.
Trade winds are expected to increase as early as Sunday, though more significantly late Monday and Tuesday as an exceptionally strong surface high of around 1040 mb develops far north of the region. This high will push a shear line or shallow front over the islands during the surge of trades sometime late Monday or Tuesday, leading to a period of increased windward rainfall. Breezy to locally windy trades and somewhat cool and dry conditions are possible for the middle of next week.

Aviation

East to southeast winds in the moderate to locally breezy range will prevail today and slightly shift more easterly tonight. Clouds and a few showers will be pushed over the east and southeast slopes of the islands. Brief MVFR conditions will be possible in the showers but overall VFR conditions are expected.
No AIRMETs are currently in effect and none are expected.

Marine

A low pressure system northwest of the Hawaiian Islands and a high pressure ridge north of the state will produce fresh to strong east to southeast winds today. The low will drift westward away from the islands through Friday with more easterly trade winds building back into the Hawaii Region. A Small Craft Advisory remains in effect for winds over exposed waters around Maui and the Big Island through tonight, and will likely continue over some of these windier areas into the weekend.
A medium period northwest (320 degree) swell energy will boost surf heights along north and west facing shores today and tonight. Overlapping medium period north (350 degree) swell and long period north-northwest (330 degree) swell energy will move into the region early Friday morning and late Saturday respectively. These swells will keep surf heights elevated along north and west facing shores at least into Sunday.
Surf along east facing shores will stay choppy as trade winds build back into the region. Small long period south swells will continue to keep surf along south facing shores from going flat through much of next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Friday 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