Photo Credit: Braden Jarvis

West Kaua’i

Today: Partly sunny. Isolated showers in the afternoon. Highs around 89 near the shore to around 78 above 3000 feet. Northeast winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 68 to 73 near the shore to around 59 above 3000 feet. Light winds.

Friday: Mostly sunny. Highs around 88 near the shore to around 77 above 3000 feet. North winds up to 10 mph shifting to the west in the afternoon.

South Kaua’i

Today: Partly sunny with isolated showers. Highs around 87. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 66 to 72. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Partly sunny. Isolated showers in the morning. Highs around 86. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 84 in the valleys to around 68 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 59 to 64 in the valleys to around 54 above 4000 feet. Light winds. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 76 to 83 in the valleys to around 67 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 80 to 89. Southeast winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 62 to 72. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Partly sunny with isolated showers. Highs 79 to 88. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 80 to 88. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 60 to 74. Northeast winds up to 10 mph. Chance of rain 20 percent.

Friday: Partly sunny with isolated showers. Highs 79 to 87. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Mostly dry and stable conditions with light easterly trade winds will continue into Friday, allowing localized overnight and early morning land breezes and daytime sea breezes to develop. Clouds and light showers will favor windward coasts through the overnight and morning periods, then interior and leeward locations during the afternoon and early evening hours where sea breezes form. Easterly trade winds will return to moderate to breezy levels over the weekend through early next week, with showers favoring our typical windward and mauka locations.

Discussion

A band of mid-level moisture streaming northward over the eastern end of the state due to a pool of deep tropical moisture passing nearby to the south and an upper low to the west will continue to support periods with mid-level cloud coverage through tonight. Recent upper air soundings at Hilo reflected this showing a moist layer between 14-18 kft, which has driven the PWs up above average (1.74 inches). Otherwise, the profiles are mostly dry (w/ 1.26 inch PWs shown at Lihue), with the inversion heights ranging from 4-6 kft. Expect some of this cloud coverage to translate in better chances for periods of mainly light rain over the Big Island summits. For the lower elevations and smaller islands, rainfall chances will remain limited with the best chances expected over windward coastal areas overnight through the morning periods, then interior and leeward sections through the afternoons where localized sea breezes form.
Guidance depicts rising upper heights with dry and stable conditions returning Friday into the weekend, which will persist through the first half of next week. The surface ridge to the north will build, supporting a return of moderate to breezy easterly trade winds beginning this weekend. Confidence is very low, but the trades could back off once again late next week as a remnant trough associated with Hurricane Jova (currently in the far eastern Pacific) moves into the central Pacific.

Aviation

A weak high pressure ridge north of the region will keep light to moderate easterly trade wind flow in the forecast, allowing local scale overnight land and daytime sea breezes to develop over leeward areas through Friday. Brief showers are possible. VFR conditions will prevail.
No AIRMETs are in effect.

Marine

A few surface troughs between the islands and surface high pressure northeast of the state will maintain gentle to locally moderate easterly trade winds over the state through tonight. Beginning Friday, surface high pressure far northwest of the state will push southeastward near 170W, as a ridge builds north of the state. This will reinforce the local pressure gradient and gradually increase trade wind speeds into the moderate to locally strong range. At this time, trades look to strengthen to Small Craft Advisory (SCA) criteria Saturday night through the middle of the week for the typical windy waters around Maui County and the Big Island.
The long-period south swell still remains elevated today as a gradual downtrend is expected through Friday. Going into the weekend, a small long period south swell is expected to fill in Sunday night and peak next Monday slightly above the summer time average before gradually declining in the middle of the week.
No other significant swells are expected through the rest of the week. A tiny northwest swell will keep surf along north facing shores just above the summer average through today. East facing shores will remain small, as the light trades hold. Long range forecasts indicate the potential for a moderate, long period easterly swell from rapidly intensifying Hurricane Jova in the east pacific arriving early next week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov