Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Highs around 90 near the shore to around 78 above 3000 feet. East winds up to 15 mph.

Tonight: Partly cloudy with isolated showers. Lows around 72 near the shore to around 61 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 90 near the shore to around 78 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 82 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 73. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 82 to 90. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 87 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 71 in the valleys to around 59 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Showers in the morning, then scattered showers in the afternoon. Highs 75 to 87 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 80 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 91. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 65 to 73. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 50 percent.

Saturday: Mostly cloudy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 78 to 90. East winds up to 15 mph. Chance of rain 60 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 75 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 65 to 76. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy with numerous showers. Highs 75 to 88. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

A moderate to locally breezy trade wind pattern will continue through this afternoon. A weak disturbance moving through the Hawaii region this weekend will increase shower trends for all islands, especially over windward and mountain areas. Drier trends return from Monday onward.

Discussion

The satellite picture this morning shows a band of unsettled showers moving into the windward and mountain slopes from Oahu to the Big Island. Local radar imagery shows periods of moderate showers affecting most of these islands, mainly along the northern and eastern slopes. This shower band will continue through the early morning hours. Elsewhere, fairly stable conditions persist today with just brief showers in the short term forecast.
In the larger scale, a high pressure ridge remains far north of the Hawaiian Islands and this ridge will continue to produce moderate to locally breezy trade winds today. Wind speeds will decrease slightly this weekend, as the ridge weakens in response to a cold front passing through the Central Pacific basin.
A weak low level trough riding in on the easterly trade winds will link up with an upper level low drifting into the islands from the north this weekend. These two systems will produce more unstable conditions statewide and increase shower trends statewide. The chances for thunderstorms have diminished in the latest forecast model solutions and they were removed from the gridded forecast for this weekend.
Drier conditions will return from Monday onward as these low pressure systems diminish and move westward away from the state. Moderate to locally breezy trade winds continue with brief overnight to early morning showers possible over windward and mountain areas.

Aviation

Breezy trades will continue for the next few days. SHRA and low cigs should favor windward and mauka locations. Brief MVFR conds can be expected in any SHRA. VFR should generally prevail elsewhere.
AIRMET Sierra for mtn obsc for windward Big Island is in effect. Conds should improve later this morning.

Marine

Fresh to strong easterly trade winds will continue through Saturday, then ease into the light to moderate range Sunday through the first half of next week as a weakness forms in the ridge to the north. The strongest winds are expected over the windier waters and channels around Maui County and the Big Island, where a Small Craft Advisory remains in effect through early Saturday. This may need to be extended through the day Saturday, before being lowered as the winds begin to trend down during the latter half of the weekend.
Surf along north facing shores will trend up through the first week of fall, beginning next Tuesday in response to a gale developing near the Kurils today, racing eastward across the Date Line near the Aleutians this weekend, then to the Gulf of Alaska early next week. Guidance shows this northwest swell peaking locally Tuesday night into Wednesday out of the northwest, then fading Thursday into Friday as it shifts out of a more north- northwest direction.
Surf along east facing shores will remain small and choppy into Saturday, then decrease Sunday into next week as the trades lower locally and upstream across the eastern Pacific.
Surf along south facing shores will remain small through the weekend, with mainly a mix of background long-period southwest and short-period southeast swells moving through. An upward trend is possible Tuesday through midweek due to a slightly larger southwest swell arriving.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Saturday for windier waters surrounding Maui and the Big Island.

Data Courtesy of NOAA.gov