Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with numerous showers in the afternoon. Highs around 83 near the shore to around 71 above 3000 feet. Light winds becoming north up to 10 mph in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers early in the evening, then partly cloudy with isolated showers in the late evening and overnight. Lows around 70 near the shore to around 59 above 3000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Memorial Day: Mostly sunny with isolated showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs around 83 near the shore to around 71 above 3000 feet. East winds up to 15 mph. Chance of rain 70 percent.

South Kaua’i

Today: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs around 80. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 66 to 71. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Memorial Day: Partly sunny with numerous showers. Highs around 80. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 70 to 77 in the valleys to around 61 above 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows 59 to 64 in the valleys to around 52 above 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

Memorial Day: Mostly cloudy. Occasional showers in the morning, then numerous showers in the afternoon. Highs 70 to 77 in the valleys to around 61 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 80 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 73 to 83. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 70. East winds up to 10 mph. Chance of rain 50 percent.

Memorial Day: Mostly cloudy with scattered showers. Highs 73 to 83. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 73 to 82. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 72. Northeast winds up to 10 mph. Chance of rain 70 percent.

Memorial Day: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 73 to 82. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Trade winds will remain on the lighter side today, then gradually strengthen tonight and Memorial Day, with moderate to locally breezy conditions prevailing Tuesday into next weekend. Clouds and showers will generally favor windward areas during nights and mornings through the holiday weekend, with the lighter winds allowing for scattered shower development over leeward areas each afternoon. A more typical trade wind pattern featuring mainly windward showers and the occasional leeward spillover should return Tuesday and linger through next weekend.

Discussion

Currently at the surface, a 1031 mb high is centered around 1250 miles north of Honolulu, with a weak trough of low pressure a few hundred miles north of the state. The trough to the north continues to influence the winds locally, keeping trades in the light to moderate range, with localized land breezes present in many areas. Infrared satellite imagery a mix of high and low clouds producing partly to mostly cloudy conditions. Meanwhile radar imagery shows isolated to scattered showers moving into windward areas, with dry conditions in most leeward locales. Main short term focus revolves around rain chances and trade wind trends.
The trough of low pressure north of the state will shift westward and dampen out during the next couple days, while a new strong high builds to the distant north. Light to moderate trades will prevail today, with localized sea breezes developing in protected leeward areas. The trades will then gradually strengthen to moderate levels tonight and Memorial Day, with moderate to locally breezy trades prevailing Tuesday into next weekend as the high to the north persists.
As for the remaining weather details, shower activity should remain confined to mainly windward areas this morning. Daytime heating and localized sea breezes should bring another round of scattered showers to the island interiors and leeward areas this afternoon, with the activity then gradually waning through the evening hours. A gradual return to more typical trade wind weather is expected tonight and Memorial Day, with showers favoring windward areas during the night and morning hours, along with scattered shower development in leeward areas Monday afternoon. Trade wind weather will then prevail Monday night into next weekend. Showers will favor windward and mauka areas, although a few showers will reach leeward areas at times as well due to the elevated inversion resulting from troughing aloft holding in place just to the north of the state. The troughing aloft should result in a slightly more showery trade wind pattern, along with periods of scattered to broken cirrus moving through.

Aviation

A high pressure ridge far north of the region and a broad low level trough north of the islands will keep light to moderate trade winds in the forecast today with day time sea breezes mainly along western slopes of each island. Clouds and brief showers will favor mountain and island interior sections in the afternoon and early evening hours. Trade winds will begin to strengthen by tonight, increasing shower trends along windward slopes of all islands. Brief MVFR conditions are possible in any showers that develop, otherwise VFR conditions will prevail.
There are no AIRMETs currently in effect.

Marine

Light to moderate easterly trade winds will continue today, then increase into the moderate to fresh range tonight into Monday as high pressure builds to the north. A return of locally strong easterly trades is possible by midweek from Maui County to the Big Island over the typically windier waters.
Surf along south facing shores will remain up through the early portion of the week as small pulses out of the south-southwest direction from recent activity moving through the Tasman Sea continue. The next pulse is expected tonight, which should linger through midweek. A brief lull is then expected through the latter half of the week, followed by a similar background, long-period south-southwest swell next weekend.
Surf along east facing shores will hover near flat levels due to the trades backing down locally and far upstream across the eastern Pacific. A slight increase in choppy surf is expected through the week as the trades return to moderate/fresh levels.
Surf along exposed north and west facing shores will see a slight increase out of the west-northwest tonight through Tuesday from a recent system lifting northeastward over the far northwest Pacific. Otherwise, back to the summertime average for the rest of the week. For the long range, WAVEWATCH III does highlight a potential small, long-period west swell associated with Tropical Cyclone Mawar in the far northwest Pacific arriving around June 6th (low confidence).

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov