Photo Credit: Brendan Stephen

West Kaua’i

Today: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 70 to 75 near the shore to around 61 above 3000 feet. East winds up to 15 mph shifting to the northeast after midnight. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs around 83. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 68 to 74. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83. East winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy with numerous showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 61 to 66 in the valleys to around 56 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Breezy. Numerous showers 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 20 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly cloudy with scattered showers. Highs 76 to 85. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 64 to 74. East winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 76 to 85. East winds 10 to 15 mph becoming up to 20 mph in the afternoon. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy with numerous showers. Highs 76 to 84. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 76. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 84. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail during the next 7 days. Fairly typical trade wind weather can be expected through the period, featuring windward and mauka showers and the occasional leeward spillover. A nearby upper level low will produce areas of high clouds across the state during the next couple of days.

Discussion

Currently at the surface, a strong area of high pressure is centered a couple thousand miles north of Honolulu, while a weakening frontal boundary is located around 625 miles west- northwest of Kauai. These features are producing moderate to locally breezy easterly trade winds in unsheltered areas early this morning. Infrared satellite imagery shows some mid and high cloud cover moving through the state, with partly to mostly cloudy conditions present in most areas. Radar imagery shows scattered showers moving into Kauai, minimal shower activity in windward areas from Oahu to the Big Island, and a few showers over leeward sections the Big Island. Main short term focus revolves around trade wind trends and rain chances during the next few days.
High pressure to the distant north will shift south- southeastward and closer to the islands during the next few days. Meanwhile, the front west of the state will edge eastward today, then stall out and weaken into a trough early in the work week, before dissipating well northwest of the islands by the middle of the week. A new high will build east-southeastward well to the north of the state during the middle of the week, with a cold front then approaching from the northwest next weekend. Overall, moderate to locally breezy trade winds are expected to prevail through Friday, with only minor fluctuations in strength. The approaching front may ease the trades next weekend.
As for the remaining weather details, the airmass is expected to moisten up slightly today, with fairly typical trade wind weather prevailing through Monday. Showers will continue to favor windward slopes/coasts during this time, with a shower or two reaching leeward areas as well. We should see an increase in shower coverage Monday night and Tuesday as some old frontal remnants move through. Fairly typical trade wind weather should then prevail Tuesday night into next weekend. Scattered to at times broken mid and high clouds will likely continue to stream overhead during the next couple days, but the coverage and thickness should be much less than what we saw yesterday.

Aviation

High pressure far northeast of the state will keep moderate to breezy trade winds in the forecast through Monday. Brief periods of showers are possible favoring windward and mountain areas mainly in the overnight to early morning hours.
AIRMET Tango remains in effect for moderate low level turbulence affecting all Hawaiian Islands below 080 over and immediately S through W of mountains. This low level turbulence will likely continue through Monday.

Marine

The large surface high far north northeast of Oahu will support a tight pressure gradient across the waters upstream of the islands. This will result in continued fresh to locally strong easterly winds across the Hawaiian Island's near and offshore waters. These amped up winds will drive rough seas over more windward waters but morning buoy wave observations are remaining under Small Craft Advisory (SCA) criteria. A SCA for winds remains in effect for the typically windier waters surrounding Maui County and Big Island through early Monday afternoon. An upper trough west of the islands will nudge ridging that is northeast of the region further east but the tight gradient will remain across and upstream of the state. Thus, an extension of the SCA in time is likely as these wind magnitudes are expected to continue through the middle of the week. The next surface high from northwest of the state will replace this high and ultimately retain the strength of the eastern Pacific pressure gradient through late in the week.
Surf will remain elevated along east-facing shores the next several days. A possible minor drop today in response to a slight easing in recent fresh east winds. Very small, background long period south swell will result in very small south-facing shore surf. In the extended outlook, a severe gale to possible storm force low southwest of the western Aleutians may send a larger, long period northwest swell into the nearshore waters next weekend. If this swell materializes, north-facing shore surf will likely exceed High Surf Advisory heights.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov