Photo Credit: Brendan Stephen

West Kaua’i

Today: Sunny and breezy. Isolated showers in the afternoon. Highs around 88 near the shore to around 77 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 71 near the shore to around 61 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Monday: Sunny and breezy. Isolated showers in the morning. Highs around 88 near the shore to around 77 above 3000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 88. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 73. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 82 to 88. East winds around 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 73 to 84 in the valleys to around 66 above 4000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 84 in the valleys to around 67 above 4000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 76 to 89. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 74. East winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 76 to 88. East winds 15 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs 73 to 85. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 76. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 73 to 85. East winds 15 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

High pressure north of the state will maintain breezy trade winds the next few days. Showers will primarily favor windward coastal and mauka slopes. Trades will slightly weaken around the middle of the week with a possible increase in late week shower activity.

Discussion

The downstream pressure gradient from a 1030 mb high centered approximately 950 miles north of Kauai remains tight enough across the island chain to continue breezy trades well into the week. The Hawaiian Islands will remain under the stabilizing influence of mid-level ridging as the area falls along the southeasterly periphery of the 700 mb ridge positioned to the northwest. Early day water vapor satellite imagery depicts a drier resident air mass over the islands. This is verified by a quieter radar of widely scattered weak trade showers.
While morning sounding precipitable waters fall in-line with late June climatology numbers (1.3-1.4 inch pwats), mid to upper level northeasterly drier air advecting into the state will limit overall shower activity today; light, isolated showers primarily confined to windward mauka slopes. Slightly higher mid-level moisture advecting in Monday, along with a 6-7 k ft fairly saturated layer, may be enough to increase shower coverage and produce a few hundredths more rain in those communities that typically stay wet during a normal trade flow pattern. Little to no movement of the lower and upper ridge planted north of the islands through Tuesday ensures breezy trades under partly to mostly cloudy windward skies…mostly to partly sunny leeward skies. High pressure at all levels begins to transition east during the latter half of the week. This will weaken the lower level pressure gradient enough to subtly suppress trade flow to more gentle magnitudes, although easterlies will still remain breezy along ridge lines and within more east-to-west orientated valleys. Lowering mid to upper heights, with periodic ribbons of higher moisture passing to the west, will increase shower frequency and areal coverage later in the week. Higher confidence in the development of an upper level disturbance east northeast of the islands will certainly boost weekend rain chances as we close out the month of June.

Aviation

Breezy to locally windy trades will continue through Monday. Showery cloud bands embedded in the trade flow will produce periods of MVFR conditions across windward/mauka areas of each island, particularly through the overnight and early morning hours each day. Conditions will improve through the late morning and afternoon periods.
AIRMET Sierra remains in effect for tempo mountain obscuration for windward slopes of most islands, which will likely continue through the early morning hours.
AIRMET Tango remains in effect for mod low-level turb over and downwind of island terrain due to the breezy trade winds. This AIRMET will continue through Monday.

Marine

Surface high pressure, centered around 850 nm north of the state, will remain nearly stationary through early this week and help generate strong easterly trades. A Small Craft Advisory will remain in effect for all local waters through Monday night. Trades are expected to then decrease slightly Tuesday through midweek as the aforementioned surface high drifts northeast, away from the islands.
Surf along east-facing shores will remain rough and choppy through Monday due to the strong trades locally and upstream of the state. A gradual downward trend is expected Tuesday through mid week.
Expect slightly elevated surf along south-facing shores through Tuesday (though still near or below seasonal norms) as a small, medium to long period, south swell moves through. The swell has already shown up on the Barbers Point Buoy with energy in the 14-16 second period range. However, this should be short-lived, with a downward trend expected by Tuesday night. Despite a blocking high that has set up over our typical swell window southeast of New Zealand, a gale has formed northeast of this high with the head of the fetch aimed at the islands within the 180 to 200 degree directional band. Given the shorter travel distance, surf associated with this source should trend up late this week.
Nearly flat conditions will exist along north-facing shores today. A small, medium period, northwest swell will bring tiny surf to these shores late Monday through mid week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for all Hawaiian waters,

Data Courtesy of NOAA.gov