West Kaua’i

Tonight: Mostly clear. Lows 69 to 74 near the shore to around 62 above 3000 feet. East winds up to 15 mph becoming around 10 mph after midnight.

Thursday: Sunny. Isolated showers in the afternoon. Highs 85 to 90 near the shore to around 74 above 3000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Thursday Night: Mostly clear. Lows around 71 near the shore to around 62 above 3000 feet. East winds around 10 mph.

South Kaua’i

Tonight: Partly cloudy with isolated showers. Lows around 73. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs 80 to 88. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy with scattered showers. Lows around 72. Northeast winds around 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Tonight: Mostly cloudy with scattered showers. Lows 64 to 69 in the valleys to around 59 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 74 to 85 in the valleys to 63 to 68 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy with scattered showers. Lows 64 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Tonight: Partly cloudy with isolated showers. Lows 66 to 73. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Highs 78 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy with scattered showers. Lows 65 to 73. East winds around 10 mph. Chance of rain 40 percent.

East Kaua’i

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 64 to 76. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday Night: Partly cloudy with scattered showers. Lows 64 to 76. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trades become locally strong this weekend into next week delivering limited clouds and showers mainly to windward and mauka areas.

Discussion

Satellite imagery shows clearly ridging established over the islands with a closed upper low established immediately to the west. Thunderstorms are common within the cold core of this low where they will remain until it shears out in the next 24-36 hours. Subtle surface pressure falls may diminish the gradient a bit or cause winds to slightly veer to ESE over the western end of the state, but this low otherwise remains inconsequential. Over the islands, the trade wind inversion is flat, registering at about 5.5kft on both the Lihue and Hilo soundings, though some diminished stability is noted on the Lihue sounding. An isolated heavy shower or two is possible over the western end of the state within any batches of deeper moisture embedded in the trades, but overall satellite imagery and model solutions indicate continued dry weather with little in the way of upstream moisture to speak of. Aloft, the resident subtropical jet funnels high clouds across area skies.
Renewed upper low development takes place directly over the islands this weekend which will maintain relatively low stability over the western end of the state, but potential appears to once again be compromised by a lack of moisture availability. Instead, expect strong mid-level ridging aligned along 150W to strengthen seasonably dry trades this weekend into next week. The best opportunity for showers will be windward/mauka zones mainly overnight.

Aviation

A stable, moderate to locally breezy trade wind flow will persist for the next couple of days. Periods of MVFR ceiling and visibility in SHRA will focused along windward slopes. VFR will dominate over most leeward areas, but sheltered terrain will experience isolated MVFR conditions each afternoon, especially on the Kona slopes of the Big Island. The stable trade wind flow will produce light turbulence below 7,000 feet, but these condition should not require SIGMET Tango through Thursday. An upper-level low to the west will send high clouds over the state and may produce some light turbulence above FL300.

Marine

High pressure will remain stationary far northeast of the islands through the week, then re-center to the north and strengthen this weekend. As a result, fresh to locally strong trades will become more widespread during the weekend into early next week. A Small Craft Advisory is in effect for the windier waters and channels around Maui County and the Big Island through Sunday.
Surf along south facing shores will remain small over the next couple of days before a small, moderate period south swell fills in Friday into the weekend. A slightly larger swell from a fetch near New Zealand could arrive early next week and hold through the middle of the week, boosting surf heights.
Surf along east facing shores will remain moderate and choppy due to moderate trade wind swell, and surf along north facing shores will remain tiny through the forecast period.

HFO Watches/Warnings/Advisories

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

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