Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Highs around 84 near the shore to around 72 above 3000 feet. Light winds becoming south up to 10 mph in the afternoon.

Tonight: Partly cloudy with isolated showers. Lows around 68 near the shore to around 61 above 3000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 84 near the shore to around 72 above 3000 feet. East winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Highs around 81. West winds up to 10 mph shifting to the southwest in the afternoon.

Tonight: Partly cloudy with isolated showers. Lows 65 to 70. West winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Wednesday: Mostly sunny with isolated showers. Highs around 81. West winds up to 10 mph shifting to the southwest in the afternoon. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Highs 71 to 78 in the valleys to around 62 above 4000 feet. Light winds becoming west up to 10 mph in the afternoon.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 60 to 66 in the valleys to around 58 above 4000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 71 to 78 in the valleys to around 62 above 4000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.

North Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Highs 74 to 83. South winds up to 10 mph shifting to the north in the afternoon.

Tonight: Partly cloudy with isolated showers. Lows 63 to 70. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 74 to 83. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Highs 74 to 82. Southwest winds up to 15 mph.

Tonight: Partly cloudy with isolated showers. Lows 58 to 71. West winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 74 to 82. Southwest winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Dry and stable conditions will persist through Wednesday, with a deep-layer ridge remaining in place over much of the region. This will result in a land and sea breeze regime, with afternoon clouds and a potentially a few brief showers over interior and leeward areas. Increased moisture from a cold front will lead to better rain chances on Thursday, particularly for northern and windward slopes as northerly winds accompany it. Another cold front will approach and potentially reach the islands late next weekend.

Discussion

Dry and stable conditions, with a deep-layer ridge in place over much of the region, are expected through midweek. The surface ridge has shifted southward over the islands in response to a progressive pattern over the northern Pacific, featuring a series of fronts passing nearby to the north. Light southerly low- level flow around the ridge axis will shift out of the southwest over the western end of the state beginning later today. This will support the land and sea breeze regime continuing, with the best chance for cloud coverage developing over interior and leeward locations during the afternoon hours. While a few brief afternoon showers can't be ruled out in these areas, accumulations will be minimal due to the suppressed environment.
For the second half of the week, there is an increasing likelihood of increasing low-level moisture and rain chances. This is due to the tail-end of one of the aforementioned cold fronts settling south into the islands from Wednesday night through Thursday. Probabilistic QPF guidance supports this, showing the best chances for some light accumulations along northern and windward slopes, with northerly winds filling in. The progressive pattern will persist into next weekend, with another front approaching and potentially reaching the islands late Sunday into early next week.

Aviation

Light winds will prevail during the next couple days, with land and seas breezes dominant statewide. Rather dry weather will continue through the period, with limited shower activity primarily confined to windward and southeast facing slopes of the Big Island.
AIRMET Tango remains in effect for moderate upper level turbulence over the Big Island. Conditions will likely improve here later today.

Marine

The high pressure ridge north of the state will remain over the islands through next weekend. This pattern shift will keep a fairly light and variable wind pattern for most days this week. A weakening cold front will drift over the area on Thursday, bringing gentle to locally moderate northerly winds. As the front and high dissipate Friday, the surface ridge will move over the islands, with light and variable winds returning into the weekend.
The strong lows passing N of the area will have significant wind fetches aimed toward the islands. Although their fast-moving nature limits the ability of these powerful (up to hurricane force at times) lows to generate fully developed seas, there will still be several bouts of large to extra-large surf along N and W facing shores through the weekend. Given recent wave model guidance underpredicting the peak heights of NW swells, especially with hurricane-force lows, the latest official forecast incorporates a swell height bias of 1-3 feet larger than model guidance.
Small surf remains in the short term forecast as we wait for the offshore buoys to respond to the next large NNW swell. Observations from 2 AM HST this morning at buoy 51001 shows very small forerunners in the 20 second band arriving that are running a little bit below wave model swell heights. However, we continue to forecast increasing swell energy from the NNW to move into the islands later today, bringing a modest increase in surf heights for N and W facing shores by this afternoon. Surf heights will then rise more significantly starting later tonight through Friday, necessitating a High Surf Warning for exposed shores during its peak on Thursday and Friday. Another XL NNW swell is anticipated to arrive in Hawaiian waters by this weekend. Combined seas will exceed 10 feet late Wednesday into Thursday, requiring a Small Craft Advisory for many zones into the weekend.
Small surf remains in the forecast for S and E facing shores. E shore surf will stay small through the week as trade winds are disrupted, aside from some swell energy wrap from larger NW swells Wednesday through the weekend. Surf along S facing shores will remain seasonally small, mainly due to short period background swell.

Fire weather

Critical fire weather conditions are not anticipated through the week due to a combination of light winds and increasing moisture later in the week as a front settles southward into the area.

HFO Watches/Warnings/Advisories

None.

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