West Kaua’i

Rest Of Today: Mostly sunny with isolated showers. Haze. Highs 80 to 86 near the shore to around 72 above 3000 feet. East winds up to 10 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Haze. Lows around 67 near the shore to around 58 above 3000 feet. Light winds.

Thursday: Sunny. Haze through the day. Isolated showers in the afternoon. Highs 80 to 87 near the shore to around 74 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

South Kaua’i

Rest Of Today: Partly sunny late in the morning then becoming sunny. Scattered showers late in the morning. Haze through the day. Highs 79 to 86. West winds up to 10 mph shifting to the south around 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly clear with isolated showers. Haze. Lows around 68. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Haze. Highs 81 to 87. East winds up to 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Rest Of Today: Partly sunny with scattered showers late in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs 74 to 81 in the valleys to around 64 above 4000 feet. Light winds. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Haze. Lows 59 to 67 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs 75 to 81 in the valleys to around 66 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 40 percent.

North Kaua’i

Rest Of Today: Mostly sunny with isolated showers. Haze. Highs 75 to 83. Southwest winds up to 10 mph late in the morning becoming light. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Haze. Lows 62 to 69. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Haze. Highs 75 to 83. Southeast winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Rest Of Today: Partly sunny late in the morning then becoming sunny. Scattered showers late in the morning. Haze through the day. Highs 73 to 85. South winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Haze. Lows 61 to 72. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers. Haze. Highs 75 to 86. Southeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to occasionally moderate east to southeasterly winds are expected to persist through the remainder of the week and into the weekend. Light showers will focus across windward areas during the overnight hours and leeward and interior areas during the afternoon hours. A deep upper-level low is progged to approach the islands early next week, potentially enhancing southwesterly winds to the area. However, confidence remains low in the forecast for next week at this time.

Discussion

At the surface, a high pressure ridge axis is located near the islands, south of a front that lies just outside of the offshore waters to the north. Latest observations show light winds across the islands, with light to moderate east-southeasterly trades prevailing over the water. Since sunrise, satellite and radar imagery has shown some shower activity, primarily favoring east and southeast slopes of the Big Island. Elsewhere, lingering land breezes within a stable environment have prevented many clouds and showers over land. The forecast in the near term was tweaked to reflect these latest trends, namely to decrease QPF over the smaller islands and increase it slightly over portions of the Big Island through midday.
For the rest of this week and into the weekend, a hybrid land/sea breeze pattern, with moderate trade winds at times, will continue as the next front moves toward the island chain and broad upper- level ridging prevails east of the state. Background winds will remain light to occasionally moderate from the southeast for the remainder of the week, keeping most of the smaller islands relatively dry since they will be largely shadowed by the Big Island. While some showers will still be carried into windward areas of the smaller islands on the east to southeast winds, the lighter flow will allow sea breezes to increase clouds and support a few light showers for leeward and interior areas each afternoon. Land breezes will then clear clouds and showers over these leeward and interior areas each night.
By next week, model guidance suggests a deep, upper-level low will develop northwest of the islands. However, there are significant differences amongst model guidance regarding the strength, positioning, and timing of this feature, creating a lot of uncertainty for the forecast beyond this weekend. For example, the ECMWF introduces a more progressive solution, with this feature quickly moving off to the northeast on Monday and then lingering far north of the islands with a front approaching the northern end of the state Tuesday into Wednesday. However, the GFS keeps the feature stalled northwest of the islands through the middle of next week. These differences would have significant impacts on moisture availability and the prevailing wind speed and direction over the main Hawaiian Islands. For now, have left the previous forecast in tact, which favors a generally dry pattern over most of the islands with the best chance for showers over Kauai from Monday onward.

Aviation

Light to moderate southeasterly winds will produce land/sea breezes over all islands. A few leeward SHRA and some isol MVFR conds can be expected today with land breezes tonight. VFR should generally prevail.
No AIRMETs are currently in effect.

Marine

A weak ridge of high pressure oriented northwest to southeast over the islands will gradually strengthen over the next few days. Expect gentle east to southeast winds over more western waters and slightly stronger moderate winds across windward Maui County and around Big Island waters today. This will result in several days of generally light to gentle easterlies, with the exception of slightly higher winds over the windward Maui and Big Island surrounding waters. Large scale east southeast winds may become light enough to initiate localized daytime coastal onshore sea breezes and overnight offshore land breeze behavior. Winds are forecast to veer to the south early next week in response to a developing low far northwest of the offshore waters.
The current medium period northwest (330 degree) swell will continue to fade. A series of small north (350-010 degree) swells will begin arriving tomorrow and persist through the weekend. This will provide a slight boost in north-facing shore surf with many sets coming in waist to head high later this week.
South-facing shores should remain small with some background long period south southwest swell expected to arrive Thursday or Friday. East-facing shore chop will remain small due to the absence of any significant trade fetch. As the series of small north swells fill in beginning Thursday, select east-facing exposures may experience a small bump in surf from north wrap.

HFO Watches/Warnings/Advisories

None.