Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 73 near the shore to around 63 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 83 to 90. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 75. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Breezy. Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 83 to 90. East winds 10 to 25 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 89 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 65 to 73 in the valleys to around 60 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 89 in the valleys to around 68 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 78 to 91. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 75. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 50 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 78 to 92. East winds up to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 75 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 77. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Highs 75 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A high pressure system far north of the Hawaiian Islands will keep breezy trade winds in the forecast through much of the week. Wind speeds will strengthen from Thursday onward, and the weather conditions may change by this weekend as the potential for tropical cyclone activity increases near the Hawaii region. Weather conditions and island by island impacts this weekend will heavily depend on the track and intensity of any tropical activity near the islands.

Discussion

Satellite imagery this morning continues to show bands of clouds drifting into each island on the easterly trade winds. These clouds approaching the islands appear slightly more stable than the past few days. A weak subtropical jet stream over the islands will produce a few high level cirrus clouds streaming from southwest to northeast across the state.
Expect mostly cloudy skies with periods of showers for most windward and mountain areas from the overnight to early morning hours. Leeward areas will be mostly sunny with only isolated shower activity. Moderate to breezy winds will increase into the breezy to strong range from Thursday onward. The longer range weather pattern from Friday through Sunday, remains less certain as the potential for tropical cyclone formation and movement into the Hawaii Region may significantly change the medium to long range weather picture. Global operational model solutions are not in good agreement with this potential tropical cyclone movement into the islands. This means we have less confidence in both formation, movement and impacts to the island weather forecast for this weekend. Predicting potential tropical cyclone impacts before the system develops is one of the most challenging forecasts we have in meteorology. Therefore, for all the above reasons, the potential island by island wind and weather impacts this weekend will depend heavily upon the strength and track of any developing tropical system. Stay tuned for updates as the weather pattern will evolve over time.
Our attention is focused on the potential track and evolution of two tropical disturbances near 10N latitude and 135W to 140W longitude; these systems are currently more than 1,000 miles east- southeast of the Hawaiian Islands. The interplay between these disturbances is key to the current model solutions which remains highly uncertain given that an organized tropical system has yet to emerge from this rather broad area of interest. Therefore, we expect some fluctuation in modeling outcomes as the system evolves over the next few days. The potential does exist for conditions to be quite windy by this weekend in addition to the potential for heavy rain. These impacts will be entirely driven by the intensity and track of any developed tropical cyclone. The Central Pacific Hurricane Center is closely monitoring the Central Pacific basin, so stay tuned for frequent updates over the next several days at www.hurricanes.gov

Aviation

Moderate to locally breezy trades should be on the increase today. Low cigs and SHRA look to mostly impact windward and mauka locations with isolated coverage over leeward areas. MVFR conds can be expected in SHRA, but VFR should generally prevail.
AIRMET Sierra is in effect for mtn obsc for Oahu, Molokai, Maui and the Big Island.
AIRMET Tango may be needed to account for moderate low level turb downwind of the terrain of all islands by early morning, but is currently not in effect.

Marine

Moderate to strong easterly trade winds will continue through the day, then become a touch stronger across most waters beginning tomorrow and lasting through the remainder of the week as high pressure strengthens north of the state. The Small Craft Advisory (SCA) remains in effect for the typical windier waters surrounding Maui County and Big Island until early Thursday morning. As areawide trades strengthen, the SCA will likely be expanded to include most of the remaining waters through the latter part of the week. There is a high chance of tropical cyclone development in the eastern Pacific over the next couple of days. If a depression or cyclone does form, it will likely enter the Central Pacific around Thursday and track west. As of tonight, the numerical forecast guidance has a tropical cyclone tracking toward the Hawaiian Islands and passing near or over the southeastern local waters sometime early next week. Needless to say, but upcoming local marine forecasts will be highly dependent upon the potential evolution, development and track of a tropical cyclone.
Surf along south-facing shores will remain around head high this morning as a moderate size, long period south southwest swell peaks out. This swell will begin to decline from this afternoon through early Thursday. Surf along north and west-facing shores will trend up Wednesday as a long period west northwest swell arrives from former Typhoon Ampil. This swell should peak Wednesday through Thursday and then ease going next weekend. East-facing shore surf will remain somewhat small today, then chop will pick up Wednesday through the remainder of the week in response to increasing trades over and upstream of the island chain.
Due to the current water levels still running around a half of a foot above prediction, minor tidal flooding is still possible again during this afternoon's high tides.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov