Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 66 to 71 near the shore to around 59 above 3000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 84 to 90 near the shore to around 76 above 3000 feet. Light winds. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 84 to 90. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 66 to 71. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 84 to 90. Light winds. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny with isolated showers. Highs 75 to 82 in the valleys to around 67 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 61 to 66 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 75 to 83 in the valleys to around 67 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 86. West winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers early in the evening. Lows 63 to 71. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 87. Light winds. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 77 to 87. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers early in the evening. Lows 62 to 74. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 76 to 88. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The background flow will remain light and variable across the western islands, with light east to southeast winds over the eastern islands. These light winds will allow afternoon sea breezes and nighttime land breezes to develop into Friday. Expect mostly clear nights and mornings, followed by clouds and spotty showers each afternoon over leeward and interior sections. Locally breezy trade winds are expected to return this weekend. A front approaching the western islands early next week may cause an increase in shower coverage over portions of the island chain.

Discussion

A weak surface ridge, which appears to be about 200 miles north of Lihue, is shifting slowly southward early this morning. The close proximity of this feature to the state has caused light and variable background flow to develop near the western islands, while light east to southeast winds are near Maui and the Big Island. These light winds allowed local land breezes to develop across most of the state overnight. Skies have cleared over most of the interior and leeward sections of the islands. However, lingering low clouds and a few showers continue to affect portions of east Kauai, as well as windward Maui and the Big Island. Note that a wildfire on the Koolau mountain range on central Oahu appears to be spreading areas of smoke over portions of that island. This smoke may affect parts of Oahu through this morning.
The moisture near the eastern and central islands may continue to maintain a few showers over the windward sides of Maui and the Big Island through this morning. The forecast guidance indicates the weak surface ridge will continue to move down closer to the islands through mid-week. This will allow sea breezes with interior and leeward clouds and spotty showers to develop each afternoon through Friday. This will be followed each evening with the development of land breezes, which will tend to cause clearing skies overnight through the end of the work week.
The forecast models continue to show that a strong surface high pressure system building far northwest of the state will likely cause northeasterly trade winds to strengthen, with locally breezy conditions developing from this weekend into Monday. The guidance also shows the surface high may eventually push a frontal boundary down near Kauai late this weekend, which could bring an increase in windward-focused rainfall to portions of the island chain starting late Sunday or Monday.

Aviation

Light and variable winds will allow overnight land breezes and daytime sea breezes to form through the 24-h forecast period as the ridge remains in the area. Although land breezes have led to clearing for most areas overnight and this morning, a band of low clouds located over the eastern end of the state supports periods of MVFR CIGS continuing through the early morning hours today. Some patchy smoke from a nearby fire along the Koolaus (east of Mililani) on Oahu could lead to reduced VSBYs this morning at HNL and HJR. Later this morning and through the afternoon hours today, clouds and light showers will favor mountain/interior locations as the sea breezes form.
AIRMET Sierra for MTN OBSC remains in effect for windward locations of Maui, BI, and Kauai. Conditions should improve later this morning.

Marine

A surface ridge will sink southward and over the western end of the state today, then remain nearly stationary through Thursday. Light and variable winds will prevail over the western islands through Thursday, while light to locally moderate east- southeasterly trades hold over the eastern end of the state. Ridging will build back north of the islands Thursday night and Friday, allowing the trade winds to return. A strengthening surface high to the distant northwest will allow for a continued strengthening of the trades to moderate and strong levels Saturday through next Monday. Small Craft Advisories may will likely be needed as early as Saturday for some waters, with the SCA conditions possibly expanding to most marine zones Saturday night through early next week.
Surf along north facing shores will remain below seasonal average this week. The current small north-northwest swell will gradually lower into Wednesday. A new moderate sized medium-period north- northwest swell will build Wednesday and Wednesday night, producing a modest increase in surf through Thursday. This swell will gradually lower Thursday night and Friday. North shore surf will then hold relatively steady through the weekend as a new northwest swell moves in and gradually shifts more northerly. A new moderate sized medium period north-northwest swell could give north shore surf another modest boost late Sunday through early next week.
The current south swell will maintain above normal south shore surf through Wednesday, with a gradual decline on Thursday. A new long-period south-southwest swell will arrive late Thursday keeping some small south shore surf in place through early next week.
Surf along east facing shores will remain small through at least Saturday, due to the lack of a significant fetch of upstream trade winds. As trades increase, east shore surf will gradually rise Sunday into early next week.
Higher than predicted water levels continue across the Hawaiian Islands, and minor coastal flooding is expected during the high astronomical tide this morning and possibly Wednesday morning as well. Higher water levels near Kauai could keep some nuisance flooding in place around the time of high tide through much of the work week. A Coastal Flood Statement remains in effect through this morning for all vulnerable coastal areas.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov