West Kaua’i

Rest Of This Afternoon: Mostly sunny with isolated showers. Highs 86 to 93 near the shore to around 78 above 3000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 72 to 77 near the shore to around 64 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Sunny and breezy. Highs 87 to 93 near the shore to around 79 above 3000 feet. East winds up to 20 mph.

South Kaua’i

Rest Of This Afternoon: Partly sunny with scattered showers. Highs 83 to 91. East winds around 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 75. East winds 10 to 15 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 91. East winds 10 to 20 mph. Chance of rain 40 percent.

Kaua’i Mountains

Rest Of This Afternoon: Partly sunny with scattered showers. Highs 77 to 86 in the valleys to around 69 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 72 in the valleys to around 61 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with scattered showers. Highs 77 to 86 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Rest Of This Afternoon: Partly sunny with scattered showers. Highs 80 to 88. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 67 to 76. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 89. Southeast winds up to 15 mph. Chance of rain 30 percent.

East Kaua’i

Rest Of This Afternoon: 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 78. East 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

Trades will strengthen over the next couple of days to moderate to locally breezy as a high north of the state builds. Clouds and showers will focus along windward and mauka areas, particularly overnight and early morning as a rather dry and stable air mass settles over the state and persists into next weekend.

Discussion

Current satellite and radar imagery show scattered to numerous clouds and showers along windward and mauka areas. Trades should be on the increase today and will be moderate to locally breezy. Mid- level ridging should provide more stability around the state this afternoon with low- level moisture returning to near summertime normals. The typical scattered showers along windward and mauka areas during the overnight and early morning hours can be expected. This pattern is will to continue into the weekend as the surface high remains parked north of the state.
Tropical cyclone activity continues far south and southeast of the Hawaiian Islands as now Major Hurricane Iona and Tropical Storm Keli continue churning westward. There is also third area the National Hurricane Center (NHC) is tracking for tropical cyclone development east of Keli also likely to continue to drift westward based on NHC advisories and global model forecasts. There is currently no immediate threat to the Hawaiian Islands from these systems. We will continue to monitor these tropical systems as they pass far south of the state for potential in lowering inversion heights, and limiting clouds and showers Wednesday into the weekend.

Aviation

Trades on the increase and over the next few days. Low cigs and SHRA will mainly focus over windward and mauka locations. MVFR conds possible in SHRA otherwise VFR prevails.
AIRMET Sierra is in effect for mtn obsc for Kauai, Oahu, Molokai and Maui. Conds should improve later this morning.

Marine

The current gentle to moderate trade wind flow will gradually build to fresh to locally strong levels starting today and lasting through the weekend. A Small Craft Advisory (SCA) remains in effect for most eastern coastal waters and channels. This SCA will likely continue over the windier waters and channels around Maui and the Big Island through the weekend.
Although the tropical cyclones are forecast to pass several hundred miles south of Hawaii over the next couple of days, more information on Hurricane Iona can be found at WMO header WTPA21 PHFO and AWIPS header HFOTCMCP1, and information on Tropical Storm Keli can be found at WMO header WTPA22 PHFO and AWIPS header HFOTCMCP2. Isolated thunderstorms along the northern periphery of these systems may effect the far southern portion of the offshore waters, and while some short-period southeast swells may reach southern shores of Hawaii, a much larger and unrelated south swell will dominate.
An active period of south swell is due this week. The first in a series of long-period swells will arrive later this afternoon or evening and will build south shore surf to near summertime average levels on Wednesday. Long period forerunners of a much larger swell will overlap the first swell on Wednesday, and the bulk of the swell will peak at around 4 to 5 feet in Hawaiian waters on Thursday, then hold surf heights in excess of the High Surf Advisory threshold through Friday. The swell will gradually decline over the weekend and will be followed by another sizable long period south swell early next week.
East shore surf will trend up over the next few days as strengthening trade winds generate larger wind waves. Surf along east facing shores will rise to seasonal average late Wednesday or Thursday and hold into the weekend, followed by a likely decline early next week.
Flat summer conditions along north facing shores may be interrupted this weekend by a small long period northwest swell from Typhoon Krosa, currently in the western Pacific.

Fire weather

Expect humidity levels to gradually lower to more typical summertime levels through today as a drier and more stable air mass builds over the state. Humidity and wind speeds will be near critical conditions Wednesday into the weekend as breezy conditions develop. Some uncertainty remains in the wind speeds later this week and will continue to monitor for possibility of any headlines.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 AM this morning to 6 PM HST Wednesday for Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.