Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny with isolated showers. Highs around 84 near the shore to around 72 above 3000 feet. Northeast winds up to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 68 near the shore to around 57 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to around 72 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 85. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 68. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy with numerous showers. Highs 70 to 77 in the valleys to around 64 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 61 in the valleys to around 53 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 71 to 77 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82. East winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 61 to 69. East winds 10 to 15 mph shifting to the southeast after midnight. Chance of rain 50 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 75 to 82. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 72 to 82. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 70. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 72 to 82. East winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A weak high pressure ridge north of the Hawaiian Islands will keep moderate trade winds in the forecast through Friday, then winds will strengthen to breezy conditions this weekend as the ridge builds north of the state. Two passing upper troughs today and Thursday will keep brief periods of showers in the forecast mainly over windward and mountain areas, favoring the overnight to early morning hours.

Discussion

A band of deeper low clouds and showers shown on GOES satellite imagery is currently drifting through Oahu and Maui County this morning. Radar imagery shows cloud tops to around 10,000 feet elevation within this band that is producing moderate showers across the central islands. These showers will linger over windward slopes of Maui and northern sections of the Big Island into the afternoon hours as these clouds continue to drift slowly down the island chain. A weakening cold front, roughly 400 miles north of Kauai, continues to slowly approach the state. This front will stall and dissipate before reaching the islands. A few high level cirrus clouds are also passing from west to east over the state, enhancing sunrise and sunset colors.
A high pressure system far northwest of the state will move towards the Hawaii region and weaken. A weakening cold frontal band between the high center and the islands will tend to keep trade wind speeds in the moderate range today. The front fades by Wednesday as the high center weakens with continued moderate trade winds in the forecast through Friday. A stronger high builds in from the west starting late Friday, this system will pass eastward, just north of the state, and produce a round of breezy trade winds over the weekend. Moderate to breezy trade winds will continue into the first half of next week as a strong high will linger northeast of the island chain. There is also the potential for a cut off upper low forming near the Big Island shown by both models around Monday.
On the weather side expect typical trade wind weather with passing upper level troughs today and Thursday keeping brief periods of showers in the forecast through Friday. These passing showers will favor windward and mountain areas in the overnight to early morning hours. The weather conditions may change a bit early next week as much will depend upon the location of an unstable upper low lurking near the Big Island.

Aviation

Moderate trade winds will persist through twenty-four hours and beyond, steering bands of showers off the Pacific towards windward slopes and coasts.
As of 2 AM this morning, late night radar imagery showed a well defined band of moderate showers extending from Oahu to just north of Maui. AIRMET Sierra for mountain obscuration is currently in effect for Oahu and Molokai, and may need to be expanded to include Maui or Windward Big Island later today. Conditions are expected to gradually improve from the west after sunrise.
AIRMET Tango for moderate turbulence over and immediately south through west of mountains remains in effect for all islands.

Marine

Surface high pressure will exist north of the state in some form over the next week, maintaining trade winds through this week. Trade winds are expected to gradually weaken a bit and shift to a more easterly direction through mid-week. Much stronger trades are possible this weekend as a strong surface high sets up far northeast of the area.
The next northwest swell is scheduled to arrive late this afternoon with marginal advisory conditions possible along many north and west facing exposures late tonight into Wednesday. Offshore buoys have picked up some energy overnight but have not indicated advisory level size surf yet. This swell will be reinforced by a more northerly swell late Wednesday into Thursday.
The trade winds over and upstream of the islands are generating choppy, rough seas along east facing shores, but will decline through the middle of the week as winds briefly taper off. East shores exposed to the north swell may see an uptick in surf by Wednesday. South shores will remain very small with a minor bump of long period background south swell to fill in later in the week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov