Photo Credit: Brendan Stephen

West Kaua’i

Today: Breezy. Mostly sunny with isolated showers. Highs around 79 near the shore to around 66 above 3000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows around 64 near the shore to around 52 above 3000 feet. Northeast winds 10 to 25 mph decreasing to up to 15 mph after midnight.

Saturday: Mostly sunny. Highs around 81 near the shore to around 68 above 3000 feet. Northeast winds up to 10 mph in the morning becoming light.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 76. Northeast winds 20 to 30 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows 61 to 67. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs around 78. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Windy. Partly sunny with scattered showers. Highs around 70 in the valleys to around 59 above 4000 feet. Northeast winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 56 in the valleys to around 48 above 4000 feet. Northeast winds 10 to 25 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Saturday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 72 in the valleys to around 61 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Breezy. Mostly sunny with scattered showers. Highs 68 to 77. Northeast winds 10 to 30 mph. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 56 to 66. Northeast winds 10 to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs 70 to 79. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

East Kaua’i

Today: Windy. Partly sunny with scattered showers. Highs 69 to 76. Northeast winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 54 to 69. North winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Partly sunny with isolated showers. Highs 71 to 78. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally strong and gusty winds will continue today for portions of the islands, as a weakening cold front lingers east of the Big Island. Northeast winds will maintain showers across mainly windward areas today. Winds will weaken tonight through Saturday, becoming light and variable for the second half of the weekend. Dry air filtering into the islands, will limit showers today through the weekend. Tropical moisture lifting northward, will increase the humidity and enhance clouds and showers across the region to begin the work week.

Discussion

Radar trends show showers favoring typical windward areas this morning, as northeast flow lingers. Current radar estimates continue to show generally light rainfall rates occurring with showers this morning. Rainfall rates will remain light today, as modeled moisture depths and PW values continue to fall in response to dry and more stable conditions filtering into the state. The best chance for any enhanced rainfall today would be in the vicinity of the Big Island, where moisture depths linger between 9k and 10k feet. Current satellite data shows a band of much lower PW values (under 0.90 inches) have dropped in now across Kauai and central smaller islands this morning. Satellite trends suggest that this drier airmass will drop across the Big Island today, supporting the idea that the areal coverage of showers and rainfall will remain limited today.
Today through the weekend…locally windy conditions this morning across typical windy areas of the islands, will diminish today dropping below advisory levels later this afternoon, then remaining breezy through this evening. The pressure gradient north of the islands, will further weaken Saturday, which should allow for some local afternoon sea breeze and night time land breeze circulations into Sunday. A stable and dry airmass will remain in place across the state (forecast model moisture depths under 8kft and dry PWs), which will limit shower chances and rainfall rates into Sunday. Temperatures will remain on the cooler side again today, along with slightly drier humidity, as the airmass today remains similar to Thursday.
Sunday night into next week, models continue to trend toward a potential wetter solution developing across the islands next week, as a feature develops and lifts northwest toward the state. This will help lift some tropical moisture across the islands through the middle of next week. Models show moisture increasing across the Big Island and vicinity Monday, then lifting up across the central smaller islands and Kauai Tuesday and Wednesday, potentially increasing rainfall chances early next week. With the developing southeast flow, the Big Island may block much of this increased moisture, with less rainfall reaching the smaller islands. Areas along the southeast slopes of the Big Island, the Pahala and Volcano areas, will see the bulk of this increased moisture.

Aviation

A dying cold front has stalled just southeast of the Big Island. Cool northerly flow has filled in behind the front and encompasses the whole of the state. Moderate to strong north- northeast winds are expected to persist most areas through this afternoon then gradually diminish for the weekend.
As of 2 AM, late night satellite imagery revealed a mostly dry air mass in the wake of the front. However, bands of mid-topped Pacific showers could also be seen just upstream of the state. These showers are expected to move onto the windward slopes and coasts of the smaller islands by morning then quickly dissipate after sunrise. Isolated convective showers are expected over higher terrain of the Big Island and Maui in the afternoon and evening showers.
AIRMET Sierra for mountain obscuration has now been cancelled for all areas except Kauai. Conditions on Kauai are expected to improve later this morning.
AIRMET Tango for low level mechanical turbulence is currently in effect downwind of the terrain of all islands. This AIRMET will likely remain in place through Friday evening.
AIRMET Tango also remains in effect for surface winds greater than 30kts across the state, including adjacent waters. This AIRMET will likely be cancelled later today.

Marine

A deepening storm force low northeast of the islands will erode the high pressure ridge north of the state and produce weaker wind trends across the region through the weekend. Gale strength winds have decreased overnight and wind speeds will range from gentle to strong breezes today, and then diminish to light winds on Saturday and Sunday. The Gale Warning was dropped this morning and replaced with Small Craft Advisories (SCA) affecting all coastal waters. Combined seas will remain above the 10 foot SCA thresholds for most of the northern coastal waters today with SCA winds lingering over the other coastal zones and channels.
A large medium period swell from the north-northeast direction (010-030 degrees) will move into Hawaiian waters today. North facing shores will continue to see warning level surf lasting through Saturday. Trade winds will begin to diminish today, and weaken further to light and variable on Saturday. These lighter wind trends will produce cleaner sets through the weekend. High Surf Warnings (HSW) for north facing shores will likely be dropped into the High Surf Advisory range by Saturday night. High Surf Advisory conditions are likely for north facing shores from Saturday night through Sunday.
A shift in swell direction will lead to lower surf heights along west facing shores today, the current High Surf Advisory was cancelled for all west facing shores except west facing shores of the Big Island. However, another small swell from the northwest direction (290-310 degrees) will also arrive on Sunday giving a slight boost to west facing shores of Kauai and perhaps less of a boost to Oahu's west facing shores due to swell shadowing from Kauai. North swell energy will slowly subside into the first half of next week with surf height trends remaining elevated along north and west facing shores due to the medium size northwest swell expected to peak on Tuesday.
The current north and north-northeast swells will combine with the early morning high spring tide during the pre-dawn hours today through Saturday, increasing the probability of significant overwash issues and large wave run up along many north facing shores. There is also the potential for harbor surges at both Kahului and Hilo harbors through the weekend.
Surf along east-facing shores will remain elevated as north- northeast swell energy wraps into exposed east facing shores. South shore surf will remain small.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Saturday for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, Koolau Windward, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala, Big Island East, Big Island North.
Wind Advisory until 6 PM HST this evening for Kauai Mountains, Waianae Coast, Oahu North Shore, Olomana, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Kauai North, Kauai East, Kauai South, Ewa Plain, Koolau Windward, Koolau Leeward, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley South, Big Island Southeast, Big Island East, Big Island North.
High Surf Advisory until 6 PM HST Saturday for Kohala.
Small Craft Advisory until 6 AM HST Saturday for all Hawaiian waters,

Data Courtesy of NOAA.gov