Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 79 near the shore to around 67 above 3000 feet. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Gusts up to 50 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 69 near the shore to around 58 above 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs around 77 near the shore to around 65 above 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

South Kaua’i

Today: Breezy. Mostly sunny with scattered showers. Highs around 78. East winds 15 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 65 to 70. East winds 15 to 25 mph. Chance of rain 70 percent.

Friday: Breezy. Mostly cloudy with numerous showers. Highs around 76. East winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Partly sunny. Windy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 66 to 74 in the valleys to around 61 above 4000 feet. East winds 10 to 35 mph. Chance of rain 70 percent.

Tonight: Breezy and showers. Lows 58 to 63 in the valleys to around 52 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

Friday: Breezy and showers. Highs 64 to 72 in the valleys to around 59 above 4000 feet. East winds 10 to 25 mph. Chance of rain near 100 percent.

North Kaua’i

Today: Breezy. Partly sunny with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 71 to 78. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Gusts up to 50 mph. Chance of rain 70 percent.

Tonight: Breezy and showers. Lows 61 to 70. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain near 100 percent.

Friday: Showers. Highs 69 to 76. East winds up to 15 mph. Chance of rain near 100 percent.

East Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 71 to 78. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy and showers. Lows 59 to 71. East winds 10 to 20 mph. Chance of rain near 100 percent.

Friday: Showers. Highs 69 to 76. East winds 10 to 15 mph. Chance of rain near 100 percent.

Detailed Forecast

Synopsis

Windy conditions will persist across much of the state today, with a gradual decline expected tonight and Friday. Showery conditions are expected over the eastern islands today, with the showery weather spreading to Oahu and Kauai tonight and Friday. A few downpours and thunderstorms will be possible at times, with the highest potential for thunderstorms expected on the Big Island. Fewer showers and lighter winds are then expected over the weekend. A series of fronts will move through the islands next week, bringing moderate to breezy southwest winds to the area, and shifting the favored areas for rainfall to the west through south facing slopes and coasts.

Discussion

Currently at the surface, a 1037 mb high is centered around 1000 miles north of Honolulu, while a surface trough is positioned around 650 miles southeast of the Big Island. The pressure gradient across the island chain remains strong early this morning, with windy conditions prevailing across the state. Infrared satellite imagery shows mostly cloudy conditions over much of Maui County, the Big Island, and windward sections of Kauai and Oahu. Partly cloudy skies prevail elsewhere. Radar imagery shows scattered to numerous affecting the smaller islands, while widespread shower activity and even a few thunderstorms continue to move across the Big Island. Main short term concerns revolve around Wind and Winter Weather Headlines.
High pressure north of the state will gradually weaken during the next few days, while a trough of low pressure lingers to the southeast of the island chain. The trades will gradually weaken during this time, but will remain windy today and potentially tonight. Winds have eased up enough that the High Wind Warning has been cancelled for areas over and downwind of the Kohala mountains on the Big Island. A Wind Advisory is now in effect for most of the state through 6 PM this evening. The winds will continue to ease tonight and Friday, but breezy conditions are expected to persist.
The trades will ease further over the weekend, with moderate trades Saturday becoming light and variable on Sunday as a weakening front approaches from the west. Winds are forecast to pick up out of the southwest at moderate levels on Monday, then become locally breezy out of the southwest and west Tuesday and Wednesday as a series of fronts move through the island chain.
As for the remaining weather details, rather showery trade wind weather will continue through Saturday, particularly over the eastern end of the state. Some brief downpours and a rumble or two of thunder will be possible at times through Saturday as well given the upper level disturbance lingering overhead, with thunder chances highest over the Big Island. We should see a pattern shift beginning Sunday, with land and sea breezes leading to the development of afternoon and early evening showers over primarily interior and mauka areas. The typical leeward areas will become windward areas beginning Monday and continuing through the middle of next week, with showers favoring west through south facing slopes and coasts.
The Winter Weather Advisory for the Big Island summits has been replaced by a Winter Storm Warning due to heavy snow overnight that is expected to continue today. In fact, a couple inches of snow was reported below the Mauna Kea visitor center which is roughly around 9,000 feet. The Winter Storm Warning is in effect through 6 PM this evening. Wintry weather will likely continue to affect the summits through Saturday, and an extension of new issuances of Winter Weather headlines may be required.
We will continue to monitor conditions closely on the Haleakala summit, as temperatures are forecast to remain just above freezing and any slight dip could bring some wintry weather to the highest elevations, at or above 9,000 feet.

Aviation

The high pressure system far north of the state will weaken through the weekend. Strong and gusty trade winds are forecast to continue today before decreasing from Friday onward. The combination of unstable conditions and strong winds will allow clouds and showers to be enhanced along the mountains of each island. Expect scattered MVFR conditions with brief IFR conditions over windward and mountain areas in showers. Most of the heavy showers and isolated IFR conditions will be focused over the eastern end of the state this morning, along with a continued isolated thunderstorms over the windward areas of Maui and the Big Island.
AIRMET Sierra remains in effect for mountain obscurations over the Big Island, Maui, Molokai, Oahu and Kauai. This AIRMET will likely decrease in coverage later this morning.
AIRMET Tango remains in effect for low level moderate to isolated severe turbulence over and downwind of all island mountains. AIRMET Tango also remains in effect for strong surface winds across the entire state. These AIRMETs will likely continue through this evening.
Light icing is also expected IC from the Big Island to Molokai in a layer 100-160.

Marine

Rough conditions due gales and large seas will continue today as strong high pressure (1037 mb) remains positioned to the north. Satellite data showed 25-35 kt winds with seas hovering in the 12-15 ft range, which line up well with buoy observations at the exposed PacIOOS Mokapu station and a SOFAR drifter buoy that has entered the Alenuihaha Channel over the past 24-hrs. Guidance supports gales continuing today over the windier waters and channels of Maui County and the Big Island, then dipping to advisory levels tonight into Friday. A pattern transition is likely late Friday through the weekend as a cold front approaches, which means a break in the strong winds/seas. Guidance supports moderate to fresh southwest winds early next week as the front moves into the area.
Surf along east facing shores will remain rough, with heights holding around the warning threshold of 15 ft (faces) today due to the aforementioned winds over and upstream of the islands. A downward trend is expected late Friday through the weekend as the ridge weakens and winds ease.
Surf along north facing shores will remain well below the seasonal average each day through early next week, with the exception of the shores exposed to the large easterly seas wrapping in. A small west-northwest swell arriving Friday from a recent gale that tracked eastward from the Kurils to the Date Line will linger into the weekend. A small long-period pulse is possible Tuesday out of the north-northeast from a gale predicted to move through the Gulf of Alaska over the weekend. For the long- term (low confidence), despite the differences shown in the various model solutions, a more significant winter-like scenario unfolding will become a possibility through the second half of next week in response to broad low pressure evolving north- northwest of the islands. Confidence through the extended portion of the forecast should improve over the coming weekend.
Surf along south facing shores will remain near the seasonal average each day, with mainly wind swell wrapping into exposed areas. Short-period and choppy surf conditions are possible early next week if the fresh southwest winds develop as advertised.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Kauai Leeward, Kauai Mountains, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Kauai North, Kauai East, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Koolau Windward, Koolau Leeward, Molokai, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
High Surf Warning until 6 PM HST this evening for Olomana, Maui Windward West, Kauai East, Kauai South, East Honolulu, Koolau Windward, Molokai Windward, Molokai Southeast, Windward Haleakala, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Winter Storm Warning until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 PM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Gale Warning until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov