Photo Credit: Jason Weingardt

West Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 76 to 84 near the shore to around 69 above 3000 feet. Northeast winds up to 10 mph shifting to the south in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 61 to 67 near the shore to around 55 above 3000 feet. Light winds becoming northeast up to 10 mph after midnight. Chance of rain 20 percent.

Saturday: Mostly sunny. Highs 76 to 84 near the shore to around 70 above 3000 feet. Northeast winds up to 10 mph shifting to the southwest in the afternoon.

South Kaua’i

Today: Partly sunny early in the morning then becoming mostly sunny. Isolated showers in the morning. Highs 76 to 83. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 65. North winds up to 15 mph increasing to 10 to 15 mph after midnight.

Saturday: Mostly sunny. Breezy. Highs 76 to 83. Northeast winds 10 to 20 mph.

Kaua’i Mountains

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 69 to 75 in the valleys to around 61 above 4000 feet. North winds up to 10 mph. Chance of rain 60 percent.

Tonight: Partly cloudy with isolated showers. Lows 55 to 64 in the valleys to around 52 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 69 to 76 in the valleys to around 62 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

North Kaua’i

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 70 to 79. North winds up to 10 mph. Chance of rain 60 percent.

Tonight: Partly cloudy with isolated showers. Lows 58 to 66. Southeast winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 71 to 80. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 70 to 81. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 58 to 69. North winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 69 to 80. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Showers will remain in the forecast today as a cold front advances down the island chain. Cooler and drier conditions, with light to moderate north to northeast winds, are expected tonight through the weekend, followed by a more typical trade wind pattern early next week. By midweek, another cold front may push into the forecast area, potentially resulting in increasing rainfall chances and isolated thunderstorms across parts of the state.

Discussion

Latest satellite imagery shows a quick-moving shortwave trough and associated cold front continuing to advance down the island chain this morning, that has led to increasing shower coverage and disrupted our typical trade winds. However, rainfall accumulations have been relatively minimal overnight, according to the latest rain gauge reports as the front moved through Kauai. Shower activity will steadily increase over the eastern end of the state through the day, respectively, as the front continues down the island chain. Although the best chance for thunderstorms will remain north of the area, an isolated thunderstorm or two cannot be ruled out along and ahead of the front for portions of Maui County and the Big Island today.
Conditions transition to a drier and cooler pattern this weekend, as moderate to locally breezy northerlies are advected across the region, resulting in dewpoints falling well into the 50s. This, in conjunction with the aforementioned winds, will lead to borderline fire weather conditions (see Fire Weather section for further details).
As the remnant trough associated with the front exits the region, the latest analysis shows a broad mid-level ridge just to the west, which will build eastward toward the islands, further stabilizing conditions for the next several days. Trades reestablish during the early portion of next week, which will lead to a return of windward and mauka showers. Latest model guidance in the extended outlook showcases another shortwave trough and associated cold front pushing its way into the forecast area, disrupting the trade wind pattern and potentially bringing more widespread showers and isolated thunderstorms across parts of the state. However, given that this event is still several days out, confidence remains low regarding specific details at this time.

Aviation

A shallow cold front will continue to break apart as it moves through the Hawaiian Islands today. Brief MVFR conditions are possible over some areas as shower bands break off from the dissipating frontal band. Northerly winds will slowly build in through the day.
No AIRMETs currently in effect.

Marine

The southern tail of a cold front passing north of the state will travel across the islands today. The front will back winds around to the north northeast as it passes east of Kauai early this morning and past Oahu by early afternoon. The boundary is timed to reach Big Island early tomorrow. The bulk of the thunderstorm activity associated with this front should remain confined to the far northeast waters today but an isolated storm popping up over windward Maui County and Big Island waters cannot be ruled out. High pressure building in behind the front this weekend will kick off a period of moderate to locally strong trade winds that will persist through Monday night.
A large, long period west-northwest (300-320 degree) swell is filling in through the day, peaking this afternoon and evening. This swell will produce warning level surf across most north and west-facing shores today. High to XL size north surf should hang in through Saturday. A High Surf Warning is in effect for the north and west-facing shores of Niihau, Kauai, Oahu, Molokai, along with north Maui shores through Saturday afternoon. There will be a westerly component to this swell that will increase west Big Island surf to warning levels. The High surf Warning for Big Island will be in effect through late tonight. Seas best exposed to this swell will lift to 10 feet or higher. This has prompted an all water Small Craft Advisory that will be in effect through Saturday evening. The swell will gradually decline from late Saturday into Monday. The next northwest swell is scheduled to arrive next Wednesday.
An out-of-season south swell continues to slowly fill in through today and will gradually decline this weekend. This will increase south-facing shore surf to near or slightly below summer average heights during the swell's peak from this afternoon through early Saturday.
East-facing shore surf will remain small the next couple of days as a result of disrupted trades downstream of the front. East shore surf becomes more rough Sunday and Monday in response to strengthening northeasterlies. Select east surf spots may experience some wrap from the passing large northwest swell.

Fire weather

Although there is a low chance, red flag conditions can't be completely ruled out over the weekend as very dry air and moderate to breezy northerly winds fill in behind the front. The most likely time for these conditions will be through the afternoon hours on Saturday and Sunday.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Saturday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Maui Central Valley North, Windward Haleakala.
High Surf Warning from 10 AM this morning to 6 AM HST Saturday for Kona, Kohala, Big Island South.
Small Craft Advisory until 6 AM HST Sunday for all Hawaiian waters,

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