Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Breezy. Highs around 75 near the shore to around 63 above 3000 feet. Northeast winds up to 20 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 65 near the shore to around 54 above 3000 feet. Northeast winds up to 20 mph with gusts to 45 mph. Chance of rain 20 percent.

Sunday: Breezy. Mostly sunny with isolated showers. Highs around 76 near the shore to around 64 above 3000 feet. East winds up to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny. Breezy. Highs around 74. Northeast winds 15 to 25 mph with gusts to 45 mph.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 61 to 66. Northeast winds 15 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs around 75. East winds 15 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Windy. Partly sunny with isolated showers. Highs 62 to 70 in the valleys to around 57 above 4000 feet. Northeast winds 10 to 30 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 54 to 59 in the valleys to around 48 above 4000 feet. Northeast winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 63 to 71 in the valleys to around 58 above 4000 feet. East winds 10 to 25 mph with gusts to 45 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 67 to 74. Northeast winds 10 to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 57 to 66. East winds 10 to 20 mph with gusts to 45 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 68 to 75. East winds up to 20 mph with gusts to 45 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny. Breezy. Isolated showers in the afternoon. Highs 67 to 74. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 55 to 67. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 68 to 75. East winds 10 to 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

High pressure building north of the state in the wake of a cold front, will keep cool and windy weather in place through the weekend. Some showery weather will hang on over windward Big Island this morning with improving conditions expected this afternoon. Elsewhere, mostly dry weather will prevail. The airmass will gradually moisten up tonight and Sunday, bringing a return of trade showers. The remnants of an old front will bring showery weather to windward areas Sunday night into Monday and send more showers into leeward communities as well. Breezy to locally windy trades are expected Monday afternoon through Wednesday, before easing off for the tail end of the work week. Showers will continue to favor windward slopes and coasts.

Discussion

Currently at the surface, a strong cold front has moved south of the Big Island, while a 1031 mb high is centered around 750 miles north-northwest of Kauai. Breezy to windy north-northeast trades prevail across the island chain early this morning, ushering in much cooler conditions with temperatures now in the 50s in most areas with the exception of windward Big Island. Infrared satellite imagery shows mostly cloudy conditions in windward areas, with mostly clear to partly cloudy skies in leeward locales. Radar imagery and rain gage observations show the majority of the shower activity is now confined to windward slopes of the Big Island, with some lingering showers across Maui County, and dry conditions elsewhere. Main short term focus remains on the strong winds during the next couple days.
The strong high to the north-northwest will build northeast and strengthen during the next couple days. Windy conditions are expected statewide through the weekend as winds shift from the north-northeast around to a more typical east-northeasterly trade wind direction. Based on the latest observational trends, a Wind Advisory appears to be handling the current situation well, and remains posted for the entire entire island chain through 6 PM Sunday.
The high will settle slowly southward well northeast of the state Monday through Wednesday, keeping breezy to locally windy easterly trades blowing across the island chain. An extension to the Wind Advisory may be required for some of the typically windy areas in Maui County and the Big Island Monday and Tuesday. The high will then weaken for the second half of next week while a couple fronts approach from the northwest. This will gradually ease the trade winds from west to east across the island chain.
As for the remaining weather details, trailing moisture behind the front will linger over windward Big Island this morning, keeping showery conditions in place, with improving conditions expected for the afternoon. Elsewhere, the dry air mass will keep shower activity minimal, with only a few very light showers possible along windward slopes. The strong winds in combination with dewpoints in the 50s will make it feel quite cool, with high temperatures topping out in the mid 70s in most areas to around 80 over leeward Big Island.
The boundary layer will begin to moisten up tonight as the upstream fetch of northeasterly trades expands with lapse rates in the 1000-900 mb layer holding at an impressive 9-10C. This is expected to bring a gradual increase in trade wind showers through the night. Little change to this pattern is expected through Sunday, with showers favoring windward slopes and coasts, although the strong trades could carry a few showers leeward. The models show a band of moisture associated with an old front moving through Sunday night into Monday morning, which will likely bring an increase in trade wind showers and sending them leeward more frequently as well. Fairly typical trade wind weather should then persist from Monday afternoon through Wednesday, with showers favoring windward slopes and coasts and a few showers reaching leeward areas from time to time. As the flow tips more east- southeast late next week, showers will continue to favor windward areas, with afternoon clouds and a few showers expected each day in leeward locales.

Aviation

A cold front will push south and east of the state today and exit the region. Behind the front, a drier airmass, along with strong and gusty north northeasterly winds, will advect across the state. This flow will likely cause tempo moderate turbulence along the lee of all mountain ranges. See AIRMET TANGO for more details.
Isolated showers may affect areas along windward portions of the smaller islands with scattered showers for windward portions of the Big Island.
AIRMET SIERRA remains in effect for north through east portions of the Big Island above 2500 feet due to mountain obscuration from low clouds and showers.
AIRMET TANGO remains in effect below 10000 feet immediately south through west of mountains of all islands.

Marine

Strong- to gale-force northeast winds associated with high pressure building north of the state will continue today, then shift out of the east Sunday through early next week. A combination of rough, short-period wind waves in response to these winds and a large, north-northeast swell moving through support hazardous marine conditions persisting across all Hawaiian waters through early next week. Gales are expected over the typically windier channels between Maui County and the Big Island, the leeward waters of Maui County, Maalaea Bay (north winds), and over the waters around South Point of the Big Island through early Monday. Strong easterly trades will hold Monday through Wednesday, then potentially begin to ease and shift out of the east- southeast late next week as the ridge begins to weaken.
Surf along exposed north and east facing shores will remain rough due to a mix of locally-driven wind waves and a large medium- to long-period north-northeast (020 deg) swell moving through. Observations at the near and offshore buoys reflect this and show much higher seas than predicted this morning, which is typical with this scenario. Surf will hold at warning levels for northern exposures today, then likely dip to advisory levels on Sunday as the winds shift out of the east and the north-northeast swell slowly eases. For east facing shores, where the warning and advisory thresholds are lower compared to the north facing shores, expect the warning to potentially linger into Sunday before lowering to advisory levels going into Monday.
Surf along north and west facing shores will trend up late Sunday through early next week as a long-period (forerunners expected to arrive through the day Sunday) northwest (310-320 deg) swell arrives. This swell will peak on Monday (advisory to near warning- level surf), then ease Tuesday through the second half of the week. For the long range (low confidence), guidance shows the next significant northwest swell arriving late next weekend (2/11).

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Sunday for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, East Honolulu, Koolau Windward, Molokai Windward, Molokai North, Maui Central Valley North, Windward Haleakala, Kipahulu, Big Island East, Big Island North.
Wind Advisory until 6 PM HST Sunday for Niihau, Kauai Leeward, Kauai Mountains, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kona, Kohala, 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 East, Big Island North.
High Surf Advisory until 6 PM HST Sunday for Maui Leeward West, Kohala.
Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST early this morning for Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Gale Warning from 6 AM this morning to 6 PM HST Sunday for Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov