Photo Credit: Jason Weingardt

West Kaua’i

Today: Breezy. Partly sunny with isolated showers. Highs around 80 near the shore to around 67 above 3000 feet. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers after midnight. Lows around 66 near the shore to around 55 above 3000 feet. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Saturday: Partly sunny. Breezy. Isolated showers in the morning. Highs around 79 near the shore to around 67 above 3000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Highs 76 to 81. Northeast winds 20 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 68. Northeast winds 20 to 25 mph. Chance of rain 50 percent.

Saturday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 78. Northeast winds 20 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Windy. Mostly cloudy with numerous showers. Highs 66 to 74 in the valleys to around 61 above 4000 feet. Northeast winds 20 to 30 mph. Chance of rain 70 percent.

Tonight: Windy. Mostly cloudy with numerous showers. Lows 56 to 61 in the valleys to around 49 above 4000 feet. Northeast winds 20 to 30 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. 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 20 to 30 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Highs 71 to 79. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 58 to 68. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Saturday: Breezy. Partly sunny with scattered showers. Highs 71 to 78. East winds 15 to 25 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Mostly cloudy with scattered showers. Highs 71 to 79. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 56 to 69. Northeast winds 20 to 25 mph. Chance of rain 50 percent.

Saturday: Breezy. Mostly cloudy with scattered showers. Highs 71 to 78. Northeast winds around 20 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Trade winds will remain locally strong and gusty through the weekend. Expect decreasing showers across Kauai and Oahu into the weekend. However, the Big Island and Maui will continue to see abundant windward showers. Another period of enhanced rainfall is possible statewide starting late Monday.

Discussion

A strong 1033 mb high pressure 1030 nm northwest of the main Hawaiian Islands continues to drive breezy trades across local waters. The upper trough extending northeast to southwest across the chain that brought active weather these past couple of days is breaking down as an upper level low pinches off to the southwest and the remaining trough feature tracks east of the state. Radar imagery shows more typical trade wind showers moving through Kauai and Oahu with some enhanced showers over and upstream of Maui County and the Big Island. High clouds continue to stream over the southern end of the state marking the eastern flank of the subtropical jetstream. Deep moisture and some lingering instability near the Big Island will keep periods of snowfall and freezing rain in the forecast, especially during the morning hours, thus a Winter Weather Advisory has been extended through 6 PM this evening but may end sooner as upper level temperatures slowly warm and moisture depths decrease.
A moisture gradient has developed over the state, with PW dropping below an inch over Kauai and Oahu but remaining near 1.6 inches over the Big Island. Expect continued wet conditions over windward Big Island and possibly Maui, with fewer windward showers elsewhere through the weekend. In addition the high to the northwest will strengthen slightly and shift southeast just north of the state. This will keep strong trades in the forecast into Monday. The pinched off upper low will move back over the islands from the southwest early next week, bringing a statewide increase in showers from Monday night into Wednesday. Temperatures aloft are not expected to be as cold as they are currently, making thunderstorms less likely, but heavy showers are possible again riding in with the trades at that time. The high will then move quickly northeast away from the area as a strong front moves into the central North Pacific, causing trades to weaken Tuesday into Wednesday. The front is forecast to move down the island chain Wednesday and Thursday. Strong north winds will usher in a cool and dry air mass after the front passes.

Aviation

A strong high pressure system building north of the state will keep breezy to locally windy trade winds in the forecast lasting into the weekend. An upper level low will also produce periods of unstable showers, possibly heavy at times, and gusty winds. Expect mainly VFR conditions with periods of MVFR and local IFR conditions under passing showers.
AIRMET Sierra for mountain obscuration remains in effect for north through east sections of Kauai, Oahu, Molokai, Maui and the Big Island. This AIRMET will likely diminish in coverage later this morning.
AIRMET Tango for moderate to locally severe turbulence over and south through west of island mountains remains in effect. This AIRMET will likely continue through the weekend.
AIRMET Tango for moderate turbulence aloft between FL200 and FL450 remains in effect for all islands. This AIRMET will diminish by this evening.
Severe turbulence is also forecast from Kauai westward between FL280 and FL400 as a subtropical jet stream moves through the region.

Marine

A strong high pressure cell will be nearly stationary far NNW of the islands through the weekend, then move rapidly E Monday and Tuesday. Strong to gale-force trade winds are anticipated the next couple of days, strongest in the channels around Maui and the Big Island. Additional details are contained in the Marine Weather Message (MWWHFO). Winds will gradually diminish and veer to the ESE as the high moves away and a front approaches from the NW.
The strong trades will continue to generate rough, choppy surf along E facing shores through the weekend, gradually easing early next week. Surf along N and W facing shores will remain small today, but a new, long-period NNW swell will arrive tonight and peak Saturday, then diminish Sunday. Peak surf heights will approach High Surf Advisory levels along exposed N facing shores. A moderate-sized, long-period NW swell is possible Monday into Wednesday of next week, with the potential for a larger NNW swell later next week. A small, long-period SW swell is possible late this weekend and early next week.

HFO Watches/Warnings/Advisories

Winter Weather Advisory until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 PM HST Saturday 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 Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov