West Kaua’i

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 68 near the shore to around 58 above 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs around 80 near the shore to around 69 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Wednesday Night: Breezy. Mostly cloudy with scattered showers. Lows around 67 near the shore to around 57 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 67. East winds 15 to 20 mph. Chance of rain 70 percent.

Wednesday: Breezy. Partly sunny with scattered showers. Highs 74 to 81. East winds 15 to 20 mph. Chance of rain 50 percent.

Wednesday Night: Breezy. Mostly cloudy with scattered showers. Lows around 67. East winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with showers. Lows 58 to 66 in the valleys to around 55 above 4000 feet. East winds up to 25 mph with gusts to 45 mph. Chance of rain 90 percent.

Wednesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 70 to 76 in the valleys to around 60 above 4000 feet. East winds up to 20 mph with gusts to 45 mph. Chance of rain 70 percent.

Wednesday Night: Breezy. Mostly cloudy with showers. Lows 58 to 66 in the valleys to around 55 above 4000 feet. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 80 percent.

North Kaua’i

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 61 to 69. East winds up to 20 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers. Highs 71 to 80. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with numerous showers. Lows 60 to 68. East winds up to 15 mph. Chance of rain 70 percent.

East Kaua’i

Tonight: Mostly cloudy with numerous showers. Lows 61 to 71. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy with scattered showers. Highs 68 to 79. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with numerous showers. Lows 61 to 71. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

High pressure north and northeast of the islands will continue to deliver windward and mauka showers on breezy to windy trades through early next week.

Discussion

Westward push of dry air in the 850-700mb layer has provided an extra downward push in maintainence of downsloping winds for much of this afternoon. However, with increased moisture arriving in the trade winds and current observations lacking gusts to 50 mph, the Wind Advisory has been cancelled for Maui County and the Big Island. Incoming band of showers is presently draped over Kauai, Oahu, and Maui County and is a couple hours from the Big Island. The increase in showers will continue through this evening for the former while lasting for most or all of the overnight period for the latter. Further, temperatures on the Big Island summits have risen slightly above freezing but are forecast to return to sub- freezing overnight. The potential exists for showers to deposit freezing rain on the summits as moisture deepens late tonight into early Wednesday. The presence of mid-level moisture also supports mention of snow. Suspect temperatures will again become marginal during Wednesday, but prospects for upslope convection also suggest potential for a transition to a dominant ptype of snow which would be easier to sustain with marginal boundary layer temps. Going forward, strong trades gradually become moderately stable and continue through the weekend delivering clouds and showers mainly windward and mauka.

Aviation

Gusty trades continue for most sites outside of the Big Island this afternoon. Light showers will also affect mauka and windward areas, making for intermittent MVFR conditions at times, particularly for HLI which has seen MVFR for much of the day today. A band of moisture is expected to impact the Big Island this evening and overnight, before drier conditions prevail for Wednesday, with breezy trades still in place.
AIRMET Sierra is in effect for mtn obsc for all of Kauai and Oahu, as well as the N thru SE sections of Molokai, Maui, and the Big Island.
AIRMET Tango is in effect for moderate to isolated severe turb below 070 for leeward sides of the islands and mod tempo turb between FL220 to FL380 over entire area.
Light icing remains possible in cloud layer 120-FL250 across the state.

Marine

A strong high pressure system far north of the Hawaiian Islands will slowly drift eastward over the next few days. Trade wind speeds will gradually weaken from strong to gale force tonight to fresh to strong from Wednesday onward. A Gale Warning is in effect for windier waters and channels around Maui and the Big Island, while a Small Craft Advisory (SCA) is posted for all remaining waters through tonight. Expect the Gale Warning to drop back to SCA levels for windier coastal waters from Wednesday on into the weekend.
The strong trade winds will keep high surf and very rough seas along east facing shores of most islands tonight. A High Surf Advisory is in effect through early Wednesday morning to cover these conditions. Slowly decreasing easterly trade winds tomorrow will cause surf heights to fall along east facing shores below advisory thresholds by Wednesday morning. However, elevated surf heights along east facing shores will keep rough conditions in the forecast just below surf advisory thresholds into Friday.
Small to medium northwest swells will continue through the week with smaller surf lingering in the forecast along north and west facing shores for the foreseeable future. Small background medium period south swell energy will keep surf heights along the south facing shores on the tiny side lasting into early next week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Wednesday for Olomana, Kahoolawe, Maui Windward West, Kauai East, East Honolulu, Koolau Windward, Molokai Windward, Molokai Southeast, Windward Haleakala, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Winter Weather Advisory from 6 PM this evening to 6 PM HST Wednesday for Big Island Summits.
Small Craft Advisory until 6 AM HST Wednesday 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 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov