West Kaua’i

Tonight: Partly cloudy. Breezy. Lows 65 to 70 near the shore to around 58 above 3000 feet. Northeast winds up to 15 mph increasing to 10 to 20 mph after midnight.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 80 to 87 near the shore to around 72 above 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tuesday Night: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 71 near the shore to around 59 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

South Kaua’i

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 69. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tuesday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 85. Northeast winds 15 to 25 mph. Chance of rain 70 percent.

Tuesday Night: Breezy. Mostly cloudy with scattered showers. Lows around 70. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 58 to 69 in the valleys to around 57 above 4000 feet. East winds up to 25 mph increasing to 10 to 25 mph after midnight. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 78 in the valleys to around 63 above 4000 feet. East winds 10 to 25 mph. Chance of rain 80 percent.

Tuesday Night: Mostly cloudy. Breezy. Numerous showers in the evening, then occasional showers after midnight. Lows 59 to 69 in the valleys to around 58 above 4000 feet. East winds 10 to 25 mph. Chance of rain 80 percent.

North Kaua’i

Tonight: Mostly cloudy with isolated showers. Lows 62 to 70. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Breezy. Partly sunny with scattered showers. Highs 74 to 83. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tuesday Night: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 69. East winds up to 20 mph. Chance of rain 70 percent.

East Kaua’i

Tonight: Mostly cloudy with isolated showers. Lows 62 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 72 to 83. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Tuesday Night: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 63 to 73. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy to strong trades will continue through the forecast period bringing a return to a typical distribution of clouds and showers focused mainly over windward and mauka areas.

Discussion

Currently at the surface, a weakening stationary front is located around 125 miles north of Kauai, while a strong 1033 mb high is centered around 800 miles north of Honolulu. The gradient locally has tightened up considerably during the past 24 hours, with breezy trades in place across the entire state. Infrared satellite imagery shows partly cloudy conditions in most areas, with a bit more cloud cover in some windward and mauka locations as well as leeward sections of the Big Island. Radar imagery showers a few showers moving into windward Maui and the Big Island, with mostly dry conditions elsewhere. Main short focus revolves around the strong winds and the potential need for a Wind Advisory across portions of the state during the next couple days.
A strong area of high pressure north of the state will build eastward well to the north of the islands during the next couple days. This high will weaken Thursday and Friday, before being quickly replaced by a new strong high building north of the area over the weekend into early next week. An extended period of breezy to windy trades can be expected across the island chain. The winds appear particularly strong Tuesday through Wednesday, and a Wind Advisory may be required for some of the windier Maui County and Big Island zones. We will monitor observations closely through the night and make a decision on the need for an advisory with the morning forecast package.
As for the remaining weather details, fairly typical trade wind weather featuring windward and mauka showers along with the occasional leeward spillover can be expected over the eastern islands through Tuesday. Rather dry weather should prevail across Kauai and Oahu however, with only a few light showers possibly mainly windward and mauka. There could be an increase in trade wind showers here Tuesday afternoon as some deeper moisture begins to move in from the east. A more uniform and typical trade wind regime should take hold across the entire state Tuesday night through Wednesday night, with showers favoring windward/mauka areas and a few showers reaching leeward areas from time to time. Moisture assoicated with an old front appears to get pushed through the islands Thursday, increasing trade wind shower coverage. Fairly typical trade wind weather should fill back in Thursday night and continue through early next week, with periodic bands of moisture moving in on the trades and increasing shower coverage as they do.

Aviation

Strong surface high pressure will pass north of the Main Hawaiian islands over the next several days and bring breezy to locally windy trade winds. Periods of clouds and brief showers will favor windward and mauka areas during the overnight to early morning hours. Brief MVFR conditions will be possible in showers. Otherwise, VFR conditions will prevail.
AIRMET TANGO for low-level turbulence over and downstream of island terrain is in effect due to the strengthening trade winds and will likely be extended through the next several days.

Marine

Fresh to strong easterly trade winds will strengthen into strong to near gale force levels from tonight into early Thursday as high pressure builds north of the island chain. Winds should trend slightly lower from late Thursday into Saturday, as a cold front approaches the island waters from the north. Seas will remain rough through the week, with a combination of short period wind waves and northwest swells moving through the Hawaii Region. Small Craft Advisory conditions are expected to continue for all Hawaiian waters through much of the week due to a combination of strong winds and higher seas.
Surf along exposed north and west facing shores will peak this evening through early Tuesday as a fresh northwest (310-320 degrees) swell builds down the island chain. Offshore buoy observations seem to reach the predicted peak this afternoon and evening. Expect surf heights to reach low end advisory levels for exposed north and west facing shores through early Tuesday, then gradually ease late Tuesday through midweek. Another upward trend is expected late Thursday through Saturday as a couple of northwest (320-330 degrees) swells arrive, peaking Friday night into Saturday. This may push surf heights back to advisory levels at the peak late Friday into Saturday. A downward trend is then expected through early next week.
Surf along east-facing shores will remain rough through the week due to strong easterly trade winds.
Surf along south-facing shores will remain small, with mainly background south and southeast swells.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Tuesday 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.
Small Craft Advisory until 6 PM HST Wednesday for all Hawaiian waters,

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