Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the late morning and afternoon. Highs 84 to 89 near the shore to around 74 above 3000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 68 to 74 near the shore to around 60 above 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers. Highs 83 to 88 near the shore to around 73 above 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Partly sunny early in the morning then becoming mostly sunny. Breezy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs 81 to 89. East winds 20 to 25 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 70. East winds 15 to 25 mph. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 88. East winds 15 to 20 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Partly sunny with scattered showers early in the morning, then mostly sunny with isolated showers in the late morning and afternoon. Highs 72 to 79 in the valleys to around 64 above 4000 feet. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 68 in the valleys to around 57 above 4000 feet. East winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 71 to 79 in the valleys to around 64 above 4000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny early in the morning then becoming mostly sunny. Breezy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs 75 to 85. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 72. East winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 85. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 72 to 83. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 74. East winds 15 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 72 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A strong high pressure system to the north will generate breezy to strong trade winds into Tuesday. Brief passing showers are expected mainly over windward and mountain areas through Wednesday. A cold front will sweep from west to east down the island chain from Wednesday evening through Thanksgiving Day, delivering a period of showers for all islands, followed by another round of strong and gusty northeast winds that will ease by Friday night. Lighter winds are forecast from Sunday onward as the ridge north of the region weakens.

Discussion

A strong high pressure system north of the state will produce breezy to strong trade winds across the region into Tuesday. An approaching cold front will weaken the ridge north of the state and decrease wind speeds to more moderate levels from Tuesday night through Wednesday.
A wind advisory remains in effect until 6 PM HST this evening for portions of Oahu including most areas in Maui and Hawaii Counties. Trade wind temperature inversion heights will lower later today with decreasing shower activity lasting into Tuesday night. Expect brief passing showers mainly over windward and mountain areas, favoring the overnight to early morning hours in this pattern. One exception to this forecast will be more numerous showers over windward areas of East Maui and the windward Big Island through Wednesday. Shower activity will then trend upwards across all islands by Wednesday afternoon as prefrontal convergence bands produce showers ahead of the approaching cold front.
A vigorous cold front will sweep from west to east across the state from Wednesday night through Thursday. Expect a 6 hour or less period of rainfall for all islands as the frontal cloud band moves quickly through the region. A strong high pressure ridge will build in behind the front with another round of strong and gusty winds in the forecast from Thanksgiving Day into Friday. These strong northeast winds will likely exceed our wind advisory thresholds and create problems for outdoor holiday events. Please consider indoor party planning for this Thanksgiving as winds this strong may blow away small items and tents.
Winds are expected to ease from Friday into the weekend as a cut off low forms on the front northeast of the islands, and the high rapidly weakens. Light winds will develop from Sunday onward with land and sea breezes forming over all islands.

Aviation

Strong, gusty trades will continue through the forecast period and will focus clouds and showers mainly over windward and mauka areas. Shower intensity will tend to be limited over the western end of the state due to increasing stability. However, pockets of deeper moisture within the comparatively low stability environment over the eastern end of the state will favor periods of heavier showers over Windward Big Island and Maui. This will especially be the case this evening when an expanding coverage of showers will likely bring widespread MVFR to these areas.
AIRMET Tango for lee turbulence will remain in effect through the forecast period.
AIRMET Sierra for mountain obscuration may be needed this evening.

Marine

A tight pressure gradient across Hawaii will result in strong to gale force trade winds across the coastal waters through tonight. A Gale Warning is in effect for Pailolo and Alenuihaha channel through this evening. A Small Craft Advisory (SCA) is also in effect for all Hawaiian waters through today, with the likelihood that at least some of the waters will be extended into beyond then. A slight weakening in the winds is forecast Tuesday through the day Wednesday as the driving high moves away. In its place, a vigorous cold front will impact the area beginning Wednesday night and continuing through Friday, which will produce gale force winds and rough seas in combination with a large north northwest swell.
Currently, a long-period northwest swell (310 degrees) will fill in throughout the morning. A High Surf Advisory (HSA) is now in effect through 6 am Tuesday as the offshore buoys have indicated the swell coming in slightly above guidance. The swell is expected to decline Tuesday and Wednesday. A much larger north northwest swell will build overnight Wednesday night into Thanksgiving Day. The peak of this swell could reach warning levels and it could coincide with the spring high tide during the early morning hours Thursday. Adding the potential for gale force winds along the cold front, there could be significant overwash issues and large wave run up along north facing shorelines both on the mornings of Thanksgiving and Friday. Latest wave run up forecast from PACIOOS is indicating wave run- up heights exceeding 8 feet and approaching 10 feet. Above 8 feet, overtopping of lower roadways closer to the shore should be expected. Areas exposed to north swells on other shorelines should see a significant rise in surf as the north northwest swell moves in.
Surf along east facing shores will see a steady rise during the next few days as the trades strengthen. Other than some wind swell wrap, south facing shores will see minimal energy for the foreseeable future.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Tuesday for north and west facing shores of Niihau, Kauai, Oahu and Molokai.
Red Flag Warning from 9 AM HST this morning to 6 PM HST this evening for all leeward areas.
Wind Advisory until 6 PM HST this evening for portions of Oahu and most areas of Maui and Hawaii Counties.
Small Craft Advisory until 6 PM HST this evening for all Hawaiian coastal waters.
Gale Warning until 6 PM HST this evening for Pailolo Channel, Alenuihaha Channel.

Data Courtesy of NOAA.gov