Photo Credit: Jason Weingardt

West Kaua’i

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 70 near the shore to around 60 above 3000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 83 to 88 near the shore to around 74 above 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

South Kaua’i

Today: Partly sunny with scattered showers. Highs 78 to 86. East winds around 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 72. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 78 to 86. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 71 to 82 in the valleys to around 63 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 69 in the valleys to around 57 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Tuesday: Mostly cloudy with numerous showers. Highs 72 to 82 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with scattered showers. Highs 74 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 72. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 74 to 86. East winds 10 to 15 mph. Chance of rain 70 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 70 to 83. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 75. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy with numerous showers. Highs 70 to 83. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy to locally windy trade winds will weaken through the day. This downtrend in wind speed will continue the next couple of days. Occasional showers caught up in the trades will primarily focus along more windward exposures and higher terrain with a few showers reaching leeward communities. As an upper low meanders near Big Island through tomorrow, more frequent heavier showers may occur over the eastern half of the state. Drier, more stable weather will commence Wednesday. Mainly dry conditions and light winds are expected from Thursday into the weekend.

Discussion

A large 1037 mb surface high is centered approximately 1,400 miles north northeast of Oahu. The pressure gradient between the high and the islands is what has been driving recently breezy to windy trade winds across the region the past several days. Select better wind-exposed or downslope channeling locations on both Big Island and Maui have been near or slightly exceeding Wind Advisory criteria of 30 mph with gusts to over 50 mph early this morning. Thus, while expiring the Wind Advisory on Molokai and Lanai last night, have extended the Wind Advisory over Kahoolawe, Maui, and Big Island through Noon HST today. IR satellite imagery has the latest ragged band of broken lower clouds coming onshore and enhancing pre-dawn shower activity. Breezy easterly steering flow will likely bring another round or two of similar cloud bands onshore. These will produce more frequent periods of light to moderate shower activity across windward Big Island and Maui communities this morning.
Mostly cloudy windward conditions will occur through tomorrow (Tuesday) whereas the bulk of the precipitation will mainly be confined to mauka slopes and east-facing coastal areas. Leeward areas will remain partly cloudy with less frequent, lower intensity shower behavior. Recent local area upper air soundings are evidence of a stable island environment. A capping inversion exists near 8k ft feet with very dry air above 10k feet. This suggests a resident boundary layer that is is deep enough to efficiently produce return periods of rain. Relatively low precipitable water values by mid-November standards may somewhat limit overall shower frequency and daily rainfall totals the next couple of days. The presence of an upper low drifting in the proximity of Big Island is offering some minor cooling aloft through Tuesday morning. This low may be an impetus to lessened stability but the high amount of mid to upper level dry air will be hard to overcome. Thus, the potential for any thunder and wintry weather for Big Island summits will be low through the middle of the week. While this upper low will focus higher rainfall accumulations over the eastern half of the island chain, from the Kaiwi Channel eastward through early Wednesday, the majority of the higher 48 hour rainfall amounts will be near 3 inches or less. A drier, more stable air mass will build in at mid week. Statewide dry conditions are expected from Wednesday into the weekend.
The high north of the state will shift southeastward and gradually weaken as it moves closer to the state. This scenario will weaken trades to more areawide gentle to locally breezy magnitudes into early Tuesday. Trades will continue to fall off Tuesday and Wednesday per weak surface high pressure as upper ridging envelops the region from the west. Winds will become light from Thursday into next weekend as the resident ridge is pushed south and further weakened by an approaching diffuse cold front to the north. This situation will lend itself to local land and sea breezes taking root and becoming the late week wind regime.

Aviation

Breezy trade winds will persist through this afternoon, however the speeds will be lower than what was experienced across the state yesterday. Low clouds and showers will bring some MVFR cigs/vsbys to windward and mauka areas, with a few decaying showers reaching leeward areas at times where VFR conditions should prevail.
AIRMET Sierra remains in effect for mountain obscuration over windward sections of most islands. Conditions should improve in most areas by mid morning.
AIRMET Tango remains in effect for moderate low-level turbulence over and downwind of island terrain. This AIRMET will likely remain in effect through the day.

Marine

Strong high pressure centered far northeast of the Hawaiian Islands will shift southeastward today due to a low passing far north of the area. Blustery trade winds across the coastal waters will trend downwards in response to the slackening trade winds. The Gale Warning for the windier waters surrounding Maui County and the Big Island has expired. The Small Craft Advisory (SCA) is now in effect for most windward waters as well as the typically windy bays and channels. Winds are expected to drop below SCA thresholds early Tuesday when a new front will move into the Northeast Pacific and forces the now weakened high pressure southward.
East-facing shore surf will remain rough and choppy for the next couple days. A High Surf Advisory (HSA) will remain in effect for all east- facing shores through this afternoon. North and south- facing shorelines exposed to these easterly wind waves may also experience elevated surf and rough waves today.
The current small, medium period northwest (320 degree) swell will drop off quickly this evening. A similar pulse from the northwest is possible late Wednesday night into Thursday. A small to moderate size north swell should arrive toward the end of the week. This last swell will originate from a North Pacific low that comes within proximity of the north offshore waters.
High tides are expected to be at their monthly maximum today. Combined with elevated seas from strong trade winds, this morning's high tide could result in coastal inundation in historically vulnerable locations. A Coastal Flood Statement will remain in effect through the late morning hours to address nuisance coastal flooding.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Olomana, Maui Windward West, Kauai East, Koolau Windward, Molokai Southeast, Windward Haleakala, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Wind Advisory until noon HST today for Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST this evening for Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov