West Kaua’i

Rest Of Today: Breezy. Mostly cloudy with scattered showers. Highs 83 to 88 near the shore to around 73 above 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 69 to 74 near the shore to around 62 above 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 83 to 89 near the shore to around 74 above 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

South Kaua’i

Rest Of Today: Breezy. Cloudy with numerous showers. Highs 78 to 86. Northeast winds 20 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 73. Northeast winds 15 to 25 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 78 to 87. East winds 15 to 25 mph. Chance of rain 50 percent.

Kaua’i Mountains

Rest Of Today: Cloudy and breezy. Numerous showers late in the morning, then occasional showers in the afternoon. Highs 71 to 79 in the valleys to around 63 above 4000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Tonight: Windy. Cloudy with numerous showers. Lows 64 to 70 in the valleys to around 59 above 4000 feet. East winds 10 to 30 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 81 in the valleys to around 64 above 4000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

North Kaua’i

Rest Of Today: Breezy. Mostly cloudy with numerous showers. Highs 74 to 85. East winds up to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then scattered showers after midnight. Lows 65 to 73. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Gusts up to 40 mph. Chance of rain 70 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 75 to 86. East winds up to 20 mph. Chance of rain 50 percent.

East Kaua’i

Rest Of Today: Cloudy with numerous showers. Highs 70 to 82. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 65 to 76. East winds 10 to 15 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 71 to 83. East winds 10 to 15 mph. Chance of rain 70 percent.

Detailed Forecast

Synopsis

Breezy to locally windy trade winds will push deep tropical moisture over the state today. Moderate to locally heavy rainfall will possible mainly along windward and mauka areas of Maui and the Big Island this morning before spreading to the other islands this afternoon. The chance of heavy rainfall will diminish later today, but breezy and showery trades will persist through Thursday. Mid level drying will limit clouds and showers Friday into early next week. Easing trade winds over the weekend could allow for more of a hybrid land/sea breeze pattern over the weekend. Drier moderate trades should return Sunday.

Discussion

Made a quick update to the forecast to remove the mention of snow on the Big Island summits today based on the latest observations. Any precip that falls on the summits this afternoon with be rain as temperatures climbed above freezing. However, guidance continues to show deep tropical moisture lingering over the summits through Thursday morning with temperatures falling to near or below freezing tonight. As such, decided to extend the current Winter Weather Advisory through noon on Thursday as the summits will likely see a mix of rain and snow showers tonight, with a slight chance of light freezing rain possible. /Ahue
Relevant portions of the previous discussion issued this morning at 352 AM follows…So far overnight rainfall totals have been modest with most rainfall located along windward and mauka areas of Kauai, Maui and the Big Island ranging from .10 to .20 inches. An extensive cloud deck and embedded showers which has remained mostly off the eastern shores of the Big Island overnight and is now moving onshore. Radar shows scattered moderate to locally heavy showers moving along windward and mauka areas of Maui County and Big Island. High resolution model guidance continues to show of rainfall picking up through the morning hours as stronger trade winds pushes a north to south orientated axis of moisture westward. The main chance of locally heavy rainfall remains along windward and mauka areas of Maui County and the Big Island. Some locally heavy rainfall of 1-2 inches per hour could produce nuisance flooding but so far showers have been very small and brief. The threat for heavy rain will decrease later today as upper level instability shifts north and west of the state. Winds will near advisory levels for the windier areas of Maui County and the Big Island a high builds north of the state.
As for the rest of the state, scattered light to moderate showers will mainly focus along the windward and mauka regions this morning as trade wind speeds pick up. Inversion heights are expected to increase throughout the day as the airmass becomes more mixed, allowing showers to become more moderate and spilling over to leeward areas at times. Locally heavy rainfall could be possible later this afternoon into the evening hours.
The strong surface high passing north will maintain breezy trade winds into Thursday. A band of low level clouds currently near 140W, is progged to move over the state during the day Thursday keeping a rather cloudy and wet tradewind pattern in place.
Trade winds are expected to ease Friday into the weekend as a front approaches the state from the far northwest. Mid level drying should limit clouds and showers. A few high clouds may remain as an upper level short wave trough passes north of the state Friday. A hybrid trade wind and sea breeze pattern could develop Saturday as winds relax allowing for clouds and showers to develop along leeward and interior areas and low level moisture from the dissipating front moves over the state. However, cloud heights and showers will continue to be limited due to dry mid levels. The greatest chance of showers will be around Big Island where lingering moisture will be the deepest. Drier and more stable conditions will fill in Sunday into early next week as mid to upper level ridging builds over the state and moderate trades return. /Almanza

Aviation

Widespread MVFR to localized IFR along windward sections of Maui and the Big Island this morning as breezy trades push a deep slug of moisture onshore. Conditions likely to deteriorate further over Windward Big Island through midday followed by improvement tonight. Elsewhere, shallower and less organized shower activity focuses over windward and mauka zones with little impact. 12z Hilo sounding indicates a substantial dry layer within the potential icing layer, but pockets of saturation remain possible with deeper showers. As such, retained mention of tempo light icing in the AIRMET Zulu section.
AIRMET Tango in effect for lee turb.
AIRMET Sierra for mountain obscuration in effect for Windward Maui through Big Island.

Marine

Strong trade winds will continue through Thursday, then trend down through the weekend. A Small Craft Advisory is out through Thursday for contributions from both winds and seas. With the swells and winds expected to taper off Thursday night and Friday, the SCA will likely be paired back during this period, and then dropping all together this weekend.
An overlapping north and northwest swell will bring advisory conditions to north and west facing shores today through midday Thursday. Most of the focus of the north swell will be directed towards Niihau and Kauai. A High Surf Advisory has been posted for Niihau, Kauai, Oahu and Molokai. Both swells will fall through the day Thursday. Another northwest swell pushing surf back near the advisory level Saturday.
East shore surf will be on the rise today and Thursday, primarily from increased short period trade wind swell. Kauai and Niihau may get some wrap around swell out of the north pushing surf heights just below advisory level. East shore surf will decline through the weekend as trades weaken over and upstream of the islands.
For south shores, tiny background south swell energy will persist.

Fire weather

Critical fire weather conditions not expected through the forecast period. Periods of heavy rain remain possible over Maui County and the Big Island through today. Gusty trades continue into Thursday, with winds eases below critical thresholds thereafter. Lingering moisture will keep relative humidities above critical thresholds.

HFO Watches/Warnings/Advisories

High Surf Advisory until noon HST Thursday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Kauai North, Molokai Windward, Molokai North, Molokai West.
Winter Weather Advisory until noon HST Thursday for Big Island Summits.
Small Craft Advisory until 6 PM HST Thursday for all Hawaiian waters,

Kauai Now Weather is brought to you by Blue Hawaiian Helicopters.