West Side

Today: Windy. Mostly cloudy with scattered showers. Highs 76 to 82. East winds 15 to 30 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Windy. Isolated showers in the evening. Lows 68 to 75. East winds 20 to 30 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Windy. Highs 78 to 84. East winds 20 to 30 mph shifting to the northeast 10 to 30 mph in the afternoon.

South Side

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84. Northeast winds up to 20 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy. Breezy. Lows 68 to 76. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Thursday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 87. Northeast winds 10 to 20 mph decreasing to up to 20 mph in the afternoon.

North Shore

Today: Windy. Occasional showers. Highs around 80 near the shore to around 63 near 5000 feet. East winds 10 to 30 mph. Chance of rain near 100 percent.

Tonight: Cloudy and windy. Numerous showers in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 52 near 5000 feet. East winds 10 to 30 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Central Maui

Today: Windy. Mostly cloudy with scattered showers. Highs 79 to 85. East winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Windy. Isolated showers in the evening. Lows around 71. East winds 10 to 30 mph. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning then becoming partly sunny. Windy. Highs 81 to 87. East winds 10 to 30 mph.

Upcountry

Today: Breezy. Cloudy with numerous showers. Highs around 58 at the visitor center to around 66 at the summit. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 47 at the visitor center to around 45 at the summit. East winds 10 to 25 mph. Chance of rain 50 percent.

Thursday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 60 at the visitor center to around 67 at the summit. East winds 10 to 25 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Windy. Occasional showers. Highs around 80 near the shore to around 63 near 5000 feet. East winds 10 to 30 mph. Chance of rain near 100 percent.

Tonight: Cloudy and windy. Numerous showers in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 52 near 5000 feet. East winds 10 to 30 mph. Chance of rain 70 percent.

Thursday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 80 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Lanai City

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 71 to 80. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy. Breezy. Lows around 67. Northeast winds 10 to 20 mph.

Thursday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs 72 to 81. Northeast winds 10 to 25 mph.

Kaunakakai

Today: Breezy. Partly sunny with scattered showers. Highs 68 to 86. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Lows 59 to 75. East winds 15 to 25 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Breezy. Highs 69 to 86. East winds 15 to 25 mph.

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

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.
Increasing thick clouds over the Big Island summits could briefly produce light snow accumulations this morning as precipitation increases, however the snow will quickly transition to rain after sunrise. The Winter Weather Advisory currently runs through today and could be extended through Thursday morning as the deep moisture lingers and overnight temperatures dip to near freezing.
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.

Aviation

Layered clouds moving S to N primarily over Big Island this morning will cause light icing from FL140-FL260 as highlighted in AIRMET ZULU. AIRMET Tango continues for moderate turbulence between FL250 and FL400 over all islands. Tango will likely be dropped by 2200Z as turbulence is expected to decrease through the morning.
Trades will strengthen a bit today, becoming gusty and peaking near 25 knots at more windward facing airfields. There is still a slight chance for a windward AIRMET Sierra these next few hours for mountain obscuration. Ceilings may lower to MVFR within afternoon showers.

Marine

Moderate trade winds will increase over the next 12 hours. The weakening front to the north is not expected to push much farther east, and northeast winds are already increasing at NOAA buoy 51001 as strong surface high behind the front is starting to exert influence. As the front dissipates and the surface high moves north of the state today, expect trade winds to ramp up, eventually reaching near gale strength in the Alenuihaha Channel. A Small Craft Advisory (SCA) is in effect for the typical windy waters around the Big Island and Maui and expands to cover all waters at 6AM today through Thursday as trades rapidly build. The high will be pushed to the east by a North Pacific front late Thursday and Friday, leading to a gradual decline in the trades. Trades may decline further this weekend as the front passes north of the islands.
A northwest swell is moving in this morning and will gradually increase surf along exposed north and west shores from Kauai to Maui. A High Surf Advisory may be needed later today as the swell shifts out of the north- northwest and continues to build. The northwest swell will be accompanied by a small to moderate short period north swell aimed primarily west of Kauai, while building trades produce increased wind waves. The combined seas from all of these sources will be in excess of 10 feet that will contribute to the need for the SCA. The north- northwest swell will gradually decline Thursday and Friday, with 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, though the western end of the island chain could also experience a brief short period north (350-010 degrees) swell of 3 to 6 feet at 10 seconds. As mentioned above, this north swell will be primarily aimed west of Kauai, but some wrapping energy could push east shores of Kauai near the High Surf Advisory level later today. The north swell will rapidly fade on Thursday, when peaking trade wind swell will produce surf just below the advisory level on east shores of all islands. 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

Winter Weather Advisory until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory from 6 AM this morning to 6 PM HST Thursday 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.
Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov