West Side

Today: Windy. Partly sunny with scattered showers. Highs 72 to 82. Southwest winds 20 to 30 mph. Chance of rain 50 percent.

Tonight: Windy. Mostly cloudy with scattered showers in the evening, then partly cloudy with showers likely after midnight. Lows 62 to 69. South winds 15 to 30 mph decreasing to up to 30 mph after midnight. Chance of rain 60 percent.

Tuesday: Mostly sunny. Showers likely in the morning. Highs 71 to 81. North winds up to 10 mph. Chance of rain 70 percent.

South Side

Today: Windy. Partly sunny with scattered showers. Highs 74 to 83. Southwest winds 25 to 30 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Scattered showers. Lows around 65. South winds 10 to 25 mph with gusts to 45 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Showers likely in the morning, then isolated showers in the afternoon. Highs 72 to 82. Northeast winds up to 10 mph. Chance of rain 70 percent.

North Shore

Today: Sunny and windy. Highs around 82 near the shore to around 66 near 5000 feet. Southwest winds 10 to 30 mph decreasing to up to 30 mph in the afternoon. Gusts up to 50 mph.

Tonight: Mostly clear. Windy. Scattered showers after midnight. Lows around 66 near the shore to around 51 near 5000 feet. Southwest winds 10 to 30 mph decreasing to up to 30 mph after midnight. Gusts up to 50 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 64 near 5000 feet. Northwest winds up to 15 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Windy. Isolated showers until late afternoon, then scattered showers late in the afternoon. Highs around 82. Southwest winds 25 to 30 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Windy. Partly cloudy with scattered showers. Lows around 65. Southwest winds 25 to 30 mph shifting to the south 10 to 30 mph after midnight. Gusts up to 50 mph in the evening. Chance of rain 50 percent.

Tuesday: Mostly sunny. Showers likely in the morning. Highs around 80. Northwest winds 10 to 15 mph. Chance of rain 70 percent.

Upcountry

Today: Mostly sunny. Very windy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 50 to 68. Southwest winds up to 40 mph. Gusts up to 60 mph increasing to 70 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy. Very windy. Isolated showers in the evening, then scattered showers after midnight. Lows around 42 at the visitor center to around 40 at the summit. West winds 10 to 40 mph with gusts to 70 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Windy. Showers likely in the morning, then isolated showers in the afternoon. Highs 49 to 67. West winds up to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

East Maui

Today: Sunny and windy. Highs around 82 near the shore to around 66 near 5000 feet. Southwest winds 10 to 30 mph decreasing to up to 30 mph in the afternoon. Gusts up to 50 mph.

Tonight: Mostly clear. Windy. Scattered showers after midnight. Lows around 66 near the shore to around 51 near 5000 feet. Southwest winds 10 to 30 mph decreasing to up to 30 mph after midnight. Gusts up to 50 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 64 near 5000 feet. Northwest winds up to 15 mph. Chance of rain 70 percent.

Lanai City

Today: Windy. Partly sunny with scattered showers. Highs 67 to 77. Southwest winds 20 to 30 mph. Chance of rain 50 percent.

Tonight: Windy. Mostly cloudy with scattered showers in the evening, then partly cloudy with showers likely after midnight. Lows 56 to 63. Southwest winds 20 to 30 mph decreasing to 10 to 30 mph after midnight. Chance of rain 60 percent.

Tuesday: Sunny. Showers likely in the morning. Highs 66 to 76. Northwest winds up to 10 mph. Chance of rain 70 percent.

Kaunakakai

Today: Windy. Partly sunny with scattered showers. Highs 67 to 83. Southwest winds 20 to 30 mph with gusts to 50 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy until early morning then becoming partly cloudy. Windy. Scattered showers early in the evening, then showers likely in the late evening and overnight. Lows 52 to 68. Southwest winds 20 to 30 mph shifting to the west 10 to 30 mph after midnight. Gusts up to 50 mph in the evening. Chance of rain 70 percent.

Tuesday: Sunny. Scattered showers in the morning. Highs 65 to 82. North winds up to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A cold front will march eastward down the island chain from later this afternoon onward, finally stalling out and diminishing near the Big Island by Tuesday afternoon. Southerly to southwesterly winds will strengthen into the breezy to strong range with higher gusts through tonight. Northwesterly winds with cool and dry conditions will follow behind the frontal passage. A stronger weather system may produce more significant weather impacts across from late Friday onward with the potential for periods of heavy rain and thunderstorms.

Discussion

This mornings infrared satellite imagery over the Central Pacific basin shows bands of clouds riding into each island in the southwesterly winds ahead of an approaching cold front roughly 200 miles northwest of Kauai at this hour. Strong and gusty south to southwest winds will increase to Wind Advisory levels across all Hawaiian Island today with wind gusts up to 50 mph possible in wind favored locations. The strongest wind gusts will favor mountain ranges and areas north and east of island terrain features. Surface wind speeds continue to trend upward this morning with the highest winds already reaching the 20 to 30 MPH range in some areas with gusts near 40 MPH. A Wind Advisory was issued this morning to cover these stronger wind threats. Even stronger winds will blow across the highest summits on the Big Island, strengthening to warning levels later this afternoon. A High Wind Warning was issued for the Big Island summits of Mauna Kea and Mauna Loa lasting into Wednesday. Expect these stronger winds to decrease below advisory thresholds as weaker northwesterly winds blow in after the front passes through each island.
The cold front continues to quickly approach the Hawaiian Islands from the northwest direction this morning, the front will swiftly march eastward down the island chain through Tuesday. The highest rainfall amounts will develop over a four to six hour time period along the main frontal cloud band as it passes through each island. Based on all available data, the front will move into Niihau and Kauai around noon, reaching Oahu by mid afternoon, then onward to Molokai and Lanai in the evening hours, into Maui around midnight, and finally the remnants of the frontal band with significantly less shower activity will reach the Big Island on Tuesday morning. Expect cooler and drier northwesterly winds to develop after frontal passage. This drier air will keep cooler overnight to early morning temperatures in the 60's as the atmosphere will more efficiently radiate heat into outer space each night.
Lighter winds return to the region from Tuesday night into Thursday as a weak high pressure system just north of the state drifts slowly eastward. Light to moderate southwest winds will develop from Thursday night into Friday ahead of the next even stronger cold front approaching Hawaii from the northwest direction. This next front appears to stall out near Kauai and Oahu from Saturday night to Sunday, as the cold pool aloft transforms into a cut off low near the islands.
There remains a tremendous amount of uncertainty on the impacts with this next cut off low setting up near the islands this weekend. On one hand, the front stalls out earlier over the western islands and remains less progressive than what was forecast just 24 hours ago. This upper low has the potential to produce periods of heavy rain and thunderstorms with potential for flood threats to portions of the state from Saturday through Monday. However, the recent 24 hour trends in the operational and ensemble models are driving the track of this low farther east over time. Any significant impacts with this system are highly dependent upon where the low sets up relative to each island. As of this moment, we are closely watching this system evolve as the time period grows shorter for changes in track and intensity. For now, the latest forecast guidance suggests that the most intense part of this storm will remain just west of the state; limiting potential impacts. The best chances for heavy rain and thunderstorms remains over the western islands of Niihau, Kauai and Oahu this weekend. Stay tuned.

Aviation

Breezy and gusty southwesterly winds will affect the islands today as a cold front approaches from the northwest. In advance of the front, scattered showers will bring MVFR cigs/vsbys to south and west facing slopes and coasts at times, while mainly VFR conditions prevail elsewhere. The front will move into Kauai late this afternoon, then shift rapidly down the island chain tonight, nearing the Big Island around daybreak Tuesday. A band of gusty showers will accompany the front, with MVFR cigs and/or vsbys affecting many of the TAF sites as the front moves through. Winds will shift northwesterly at moderate to locally breezy levels behind the front with conditions improving from northwest to southeast down the island chain as drier more stable air moves in.
AIRMET Sierra remains in effect for mountain obscuration across portions of Kauai, Oahu, Molokai, Lanai, and Maui. Conditions will likely improve in most areas later this morning, but may redevelop later this afternoon on Kauai.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely remain in place through late this evening.

Marine

A strong front has entered the far northwest offshore waters and will move through the state later this afternoon through Tuesday. A Small Craft Advisory (SCA) has been expanded to all waters due to increasing southwesterly wind speeds as the front approaches the state today. The front will swiftly move through Kauai late this afternoon and evening with moderate to strong northwesterly winds filling in behind. The front will weaken and winds will gradually ease to moderate to fresh speeds as the front progresses through the eastern half of the island chain overnight through Tuesday. Winds will shift out of the east on Wednesday as a weak high quickly moves from west to east over the state. Light to gentle southerly winds will return Thursday as another front approaches the state from the northwest. Southerly winds will gradually strengthen to moderate to fresh speeds Friday ahead of the next front with moderate to locally strong northerly winds filling in behind the front as the front moves southeast over the state Friday into the weekend.
The current west-northwest swell will continue to decline through today with surf heights dropping below average. Forerunners of an extra large northwest swell (310 to 325 degrees) have reached the offshore buoy 51001 and should trickle in locally through the day. In addition there is another moderate, short to medium period northwest swell overlapping that will provide a slight bump in surf along north and west facing shores this afternoon. Surf heights will then rapidly build this evening and peak Tuesday well above High Surf Warning levels along most north and west facing shores as the extra large northwest swell builds in. Overlapping pulses will keep surf elevated through Wednesday before subsiding below High Surf Advisory levels Thursday night into Friday. This swell will also push combined seas well above the 10 foot SCA threshold in many areas. Another extra large swell is possible late Friday and Saturday.
Rough choppy surf along south facing shores will hold through today as southerly winds remain strong ahead of the front. Surf along east facing shores will remain tiny through much of the week due to lack of strong trades near and upstream of the state. An increase surf is possible along east shores this weekend.
A Coastal Flood Statement remains in effect until noon today, as peak monthly tides coincide with higher than predicted ocean levels. Expect minor flooding of low-lying coastal infrastructure as well as some some beach erosion during the peak high tide through the morning hours.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 AM HST Tuesday for all Hawaiian Islands.
High Wind Warning until 6 PM HST Wednesday for Big Island Summits of Mauna Kea and Mauna Loa.
Small Craft Advisory until 6 AM HST Tuesday for all Hawaiian waters.

Data Courtesy of NOAA.gov