Photo Credit: Jeni Ji Cousins

West Side

Rest Of Today: Mostly sunny. Windy. Isolated showers in the morning. Highs 72 to 79. Northeast winds 20 to 30 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows 61 to 68. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Breezy. Highs 72 to 79. East winds 10 to 20 mph.

South Side

Rest Of Today: Sunny and breezy. Highs around 80. Northeast winds 10 to 25 mph.

Tonight: Partly cloudy. Breezy. Lows 60 to 68. Northeast winds 10 to 20 mph.

Wednesday: Mostly sunny. Breezy. Highs around 80. Northeast winds 15 to 25 mph.

North Shore

Rest Of Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 77 near the shore to around 61 near 5000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then occasional showers after midnight. Lows around 64 near the shore to 43 to 49 near 5000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Wednesday: Breezy. Mostly cloudy with numerous showers. Highs 73 to 78 near the shore to around 62 near 5000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Central Maui

Rest Of Today: Mostly sunny. Windy. Isolated showers in the morning. Highs around 79. Northeast winds 15 to 25 mph shifting to the east 25 to 30 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 61 to 66. East winds 15 to 25 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 76 to 82. East winds 15 to 20 mph. Chance of rain 20 percent.

Upcountry

Rest Of Today: Breezy. Mostly sunny with scattered showers. Highs 53 to 64. East winds 10 to 25 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 45 at the visitor center to around 38 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Mostly sunny with scattered showers. Highs 52 to 64. East winds 10 to 20 mph. Chance of rain 50 percent.

East Maui

Rest Of Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 72 to 77 near the shore to around 61 near 5000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then occasional showers after midnight. Lows around 64 near the shore to 43 to 49 near 5000 feet. East winds 10 to 25 mph. Chance of rain 90 percent.

Wednesday: Breezy. Mostly cloudy with numerous showers. Highs 73 to 78 near the shore to around 62 near 5000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Lanai City

Rest Of Today: Sunny and windy. Highs 67 to 75. Northeast winds 15 to 30 mph.

Tonight: Mostly clear. Breezy. Lows around 60. Northeast winds 10 to 25 mph.

Wednesday: Sunny and breezy. Highs 67 to 74. Northeast winds 15 to 20 mph.

Kaunakakai

Rest Of Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 61 to 80. Northeast winds 20 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 52 to 68. Northeast winds 15 to 25 mph.

Wednesday: Mostly sunny. Breezy. Highs 61 to 80. East winds 20 to 25 mph.

Detailed Forecast

Synopsis

High pressure to the north of Hawaii will maintain breezy trade winds into the weekend. Clouds and showers will favor windward and mauka areas, with the gusty winds carrying some showers over leeward areas at times.

Discussion

As expected, no significant changes to the forecast with the morning package. The 1037 mb high remains about 1200 miles north of Oahu early this morning, and continues to bring a stable and breezy trade wind patter to the region. The overnight sounding at Lihue continued to show a trade wind inversion around 8000 ft, while the Hilo sounding inversion was around 11,000 ft. In part to showers in the area at the launch time, the Hilo sounding reported precipitable water (PW) to be about 1.33 inches, while Lihue had 0.98. The Lihue value is near normal, while Hilo's was on the high end of normal. A showery low cloud band is moving onto the windward sides of Maui and the Big Island early this morning, with showers expected to thin out there later this morning. With the trade winds, expect showers to be focused over the windward slopes of all the islands, with a few additional spotty showers possible over the Kona slopes of the Big Island.
No significant change is expected through tomorrow as the high is expected to weaken slightly and drift southward, but the pressure gradient over the region will change little, maintaining the breezy and gusty trade winds. Another high setting up far north of islands tomorrow will keep breezy trades in place through at least Friday. Random patches of moisture in the stable trade wind flow will bring periodic boosts in mainly windward rainfall over the next couple of days. Chances for more widespread shower activity, some briefly heavy, and thickening high clouds will increase on Thursday and Friday as an upper-level trough passes over the islands.
There is some uncertainty heading into the weekend. Trades should persist, but the GFS and ECMWF differ significantly on the strength, with the GFS leaning towards breezy and gusty conditions. The GFS and ECMWF are trending toward another upper level trough moving in from the west, potentially bringing an increase in high clouds and shower activity on Sunday.

Aviation

Breezy trade winds will remain in place through the remainder of the week. Clouds and light showers will favor windward coasts and slopes and be most active in the late night and early morning hours.
In the afternoon and early evenings, lee-side sea breezes and daytime heating will encourage cumulus build-ups along south and west facing slopes of the Big Island, but a strong inversion aloft around 8000 ft will limit their growth and rainfall potential.
AIRMET Sierra for mountain obscuration is currently in effect for portions of Maui and Windward Big Island. Conditions are expected to improve by late morning.
AIRMET Tango remains in effect for moderate low-level turbulence, and will likely be needed through midweek. Additionally, moderate upper level turbulence could become an issue for the western half of the state later today thanks to a passing upper level jet streak.

Marine

Rough conditions will continue across the Hawaiian waters through the week due to fresh to strong easterly trades. Seas will remain around and just above the 10 ft Small Craft Advisory threshold over exposed waters into early Wednesday due to a combination of a medium-period northeast swell and locally generated wind waves. Seas will drop slightly through the second half of the week as the northeast swell moves out.
Surf along exposed east facing shores will remain rough through the week, with heights hovering around the advisory level through tonight. Heights should dip below the advisory level Wednesday as the northeast swell begins to move out.
Surf along north facing shores will remain small into Friday, except for shores exposed to northeast swells. An upward trend is expected late Friday through the weekend due to a combo of a medium- to long-period north-northeast swell and a long-period west-northwest swell expected. The north-northeast swell should steadily fill in late Friday, then peak over the weekend. The west-northwest swell is forecast to build down the island chain through the day Saturday, then peak near the advisory levels for exposed north and west facing shores late Sunday.
Surf along south facing shores will remain small through midweek with mainly background energy moving through. An upward trend is expected Friday as a long-period south-southwest swell arrives. This swell will peak late Friday into Saturday, then ease Sunday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Olomana, Maui Windward West, Kauai East, Kauai South, Koolau Windward, Molokai Windward, Molokai Southeast, Windward Haleakala, Kipahulu, Big Island East, Big Island North.
Small Craft Advisory until 6 PM HST Wednesday for all Hawaiian waters,

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Data Courtesy of NOAA.gov