Photo Credit: Tyler Rooke

West Side

Today: Breezy. Mostly cloudy with isolated showers. Highs 77 to 85. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 66 to 72. East winds 10 to 20 mph. Chance of rain 50 percent.

Friday: Breezy. Mostly cloudy with isolated showers. Highs 76 to 84. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly cloudy. Breezy. Highs around 86. North winds up to 20 mph.

Tonight: Mostly cloudy. Breezy. Lows around 68. North winds up to 20 mph.

Friday: Mostly cloudy. Breezy. Highs around 85. Northeast winds up to 20 mph.

North Shore

Today: Breezy. Mostly cloudy with showers likely. Highs 77 to 82 near the shore to 58 to 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 66 to 71 near the shore to around 51 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Friday: Breezy. Mostly cloudy with showers likely. Highs 76 to 81 near the shore to around 61 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Central Maui

Today: Breezy. Mostly cloudy with isolated showers. Highs 82 to 87. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows around 68. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Breezy. Mostly cloudy with isolated showers. Highs 81 to 86. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 58 at the visitor center to around 52 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 46 at the visitor center to around 41 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Friday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 59 at the visitor center to around 54 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Mostly cloudy with showers likely. Highs 77 to 82 near the shore to 58 to 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 66 to 71 near the shore to around 51 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Friday: Breezy. Mostly cloudy with showers likely. Highs 76 to 81 near the shore to around 61 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly cloudy. Breezy. Isolated showers in the afternoon. Highs 71 to 80. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

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

Friday: Mostly cloudy. Breezy. Isolated showers in the afternoon. Highs 70 to 79. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly cloudy with isolated showers. Highs 72 to 82. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 60 to 70. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Windy. Mostly cloudy with isolated showers. Highs 72 to 82. East winds 10 to 20 mph increasing to 15 to 30 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

High pressure sliding by to the north and northeast of the state will keep moderate to breezy trade winds in place through the middle of next week, with only minor fluctuations in strength. A mid and upper level low west of the state will bring considerable high cloud cover to the islands today and Friday, with the high clouds thinning out Saturday and vacating the area entirely on Sunday. Otherwise, fairly typical trade wind weather can be expected through the next 7 days, with showers favoring windward and mauka areas and a stray shower reaching leeward communities from time to time.

Discussion

Currently at the surface, a 1027 mb high is centered around 1400 miles northwest of Kauai, with a ridge extending southeastward to near 30N, then eastward to a position around 500 miles north of the Garden Isle. The gradient produced by this ridging north of the islands is driving moderate to breezy trade winds across the island chain early this morning. Infrared satellite imagery shows mostly cloudy conditions over the Big Island and Maui County, as well as windward sections of Oahu, with partly cloudy conditions elsewhere. Radar imagery shows scattered showers moving into windward and mauka locations, with a stray shower spilling leeward from time to time. Main short term focus revolves around rain chances and high cloud coverage.
The surface high currently located far northwest of the state, will slide eastward and strengthen during the next couple days before anchoring to the distant northeast of the islands over the weekend. This high will be replaced by another strong high building northeast of the area through the first half of next week. As a result, we expect moderate to breezy trades to prevail during the next 7 days, with the strongest trades expected tonight through Saturday.
As for the remaining weather details, with the mid and upper low now positioned several hundred miles west-southwest of Kauai, the airmass locally has stabilized considerably. This is confirmed by the 12Z Hilo and Lihue soundings showing a strengthening low level inversion around 7-8 kft. The low aloft will shift slowly west through Friday, then open up and lift northeast and away from the region over the weekend. Overall, fairly typical trade wind weather can be expected through the forecast period, with shower bands occasionally moving through the islands. Showers will favor windward and mauka areas, with a few showers reaching leeward communities at times.
High clouds over the eastern half of the state will spread over the remaining islands early this morning, with considerable high cloud cover then expected statewide through Friday night. The high clouds appear to begin thinning out on Saturday, and exit the area entirely by Sunday.

Aviation

Breezy trade winds will likely persist through Friday. An upper- level low located west of Kauai is moving westward away from the state, and its influence on our local weather is gradually diminishing. However, abundant moisture remains in the vicinity of the islands. The low-level trade wind flow will continue to transport broken low clouds and scattered showers into the windward sides of most islands through Friday. The locally strong trades will also carry brief showers over to leeward sections of some the smaller islands, especially this morning. In addition, a few showers are also possible along the upslope sections of the leeward Big Island from this afternoon into this evening. Expect periods of MVFR conditions due to lower ceilings and/or reduced visibilities along windward facing slopes and coasts today. Note that there is a band of high clouds streaming up from the south- southwest over the eastern half of the state this morning.
AIRMET Sierra for mountain obscuration remains in effect for terrain above 2500 feet over windward sections of the Big Island. We will monitor the windward sides of the remaining islands in case AIRMET Sierra needs to be added elsewhere later today.
AIRMET Tango for mechanical low-level turbulence leeward of the higher terrain on all islands remains in effect. These turbulent conditions are expected to persist through tonight.

Marine

Fresh to strong easterly trade winds will increase to strong levels for most waters tonight through much of the upcoming weekend. These winds combined with the mix of northwest and south swells have led to rough boating conditions across exposed waters. As a result, the Small Craft Advisory has been extended through this evening for all waters and will continue into the weekend for most windward waters and channels. Fresh to strong trades will likely continue through next week.
Surf along south facing shores will hold at advisory levels today before slowly easing into the weekend as the significant early season south swell continues to impact the islands. A new pulse has arrived and showing in the 18 to 22 second band (up to 5 ft) at the Barbers Point PacIOOS buoy this morning. The offshore buoys to the south also depict this long-period energy, which supports the surf holding through a good portion of the day today before beginning to slowly back off. Looking ahead into next week, no significant sources are expected from the south due to large high pressure setting up near our swell window around New Zealand.
Surf along exposed north and west facing shores will remain up today, then drop off later Friday into the weekend as a late- season northwest swell moves out. Expect the summer-like trend up north to return for next week.
Surf along east facing shores will remain rough through next week due to the aforementioned strong trades in place locally and upstream of the islands. Guidance shows the upstream fetch expanding over the weekend as 1035 mb high pressure sets up across the northeast Pacific.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Waianae Mountains, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai West, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 PM HST Saturday for Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Leeward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov