Hilo

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 70 near the shore to around 56 at 4000 feet. Northeast winds up to 15 mph shifting to the northwest after midnight. Chance of rain 60 percent.

Thursday: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 79 to 84 near the shore to 64 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 71 to 76 near the shore to around 57 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 86 to 91 near the shore to around 71 near 5000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 40 percent.

Waimea

Today: Mostly sunny. Windy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 30 mph increasing to 10 to 30 mph in the afternoon. Chance of rain 40 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 68 to 88. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Mostly sunny. Windy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 83 near the shore to 70 to 80 near 3000 feet. East winds up to 30 mph increasing to 10 to 30 mph in the afternoon. Chance of rain 40 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows around 70 near the shore to 58 to 64 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 68 to 88. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny. Windy. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 30 mph increasing to 10 to 30 mph in the afternoon.

Tonight: Partly cloudy. Windy. Isolated showers in the evening. Lows around 72 near the shore to around 55 near 5000 feet. Northeast winds 10 to 30 mph. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 70 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 85 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 70 near the shore to around 56 at 4000 feet. Northeast winds up to 15 mph shifting to the northwest after midnight. Chance of rain 60 percent.

Thursday: Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Highs 79 to 84 near the shore to 64 to 73 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Breezy. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 25 mph with gusts to 45 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 74 near the shore to 53 to 60 above 4000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Thursday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 83 to 91 near the shore to 69 to 75 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy to locally windy trades will continue through Thursday as a weak low or surface trough slides by to the south of the state. The trades will ease back to moderate and locally breezy levels Friday through the weekend, and perhaps ease even further early next week. Fairly dry trade wind weather will prevail during the next 7 days, with showers favoring windward and mauka areas mainly at night and during the early morning hours. A stray shower may reach leeward areas at times, but most areas should remain dry.

Discussion

Currently at the surface, a 1030 mb high is centered around 1700 miles north-northeast of Honolulu, while a broad trough of low pressure is located around 450 miles south of the Big Island. The resulting gradient is producing breezy trade winds across the island chain early this morning. Radar imagery shows scattered showers moving into windward areas, with a stray shower or perhaps a few sprinkles making the trip over the mountains and into leeward communities at times. Main short term focus revolves around trade winds trends and rain chances.
High pressure to the distant north-northeast will shift southward and closer to the islands during the next couple days, while a weak area of low pressure, or surface trough, slides by around 300-400 miles south of the state. This will keep breezy to locally windy conditions in place through Thursday, with a peak in trade wind speeds expected today. With a sharp low level inversion in place around 5-6 kft today, we will likely see advisory level winds across portions of Maui County and the Big Island due to effective funneling and channeling of winds by the island terrain. As a result, a Wind Advisory is now in effect through 10 pm this evening. The trades should lower into the moderate and locally breezy range on Friday, then hold at these levels through the weekend. A weakness developing in the ridge north of the islands could ease the trades further early next week.
As for the remaining weather details, a fairly dry trade wind pattern should prevail through the forecast period. Showers will focus primarily over windward and mauka areas during the overnight and early morning hours. A stray shower may occasionally drift into leeward areas, although most areas will remain dry. There remains the potential for a slight increase in showers over the Big Island Wednesday night and Thursday as the weak low or surface trough slides by to the south, but guidance remains in good agreement keeping the deepest moisture associated with this feature south of the state.

Aviation

Breezy to locally windy trade winds will continue over the islands through the TAF period, as an area of high pressure remains anchored well north-northeast of the state. Limited moisture will generate mainly VFR conditions through early Thursday, with showers affecting mainly windward and mauka sections. Some MVFR cigs will occasionally drift across windward areas this morning, continuing the potential need for AIRMET Sierra due to tempo mountain obscurations for some windward areas, especially the Big Island and Maui.
AIRMET Tango remains in effect for low-level mechanical turbulence leeward of mountains due to windy trades. These turbulent conditions will continue across the islands through tonight.

Marine

The islands are sandwiched between a strong surface high pressure system located far north-northeast of the area, and an elongated surface trough located well to the south. This is producing strong trade winds, especially over the eastern half of the island chain. A Small Craft Advisory (SCA) remains in effect for all of the waters surrounding the islands of Maui County and the Big Island, as well the waters south of Oahu through early Thursday morning. The current forecast keeps SCA conditions in the typically windier waters adjacent to the islands of Maui County and the Big Island from Thursday through Friday. The SCA may need to be extended into this weekend for these same windier waters.
The strong trades will cause the short-period wind waves to increase during the next couple of days. Therefore, expect choppy surf to peak near, or slightly above the seasonal average along east facing shores through Thursday. Surf heights may trend down along east facing shores as the trade winds ease to moderate speeds this weekend. A very small, long-period south swell, and a small, short-period southeast swell will continue to produce modest surf along south facing shores through Thursday. Another small, medium-period south swell may arrive Saturday, which would maintain small surf along south facing shores this weekend. Elsewhere, expect nearly flat conditions to persist along most north facing shores through this weekend.
Monthly high tides are expected to peak during the next couple of days, with the maximum astronomical high tides occurring during the afternoon hours. Tide station observations are showing close to the predicted water levels for most stations around Hawaii. We do not plan to issue a Coastal Flood Statement at this time, since the guidance indicates the water level values will likely remain just below the significant impact levels.

Fire weather

Strong trade winds and low relative humidity values will result in elevated fire danger today. As a result, a Red Flag Warning is in effect from 10 AM to 6 PM. Outdoor burning should be avoided.

HFO Watches/Warnings/Advisories

Red Flag Warning from 10 AM this morning to 6 PM HST this evening for Niihau, Kauai Leeward, Oahu South Shore, Waianae Coast, Oahu North Shore, Central Oahu, Waianae Mountains, Molokai Leeward, Lanai Makai, Lanai Mauka, Kahoolawe, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, South Big Island, Kohala.
Wind Advisory until 10 PM HST this evening for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 AM HST Thursday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov