Hilo

Today: Showers in the morning, then showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 82 near the shore to around 71 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 57 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Kona

Today: Partly sunny with isolated showers in the morning, then cloudy with showers likely and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows around 74 near the shore to around 58 near 5000 feet. Light winds. Chance of rain 40 percent.

Sunday: 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. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Windy. Showers in the morning, then showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds 10 to 30 mph. Chance of rain near 100 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows around 71 near the shore to 59 to 65 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Windy. Isolated showers. Highs around 82 near the shore to 70 to 80 near 3000 feet. East winds up to 30 mph increasing to 15 to 30 mph in the afternoon. Chance of rain 20 percent.

Kohala

Today: Windy. Showers in the morning, then showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds 10 to 30 mph. Chance of rain near 100 percent.

Tonight: Windy. Mostly cloudy with scattered showers. Lows around 71 near the shore to 59 to 65 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Windy. Isolated showers. Highs around 82 near the shore to 70 to 80 near 3000 feet. East winds up to 30 mph increasing to 15 to 30 mph in the afternoon. Chance of rain 20 percent.

South Big Island

Today: Mostly cloudy. Windy. Scattered light showers in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. East winds up to 30 mph. Chance of rain 70 percent.

Tonight: Windy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 73 near the shore to around 56 near 5000 feet. East winds 10 to 30 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Windy. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 30 mph.

Puna

Today: Showers in the morning, then showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible. Highs around 82 near the shore to around 71 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then scattered showers after midnight. Lows around 71 near the shore to around 57 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Sunday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84 near the shore to 70 to 75 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 40 percent.

Waikoloa

Today: Partly sunny. Windy. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 86 near the shore to 70 to 76 above 4000 feet. Northeast winds up to 30 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 75 near the shore to 54 to 61 above 4000 feet. East winds up to 25 mph. Chance of rain 20 percent.

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

Detailed Forecast

Synopsis

Locally strong trades will focus moisture associated with decaying Tropical Cyclone Darby over windward Big Island today, where periods of heavy rain can be expected. Elsewhere, fairly typical trade wind weather will prevail with passing windward showers and the occasional shower reaching leeward areas. Conditions will improve over the Big Island this evening, with a fairly dry trade wind pattern then holding in place statewide through Tuesday. A more typical trade wind shower regime will return Tuesday night and hold in place through late next week. Aside from some slightly stronger winds associated with the passage of Darby south of the islands on today, moderate to breezy trade winds will prevail through the forecast period.

Discussion

Currently at the surface, Tropical Storm Darby is located around 200 miles southeast of Hilo, while a 1031 mb high is centered around 1200 miles north of Honolulu. The resulting gradient is producing moderate to breezy trade winds across the island chain early this morning. Infrared satellite imagery shows mostly cloudy conditions in many windward areas, with partly cloudy skies prevailing in most leeward locales. Radar imagery shows scattered showers moving into windward areas, with coverage the greatest over the Big Island. Main short term concerns revolve around the peripheral effects of Darby moving by to the south of the island chain.
The latest forecast from the Central Pacific Hurricane Center shows Darby sliding by around 100 miles south of the Big Island today, then weakening into a post-tropical remnant low tonight. Model solutions have been very consistent on the forecast track during the past several days, indicating the brunt of the moisture associated with the decaying system will focus over the Big Island. Showers will continue to increase this morning over windward Big Island, while typical trade wind weather prevails over the remainder of the state. There remains the potential for some locally heavy rain and thunderstorms over the Big Island today, with average windward totals of 2-4 inches still appearing on track. Elsewhere, no significant rainfall is expected.
Conditions are expected to improve over the Big Island this evening, followed by a rather dry trade wind pattern statewide through Tuesday. The airmass begins to moisten back up Tuesday night, bringing a return of more typical trade wind weather through the end of the work week.
A Wind Advisory is now in effect for the typically windy areas of Maui County and the Big Island, as well as the higher elevations summits through 6 PM this evening, as Darby makes its closest approach. Otherwise, moderate to breezy trade winds will prevail through the forecast period with only minor variations in strength.

Aviation

Breezy to locally strong trade winds will continue through the remainder of the weekend, the result of strong high pressure anchored far north of the state. AIRMET Tango for low level mechanical turbulence downstream of higher terrain will remain in effect. Low level wind shear could become an issue for portions of leeward Big Island or Central Maui today.
Tropical storm Darby is in the process of weakening, but will still have some impacts on the Big Island today. Darby is forecast to track due westward and pass about 90 nm south of South Point this afternoon. AIRMET Sierra for mountain obscuration is already in effect for portions of windward Big Island: conditions are expected to become more widespread and persist into early evening. Strong surface winds are expected to develop across the higher elevations of the Big Island within the next few hours and linger through the afternoon. An AIRMET for surface winds greater than 30 kt will likely be issued with the morning package. Also, there will be a slight chance of thunderstorms in the afternoon.
For the smaller islands, clouds and showers will favor east and northeast facing slopes and coasts. Isolated spillover showers are to be expected over leeward areas, especially in the late night and morning hours. Brief periods of MVFR are likely in passing showers, otherwise VFR conditions will prevail from Kauai to Maui.

Marine

Tropical Storm Darby is located roughly 200 miles southeast of the Big Island this morning. This system has been moving westward at about 19 kt. The Central Pacific Hurricane Center's latest forecast indicates Darby will continue to weaken, and has entered the southeast offshore waters as a Tropical Storm. A Tropical Storm Warning remains in effect for the offshore waters.
A surface high pressure system will remain far north of the islands through early next week. In the near-term, the trades winds are expected to strengthen as Tropical Storm Darby moves closer to the region. In addition, combined seas will be elevated and rough due to a combination of local wind waves, and large south and east swells. A Small Craft Advisory (SCA) is in effect for all Hawaiian Waters through 6 PM Sunday, and may need to be extended.
A historic south swell will continue to build today, generating Warning level surf along south facing shores through Sunday. A Marine Weather Statement has been issued to account for the combination of large surf and regular predicted water levels that could lead to flooding of beaches that typically remain dry and harbor surges, especially at and around the peak daily high tide. The historic south swell should slowly subside through the first half of next week.
Surf along east facing shores will remain elevated and rough into early next week. A High Surf Advisory has been issued for east facing shores of the Big Island for the combined elevated, rough trade wind surf and swells generated by Darby through tonight.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 AM HST Monday for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kohala, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Southeast, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Wind Advisory until 6 PM HST this evening for Lanai Mauka, Kahoolawe, Maui Leeward West, Haleakala Summit, Kohala, Big Island Interior, Big Island Summits, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
High Surf Advisory until 6 AM HST Sunday for Big Island East, Big Island North.
Small Craft Advisory until 6 PM HST Sunday for all Hawaiian waters,

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Data Courtesy of NOAA.gov