Hilo

Tonight: Mostly cloudy with showers likely. Lows around 67 near the shore to around 53 at 4000 feet. Northeast winds 10 to 15 mph shifting to the north after midnight. Chance of rain 70 percent.

Monday: Mostly cloudy with showers likely. Highs 78 to 84 near the shore to 66 to 71 at 4000 feet. Northwest winds up to 15 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Monday Night: Mostly cloudy with numerous showers. Lows around 67 near the shore to around 53 at 4000 feet. Southeast winds up to 10 mph shifting to the west after midnight. Chance of rain 70 percent.

Kona

Tonight: Partly cloudy with isolated showers. Lows 67 to 72 near the shore to around 53 near 5000 feet. West winds up to 10 mph shifting to the northeast after midnight. Chance of rain 20 percent.

Monday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows 67 to 72 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Tonight: Windy. Mostly cloudy with showers likely. Lows around 66 near the shore to 53 to 60 near 3000 feet. East winds 10 to 30 mph decreasing to up to 30 mph after midnight. Chance of rain 70 percent.

Monday: Breezy. Mostly cloudy with showers likely. Highs around 80 near the shore to 71 to 78 near 3000 feet. East winds up to 25 mph. Chance of rain 70 percent.

Monday Night: Partly cloudy with scattered showers. Lows around 66 near the shore to 53 to 60 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Windy. Mostly cloudy with showers likely. Lows around 66 near the shore to 53 to 60 near 3000 feet. East winds 10 to 30 mph decreasing to up to 30 mph after midnight. Chance of rain 70 percent.

Monday: Breezy. Mostly cloudy with showers likely. Highs around 80 near the shore to 71 to 78 near 3000 feet. East winds up to 25 mph. Chance of rain 70 percent.

Monday Night: Partly cloudy with scattered showers. Lows around 66 near the shore to 53 to 60 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Mostly clear. Windy. Lows around 67 near the shore to around 52 near 5000 feet. East winds 15 to 30 mph.

Monday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 83 near the shore to around 72 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Monday Night: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 67 near the shore to around 52 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Tonight: Mostly cloudy with showers likely. Lows around 67 near the shore to around 53 at 4000 feet. Northeast winds 10 to 15 mph shifting to the north after midnight. Chance of rain 70 percent.

Monday: Mostly cloudy with showers likely. Highs 78 to 84 near the shore to 66 to 71 at 4000 feet. Northwest winds up to 15 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Monday Night: Mostly cloudy with numerous showers. Lows around 67 near the shore to around 53 at 4000 feet. Southeast winds up to 10 mph shifting to the west after midnight. Chance of rain 70 percent.

Waikoloa

Tonight: Windy. Mostly clear with isolated showers. Lows around 70 near the shore to 49 to 56 above 4000 feet. Northeast winds up to 30 mph shifting to the east after midnight. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 67 to 73 above 4000 feet. East winds up to 15 mph shifting to the north in the afternoon. Gusts up to 40 mph. Chance of rain 50 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 70 near the shore to 49 to 56 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Blustery trades will ease on Monday, then continue to diminish through the middle of the week. Expect trades to push showers across windward slopes and coasts, with a few showers spreading leeward at times. Showers could be a bit heavier over the eastern end of the state through Tuesday as an upper low meanders near the Big Island. Drier and more stable weather will build in on Wednesday, with mostly dry conditions and light winds expected Thursday into next weekend.

Discussion

A strong high far north of the main Hawaiian Islands continues to drive blustery trades across the island chain and local waters this afternoon. Satellite loop shows ragged bands of broken low clouds extending far east of the islands, with the blustery trades providing a steady supply of windward and mauka cloud cover. Mostly cloudy conditions are noted across windward areas, while partly cloudy to clear skies dominate leeward locales. Radar shows scattered to numerous showers moving onto windward slopes and coasts, with a few showers reaching leeward areas at times. Afternoon soundings show a strong capping inversion persists near 7000 feet which, along with rather low PW values between 1.1 and 1.3 inches, acts to limit overall shower coverage and caps the depth of cloud development. That said, the presence of an upper low near the Big Island acts to keep our airmass a bit unstable.
Models show the high north of the state will shift southeastward and gradually weaken, with trades easing to breezy levels on Monday. However, winds will remain blustery through this evening, so a Wind Advisory in effect for Maui County and the Big Island has been extended through midnight tonight. Trades will continue to decrease Tuesday and Wednesday as the ridge north of the islands, extending west from the diminishing high, weakens. Winds will become light Thursday into next weekend as the ridge is pushed southward near or over the state by an approaching cold front to the north, with land and sea breezes becoming common.
Trades will continue to deliver showers to windward slopes and coasts during the next few days, with a few showers reaching leeward areas at times. The upper low will meander over or near the Big Island through Tuesday, enhancing showers across the eastern end of the state. Our airmass will cool aloft but will also remain very dry, keeping the potential for thunderstorms and wintry weather across the Big Island summits low. A drier and more stable airmass will build in on Wednesday, with rather dry conditions expected statewide Thursday into next weekend.

Aviation

Strong trade winds that are prevailing across the islands will gradually ease through Monday as high pressure north of the state shifts southeastward and gradually weakens. Meanwhile, showers embedded within the trade wind flow will favor north through east sections of the islands throughout the next few days. VFR flight conditions will generally prevail, but occasional MVFR ceilings and visibilities will be possible within any showers that move through.
AIRMET Tango remains in effect for moderate low-level turbulence over and downwind of island terrain. This AIRMET will likely remain in effect through Monday. Additionally, mountain obscuration could become an issue this evening or tonight as showers move into windward locations on the trades.

Marine

Strong high pressure centered far northeast of the Hawaiian Islands will support strong to locally gale force trade winds across the coastal waters. The high will weaken and drift southeast tonight into Monday in response to a low passing far north of the area. A Gale Warning remains in effect through tonight for the windier waters surrounding Maui County and Big Island. A Small Craft Advisory (SCA) also remains in effect through tonight for strong east trades and seas greater than 10 feet over the remaining coastal waters. The SCA will likely be extended for many zones into Monday and Monday night including those areas currently under the Gale Warning. Winds are expected to drop below SCA thresholds Tuesday as the high weakens and is replaced by a low pressure system and front in the Northeast Pacific.
East-facing shore surf will continue to remain rough and choppy tonight in response to strong east trades, which are expected to decline through the first half of the week. The High Surf Advisory (HSA) for all east-facing shores has been extended through the day Monday. North and south- facing shorelines exposed to these easterly wind waves may experience elevated surf and rough waves through the day.
A small, medium period northwest (320 degree) swell is expected through Monday afternoon. A similar pulse from the northwest is possible late Wednesday night into Thursday. A small to moderate size north swell may arrive toward the end of the week. This swell will originate from a North Pacific low that comes within proximity of the north offshore waters.
Peak monthly tides will occur during the early morning hours Monday morning. These high tides, combined with elevated seas from strong trade winds, may increase coastal inundation impacts for historically vulnerable locations during high tides. A Coastal Flood Statement is in effect through early Monday morning to address nuisance coastal flooding.

Fire weather

Blustery winds, dry fuels, and relative humidity just above critical levels will keep fire danger elevated today. Winds will ease below critical levels on Monday, with the trades continuing to decrease as the week progresses.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Monday for Olomana, Maui Windward West, Kauai East, Koolau Windward, Molokai Southeast, Windward Haleakala, Kipahulu, South Haleakala, Big Island Southeast, Big Island East, Big Island North.
Wind Advisory until midnight HST tonight for Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Molokai North, Molokai West, Molokai Leeward South, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Gale Warning until 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov