Photo Credit: James Grenz

Hilo

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 82 near the shore to 65 to 70 at 4000 feet. North winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 51 to 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 83 near the shore to 65 to 71 at 4000 feet. West winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 67 near 5000 feet. Southeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 66 to 72 near the shore to 45 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 80 to 86 near the shore to around 68 near 5000 feet. Northeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Waimea

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 65 to 84. East winds up to 20 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 61 near the shore to 50 to 59 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 65 to 84. East winds up to 20 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 65 to 84. East winds up to 20 mph. Chance of rain 40 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 61 near the shore to 50 to 59 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 65 to 84. East winds up to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 81 near the shore to around 66 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows around 69 near the shore to around 48 near 5000 feet. Northeast winds up to 20 mph.

Monday: Sunny and breezy. Isolated showers in the afternoon. Highs around 81 near the shore to around 67 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 77 to 82 near the shore to 65 to 70 at 4000 feet. North winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 68 near the shore to 51 to 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 77 to 83 near the shore to 65 to 71 at 4000 feet. West winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 79 to 85 near the shore to 64 to 70 above 4000 feet. Southeast winds up to 20 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Lows 64 to 72 near the shore to 45 to 52 above 4000 feet. Southeast winds up to 20 mph.

Monday: Sunny. Isolated showers in the afternoon. Highs 80 to 85 near the shore to 64 to 71 above 4000 feet. Southeast winds up to 15 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Pleasant conditions are anticipated through Monday, with breezy easterly trade winds and temperatures running slightly above normal. The best chance for light showers will be through the late night and early morning hours over windward and mauka locations, leaving most leeward locations dry. Trade winds will trend down Monday night through midweek, and some moisture moving in from the southeast could boost rainfall chances for some locations. A more typical trade wind pattern will return Thursday through Saturday.

Discussion

Guidance remains in good agreement and depicts the breezy easterly trades holding into Monday, then easing Monday night through midweek as a front passes to the north. Plenty of dry air combined with an upper ridge over the region will limit rainfall chances and keep the temperatures hovering slightly above average for this time of year. Any showers that do form will be brief and favor windward and mauka locations overnight through the early morning hours and over the Kona slopes through the afternoon periods.
As the trades weaken Monday night through midweek, guidance shows a decent-sized area of enhanced low-level moisture moving in from the southeast – first over the Big Island and Maui County Monday night into Tuesday, then the western end of the state Tuesday night through Wednesday. Lowering upper heights due to an approaching shortwave trough from the northwest along with this moisture support a slight increase in rainfall chances. Although most showers will favor windward areas, a few interior/leeward showers can't be ruled out through the afternoons where sea breezes form. A more typical trade wind pattern will return Thursday through Saturday.

Aviation

Breezy easterly trade winds will continue today as a surface ridge remains in place north of the state. Additionally, a ridge aloft is resulting in mostly stable conditions, which will limit shower chances into Monday. Showers that are able to develop will favor north through east facing sections of the islands throughout the forecast period. Meanwhile, weaker winds on the leeward side of the Big Island will promote cloud development again this afternoon, but will diminish again overnight. VFR flight conditions will prevail across the state with only brief periods of MVFR possible within windward showers.
AIRMET Tango for tempo moderate turbulence below 8,000 feet continues across portions of the state over and immediately S thru W of the mountains. These turbulent conditions are expected to continue through today but should improve by Monday as surface winds begin to weaken.

Marine

A surface ridge north of the state will persist into Monday producing moderate to locally strong trade winds across the region. A Small Craft Advisory (SCA) for typically windier waters around Maui County and the Big Island was extended through Monday afternoon. A northwest swell moving into the region by Monday may increase significant wave heights for northern coastal waters above the SCA thresholds. An approaching cold front will stall north of the area through the middle of next week and will keep light to fresh trades through the rest of the forecast period.
The current west-northwest swell will hold today maintaining small to moderate surf heights along north and west facing shores. The next northwest swell (320 direction) will build in this evening through Monday, and should exceed High Surf Advisory thresholds along most north and west facing shores. SOFAR drifter buoys within the fetch area, northwest of the islands, are running 2 feet above GFS Wave model guidance. We increased our swell heights by 2 feet to compensate for this low model bias Sunday night through Tuesday. This northwest swell will then slowly subside from Monday night through Wednesday. A medium period, moderate northwest swell will continue to keep surf heights elevated along north and west facing shores during the second half of the week.
Background south swells will keep surf heights small along south facing shores through Friday. Small surf heights will also persist along east facing shores.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM 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