Weather Forecast

Hawaii County Weather Forecast for December 17, 2021

December 17, 2021, 7:15 AM HST
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Hilo

Today: Partly sunny in the morning with isolated showers. Mostly cloudy in the afternoon with scattered showers and a slight chance of a storm. Locally heavy rainfall possible in the afternoon. Highs 76 to 81 near the shore to around 65 at 4000 feet. Northwest winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely and isolated thunderstorms early in the evening, then showers likely in the late evening and overnight. Lows 61 to 68 near the shore to around 54 at 4000 feet. Southwest winds up to 10 mph shifting to the west after midnight. Chance of rain 70 percent.

Saturday: Mostly cloudy. Showers likely in the morning, then occasional showers in the afternoon. Highs around 77 near the shore to 61 to 66 at 4000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 80 percent.

Kona

Today: Mostly sunny in the morning. Mostly cloudy with scattered showers and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 83 near the shore to around 65 near 5000 feet. Light winds. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 72 near the shore to 47 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

ARTICLE CONTINUES BELOW AD

Saturday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

ARTICLE CONTINUES BELOW AD

Today: Mostly sunny early in the morning then partly sunny. Isolated showers early in the morning. Slight chance of thunderstorms. Scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 63 to 81. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers and isolated thunderstorms early in the evening, then scattered showers in the late evening and overnight. Lows 60 to 67 near the shore to 53 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy. Breezy. Scattered showers in the morning, then showers likely in the afternoon. Highs 62 to 81. East winds 10 to 20 mph. Chance of rain 70 percent.

Kohala

ARTICLE CONTINUES BELOW AD

Today: Mostly sunny early in the morning then partly sunny. Isolated showers early in the morning. Slight chance of thunderstorms. Scattered showers in the afternoon. Locally heavy rainfall possible in the afternoon. Highs 63 to 81. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers and isolated thunderstorms early in the evening, then scattered showers in the late evening and overnight. Lows 60 to 67 near the shore to 53 to 61 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy. Breezy. Scattered showers in the morning, then showers likely in the afternoon. Highs 62 to 81. East winds 10 to 20 mph. Chance of rain 70 percent.

South Big Island

Today: Mostly sunny in the morning. Mostly cloudy in the afternoon with scattered showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs around 81 near the shore to around 65 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows around 70 near the shore to around 51 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 80 near the shore to around 65 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Puna

Today: Partly sunny in the morning with isolated showers. Mostly cloudy in the afternoon with scattered showers and a slight chance of a storm. Locally heavy rainfall possible in the afternoon. Highs 76 to 81 near the shore to around 65 at 4000 feet. Northwest winds up to 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely and isolated thunderstorms early in the evening, then showers likely in the late evening and overnight. Lows 61 to 68 near the shore to around 54 at 4000 feet. Southwest winds up to 10 mph shifting to the west after midnight. Chance of rain 70 percent.

Saturday: Mostly cloudy. Showers likely in the morning, then occasional showers in the afternoon. Highs around 77 near the shore to 61 to 66 at 4000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 80 percent.

Waikoloa

Today: Mostly sunny in the morning, then mostly cloudy in the afternoon with scattered showers and slight chance of thunderstorms. Locally heavy rainfall possible. Highs around 82 near the shore to around 66 above 4000 feet. Light winds becoming southeast up to 10 mph in the morning, then shifting to the northwest in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows around 70 near the shore to 47 to 54 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 81 near the shore to around 66 above 4000 feet. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Update

Forecast has been updated for the Big Island. A land breeze has been keeping the showers and thunderstorms from moving ashore. Will still maintain a few showers for the Puna and Hilo districts for this morning. Scattered showers and a slight chance of a thunderstorm is still on for all parts of the Big Island this afternoon, fuel primarily by ample moisture and daytime heating, aided by an upper level trough passing through the island.

Synopsis

Trade winds are expected to gradually strengthen tonight through Saturday, as a strong surface high sets up north of the islands. Clouds and showers will favor the typical windward areas into the weekend. A wet trade wind pattern is expected early next week aided by a nearby upper level low and a front settling over the islands.

Discussion

The forecast trend remains the same in the coming days, that is toward a very windy, wet and unsettled regime.
Showers and thunderstorms, heavy at times, flared up across windward Maui in the evening, leading to a flood advisory. A second surge is now occurring over the same windward location, and is being watched closely. The likely cause of this weather is the upper trough enhanced the moisture that had moved in from the east. This trough is expected to move over the Big Island later. So, the focus of the weather will be shifting to the Big Island and its adjacent waters as the day progresses. The heaviest of weather is likely to occur this afternoon with locally heavy showers and a couple of thunderstorms.
The remaining islands will likely see periods of showers, a few locally heavy through this afternoon. A slight chance of thunderstorms is in place over the windward near-shore waters from the Kaiwi Channel eastward to the Big Island for this morning. By this afternoon, the area is scaled down, confined to the windward waters off Maui and the surrounding waters of the Big Island. As for Kauai, there is a surge of trade showers pushing into the windward areas now. This should be the pattern for the rest of the day. Later this afternoon, expect some scattered showers to develop over the island’s interior.
The upper trough stalls east of the Big Island later tonight and fills through Saturday. The next major feature is the upper low that drops south to a point 950 miles west-northwest of Kauai Saturday night. The upper low then turns southeastward coming to a point 300 miles southwest of Oahu Monday night before opening up to a trough on Tuesday. The surface low that was mentioned in previous discussion is forecast to stall and dissipated south of Midway Atoll Sunday night. The threat of thunderstorms up to this point should be low over the islands but high over the offshore waters west of Kauai. A cold front is expected to drop over the islands Monday afternoon from the north. Coupled with the nearby upper low/trough, will result in some active showers, likely lasting into Tuesday.
We will be dealing with some strong trade winds late in the weekend and through early next week. The trades will start off in the light to moderate range today, with the stronger winds favoring Maui, the Big Island, and their adjacent windward waters. From tonight on, the trade winds will be on the upswing, becoming breezy by Saturday evening over the typically windy areas, that is Maui and Hawaii counties. Another boost in the trades will come on Sunday, where it becomes pretty windy area-wide. There is a potential for a low level wind advisory for most of the islands at this point. These winds and showers are expected to last into Tuesday.

Aviation

Moderate east to southeast winds will continue into the weekend as a front passes far to the north. An upper trough over the region combined with a sufficient amount of moisture moving in from the east has led to increasing shower coverage, which prompted AIRMET SIERRA for windward Oahu, Molokai, and Maui for MTN obscuration. Expect this trend to persist through the day today, with some leeward and interior areas becoming more active where sea breezes form this afternoon. Additionally, a few thunderstorms can’t be ruled out today, especially over the Big Island slopes during the peak heating hours.

Marine

A cold front approaching the region from the northwest will continue to weaken the ridge north of the islands and keep light to moderate trade winds with land and sea breezes over terrain sheltered areas through this afternoon. Trade winds will slowly increase from tonight onward as high pressure builds back in north of the state. Fresh to strong trade winds are forecast over Hawaiian coastal waters from Saturday through Wednesday, with periods of near gale strength trades in the windier waters around Maui and the Big Island. An upper level disturbance will bring increasing shower trends along with isolated thunderstorms into the weekend.
Two overlapping northwest swells, primarily from a 310 direction, will increase surf heights along north and west shores through Sunday. These surf heights may approach High Surf Advisory levels this weekend and then decline on Monday. A small medium period north-northeast swell arriving Monday night should keep surf heights elevated along north facing shores with some wrap into eastern shores through Wednesday. East facing surf heights will begin to rise today as trade winds begin to increase upstream of the Hawaiian Islands. Stronger trade winds this weekend will boost surf heights along east facing shores into early next week. South facing shores will remain flat through the week.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov

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