Weather Forecast

Hawaii County Weather Forecast for May 20, 2022

May 20, 2022, 7:15 AM HST
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Hilo

Today: Partly sunny. Slight chance of showers in the morning, then chance of showers in the afternoon. Highs around 83 near the shore to 66 to 71 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with slight chance of showers in the evening, then partly cloudy with chance of showers after midnight. Lows 65 to 70 near the shore to around 54 at 4000 feet. Light winds. Chance of rain 30 percent.

Saturday: Mostly sunny with isolated showers. Highs around 83 near the shore to 66 to 71 at 4000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Kona

Today: Partly sunny. Slight chance of showers in the morning, then chance of showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then mostly clear after midnight. Lows 68 to 75 near the shore to around 55 near 5000 feet. Light winds.

ARTICLE CONTINUES BELOW AD

Saturday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

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Today: Partly sunny. A 40 percent chance of showers in the afternoon. Highs around 82 near the shore to 66 to 77 near 3000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy in the evening then becoming mostly clear. A 20 percent chance of showers. Lows around 67 near the shore to 55 to 62 near 3000 feet. Light winds.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 82 near the shore to 66 to 77 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Kohala

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Today: Partly sunny. A 40 percent chance of showers in the afternoon. Highs around 82 near the shore to 66 to 77 near 3000 feet. East winds up to 15 mph.

Tonight: Mostly cloudy in the evening then becoming mostly clear. A 20 percent chance of showers. Lows around 67 near the shore to 55 to 62 near 3000 feet. Light winds.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 82 near the shore to 66 to 77 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Big Island

Today: Partly sunny. Breezy. Chance of showers in the morning, then slight chance of showers in the afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Lows around 69 near the shore to around 54 near 5000 feet. Northeast winds up to 15 mph.

Saturday: Sunny and breezy. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 20 mph.

Puna

Today: Partly sunny. Slight chance of showers in the morning, then chance of showers in the afternoon. Highs around 83 near the shore to 66 to 71 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with slight chance of showers in the evening, then partly cloudy with chance of showers after midnight. Lows 65 to 70 near the shore to around 54 at 4000 feet. Light winds. Chance of rain 30 percent.

Saturday: Mostly sunny with isolated showers. Highs around 83 near the shore to 66 to 71 at 4000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Waikoloa

Today: Mostly sunny with slight chance of showers in the morning, then mostly cloudy with chance of showers in the afternoon. Highs around 85 near the shore to 67 to 73 above 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then mostly clear after midnight. Lows 69 to 75 near the shore to 51 to 58 above 4000 feet. North winds up to 10 mph in the evening becoming light.

Saturday: Sunny in the morning then becoming partly sunny. Breezy. Highs around 85 near the shore to 67 to 73 above 4000 feet. Northeast winds up to 10 mph increasing to up to 20 mph in the afternoon.

Detailed Forecast

Synopsis

Moisture along a weakening front will maintain higher shower chances for Kauai into tonight. The rest of the state will experience mainly spotty showers under decreasing southeast to south winds. High clouds will gradually diminish as humid conditions persist through Friday. Moderate trade winds will build during the weekend and will hold into next week.

Discussion

Have made some tweaks to the forecast into tonight mainly boosting PoPs and associated fields over the western end of the state. While the PoPs have been nudged higher, they are still below several of the high resolution models.
Overnight saw a band of showers move over Kauai, with rain gages showing most of the rain fell over the southern half of the island. Radar showed the heaviest rain remained to the southwest of Kauai, and that it has weakened as it moved towards Oahu. There is good model agreement across high resolution and global models that show the moisture axis will remain near Kauai today. Winds have weakened as expected, so look for some land and sea breezes today and tonight. With the afternoon sea breezes, additional showers are expected to form over the interior and northern shores of Kauai and Oahu, but with the moisture band near the western islands, other showers will also be around, particularly over Kauai. Spotty showers will be found over Maui County and the Big Island.
The weakening front remains near the western end of the state and continues to bring a humid, slightly unstable, and southerly flow over the islands. The atmosphere is becoming more stable with time. Layered clouds will linger near Kauai, and upper clouds over the remainder of the state will continue to thin as the upper level trough continues to move away from the state. Dewpoints in the low to mid 70s will keep humidity values high. Expect some gradual decline in dewpoints in a couple days. Upper level ridging will slowly build in, but there is still some lingering instability which could lead to briefly heavy rainfall.
Look for a more stable trade wind pattern to set up this weekend as high pressure strengthens northeast of the state. A mid level ridge building overhead will help to stabilize the atmosphere, leaving to a more typical trade wind weather pattern that will hold into next week.

Aviation

Showery weather will persist statewide, the result of a weak front stalled over the western end of the state. Low level winds will be mainly out of the south through this morning with deep low level moisture concentrated over Kauai and Oahu. This afternoon, drier easterly flow will develop over the Big Island and spread across the remainder of the state by Saturday morning.
The air mass over the state will gradually stabilize from the east as the front in the west decays. Nevertheless, locally heavy showers are still possible over Kauai. Elsewhere, shower activity should remain light and intermittent.
AIRMET Sierra for mountain obscuration remains in effect for Kauai. Conditions may improve briefly in the early evening, but will likely lower again after midnight.

Marine

A front stalled near Kauai this morning will continue to weaken and drift northward. Lighter winds are forecast with local scale land and sea breezes in the near shore waters. A high pressure ridge will begin to build back into the region today with easterly trade winds strengthening from east to west through the weekend. SCA conditions will likely return to the typical windier waters and channels around Maui County and the Big Island on Saturday and Sunday. This trade wind weather pattern with more stable conditions will continue into the middle of next week.
Surf heights along south facing shores will remain elevated into next week as the current south swell becomes reinforced by additional long period south swells arriving on Saturday, Monday and next Thursday. In the long range, models continue to show quite a bit of activity in the southern hemisphere, which could translate to additional south shore surf events lasting into early June.
Surf along north and west facing shores will slowly decline as medium period northwest (300-320 degrees) swell energy diminishes over the next 2 days. A return to nearly flat pancake summer conditions is expected from Sunday into the first half of next week as this current northwest swell energy fades.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov

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