Weather Forecast

Hawaii County Weather Forecast for May 23, 2021

May 23, 2021, 7:15 AM HST
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Hilo

Today: Showers likely, mainly before 1pm. Mostly cloudy, with a high near 83. South wind 5 to 9 mph becoming east in the morning. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 66. East southeast wind around 5 mph becoming south after midnight. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers. Mostly cloudy, with a high near 82. Light and variable wind becoming east southeast 5 to 9 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers, mainly after 1pm. Increasing clouds, with a high near 79. Calm wind becoming west southwest around 5 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before 7pm. Mostly cloudy, with a low around 64. Light and variable wind. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

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Monday: Scattered showers, mainly after 7am. Mostly cloudy, with a high near 79. Calm wind becoming west around 6 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

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Today: Scattered showers. Increasing clouds, with a high near 75. West wind around 6 mph becoming calm in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 53. Light and variable wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers, mainly after noon. Mostly cloudy, with a high near 75. Calm wind becoming west northwest around 5 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

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Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 61. Light and variable wind. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 51. Light and variable wind. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers. Mostly cloudy, with a high near 61. Calm wind becoming east around 5 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Scattered showers. Partly sunny, with a high near 81. Breezy, with an east wind 14 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers. Mostly cloudy, with a low around 71. Breezy, with an east northeast wind 15 to 17 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Monday: Scattered showers, mainly after noon. Partly sunny, with a high near 81. Breezy, with an east wind around 16 mph, with gusts as high as 21 mph. Chance of precipitation is 30%.

Puna

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 80. South southeast wind 5 to 9 mph becoming east in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 63. East wind around 6 mph becoming calm in the evening. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers. Mostly cloudy, with a high near 79. Light southeast wind becoming south southeast 6 to 11 mph in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Scattered showers, mainly after noon. Increasing clouds, with a high near 82. West northwest wind 5 to 8 mph becoming calm in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. Light and variable wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers after noon. Partly sunny, with a high near 82. West northwest wind 5 to 9 mph becoming calm in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

The trade winds will continue to trend toward light and variable over the smaller islands by this afternoon, and persist through Tuesday. This is in response to a front that will stall and dissipate northwest of the islands Monday night through Tuesday. Expect a rise in humidity with the light winds, too. Cooling trade winds will return Wednesday and continue through the rest of next week.

Discussion

There is a change to the winds for today through Tuesday night. The ECMWF and high res models have indicated that a light easterly background wind flow will linger today through Tuesday night, most noticeable across the windward waters west of Maui. A slightly stronger southeast wind flow is expected to settle in over the windward Maui and windward Big Island waters later today and continue through Tuesday night. This create a hybrid mix of trades and land and sea breezes over land. The trades will continue to bring in a few showers into the windward areas day and night, while the land and sea breezes cover the rest of each island. Daytime heating and light winds will promote a daytime sea breeze. and with ample moisture, result in some scattered showers over the interior and lee areas each afternoon through Tuesday. At night, a land breeze will nudge most of the showers to off the island or to the coastline.
The intensity of these showers is uncertain at this time, but the models are indicating the air mass becoming unstable Monday and persisting through Tuesday. The EC solution also has an upper level short wave trough to drop down on the islands Monday night and Tuesday, which will bring a boost to the showers and a chance of a afternoon thunderstorm for the Big Island summits. Today’s Sunday weather looks fine. Some spotty afternoon showers are expected over interior and leeward areas. An exiting upper level trough over the Big Island will favor an thunderstorm or two over the higher elevations of the Big Island.
The Koolau and windward Oahu, mainly the Kahana and Punaluu areas, have had a wet evening with just over an inch of rain. Scattered showers are still ongoing and will be monitored closely. Scattered showers are also present across windward Kauai, southeast Maui, and windward Big Island.
Cooling trade winds will return Wednesday, strengthening to locally strong Thursday night or Friday.

Aviation

A low pressure system passing by north of the region will weaken the ridge north of the islands, producing a light and variable wind regime. Sea breezes will start to develop around 19Z with clouds building over island interior sections along with a few showers favoring the afternoon to early evening hours. Land breezes will form after sunset with diminishing cloud cover for most islands in the overnight hours. This light and variable wind pattern will continue into Tuesday.
AIRMET Sierra in effect for Tempo Mountain Obscurations over north and east sections of Oahu and Kauai. These low cloud ceilings will likely diminish later this morning.
Light icing is possible near the Big Island this morning between 130-160.

Marine

A front approaching the region from the northwest will cause the background flow to weaken and shift out of the east-southeast today. These light east-southeast winds will likely persist from tonight through Tuesday as the front eventually stalls and weakens northwest of the area. High pressure is expected to gradually build northeast of the islands by mid-week. This will allow moderate trade winds to return to the state from Wednesday through early Thursday. Looking ahead, the trade winds are forecast to approach the Small Craft Advisory criteria across the typically windier waters adjacent to the islands of Maui County and the Big Island starting Thursday night or Friday.
Expect only small background surf along south facing shores today. A series of small, long-period south-southwest and south swells, which are expected to start spreading across the area starting Monday, will likely cause surf heights to increase to slightly above seasonal values from Tuesday into Friday. Surf heights are expected to drop to near seasonal values by next weekend as the swells originating from the Southern Hemisphere gradually diminish.
A small north-northwest swell is expected arrive later today, and peak on Monday. This swell will likely provide a small boost to surf heights along most north and west facing shores before it gradually fades on Tuesday. Another small northwest swell is expected to increase surf heights along most north and west facing shorelines of the smaller islands from Wednesday night through Friday.
Despite the weaker trade wind regime, a fetch of moderate trade winds immediately upstream of the islands will likely keep small background surf along east facing shores through mid-week.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov

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