Hilo

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 82. West wind 5 to 10 mph becoming east in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. West southwest wind around 6 mph becoming calm after midnight. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers. Mostly cloudy, with a high near 80. Calm wind becoming east 5 to 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Partly sunny, with a high near 79. Calm wind becoming west 5 to 7 mph in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before 8pm. Partly cloudy, with a low around 63. Northwest wind around 5 mph becoming calm after midnight. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers after noon. Increasing clouds, with a high near 77. Light and variable wind becoming west northwest 5 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 75. Light and variable wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before 8pm. Partly cloudy, with a low around 52. Calm wind becoming north northeast 5 to 7 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers, mainly after noon. Increasing clouds, with a high near 73. Light north northeast wind becoming northeast 5 to 9 mph in the morning. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 61. Calm wind. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before 8pm. Partly cloudy, with a low around 50. Calm wind becoming east 5 to 8 mph in the evening. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers, mainly after noon. Partly sunny, with a high near 59. East wind 6 to 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Scattered showers, mainly before noon. Partly sunny, with a high near 81. Breezy, with an east wind 16 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 30%.

Tonight: Scattered showers, mainly after 8pm. Mostly cloudy, with a low around 72. Breezy, with an east northeast wind 16 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 30%.

Tuesday: Scattered showers, mainly before noon. Partly sunny, with a high near 81. Breezy, with an east wind 13 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 30%.

Puna

Today: Scattered showers. Mostly cloudy, with a high near 79. West wind 5 to 9 mph becoming east southeast 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 62. East southeast wind around 6 mph becoming light and variable after midnight. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers. Mostly cloudy, with a high near 77. Light and variable wind becoming east northeast 5 to 10 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 after 1pm. Mostly sunny, with a high near 82. Light and variable wind becoming northwest 5 to 9 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before 9pm. Mostly cloudy during the early evening, then becoming mostly clear, with a low around 64. West wind around 5 mph becoming calm. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers after 1pm. Increasing clouds, with a high near 80. East wind 5 to 8 mph becoming west southwest in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

Warm and humid conditions with light east to southeast winds are expected through the first half of the week. Clouds and showers will favor interior and leeward locations as the sea breezes develop through the afternoon and early evening periods. A return of light to moderate easterly trade winds will be possible through the second half of the week. Light east to southeast winds will be possible once again next weekend as another front stalls to the northwest.

Discussion

Short-term guidance remains in good agreement and depicts a weakness in the ridge lingering through the start of the week due to a front stalling and diminishing to the northwest. The low- level flow in the islands has veered out of the east-southeast direction in response to the loosened pressure gradient and the ridge shifting southward into the area. This will result in a land and sea breeze regime through at least Tuesday. Showers will shift from the typical windward and mountain locations to leeward and interior areas through the afternoon periods due to daytime heating and sea breezes. Added instability associated with a shortwave trough digging southeastward to an area north of the islands today through Tuesday could support better afternoon shower coverage. The limiting factor, however, will be the lack of low- to mid-level moisture available. Earlier model cycles were advertising a better source of moisture pulling up over the islands from the east through this time with PWs rising toward 1.6″. This has changed in the latest model guidance, which now shows drier profiles with PWs only reaching 1.3″ to 1.5″. Over the Big Island, similar to the past few days, a thunderstorm or two can’t be ruled out over the slopes through the afternoon periods (decent mid-level lapse rates).
For the extended period, guidance remains in decent agreement and shows a return of a more typical trade wind pattern setting up through the second half of the week as the front to the northwest diminishes and the ridge strengthens to the north. Low-level flow will shift back out of the east, but potentially remain in the light to moderate category – which could allow localized sea breezes to develop in the sheltered leeward areas. For the upcoming holiday weekend, a replay of early this week seems possible as another front moves in from the northwest and the local winds shift out of the east-southeast.

Aviation

Light ESE flow has given way to land breezes and clearing skies this morning. The onset of diurnal heating will give rise to sea breeze development during the morning. Inland clouds and a few showers will bring the potential for brief MVFR to inland and leeward areas. Meanwhile, afternoon convection over Big Island will likely be less vigorous than previous days as mid-level stability has increased. Nonetheless, isolated thunder will remain a possibility, mainly over the slopes of Leeward Big Island. Land breezes and clearing skies will develop again tonight.

Marine

A front approaching the region from the northwest will stall to the northwest of the islands as it weakens into a trough. This will weaken trade winds to variable breezes over the western islands while veering gentle winds east southeast over more eastern windward waters through Tuesday. As the weak trough washes out north of the islands through the middle of the week, high pressure to the northeast will reestablish itself and allow for the return of more moderate trades the second half of the week.
A small north northwest swell will peak today. This will provide a small boost to surf heights along most north and west facing shores before it gradually fades Tuesday. The next small northwest swell is expected to increase north and west facing shore surf Wednesday night through Friday. While confidence is low, the arrival of a larger Memorial Day northwest swell could significantly pick up late May surf along many northern and western exposures. A series of small, long period southwest to south swells, which are expected to arrive through today and persist through Friday, will provide a minor boost to surf heights to near seasonal values through the week. Despite the weaker trade wind regime over the islands, a fetch of moderate trade winds just upstream of the islands will likely maintain small surf along east facing coasts through mid-week.
High astronomical tides, along with water levels running about a third of a foot above normal, could combine to produce nuisance coastal flooding around afternoon/evening high tides this week. Flooding impacts, such as inundation of normally dry beaches and coastal infrastructure could be experienced as early as Tuesday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov