Hilo

Today: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 82. East northeast wind 5 to 9 mph becoming light and variable in the afternoon. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Showers likely. Mostly cloudy, with a low around 67. Light and variable wind becoming west southwest around 6 mph in the evening. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 83. East southeast wind 6 to 11 mph. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Kona

Today: Isolated showers, then scattered showers and thunderstorms after noon. Partly sunny, with a high near 79. Light and variable wind becoming west 5 to 9 mph. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers, mainly before midnight. Mostly cloudy, with a low around 65. Calm wind becoming northwest around 5 mph after midnight. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers and thunderstorms after noon. Partly sunny, with a high near 79. Northwest wind around 5 mph becoming calm in the morning. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Waimea

Today: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 75. Northeast wind 11 to 13 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers. Mostly cloudy, with a low around 54. Northeast wind 6 to 11 mph becoming light and variable after midnight. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Scattered showers and thunderstorms after noon. Partly sunny, with a high near 75. Light and variable wind. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Kohala

Today: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 61. Calm wind becoming east 5 to 9 mph in the afternoon. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Showers likely. Mostly cloudy, with a low around 52. East wind 5 to 9 mph becoming calm in the evening. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 61. Light and variable wind. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

South Big Island

Today: Scattered showers and thunderstorms after noon. Partly sunny, with a high near 81. Windy, with an east wind 17 to 23 mph, with gusts as high as 30 mph. Chance of precipitation is 30%.

Tonight: Scattered showers, mainly after midnight. Partly cloudy, with a low around 72. Breezy, with an east northeast wind 14 to 18 mph, with gusts as high as 23 mph. Chance of precipitation is 30%.

Sunday: Isolated showers, then scattered showers and thunderstorms after noon. Partly sunny, with a high near 81. Breezy, with an east northeast wind around 15 mph, with gusts as high as 18 mph. Chance of precipitation is 30%.

Puna

Today: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 79. West northwest wind 7 to 11 mph becoming east northeast in the afternoon. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Showers likely. Mostly cloudy, with a low around 64. East northeast wind 5 to 7 mph becoming west in the evening. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Scattered showers, with thunderstorms also possible after noon. Mostly cloudy, with a high near 80. East southeast wind 5 to 10 mph. Chance of precipitation is 40%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Waikoloa

Today: Scattered showers and thunderstorms after noon. Mostly sunny, with a high near 82. Breezy, with an east wind 11 to 16 mph becoming north 5 to 10 mph in the morning. Winds could gust as high as 22 mph. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Isolated showers. Partly cloudy, with a low around 66. Northeast wind 5 to 7 mph becoming calm after midnight. Chance of precipitation is 20%.

Sunday: Scattered showers and thunderstorms after noon. Partly sunny, with a high near 82. Light and variable wind. Chance of precipitation is 50%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Detailed Forecast

Synopsis

A front near the islands will bring an interruption to the cooling trade winds between Sunday and Tuesday of next week. The rain pattern shifts as well, from windward and mauka showers to interior and leeward areas during the afternoon hours. Humid conditions will also accompany the light winds. Trade winds are expected to return Wednesday and last through the second half of the week with high pressure north of the islands.

Discussion

Locally strong trade winds will continue to trend down today, becoming light and variable over the smaller islands by Sunday, and persist through Tuesday. Light to moderate east to southeast winds will be the background flow between Sunday and Tuesday, most noticeable over the island’s windward waters. With the light winds over land, we can expect a nighttime land breeze with most clouds/showers clearing back to the shoreline, and a daytime sea breeze where clouds and showers form over the interior and lee areas. The most active days are Monday and Tuesday due to an upper level impulse dropping over the islands from the northwest.
The break in the trades is due to a eastward moving front that appears near Midway Atoll this afternoon. The front progresses to where it weakens and dissipates north of the islands between Monday night and Tuesday.
A slow moving weak upper level low is present over the islands this morning. It has already help set off a thunderstorm or two over the Big Island summits Friday afternoon. This upper low will weaken to a trough as it moves eastward to over the Big Island on Sunday. Sufficient instability will favor a thunderstorm or two through Sunday for mainly the higher elevation and lee areas of the Big Island. Thunderstorms are not in the Monday forecast as the upper trough will be east of the Big Island.
Trade winds will return to the islands as early as Tuesday night, and gradually strengthening to locally strong by Friday as the front dissipate north of the islands and high pressure takes over.

Aviation

High pressure north of the region will keep moderate to breezy trade winds in the forecast into the weekend. Expect brief periods of MVFR conditions in showers over windward and mountain areas. Isolated thunderstorms will likely redevelop Saturday afternoon over the Big Island.
AIRMET Tango remains in effect for moderate turbulence south through west of island mountains due to stronger trade winds.

Marine

The trades will ease today and tonight, then become disrupted Sunday through Tuesday as a front approaches and stalls out northwest of the islands. The trades will likely remain at advisory levels in the windier waters around the Big Island, so the Small Craft Advisory (SCA) has been extended through 6 PM this evening here. Elsewhere, winds have dropped below SCA thresholds. As the front moves closer to the islands on Sunday, winds will shift east-southeasterly, allowing for a land and sea breeze pattern to develop over the western waters, while moderate east-southeast winds prevail near the Big Island. Moderate trade winds are expected to return during the middle of next week.
A small north-northwest swell is scheduled to arrive Sunday afternoon and peak Monday, providing a small bump along north and west facing shores. Another small northwest swell will bring a boost to north shore surf Wednesday night through Friday.
Background south swells will keep small surf in place along south facing shores through the weekend. South shore surf will then trend up Monday and rise to near or slightly above seasonal levels Tuesday through Thursday as a series of overlapping long- period south swells move through. Surf will drop off a notch late next week, but will remain near seasonal levels.
East shore surf will trend down slightly on today, then hold steady Sunday through late next week, below typical levels for this time of year.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov