Hilo

Today: Scattered showers, mainly before 1pm. Partly sunny, with a high near 77. Northwest wind 5 to 8 mph becoming northeast in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after 7pm. Mostly cloudy, with a low around 61. North northeast wind 5 to 7 mph becoming calm after midnight. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers, mainly before 1pm. Partly sunny, with a high near 76. Calm wind becoming northeast 5 to 7 mph in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Mostly sunny, with a high near 79. Light and variable wind becoming southwest 5 to 7 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly cloudy, with a low around 59. West wind around 5 mph becoming calm in the evening. Chance of precipitation is 20%.

Saturday: Isolated showers after noon. Partly sunny, with a high near 78. Calm wind becoming southwest around 6 mph. Chance of precipitation is 20%.

Waimea

Today: Scattered showers, mainly after 1pm. Mostly sunny, with a high near 74. Breezy, with a northeast wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after 1am. Mostly cloudy, with a low around 50. Northeast wind 10 to 13 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers, mainly before 7am. Partly sunny, with a high near 73. Northeast wind 5 to 10 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kohala

Today: Scattered showers. Partly sunny, with a high near 70. Breezy, with an east northeast wind 11 to 20 mph, with gusts as high as 29 mph. 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 43. East northeast wind 5 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers, mainly before noon. Partly sunny, with a high near 69. Calm wind becoming south southwest around 6 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 79. Windy, with an east wind 17 to 24 mph, with gusts as high as 30 mph.

Tonight: Mostly cloudy, with a low around 67. Breezy, with an east wind 17 to 20 mph, with gusts as high as 25 mph.

Saturday: Mostly sunny, with a high near 78. Breezy, with an east northeast wind 9 to 18 mph, with gusts as high as 23 mph.

Puna

Today: Scattered showers. Partly sunny, with a high near 76. North northeast wind 7 to 10 mph. 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 59. North wind 5 to 9 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers. Mostly cloudy, with a high near 75. Light and variable wind becoming east northeast around 6 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waikoloa

Today: Mostly sunny, with a high near 80. Breezy, with an east wind 9 to 18 mph becoming north in the afternoon. Winds could gust as high as 26 mph.

Tonight: Mostly cloudy, with a low around 59. Breezy, with an east northeast wind 7 to 16 mph, with gusts as high as 23 mph.

Saturday: Mostly sunny, with a high near 79. East northeast wind 5 to 8 mph becoming calm in the afternoon.

Detailed Forecast

Synopsis

High pressure north of the area will continue to funnel in cool temperatures on moderate northeasterly trades through tonight, with passing showers favoring windward and mauka areas. Over the weekend the trades will diminish, allowing land and sea breezes to develop in the more sheltered areas. Showers will favor windward slopes and coasts at night and during the morning, with a few showers developing over interior and leeward areas each afternoon. The trades will be on the increase through the first half of next week, with more typical trade wind weather returning.

Discussion

Currently at the surface, a 1034 mb high is centered around 1650 miles north of Honolulu, while a 1015 mb low is located around 750 miles northeast of Hilo. These features continue to deliver cool northeasterly trade winds to the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions in windward areas, with clear to partly cloudy skies in most leeward locales.Radar imagery shows scattered showers moving into windward areas, with a few decaying showers making it over the mountains and into leeward communities. Main short term concern revolves around trade wind trends during the next couple days.
Very little change is expected in the overall weather pattern through tonight. High pressure north of the state and low pressure to the northeast, will continue to funnel in cool temperatures on moderate northeasterly trades. Passing showers will favor windward and mauka areas, mainly during the early morning hours and at night, with a stray shower or a few sprinkles reaching leeward sections from time to time.
Over the weekend, a strong upper level trough will dig southeastward and over the islands, amplifying the surface troughing to the east of the state. This will ease the trade winds into the light to locally moderate range, allowing land and sea breezes to develop in some of the more sheltered areas. Showers will favor windward slopes and coasts at night and during the early morning hours and interior and leeward locales during the afternoon and evening. A more active shower pattern is expected on Sunday as the upper trough passes overhead, and it’s not out of the question that a thunderstorm or two could develop, particularly over the Big Island slopes in the afternoon.
The upper level trough will slide further east early next week, pushing the surface trough further away from the island chain. This will allow a new strong high building northwest of the state to gradually become more dominant. As a result, we expect a slow strengthening of the northeasterly trades through the middle of next week. Fairly typical trade wind weather can be expected during this time, although it may be slightly wetter on Monday as the upper trough exits to the east. Otherwise, showers are expected to favor windward and mauka areas through the period, with a stray shower occasionally spreading leeward. The remnants of an old front may move into the islands late next week, bringing an increasing in shower coverage.

Aviation

Moderate to locally breezy northeast trade winds will persist through this afternoon. Winds are expected to gradually weaken over the next twenty-four hours as the ridge of high pressure to the north weakens and retreats northward. AIRMET Tango for low level mechanical turbulence to the lee of higher terrain will likely be canceled later this morning.
Bands of scattered light showers, steered by the trade winds, can be seen on satellite streaming towards the islands. Showers will continue to impact mainly north and east facing slopes and coasts, but isolated spillover showers are possible across leeward areas of the smaller islands. AIRMET Sierra is now in effect for mountain obscuration across Windward Big Island. Mountain obscuration could also become an issue on Kauai later today.
Regarding interior and leeward Big Island, weak land breezes this morning will give way to light sea breezes this afternoon. Cumulus build- ups are expected to redevelop along south and west facing slopes throughout the afternoon and evening, but a capping inversion around 08 kft will limit shower activity.

Marine

With the high pressure ridge eroding northwest of the islands, trade winds have been easing. However, a Small Craft Advisory does remain in effect through this afternoon for the typically windier zones around Maui County and the Big Island. Winds will likely then remain light to moderate over all areas into early next week.
The current north-northeast swell will continue to slowly decline through the weekend, though surf along north- and east-facing shores will remain somewhat elevated through tonight. South shore surf will remain small, with a boost possible this weekend into early next week with energy moving in from the southern hemisphere. For north- and west-facing shores, a small, medium period, northwest swell is forecast to arrive early next week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov