Hilo

Today: Showers likely, mainly before 1pm. Partly sunny, with a high near 77. West wind 5 to 9 mph becoming north northeast in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after 1am. Mostly cloudy, with a low around 61. North northeast wind 5 to 8 mph becoming light and variable after midnight. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Showers likely, mainly before 1pm. Partly sunny, with a high near 77. Light and variable wind becoming northeast 5 to 8 mph in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after 1pm. Mostly sunny, with a high near 79. Calm wind becoming west southwest 5 to 7 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before 1am. Partly cloudy, with a low around 59. South southeast wind 3 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Isolated showers before 7am, then scattered showers after 1pm. Mostly sunny, with a high near 79. Light and variable wind becoming south 5 to 7 mph in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Mostly sunny, with a high near 74. Breezy, with a northeast wind around 18 mph, with gusts as high as 25 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 50. Breezy, with a northeast wind 14 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Scattered showers. Mostly sunny, with a high near 74. Breezy, with a northeast wind 9 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Showers likely, mainly before noon. Partly sunny, with a high near 70. Windy, with an east northeast wind 21 to 26 mph decreasing to 15 to 20 mph in the afternoon. Winds could gust as high as 38 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Partly cloudy, with a low around 43. Breezy, with an east northeast wind 15 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Friday: Showers likely, mainly before noon. Partly sunny, with a high near 70. Breezy, with an east northeast wind 16 to 21 mph decreasing to 8 to 13 mph in the afternoon. Winds could gust as high as 29 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers after noon. Sunny, with a high near 79. Windy, with an east wind 23 to 25 mph, with gusts as high as 33 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly clear, with a low around 67. Windy, with an east wind 21 to 24 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Friday: Isolated showers. Sunny, with a high near 79. Windy, with an east wind 18 to 25 mph, with gusts as high as 33 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before noon. Partly sunny, with a high near 76. North northeast wind 8 to 13 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 59. Northwest wind 7 to 13 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Showers likely, mainly before noon. Partly sunny, with a high near 76. North northwest wind 8 to 11 mph becoming northeast in the afternoon. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers after noon. Sunny, with a high near 80. Windy, with an east northeast wind 22 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly clear, with a low around 59. Breezy, with an east wind 16 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Friday: Isolated showers after noon. Sunny, with a high near 80. Breezy, with a northeast wind 16 to 21 mph decreasing to 6 to 11 mph in the afternoon. Winds could gust as high as 29 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

High pressure north of the area will keep cool and locally breezy northeasterly trades in place through Friday, 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 early next week, with more typical trade wind weather returning, and breezy conditions developing by mid week.

Discussion

Currently at the surface, a 1036 mb high is centered around 1550 miles north of Honolulu, while a 1016 mb low is located around 925 miles northeast of Hilo. These features are delivering cool and breezy northeasterly trade winds to the island chain early this morning. Infrared satellite imagery shows mostly cloudy skies in windward areas, with partly cloudy conditions in leeward locales. Meanwhile, radar imagery shows scattered to numerous showers moving into windward areas, with a few showers reaching leeward sections occasionally. Main short term concern revolves around trade wind trends during the next few days.
Very little change in the weather pattern is expected through the remainder of the work week. High pressure north of the state and low pressure to the northeast, will continue to deliver cool and locally breezy trades. Passing showers will favor windward and mauka areas, particularly at night and during the early morning hours, with a stray shower or a few sprinkles reaching leeward areas from time to time.
Over the weekend, a 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, with localized land and sea breezes developing 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 slightly wetter pattern may develop on Sunday as the upper trough passes overhead.
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 to see a strengthening of the northeasterly trades early next week, with the trade becoming breezy by mid week. Fairly typical trade wind weather can be expected through the first half of next week, 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.

Aviation

Fresh to locally strong trade wind flow will continue through 24 hours and possibly beyond. Low topped clouds and scattered showers will continue to be steered towards north thru east facing slopes and coasts. Expect periods of MVFR CIG and VIS in passing showers, especially on the Big Island and Kauai. AIRMET Sierra is now in effect for northeast slopes of the Big Island and is expected to remain necessary through late morning.
AIRMET TANGO remains in effect for mechanical low-level turbulence below 9000 feet over and immediately south through west of the higher terrain due to the breezy trades. This AIRMET will likely remain necessary through at least the evening hours.
Despite the strength of the trade winds, light sea breezes and cumulus build-ups are expected to develop across leeward Big Island this afternoon. A capping inversion around 09 kft, however, will inhibit vertical development and limit shower activity.

Marine

As a high weakens far north of the islands over the next several days, trade winds will be trending down. However, a Small Craft Advisory remains in effect through Friday afternoon for the typically windier waters around Maui County and the Big Island.
The current north-northeast swell will begin a slow decline today, and continuing through the weekend. This will maintain elevated surf along many north and east facing shores through the remainder of the work week. A High Surf Advisory remains in effect for most east facing shores through this afternoon, though it may need to be extended into tonight or Friday as surf slowly lowers below the 8-foot threshold. This swell may also produce enough surge in north facing harbors, including Kahului and Hilo, to create unsafe marine operations through this afternoon.
South shore surf will remain small through the work week, though a bump up in surf heights is possible this weekend into early next week. It appears that surf along north and west shores will also see a small to moderate boost by early next week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for east facing shores of Kauai, Oahu, Molokai, Maui, and the Big Island.
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov