Photo Credit: James Grenz

Hilo

Today: Scattered showers. Mostly cloudy, with a high near 84. Calm wind becoming east 5 to 9 mph in the afternoon. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 65. East wind 5 to 8 mph becoming light and variable. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Showers likely, mainly before noon. Partly sunny, with a high near 83. East northeast wind 5 to 9 mph becoming light and variable in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Partly sunny, with a high near 80. Light and variable wind becoming north northwest 5 to 10 mph in the morning. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Partly cloudy, with a low around 64. North northwest wind 5 to 10 mph becoming light and variable after midnight. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Scattered showers after noon. Partly sunny, with a high near 79. South southwest wind 5 to 8 mph becoming calm in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Partly sunny, with a high near 79. Breezy, with a northeast wind 16 to 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. Mostly cloudy, with a low around 57. Windy, with a northeast wind 18 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Scattered showers. Partly sunny, with a high near 78. Windy, with a northeast wind 20 to 25 mph decreasing to 10 to 15 mph in the afternoon. Winds could gust as high as 37 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Scattered showers. Mostly cloudy, with a high near 65. Breezy, with an east wind 14 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 52. Windy, with an east wind 22 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Showers likely, mainly before noon. Mostly cloudy, with a high near 64. Windy, with an east northeast wind 20 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers. Partly sunny, with a high near 85. Windy, with an east wind 21 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly before midnight. Mostly cloudy, with a low around 73. Windy, with an east northeast wind 22 to 25 mph, with gusts as high as 33 mph. Chance of precipitation is 30%.

Sunday: Isolated showers. Mostly sunny, with a high near 84. Windy, with an east wind 21 to 26 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Puna

Today: Scattered showers. Mostly cloudy, with a high near 83. West northwest wind 6 to 13 mph becoming east in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 63. East wind around 10 mph becoming north after midnight. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Sunday: Showers likely, mainly before noon. Partly sunny, with a high near 82. Northeast wind 8 to 13 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Scattered showers after noon. Partly sunny, with a high near 85. Breezy, with an east northeast wind 11 to 16 mph becoming west 5 to 10 mph in the afternoon. Winds could gust as high as 23 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before midnight. Partly cloudy, with a low around 65. Windy, with a west wind 5 to 10 mph becoming east northeast 16 to 26 mph in the evening. Winds could gust as high as 38 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: Isolated showers after noon. Mostly sunny, with a high near 84. Windy, with a northeast wind 16 to 26 mph decreasing to 5 to 15 mph in the afternoon. Winds could gust as high as 38 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Trade winds will strengthen from east to west across the island chain today, moderate to breezy conditions then expected Sunday through much of next week. The trade winds will deliver low clouds and a few showers to windward areas, particularly at night and during the early morning hours, with a few showers spilling leeward from time to time. Wispy high clouds will also periodically move over the islands through the weekend and the first half of next week.

Discussion

Currently at the surface, a weak southwest to northeast oriented trough of low pressure is located around 450 miles northwest of Kauai. Meanwhile, a 1031 mb high is centered to the distant northwest of the islands and a 1028 mb high is located to the distant northeast. The trades winds have trended upward ever so slightly overnight, although they remain generally in the light to moderate range. Infrared satellite imagery shows a mix of high and low clouds producing partly cloudy conditions in most areas, with a few localized pockets of more extensive cloud cover mainly in windward areas as well as portions of leeward Big Island. Radar imagery shows scattered showers moving into windward areas, with a shower occasionally spilling over into leeward communities. Main short term concerns revolve around trade wind trends and rain chances during the next couple days.
The surface trough to the northwest of the islands will shift further west during the next couple days, allowing high pressure to the distant northeast to become more dominant. The two highs to the northwest and northeast of the islands will then consolidate into a single strong high north of the state early next week, which will build slowly eastward as we approach next weekend. The trades are expected to continue to trend upward today, strengthen from east to west across the the island chain as the day progresses. Moderate to breezy trades should then prevail Sunday through much of next week, with only minor fluctuations in strength from day to day.
As for the remaining weather details, showers should be mainly confined to windward showers this morning, with a few daytime heating driven showers developing over leeward areas this afternoon. A transition back to more typical trade wind weather should take hold tonight and continue through much of next week, with showers favoring windward and mauka areas, particularly at night and during the early morning hours, with a stray shower spilling over into leeward communities from time to time.

Aviation

Light to moderate easterly trade winds will trend up into the breezy category later today through the second half of the weekend. Outside of the typical afternoon showers over the Kona slopes, showers will favor windward and mauka locations with the best chances overnight through the mornings. MVFR CIGS/VSBYS will remain possible in and around passing showers.
There are currently no AIRMETs in effect.
AIRMET Tango for low-level turbulence below 8000 ft over and immediately southwest through northwest of all mountains of the islands will become a possibility later today through Sunday as the trade winds increase.

Marine

A weak surface trough far northwest of the state will move slowly west the next couple of days as ridging builds in from the northeast. This will place a tight enough pressure gradient across the area to support moderate to fresh easterly trade winds this weekend. Locally strong coastal winds and resultant rough seas surrounding Maui County and those waters south of the Big Island has prompted a Small Craft Advisory that is in effect through Sunday afternoon.
A declining south swell will maintain small surf along south facing shorelines through the day. A slight strengthening of trade winds through early next week will increase choppy, short period wind waves along many eastern coasts. A recent gale east of New Zealand has sent the next swell northward within Hawaii’s southern swell window. These long period, small south swells may arrive late next week and provide a minor boost to southern shore surf.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov