Photo Credit: Tyler Rooke

West Side

Today: Sunny, with a high near 81. Breezy, with an east northeast wind 17 to 22 mph decreasing to 9 to 14 mph in the afternoon. Winds could gust as high as 31 mph.

Tonight: Mostly clear, with a low around 66. East northeast wind around 10 mph.

Friday: Sunny, with a high near 81. East northeast wind around 11 mph.

South Side

Today: Isolated showers after noon. Mostly sunny, with a high near 81. Light and variable wind becoming northeast 6 to 11 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 64. Northeast wind 11 to 13 mph.

Friday: Isolated showers after noon. Sunny, with a high near 81. Breezy, with a northeast wind 13 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

North Shore

Today: Isolated showers before noon. Mostly sunny, with a high near 79. Windy, with an east wind 15 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 65. Breezy, with an east northeast wind around 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Friday: Isolated showers before noon. Sunny, with a high near 79. Breezy, with an east northeast wind 16 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Central Maui

Today: Sunny, with a high near 79. Breezy, with an east northeast wind 16 to 20 mph, with gusts as high as 28 mph.

Tonight: Mostly clear, with a low around 63. East northeast wind around 13 mph.

Friday: Sunny, with a high near 79. East northeast wind around 14 mph, with gusts as high as 18 mph.

Upcountry

Today: Isolated showers after noon. Sunny, with a high near 66. Light and variable wind becoming east 8 to 13 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 53. Breezy, with an east wind 13 to 15 mph, with gusts as high as 21 mph.

Friday: Sunny, with a high near 67. Breezy, with an east wind 14 to 16 mph, with gusts as high as 22 mph.

East Maui

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 77. East wind 11 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after midnight. Mostly cloudy, with a low around 61. East wind around 14 mph, with gusts as high as 18 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 77. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Isolated showers after noon. Mostly sunny, with a high near 74. Breezy, with a northeast wind 9 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly clear, with a low around 63. Northeast wind 9 to 13 mph. Chance of precipitation is 20%.

Friday: Isolated showers after noon. Sunny, with a high near 74. East northeast wind 10 to 13 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Sunny, with a high near 79. Breezy, with an east northeast wind 13 to 17 mph, with gusts as high as 24 mph.

Tonight: Mostly clear, with a low around 68. Breezy, with an east wind 17 to 20 mph, with gusts as high as 28 mph.

Friday: Sunny, with a high near 79. Windy, with an east wind 20 to 23 mph, with gusts as high as 32 mph.

Detailed Forecast

Synopsis

Trade winds will gradually increase over the next couple of days as high pressure builds northeast of the state. Showers will favor windward slopes, with a few heavy showers possible as an upper trough lingers across the islands. Trade winds will shift out of the east to east-southeast and become breezy and gusty over the weekend and into early next week.

Discussion

High pressure far north of the main Hawaiian Islands is sufficiently strong to drive breezy trade winds across local waters this morning. An upper trough is parked across the state, with high clouds along its eastern flank covering much of the island chain. Instability associated with the upper trough encouraged thunderstorm development across leeward Big island slopes yesterday, but this activity ceased with the onset of overnight cooling. Otherwise, shower activity has been modest and confined to windward slopes.
Expect showers to favor windward areas through Friday. Models show the upper trough will push east of the state, leading to a decrease in high clouds, but enough instability will persist to potentially trigger brief heavy showers, especially across leeward Big Island in the afternoons. Trades will continue to gradually strengthen through Friday as surface ridging builds north of the state. Models show winds will increase and shift during the weekend as high pressure builds to around 1040 mb far north of the islands. Local winds will shift out of the east to east-southeast in response to low pressure developing to our west, with wind speeds likely becoming strong and gusty. Showers will favor windward and southeast slopes.
Strong and gusty trade winds will hold into the first half of next week. The low developing to the west of the islands should weaken, allowing winds to become more easterly. Models keep deeper moisture south and west of the islands, suggesting that showers will be focused on windward slopes.

Aviation

Trade winds will be in the moderate to breezy range through tonight as high pressure strengthens far north and northeast of the islands. Showers, and accompanying MVFR conditions, will mainly affect windward and mauka sections. With a nearby upper level disturbance, some of the showers may be heavy; and there is a slight chance of a thunderstorm or two over the leeward slopes on the Big Island this afternoon. Otherwise, VFR will predominate.
No AIRMETs are currently in effect.

Marine

Surface high pressure centered over the Northeast Pacific will provide a tight enough pressure gradient back across the local waters to produce moderate to locally strong northeast to east trade winds into Friday. This high is forecast to strengthen to near 1042 mb this weekend while the associated upper ridge firmly anchors itself northeast of the chain and ensures several days of uninterrupted trade flow. The resultant northeast to southwest pressure gradient will tighten even further this weekend and create strong to near gale force east southeast winds into early next week. A Small Craft Advisory (SCA) is in effect through the weekend for those notoriously windier channels and bays around Maui and for those waters south of the Big Island. As winds and seas increase this weekend in response to both strengthened trades and incoming higher northwest swells, the SCA will likely need to be expanded in areal coverage to include all of the remaining Hawaiian water nearshore zones.
Surf will remain below advisory levels along all shores through Friday morning with the continued passage of smaller, moderate period northwest swells. Larger, longer period northwest swells are currently being generated by a storm force low off to the distant northwest. Faster, longer period front running swells are expected to arrive from this system in Kauai and maybe Oahu through the day Friday and into the evening hours. This will build surf along Kauai and Oahu’s northern and western exposed shores to surf advisory levels during the later half of the day. Peak surf heights on Saturday may approach High Surf Warning levels along north and west-facing shorelines. This swell will quickly fade from Sunday into Monday.
Trade winds will begin to deliver relatively small, short period choppy wind waves onto east-facing coasts Friday. An increase in surf heights is expected through the weekend as trade winds further strengthen near and upstream of the islands. As a result of this higher trade wind wave swell, a High Surf Advisory for east-facing shores may be required and commence as early as Saturday. Small, long period background south southwest swells will provide a slight uptick to early week south-facing 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.

Data Courtesy of NOAA.gov