Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny, with a high near 81. Windy, with an east northeast wind 25 to 30 mph, with gusts as high as 40 mph.

Tonight: Partly cloudy, with a low around 66. Windy, with an east northeast wind 28 to 30 mph, with gusts as high as 40 mph.

Saturday: Partly sunny through mid morning, then becoming sunny, with a high near 81. Breezy, with an east northeast wind 13 to 16 mph, with gusts as high as 22 mph.

South Side

Today: Scattered showers after 1pm. Increasing clouds, with a high near 81. West wind 6 to 11 mph becoming light and variable in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers before 7pm. Mostly cloudy, with a low around 64. Light and variable wind becoming east northeast 5 to 10 mph in the evening. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Isolated showers after 1pm. Partly sunny, with a high near 81. Breezy, with a northeast wind 17 to 20 mph, with gusts as high as 26 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 20 to 29 mph, with gusts as high as 38 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly cloudy, with a low around 65. Windy, with an east wind 20 to 29 mph, with gusts as high as 38 mph. Chance of precipitation is 20%.

Saturday: Scattered showers before noon. Mostly sunny, with a high near 79. Windy, with an east northeast wind 20 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Central Maui

Today: Mostly sunny, with a high near 79. Windy, with an east northeast wind 25 to 30 mph decreasing to 16 to 21 mph. Winds could gust as high as 40 mph.

Tonight: Partly cloudy, with a low around 63. Windy, with an east northeast wind 16 to 23 mph, with gusts as high as 30 mph.

Saturday: Isolated showers between 7am and 1pm. Mostly sunny, with a high near 79. Windy, with an east northeast wind 22 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 20%.

Upcountry

Today: Isolated showers after noon. Mostly sunny, with a high near 67. West southwest wind 6 to 11 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 53. Windy, with a light and variable wind becoming east 18 to 23 mph in the evening. Winds could gust as high as 32 mph.

Saturday: Mostly sunny, with a high near 67. Windy, with an east wind 20 to 23 mph, with gusts as high as 32 mph.

East Maui

Today: Showers likely, mainly before noon. Partly sunny, with a high near 77. Breezy, with an east wind 8 to 13 mph increasing to 16 to 21 mph. Winds could gust as high as 26 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 61. Breezy, with an east wind 10 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Showers likely, mainly before noon. Partly sunny, with a high near 77. Breezy, with an east wind 17 to 20 mph, with gusts as high as 28 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. Windy, with a northeast wind 15 to 20 mph increasing to 25 to 30 mph in the morning. Winds could gust as high as 40 mph. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 63. Windy, with an east northeast wind 17 to 26 mph, with gusts as high as 34 mph.

Saturday: Isolated showers after noon. Sunny, with a high near 75. Breezy, with an east northeast wind 16 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Mostly sunny, with a high near 79. Breezy, with an east northeast wind 9 to 14 mph increasing to 17 to 22 mph in the morning. Winds could gust as high as 29 mph.

Tonight: Partly cloudy, with a low around 68. Breezy, with an east northeast wind 15 to 22 mph, with gusts as high as 31 mph.

Saturday: Sunny, with a high near 80. Breezy, with an east wind 16 to 22 mph, with gusts as high as 31 mph.

Detailed Forecast

Synopsis

Strong and gusty trade winds will become especially strong over the weekend, delivering passing clouds and showers, some briefly heavy, mainly dampening windward areas. More widespread rainfall may develop early next week as winds remain strong and shift to the southeast.

Discussion

Windy and locally wet trade wind weather will continue through the weekend, although shower frequency may be somewhat reduced today. The strong winds will shift slightly to the SE early next week, with increasing moisture potentially leading to more widespread clouds and showers from Sunday night into Wednesday.
A broad mid- and upper-level low is nearly stationary to the S of the area, with some of the associated layered clouds over the Big Island and parts of Maui. Cooler than normal mid-level temperatures associated with the low are supporting a somewhat unstable island atmosphere, with radar VWPs indicating the low-level moisture riding in on the trade flow extends as high as 10 thousand feet. With fresh to locally strong trade winds being supported by a 1035 mb high to the distant NE, orographic forcing is helping to generate showers over and immediately downstream of the terrain. Meanwhile, many leeward communities remain mostly dry.
While some drying of the upstream flow may lead to some reduction in windward shower frequency today, it is not expected to last long, and somewhat showery trade wind weather is anticipated over the weekend. Mid-level temperatures will remain cooler than normal, and strong trade winds will strengthen as the high to the distant NE moves closer to the islands. The high will be reinforced Saturday and Sunday, reaching a central pressure over 1040 mb, while a deep- layer low develops to the distant W and NW of the islands. A Wind Advisory may be required for parts of the state over the next couple of days, potentially as early as tonight.
The development of the low to the distant NW of the islands is expected to cause the winds to veer to the SE, while a moisture convergence band extending SE from the low creeps towards the islands from the S. Latest guidance indicates this band will move over portions of the islands from Monday into Wednesday – bringing PWAT close to 2″, layered cloudiness, and widespread rainfall. Deep moisture and modest instability are expected, so the chance of thunderstorms appears too low to mention thus far. A drying trend is loosely expected thereafter as the band shifts W of the area. High pressure to the distant NE will continue to support locally strong trade winds.

Aviation

Breezy to locally strong trades will persist through the forecast period. This will facilitate frequent windward showers and occasional leeward drift, particularly overnight. VFR is forecast to prevail at all forecast points with nothing more than brief MVFR within any heavier showers.
AIRMET Tango is in effect for mechanical lee turbulence below 9kft as well as for mod turbulence between FL250 and FL300.

Marine

Surface high pressure is centered far to the north-northeast of the area, resulting in moderate to locally strong trade winds. The high will get a reenforcement beginning Saturday, causing trade winds to increase across the entire area through the first part of next week. This, combined with higher seas from both a large northwest swell and the trade wind seas, has prompted expansion of the current Small Craft Advisory to include all coastal waters.
A small northwest swell will linger today. Long-period forerunners from a larger west-northwest (310 degrees) swell will fill in late today and tonight. This swell is expected to peak Saturday with an 18 second period and high-end advisory or low-end warning level surf for most north and west facing shores of the smaller islands. The more westerly direction of this swell will allow west facing shores of the Big Island to experience advisory level surf, likely later in the day Saturday. Swell and surf will lower gradually Sunday and Monday, then become rather small for this time of year on Tuesday and Wednesday.
As the trades strengthen this weekend, rough and short-period surf will gradually rise and a High Surf Advisory is likely along east facing shores for several days, beginning Saturday afternoon.
Small, mainly background, southerly swells are expected over the next several days. A slightly larger, south-southwest swell from the Tasman sea is expected to gradually fill in Monday, peak Monday night and Tuesday, then lower Wednesday through Thursday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Sunday for all Hawaiian waters.

Data Courtesy of NOAA.gov