Photo Credit: James Grenz

Hilo

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 83. West wind 5 to 9 mph becoming east northeast in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers. Low around 65. East northeast wind around 9 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Showers likely. Mostly cloudy, with a high near 83. East southeast wind around 9 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Mostly sunny, with a high near 79. South southwest wind 3 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Mostly cloudy, with a low around 64. South southwest wind around 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers after noon. Mostly sunny, with a high near 79. West wind around 9 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Mostly cloudy, with a high near 78. Windy, with a northeast wind 24 to 26 mph, with gusts as high as 38 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 around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Monday: Showers likely, mainly after 1pm. Mostly cloudy, with a high near 78. Windy, with a northeast wind 21 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 60%. New precipitation amounts between a quarter and half of an inch possible.

Kohala

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 64. Windy, with an east northeast wind 22 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.

Tonight: Showers likely. Cloudy, with a low around 52. Breezy, with an east northeast wind around 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.

Monday: Showers. High near 64. Windy, with an east wind around 23 mph, with gusts as high as 32 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

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

Tonight: Isolated showers. Partly cloudy, with a low around 73. Windy, with an east wind around 26 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Monday: Scattered showers, mainly after noon. Mostly sunny, with a high near 84. Windy, with an east wind around 26 mph, with gusts as high as 34 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Puna

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 82. Northeast wind 10 to 13 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Showers. Low around 63. Northeast wind around 11 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

Monday: Showers likely. Mostly cloudy, with a high near 82. East wind 9 to 11 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers after noon. Mostly sunny, with a high near 84. Windy, with a north northeast wind 18 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 65. Breezy, with a north northeast wind around 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Monday: Scattered showers after noon. Mostly sunny, with a high near 84. Breezy, with a north wind 8 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

A high pressure ridge will remain in place far north of the Hawaiian Islands producing moderate to breezy trade winds through the week. Passing showers will favor windward and mountain areas in this pattern with lower chances for showers over leeward locations. Periods of high level cirrus clouds are also expected through the week.

Discussion

A high pressure ridge far north of the main Hawaiian Islands will keep moderate to breezy trade winds in the forecast through the week. A narrow upper trough shown on water vapor imagery just north of the state will help to weaken the trade wind inversion, leading to higher shower coverage. Two low level troughs will move through the islands from Monday to Thursday enhancing local area showers a bit. A subtropical jet near the islands will produce periods of high level cirrus ice clouds through the week improving sunrise and sunset colors.
A moderate to breezy trade winds weather pattern will keep mostly fair weather in the forecast with passing showers favoring windward and mountain areas. Shower activity will trend higher windward locations in the overnight to early morning hours.
Model streamlines are showing a low level (700 mb) trough, currently near 146W, approaching the islands from the east. Wind convergence on the eastern side of this trough should spread enhanced showers Westward from the Big Island to Kauai on Monday. Another weak low level trough moves through the state on Wednesday enhancing local shower activity into Thursday.

Aviation

Locally strong trade winds, combined with modest instability supplied by a nearby upper-level trough, will result in active trade wind showers this morning, primarily over and near Kauai and Oahu. While VFR conditions will prevail, periods of MVFR VIS/CIG in SHRA are expected, and AIRMET Sierra for mountain obscuration is posted for N thru E sections of those islands, but clearing from E to W is expected later this morning. AIRMET Tango for low-level turbulence over and downstream of the terrain will remain posted for all islands.

Marine

As a weak surface trough far northwest of the state travels west, ridging will reestablish itself from the northeast. Northern high pressure will strengthen and move east the next few days. This will keep the northeast-to-southwest pressure gradient across the local waters tight enough to support moderate to fresh easterly trade winds the next several days. Locally strong trades has expanded the ongoing Small Craft Advisory in both time and space to include all of the waters from the Kaiwi Channel eastward through Monday afternoon.
Background southerly swell will maintain small surf along south facing shorelines through the middle of the week. A slight strengthening of easterly trades in the coming days will hold short period, slightly elevated wind waves along many eastern exposures. A series of gales traveling north and east of New Zealand will send swells northward within Hawaii’s southern swell window. These long period, small south swells may arrive sometime next weekend and provide a minor boost to southern shore surf.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for all eastern waters and channels.

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Data Courtesy of NOAA.gov