Photo Credit: Tyler Rooke

West Side

Today: Sunny and breezy. Isolated showers in the morning. Highs 76 to 85. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 65 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the morning. Highs 76 to 85. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 87. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Lows 64 to 72. North winds 10 to 15 mph.

Friday: Sunny and breezy. Highs around 86. North winds 10 to 20 mph.

North Shore

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 83 near the shore to around 65 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 46 to 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 83 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Sunny and breezy. Highs 81 to 87. East winds 10 to 20 mph.

Tonight: Mostly clear. Isolated showers after midnight. Lows 64 to 70. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Sunny. Highs 81 to 86. Northeast winds 10 to 15 mph.

Upcountry

Today: Mostly sunny. Scattered showers in the morning. Highs around 61 at the visitor center to around 56 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 45 at the visitor center to around 42 at the summit. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Scattered showers in the morning. Highs around 60 at the visitor center to around 55 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 83 near the shore to around 65 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 68 near the shore to 46 to 53 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 83 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 80. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 63. East winds 10 to 15 mph. Chance of rain 20 percent.

Friday: Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 72 to 81. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 69 to 85. East winds 10 to 20 mph.

Tonight: Mostly clear. Lows 55 to 71. East winds 10 to 15 mph.

Friday: Mostly sunny. Highs 69 to 87. East winds 10 to 15 mph.

Detailed Forecast

Synopsis

Stable, moderate to locally breezy trade winds will continue to focus clouds and rainfall over windward slopes, with a few afternoon showers over leeward Big Island slopes through Friday. A disturbance aloft will pass over the islands during the weekend, likely leading to an increase in clouds and shower activity. A return to stable trade wind weather is expected next week.

Discussion

As expected, little change to the forecast with the morning package. For the first couple of periods the forecast seems to be lining up well. Still looking at some instability moving in this weekend, but confidence remains low for thunderstorm activity.
High pressure to the northeast will maintain a stable, moderate to locally breezy trade wind pattern through Friday, with showers focused over the windward and mauka areas. A surface trough to the west of the islands continues to produce some thunderstorms, which are over 550 miles away from the islands this morning. High clouds from this feature will continue to make their way over the islands over the next several days, and thicken in coverage as we head towards the weekend.
The surface trough and its associated upper level feature are expected to move towards the islands as the week wears on, with the surface feature continuing to dissipate. The upper level feature will provide some instability that will at the very least help to enhance trade wind showers Friday night through Sunday. The latest ECMWF and GFS runs show 500 mb temperatures getting to around -12C/-11C respectively on Saturday. This corresponds to an uptick in moisture due to moisture from the surface feature reaching the area. While thunderstorms are not yet in the forecast, the last several runs of the models are building confidence in the possibility for some thunderstorms on Saturday. Mostly likely this would be over the Big Island slopes, but also wouldn't be surprised if there were a stray thunderstorm or two near the north end of the state. The upper low will also bring below freezing temperatures to the Big Island Summits and with moisture reaching the summits, any precipitation falling there could be in the form of snow showers.
Expect improving continues during the day Sunday and into Monday, with a return to a stable trade wind pattern early next week.

Aviation

Locally breezy winds continue from the east to east-southeast as high pressure persists far northeast of the state. Expect mainly VFR conditions at the terminal sites, with patchy broken low clouds windward producing occasional MVFR ceilings. Isolated showers will favor windward and mauka locations, with MVFR visibilities possible. No AIRMETS are in effect now, but we will continue to monitor for possible mountain obscuration and/or lee side mechanical turbulence.

Marine

A surface high pressure system is located far northeast of the islands early this morning. A surface ridge extends from this high to a point about 570 nm north of Honolulu. The relatively tight pressure gradient south and southwest of these features is maintaining locally strong trade winds across most Hawaiian waters. As a result, a Small Craft Advisory (SCA) remains in effect through early Sunday morning for the typically windier waters adjacent to the islands of Maui County and the Big Island. The latest forecast guidance continues to indicate a new surface high will build far northwest of the area this weekend. This will likely keep the trade winds locally strong across most Hawaiian waters into early next week. Therefore, expect the SCA to eventually be extended from Sunday through Monday for the same typically windier marine zones.
The locally strong trade winds near and upstream of the islands are producing moderate, choppy surf along most east facing shores. Once the surface high northeast of the area weakens and moves farther southeast, the trade winds upstream of the state will likely weaken. We are expecting a slight downward trend in the surf heights, with modest, choppy surf along most east facing shores from late Friday through early next week. Small, long- period south swells will maintain small surf along south facing shores into Friday. A slightly larger, long-period south swell arriving late Friday may cause surf to peak near, or slightly above the summertime average along south facing shores this weekend. This south swell will gradually lower early next week.
A series of small northwest swells will spread over the area through Saturday, which will keep small surf along exposed north and west facing shores into this weekend. A slightly larger, medium-period northwest swell arriving late Sunday is expected to cause a slight bump in surf heights along most north and west facing shores from Sunday night into Monday. Typhoon Malakas, which is currently centered almost 650 nm north-northwest of Guam, has been moving at a relatively slow forward motion toward the north-northeast at 10-15 kt. Therefore, it is passing through the swell window that is favorable for long-period west / west- northwest swell energy to arrive in the Hawaiian Islands next week. Based on the latest wave model guidance, forerunners from this long-period swell may reach exposed shorelines in the islands late Monday night or early Tuesday morning. This could produce a noticeable uptick in surf heights along some west and north facing shorelines on Tuesday. The swell will likely shift out of the northwest by Wednesday, so moderate surf will continue along most north and west facing shores during the middle of next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM 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