Hilo

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to around 67 at 4000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 67 near the shore to around 51 at 4000 feet. Northeast winds up to 10 mph shifting to the west around 10 mph after midnight. Chance of rain 40 percent.

Friday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to around 69 at 4000 feet. Southwest winds around 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 68 to 73 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Friday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 79 near the shore to 64 to 74 near 3000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows around 64 near the shore to 52 to 59 near 3000 feet. East winds around 10 mph shifting to the south after midnight. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Kohala

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 79 near the shore to 64 to 74 near 3000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows around 64 near the shore to 52 to 59 near 3000 feet. East winds around 10 mph shifting to the south after midnight. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs around 81 near the shore to 66 to 76 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Sunny in the morning then becoming mostly cloudy. Breezy. Highs around 84 near the shore to around 70 near 5000 feet. East winds up to 20 mph becoming 10 to 15 mph in the afternoon.

Tonight: Partly cloudy. Lows around 69 near the shore to around 54 near 5000 feet. Northeast winds 10 to 15 mph.

Friday: Sunny in the morning then becoming mostly cloudy. Highs around 83 near the shore to around 69 near 5000 feet. Northeast winds 10 to 15 mph.

Puna

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 80 near the shore to around 67 at 4000 feet. East winds up to 10 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 67 near the shore to around 51 at 4000 feet. Northeast winds up to 10 mph shifting to the west around 10 mph after midnight. Chance of rain 40 percent.

Friday: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to around 69 at 4000 feet. Southwest winds around 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning then becoming mostly cloudy. Breezy. Highs around 85 near the shore to 66 to 73 above 4000 feet. North winds up to 20 mph in the morning becoming light.

Tonight: Partly cloudy. Lows 67 to 72 near the shore to 49 to 58 above 4000 feet. Light winds.

Friday: Sunny in the morning then becoming mostly cloudy. Highs around 84 near the shore to 66 to 72 above 4000 feet. Southeast winds up to 10 mph in the morning becoming light.

Detailed Forecast

Synopsis

A high pressure ridge north of the islands will keep moderate to locally breezy trade winds in the forecast through Friday. Trades will continue a slightly weaker levels for most areas into next week with some sea breezes along terrain sheltered western slopes of each island. Drier conditions will continue over the next seven days with brief passing showers possible favoring windward and mountain areas in the overnight to early morning hours.

Discussion

A stable trade wind pattern continues across the region with a high pressure ridge just north of the islands. Shower activity will be limited for at least the next seven days with only brief passing showers possible. Moderate to locally breezy trade winds will continue through Friday, then wind speeds will decrease slightly heading into the weekend. Local scale sea breezes will develop by Sunday afternoon along terrain sheltered western slopes of each island due to a brief lull in trade winds.
Mostly sunny skies are expected each day with just a few scattered clouds forming over windward and mountain areas of most islands. The cloud cover exception will occur over the Big Island where trade winds and sea breezes will combine to produce mostly cloudy skies each afternoon with down slope mountain breezes clearing out the cloud cover each night. High clouds will also move into the region as a subtropical jet stream drifts up into the islands from the deep tropics, spreading high level cirrus clouds from south to north across the region. The ice crystals in these cirrus clouds will enhance sunrise and sunset colors from Friday through Sunday.
The trade wind subsidence inversion heights will remain on the low side roughly between 5,000 and 7,000 feet elevation, capping vertical cloud development and limiting rainfall potential. In this stable and dry atmosphere only brief passing showers are possible mainly over windward and mountain sections of each island, favoring the overnight to early morning hours. The windward slopes of the Big Island may see a few periods of more scattered showers through the week as trade winds drive moisture and clouds up the eastern slopes of Mauna Kea and Mauna Loa.

Aviation

Surface high pressure far north of the islands will maintain moderate to locally breezy low-level trade winds today. The atmosphere will also remain dry and stable during the next couple of days. There will continue to be patches of low clouds with embedded isolated showers carried by the low-level trade wind flow, which may produce brief periods of MVFR conditions along some windward facing sections of the islands. The greatest coverage of low clouds and trade showers will tend to be late at night and early in the morning. Otherwise, expect VFR conditions to prevail through tonight.
There are currently no AIRMETs in effect, and none are anticipated through this evening. We are monitoring the possibility of moderate upper-level clear air turbulence developing within a sub-tropical jet moving into the vicinity of the eastern islands. This may require the issuance of AIRMET Tango for the layer FL280/350 from later tonight or Friday.

Marine

Fresh to strong easterly trade winds will continue through Friday, then trend down into the light to moderate category over the weekend as the ridge weakens and shifts southward into the area. The wind direction will respond and shift out of the east to southeast for a brief period late Saturday through Sunday, which will lead to localized land and sea breeze conditions near the coasts (mainly for the western end of the state). A return of fresh to strong easterly trade winds is expected early next week as the ridge retreats northward.
Surf along south facing shores will trend up tonight through the weekend, then again next Tuesday through midweek as overlapping south swells associated with an active pattern near New Zealand move through. Peak surf associated with this long-duration spell of south swells are expected Saturday with the first swell, then Tuesday night through Wednesday for the second. Surf heights will likely reach the advisory level of 10 ft (face value) late Friday through Saturday night, then the warning level of 15 ft (face value) late Tuesday through Wednesday. Long-period forerunners associated with the first south swell should begin to show at our buoys to south through the later today based on the observations recorded over the past few days at the PacIOOS buoy at Pago Pago. For the peak expected by Wednesday of next week, recent satellite altimeter data has confirmed seas reaching the 35 to 40 ft range within the fetch near New Zealand, which enhances forecast confidence for this portion of the extended period.
Surf along exposed north and west facing shores will remain up today due to a small, north-northwest swell moving through. This should ease later tonight through Friday as it moves out. A similar northwest swell (medium period) is expected by Sunday, which will linger into Monday before easing.
Surf along east facing shores will remain small and choppy through Friday with the breezy trades in place. A downward trend is anticipated over the weekend as the winds diminish and shift out of the east to southeast.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST early this morning for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov