Hilo

Today: Partly sunny with scattered showers. Highs 76 to 81 near the shore to 63 to 68 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. Northwest winds up to 15 mph shifting to the northeast after midnight. Chance of rain 70 percent.

Friday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to 62 to 68 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Kona

Today: Mostly sunny. Scattered showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly clear with isolated showers. Lows 68 to 73 near the shore to 47 to 55 near 5000 feet. Light winds becoming northeast up to 10 mph after midnight. Chance of rain 20 percent.

Friday: Mostly sunny. Scattered showers in the afternoon. Highs around 82 near the shore to around 66 near 5000 feet. North winds up to 10 mph in the morning becoming light. Chance of rain 40 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 64 to 81. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 67 near the shore to 54 to 62 near 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs 63 to 81. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs 64 to 81. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 67 near the shore to 54 to 62 near 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Friday: Breezy. Partly sunny with scattered showers. Highs 63 to 81. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Mostly sunny with isolated showers. Highs around 81 near the shore to around 66 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows around 71 near the shore to around 51 near 5000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Friday: Sunny and breezy. Isolated showers in the afternoon. Highs around 81 near the shore to around 66 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers. Highs 76 to 81 near the shore to 63 to 68 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. Northwest winds up to 15 mph shifting to the northeast after midnight. Chance of rain 70 percent.

Friday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to 62 to 68 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny. Highs 79 to 84 near the shore to 64 to 70 above 4000 feet. South winds up to 15 mph shifting to the northeast in the afternoon.

Tonight: Mostly clear. Isolated showers in the evening. Lows 69 to 74 near the shore to 48 to 55 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Friday: Sunny. Highs 79 to 85 near the shore to 64 to 69 above 4000 feet. Northeast winds up to 10 mph.

Detailed Forecast

Synopsis

Moderate to breezy easterly trade winds remain in the forecast through the weekend as high pressure builds far north of the Hawaii region. Mostly fair weather conditions are expected through Sunday with periods of passing showers over windward and mountain areas favoring the overnight to early morning hours. A weakening cold front will drift into the islands from the north early next week enhancing shower activity across the state. High pressure building in behind this fading front will produce windy trade winds across the region from Tuesday into Wednesday.

Discussion

Easterly trade winds are pushing more stable and drier air into the Hawaii Region, with stratocumulus clouds moving across the state from east to west. Local radar imagery shows scattered showers near Niihau, Kauai and along the southeastern slopes of the Big Island. High clouds are streaming over the islands from the west.
A high pressure system building north of the Hawaiian Islands will strengthen trade wind speeds into the moderate to breezy range through Sunday. Wind speeds will approach wind advisory levels in some of the windier areas of Maui and the Big Island over the next few days. Weather model cross sections continue to show a fairly stable (low) trade wind inversion height in the 5,000 to 7,000 foot range lasting through the weekend. This trade wind temperature inversion aloft will cap vertical cloud development and tend to limit shower activity across the region. However, breezy trade winds will force moist air up the windward mountain slopes along the eastern sides of Kauai, Molokai, Maui and the Big Island over the next four days. This terrain forcing effect will allow periods of passing showers to develop over windward and mountain areas. These passing showers will tend to favor the overnight to early morning hours through Sunday. Overall a more typical fair weather pattern for the Hawaiian Islands.
The weather pattern changes a bit early next week as a weakening cold front drifts into the islands from the north. Expect increasing shower trends for north and east slopes of most islands during this time period as the fading front moves slowly through the state. Long range guidance continues to show blasting trade winds developing over the region behind this frontal trough, from late Tuesday into Wednesday, as a strong high pressure system builds in north of the region.

Aviation

Locally breezy east-southeast trade winds will shift more easterly today as building high pressure slowly pushes a band of deep moisture farther west of the state. Ridging aloft will strengthen, causing the inversion to lower. As a result, stable conditions and only modest showers will prevail, with MVFR ceilings confined to windward slopes and VFR dominating elsewhere. AIRMET Sierra remains in effect for tempo mountain obscuration along some windward portions of the Big Island, though improvement is expected by mid morning. AIRMET Tango remains in place for low level turbulence over and downwind of terrain on all islands and will likely remain posted for the next several days.

Marine

Fresh to strong east-southeast winds will shift out of the east by tonight as the kona low continues drifting away from the area and high pressure builds to the north over the weekend. These winds combined with large, short-period seas will support the rough conditions persisting. As a result, the Small Craft Advisory will likely continue for all Hawaiian waters through early Friday. Although the seas should trend down below the advisory level Friday, the strong winds will support it continuing into the weekend for the typically windier waters surrounding Maui County and the Big Island. Winds may return to strong levels for most waters by early next week as a front moves into the area.
Surf along north facing shores will remain small into the weekend with mainly a mix of short- to medium-period, northerly energy moving through. A small, north-northwest swell should arrive later today, then linger into the weekend. A long-period, northerly swell associated with a storm-force system racing eastward into the Gulf of Alaska today through Friday is forecast to arrive by Sunday night, then peak by or come Tuesday around the advisory- level for exposed north facing shores.
Surf along east facing shores will trend up today, then remain rough through early next week due to the aforementioned strong trades expected.
Surf along south facing shores will steadily ease through the second half of the week as the winds shift from southeast to east.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Friday for windier eastern waters and channels around Maui County and the Big Island.
Small Craft Advisory until 6 AM HST Friday for all Hawaiian Waters.

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Data Courtesy of NOAA.gov