Hilo

Today: Cloudy. Frequent showers in the morning, then scattered showers in the afternoon. Highs around 86 near the shore to 70 to 75 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Tonight: Cloudy. Showers likely in the evening, then frequent showers after midnight. Lows around 69 near the shore to around 55 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 80 percent.

Thursday: Cloudy. Frequent showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 86 near the shore to 70 to 75 at 4000 feet. North winds up to 15 mph. Chance of rain 80 percent.

Kona

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 70 to 76 near the shore to around 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers and slight chance of thunderstorms in the afternoon. Highs 83 to 88 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Waimea

Today: Breezy. Mostly cloudy with scattered showers. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Mostly cloudy. Breezy. Scattered showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Breezy. Mostly cloudy with scattered showers. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 69 near the shore to 57 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Mostly cloudy. Breezy. Scattered showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 84 near the shore to 70 to 81 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 71 near the shore to around 54 near 5000 feet. Northeast winds up to 20 mph in the evening becoming light. Chance of rain 20 percent.

Thursday: Mostly sunny in the morning, then partly sunny with slight chance of thunderstorms and isolated showers in the afternoon. Highs around 87 near the shore to around 74 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Puna

Today: Cloudy. Frequent showers in the morning, then scattered showers in the afternoon. Highs around 86 near the shore to 70 to 75 at 4000 feet. North winds up to 15 mph. Chance of rain 90 percent.

Tonight: Cloudy. Showers likely in the evening, then frequent showers after midnight. Lows around 69 near the shore to around 55 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 80 percent.

Thursday: Cloudy. Frequent showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 86 near the shore to 70 to 75 at 4000 feet. North winds up to 15 mph. Chance of rain 80 percent.

Waikoloa

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 71 to 76 near the shore to 52 to 59 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Breezy. Sunny in the morning, then partly sunny with slight chance of thunderstorms and isolated showers in the afternoon. Highs around 87 near the shore to 71 to 77 above 4000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Breezy easterly trades will continue today, then ease slightly and shift out of the northeast Thursday into the weekend as an upper disturbance moves over the region. Pockets of moisture combined with the upper disturbance moving through will lead to periods of showery conditions, especially overnight through the morning periods. A return of a more stable pattern with moderate easterly trades is possible by the end of the weekend through early next week.

Discussion

Guidance remains in decent agreement and depicts the breezy easterly trades holding today as strong high pressure remains anchored to the north. A band of low clouds moving through has led to better windward shower coverage this morning, with some making it into leeward areas periodically. Morning upper air soundings reflect this with very moist low-level profiles beneath elevated inversions positioned around 10,000 feet. Peak rainfall totals have ranged from half of an inch to around an inch overnight, and similar amounts can be expected through the day today as this band of moisture moves through.
A transition is anticipated Thursday as upper heights lower in response to an upper trough digging southward into the area. A weakness within the surface ridge will result and lead to our local winds backing out of the northeast and weakening slightly. Added instability (decent mid-level lapse rates) associated with the cooler temperatures aloft accompanying the upper trough combined with the trade wind inversion eroding should be enough to support locally heavy showers Thursday into the weekend for portions of the state. The best chance for thunderstorms will favor the Big Island slopes through these afternoon periods.
Despite some model differences shown, rising upper heights along with the surface ridge strengthening to the north should translate to a return of a more stable trade wind pattern Sunday through early next week.

Aviation

Surface high pressure far north of the state will continue to produce strong trade winds today. A band of broken low clouds with embedded scattered showers is being transported into the islands by the strong low-level trade wind flow. This cloud cover and precipitation is producing periods of MVFR conditions along many windward facing sections this morning. Otherwise, VFR conditions will likely prevail for most leeward areas today. By this afternoon. this band of clouds and showers may eventually push west of the islands. The forecast guidance appears to indicate a new band of clouds and showers may move into the islands later tonight or early Thursday morning.
AIRMET Tango remains in effect for Tempo moderate low-level mechanical turbulence below 9 thousand feet downwind of the higher terrain on all islands. This AIRMET will likely be needed through this evening. In addition, AIRMET Sierra is in effect for mountain obscuration above 2500 feet over windward facing slopes of the smaller islands from Kauai to Maui. We may also need this AIRMET on the windward Big Island later this morning if clouds and showers increase in coverage.

Marine

Strong to moderate trade winds will hold through this afternoon as a strong high pressure far north of state weakens as it tracks east. A Small Craft Advisory (SCA) is in effect for all Hawaiian Waters through this afternoon. The SCA will then be scaled back to typically windy waters around Maui County and the Big Island this evening through early morning Thursday as the trade winds ease and shift out of the northeast. Another high will build northwest of the state Thursday and stall north of the area over the weekend into early next week producing fresh to moderate trades.
A recent gale north of the region will be sending a series of small northwest to north swells over the next couple days. Offshore buoys are still showing some swell energy in the 10 to 12 second range which should translate to the swell peaking this afternoon and the swell direction should gradually veer toward the north. A small north swell is possible next Sunday into Monday. Otherwise, no significant swells are expected along north facing shores for the foreseeable future.
South facing shores will remain small through today with mainly background energy and windswell wrapping in. A small long- period south swell is expected to start filling in Thursday and likely peak Friday before slowly dropping over the weekend into early next week. A series of small south swells will keep the surf from going flat along south facing shores through next week. Choppy, elevate surf along east facing shores will hold through today before gradually declining Thursday through Saturday. East shore surf will gradually build Sunday into early next week as trades return.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov