Hilo

Today: Cloudy with scattered showers. Highs 75 to 80 near the shore to around 64 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 60 to 68 near the shore to 51 to 56 at 4000 feet. West winds up to 10 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to 62 to 67 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 72 near the shore to 46 to 53 near 5000 feet. Light winds. Chance of rain 50 percent.

Thursday: Partly sunny. Scattered showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Breezy. Partly sunny with scattered showers. Highs 62 to 80. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 60 to 67 near the shore to 52 to 60 near 3000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 62 to 81. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Breezy. Partly sunny with scattered showers. Highs 62 to 80. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 60 to 67 near the shore to 52 to 60 near 3000 feet. Southeast winds up to 15 mph. Chance of rain 70 percent.

Thursday: Breezy. Mostly cloudy with scattered showers. Highs 62 to 81. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. 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 80 near the shore to around 64 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Lows around 70 near the shore to around 51 near 5000 feet. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Breezy. Isolated showers in the afternoon. Highs around 81 near the shore to around 65 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Puna

Today: Cloudy with scattered showers. Highs 75 to 80 near the shore to around 64 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 60 to 68 near the shore to 51 to 56 at 4000 feet. West winds up to 10 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to 62 to 67 at 4000 feet. North winds up to 10 mph shifting to the east in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Highs 80 to 85 near the shore to around 65 above 4000 feet. South winds up to 10 mph shifting to the west in the afternoon.

Tonight: Mostly cloudy with isolated showers. Lows 68 to 73 near the shore to 46 to 53 above 4000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Thursday: Partly sunny. Isolated showers in the afternoon. Highs 80 to 85 near the shore to 63 to 68 above 4000 feet. East winds up to 10 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Trades will trend down and shift out of the east to southeast direction through the second half of the week, then become strong out of the east late in the weekend through early next week as high pressure builds to the north. Clouds and showers will favor the typical windward locations into the weekend. Although confidence remains low at this point, a return of a wet pattern remains possible early next week as low pressure develops to the west.

Discussion

Guidance depicts the ridge weakening through the second half of the week as a front passes to the north. The strong trades that were in place have already begun to ease this morning, with the low-level flow slightly veering out of the east to southeast direction. This combined with the band of moisture that brought the showery conditions to the smaller islands yesterday retreating northward and diminishing will translate to a drier pattern today through Friday.
Although confidence drops significantly over the upcoming weekend through early next week due to recent differences between various sources of guidance, the last few cycles have come into better agreement. Strong upper trough is forecast to cutoff into a broad upper low centered west-northwest of the islands over the weekend, which supports deep moisture being drawn northward into the area late in the weekend through early next week. If this materializes, expect a wet pattern to unfold across the state. In addition to the potential for a wet pattern, strong high pressure building north of the region in the wake of the tail-end of another front dipping southward into the area will lead to strong trades early next week.

Aviation

A high pressure system northeast of the state will continue to weaken and drift eastward as the next cold frontal trough approaches the region from the northwest. Trade wind speeds are decreasing this morning and veering towards the ESE direction. This lighter trade wind flow will place the smaller islands in the lee wind shadow of the Big Island and encourage land and sea breezes over terrain sheltered S and W slopes of each island through Friday.
Wind speeds have fallen below low level turbulence thresholds and AIRMET Tango was for moderate turbulence was cancelled this morning. However, a subtropical jet stream aloft will drift north into the Hawaiian Islands later today. Expect AIRMET Tango to return later this morning for moderate to occasional severe turbulence developing from 25,000 to 40,000 MSL over the islands lasting into Friday.
AIRMET Sierra remains in effect for tempo mountain obscuration above 2,000 feet for N thru E slopes of Kauai, Oahu and Molokai. This AIRMET will likely end later today as low clouds and showers begin to diminish.

Marine

High pressure to the northeast of the islands will maintain a tight enough pressure gradient down across the region to continue to support moderate to locally strong trade winds through the day. Widely scattered evening showers in association with what is left of the remnants of an old frontal boundary will come across more western island waters surrounding Oahu and Kauai through early morning. High pressure to the northeast will weaken as it shifts more east southeast and a weakening front to the northwest will approach the state later this week. Areawide trades will taper off a bit but still remain strong over the typical windier areas near Maui County and Big Island through this afternoon. The arrival of a moderate size north swell has increased significant seas to around 10 feet today, especially in the windward waters and surrounding channels. Thus, a Small Craft Advisory (SCA) is in effect to cover not only the typically windier areas today, but these elevated seas through early Thursday morning. An approaching front will clip our far northern offshore waters by Friday and weaken the gradient enough to allow late week trades to fall back to areawide moderate speeds. A large high building in from the north will restrengthen weekend trades back to fresh to locally strong magnitudes.
The north swell will be filling in around the islands through the day. The windward water nearshore PacIOOS buoys are moving up within the medium to long period bands thus confidence is growing that many north facing shores will experience double overhead surf in many sets today as this 6 to 7 foot medium period due north-in-direction swell peaks today. The northeast offshore buoy 51000 has been solid with 10 foot medium period swell. While quite the boost, north facing shore surf is expected to peak under High Surf Advisory (HSA) levels through the day. A similar, medium period northwest swell is expected to arrive late Thursday through Friday with a slightly larger reinforcing northwest swell arriving on its heels Friday. These swells will fill in through Saturday with another moderate size northwest swell arriving early next week. These series of northwest swells may push north and west facing shore surf back up to near HSA levels this weekend and early next week. The combination of this recent north swell wrap and shorter period trade wind wave swell will maintain choppy, slightly elevated east facing shore surf through tomorrow afternoon.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov