Hilo

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Haze. Lows 54 to 63 near the shore to 43 to 50 at 4000 feet. Northwest winds around 10 mph. Chance of rain 50 percent.

Wednesday: Mostly cloudy with scattered showers. Haze. Highs 71 to 78 near the shore to 58 to 64 at 4000 feet. North winds around 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Haze. Lows 56 to 64 near the shore to 45 to 52 at 4000 feet. Light winds. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 63 to 69 near the shore to 38 to 45 near 5000 feet. Light winds. Chance of rain 40 percent.

Wednesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 81 near the shore to around 63 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 64 to 69 near the shore to 40 to 45 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 55 to 63 near the shore to 47 to 54 near 3000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Haze. Highs around 74 near the shore to 63 to 72 near 3000 feet. East winds around 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Haze. Lows 56 to 65 near the shore to 48 to 55 near 3000 feet. Southeast winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

Kohala

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 55 to 63 near the shore to 47 to 54 near 3000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers. Haze. Highs around 74 near the shore to 63 to 72 near 3000 feet. East winds around 10 mph. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy in the evening then becoming partly cloudy. Scattered showers. Haze. Lows 56 to 65 near the shore to 48 to 55 near 3000 feet. Southeast winds around 10 mph in the evening becoming light. Chance of rain 50 percent.

South Big Island

Tonight: Mostly cloudy with scattered showers. Haze. Lows around 67 near the shore to around 46 near 5000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 80 near the shore to around 63 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows around 68 near the shore to around 46 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Haze. Lows 54 to 63 near the shore to 43 to 50 at 4000 feet. Northwest winds around 10 mph. Chance of rain 50 percent.

Wednesday: Mostly cloudy with scattered showers. Haze. Highs 71 to 78 near the shore to 58 to 64 at 4000 feet. North winds around 10 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Wednesday Night: Mostly cloudy with scattered showers. Haze. Lows 56 to 64 near the shore to 45 to 52 at 4000 feet. Light winds. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly clear. Lows 62 to 68 near the shore to 41 to 47 above 4000 feet. East winds up to 10 mph.

Wednesday: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs 79 to 84 near the shore to 61 to 66 above 4000 feet. North winds up to 10 mph shifting to the west around 10 mph in the afternoon. Chance of rain 50 percent.

Wednesday Night: Partly cloudy with isolated showers. Haze. Lows 64 to 69 near the shore to 42 to 48 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Shallow bands of moisture will move through the eastern half of the state through Thursday, which will allow for scattered showers across Maui County and parts of the Big Island. Generally a drier pattern is expected for the western half of the state, especially Kauai. The trade winds will weaken on Wednesday and become light easterly winds Wednesday into Thursday. Moderate trades with fair weather conditions will return Friday into the weekend.

Discussion

This afternoon's satellite imagery shows a band of shallow cumulus clouds moving into parts of Oahu, Maui County and the Big Island this afternoon. Showers have remained light, but a little uptick in intensity and coverage is expected this evening due to cloud top cooling as the sun sets. With the surface winds out of the northeast direction, the focus of the showers have be over windward and mountain areas with a few showers drifting toward leeward areas as well. Latest High Resolution Ensemble Forecast (HREF) model continues to show the greatest shower coverage around Maui County and parts of windward Big Island tonight.
On Wednesday, a ridge of high pressure will approach the state from the north and will cause the winds to veer more easterly and weaken. Light trade winds will likely be overpowered by the developing sea breezes during the middle of the day, which should allow for afternoon clouds and some scattered showers. Another upper level short-wave trough approaching the state late Wednesday, could enhance some of the showers Wednesday evening into Thursday over Maui County and the Big Island. This short-wave trough looks a little stronger than the current trough and combined with a bit more moisture, we could see some light to moderate rainfall in some areas Wednesday evening into Thursday.
Starting Friday, an upper level ridge will build overhead and a surface high will build northeast of the state. This should allow for our stable trade wind weather to return. Overall, it looks like a dry trade wind pattern Friday through Saturday, with a slight increase of passing showers possible on Sunday.
Latest USGS report continues to report above normal S02 emissions and satellite imagery is showing most of the emissions near southeast Big Island. With winds expected to decrease tonight into Wednesday, we could more haze spread around the Big Island and possibly near Maui Wednesday into Thursday. Trades should return Friday into the weekend.

Aviation

Gentle to moderate northeasterly flow will push a shallow band of moisture onto windward and northern slopes from Oahu to Big Island into Wednesday. MVFR ceilings and visibility in SHRA have already moved onto Oahu, where AIRMET Sierra is posted. These conditions are expected to spread to Molokai and Maui tonight, and may eventually reach windward Big Island after midnight. Expect slow improvement on windward and north slopes Wednesday morning. Elsewhere, VFR will prevail over leeward areas and all of Kauai, though MVFR conditions may develop over portions of leeward Big Island Wednesday afternoon.
A sharp upper level trough will continue to move over the island chain tonight and weaken on Wednesday. Satellite-derived guidance indicates a decreasing probability of moderate or greater turbulence over the state, and but model guidance is maintaining signatures of severe turbulence continuing to shift down the island chain through the evening. As a result, SIGMET Xray remains in effect between FL280 and FL340 over portions of the island chain, with AIRMET Tango for moderate turbulence below down to FL180. These conditions will diminish over the islands tonight but may persist several hundred miles to the northeast.

Marine

Winds will gradually veer to the east and weaken tonight through Thursday as a high pressure system approaches the state. The ridge will lift northward Friday through the weekend, which should return stronger trade winds this weekend.
Overlapping northeast and northwest swells will impact the state tonight. The High Surf Advisory for exposed north and east facing shores, as well the Small Craft Advisory in exposed coastal water zones and the Marine Weather Statement for Kahului and Hilo harbor surges have all been extended through the night given buoy observations, with these highlights likely dropping by morning. The northeast swell will slowly drop off Wednesday, but a reinforcing northeast swell is expected around Thursday, which could elevate surf along east facing shores near advisory thresholds. A long period northwest swell is expected to fill in late Thursday and peak on Friday near High Surf Advisory thresholds. Surf along east facing shores should continue to see moderate surf with the swell. Surf along south facing shores will remain tiny through the forecast period with mainly background energy.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 AM HST Wednesday for Niihau, Oahu North Shore, Olomana, Maui Windward West, Kauai North, Kauai East, East Honolulu, Koolau Windward, Molokai Windward, Molokai Southeast, Molokai North, Maui Central Valley North, Windward Haleakala, Kipahulu, Big Island East, Big Island North.
Small Craft Advisory until 6 AM HST Wednesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

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Data Courtesy of NOAA.gov