Hilo

Today: Cloudy with showers. Highs 77 to 82 near the shore to 62 to 68 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy with numerous showers. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. South winds up to 10 mph shifting to the east after midnight. Chance of rain 70 percent.

Wednesday: Partly sunny with isolated showers. Highs 77 to 82 near the shore to 62 to 68 at 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kona

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs 81 to 87 near the shore to around 68 near 5000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 74 near the shore to 49 to 55 near 5000 feet. Light winds becoming east up to 10 mph after midnight. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 80 to 87 near the shore to around 68 near 5000 feet. East winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Waimea

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs 65 to 85. Southwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 54 to 62 near 3000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs 64 to 84. East winds 10 to 25 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny. Isolated showers in the late morning and afternoon. Highs 65 to 85. Southwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 71 near the shore to 54 to 62 near 3000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs 64 to 84. East winds 10 to 25 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny early in the morning then becoming mostly cloudy. Breezy. Isolated showers early in the morning, then showers likely in the late morning and afternoon. Highs around 82 near the shore to around 66 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 69 to 74 near the shore to around 51 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 82 near the shore to around 67 near 5000 feet. East winds 15 to 25 mph. Chance of rain 20 percent.

Puna

Today: Cloudy with showers. Highs 77 to 82 near the shore to 62 to 68 at 4000 feet. Southeast winds up to 15 mph. Chance of rain 90 percent.

Tonight: Mostly cloudy with numerous showers. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. South winds up to 10 mph shifting to the east after midnight. Chance of rain 70 percent.

Wednesday: Partly sunny with isolated showers. Highs 77 to 82 near the shore to 62 to 68 at 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Waikoloa

Today: Sunny. Isolated showers in the afternoon. Highs 81 to 87 near the shore to 65 to 71 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 70 to 75 near the shore to 50 to 55 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 80 to 87 near the shore to 65 to 70 above 4000 feet. East winds up to 15 mph shifting to the northeast in the afternoon. Gusts up to 35 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moist southeasterly flow will deliver increased showers statewide today. Trades should begin to return late today and strengthen Wednesday, remaining strong for the remainder of the week as the area returns to a typical trade wind distribution of clouds and showers.

Discussion

Southeasterly flow prevails across local waters this morning as a front about 300 miles west of Kauai stalls. Patchy broken low clouds, along with isolated to scattered showers, continue to move across the islands within this flow. Deep tropical moisture persists and all islands should see increased cloud cover as the day wears on. Satellite loop shows far-offshore thunderstorms along and ahead of the front, just outside coastal waters northwest through southwest of Kauai. These have not moved closer to that island overnight, prompting removal of thunderstorms and heavy rain from the forecast there.
Models show that upper ridging will build over the eastern end of the state as the low and associated front begin to move away to the west today. Our winds will become more uniformly southeasterly and strengthen considerably by late today as a surface high fills in over the northeast Pacific basin. The smaller islands will initially remain partially blocked from strengthening southeast winds by the Big Island, but the long fetch of deep southeast flow will push a deep slug of moisture over the island chain from southeast to northwest through tonight. Showers will favor southeast-facing slopes of the Big Island through today. A slight chance of thunderstorms remains in the forecast for the Mauna Loa eruption site for this afternoon.
Beginning Wednesday, winds swing back to easterlies and strengthen further in response to ridge building over the central Pacific. Moisture embedded within the trades will affect windward and mauka areas as a more typical trade wind pattern becomes established. Upstream showers may receive a boost in coverage and intensity during the latter half of the week as another low develops east of the islands. As this low drifts closer to the Big Island, strong northeast winds may develop at summit level by Thursday afternoon or Thursday night. Models show additional trade wind strengthening this weekend as the low settles southeast of the Big Island and surface troughing develops, steepening the local pressure gradient.

Aviation

A fairly light southeast flow will persist through the rest of the night as a kona low far northwest of the islands heads west and a high pressure area far to the north-northeast pushes south. Showers are mainly affecting east and southeast portions of the Big Island and adjacent waters at the moment, with occasional periods of MVFR ceilings and/or visibilities. However, VFR conditions are prevailing overall. Trade winds will begin to return, from east to west, and gradually strengthen later today and beyond.
An AIRMET for mountain obscuration is in effect for east and southeast sections of the Big Island.

Marine

A high pressure system far northeast of the islands and a low pressure system just northwest of Kauai will keep southeast winds in the forecast through tonight. This low will slowly drift westward over the next few days, allowing the ridge to build in from the north and causing southeast winds to strengthen starting today and backing to a more easterly direction by Wednesday morning. A Small Craft Advisory was issued this morning for all waters around Kauai, all channels, all windward waters, and Big Island Leeward Waters for both winds and waves. These SCA conditions will expand to cover most coastal waters on Wednesday and Thursday in fresh to strong trade winds. Easterly trades will increase to near gale force winds on Friday and Saturday.
A medium period northwest (310-320 degrees) swell is building into the Hawaiian Islands this morning. Based on the morning swell height observations at buoy 51001 we issued a High Surf Advisory (HSA) this morning for north and west facing shores of Niihau, Kauai, Oahu and Molokai lasting through tonight. North facing shores of Maui will approach and may yet exceed HSA thresholds by tonight. This northwest swell will peak later tonight, with swell and surf heights diminishing quickly on Wednesday. A small NNW swell may arrive Thursday and Friday to slow the declining surf heights along north facing shores.
Strengthening trade winds will bring increasing surf to east facing shores by Wednesday and surf heights will remain elevated into the weekend, possibly large enough to require a HSA for east facing shores by Friday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov