Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 85 near the shore to around 73 above 3000 feet. Southeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 69 to 74 near the shore to around 61 above 3000 feet. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 70 percent.

Wednesday: Breezy. Cloudy with showers likely. Highs 83 to 88 near the shore to around 73 above 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

South Kaua’i

Today: Partly sunny with scattered showers. Highs 81 to 87. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows around 70. East winds 10 to 20 mph. Chance of rain 70 percent.

Wednesday: Breezy. Cloudy with showers likely. Highs 80 to 87. East winds 15 to 20 mph. Chance of rain 70 percent.

Kaua’i Mountains

Today: Breezy. Partly sunny with scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 62 to 69 in the valleys to around 59 above 4000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Wednesday: Breezy. Cloudy with showers likely. Highs 71 to 79 in the valleys to around 64 above 4000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.

North Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs 75 to 84. Southeast winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 64 to 73. Southeast winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Breezy. Cloudy with scattered showers. Highs 74 to 85. East winds 10 to 20 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 72 to 83. Southeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with numerous showers. Lows 64 to 74. East winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Breezy. Cloudy with showers likely. Highs 72 to 83. East winds 10 to 20 mph. Chance of rain 70 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.

Data Courtesy of NOAA.gov