Photo Credit: Braden Jarvis

West Kaua’i

Today: Sunny. Highs 78 to 87 near the shore to around 74 above 3000 feet. East winds 10 to 15 mph.

Tonight: Mostly clear. Isolated showers after midnight. Lows 64 to 70 near the shore to around 58 above 3000 feet. Northeast winds around 10 mph. Chance of rain 20 percent.

New Years Day: Mostly sunny with isolated showers. Highs 78 to 86 near the shore to around 72 above 3000 feet. Northeast winds around 10 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 86. Northeast winds around 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 69. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

New Years Day: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 85. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Kaua’i Mountains

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 72 to 80 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 30 percent.

Tonight: Breezy. Partly cloudy with scattered showers in the evening, then mostly cloudy with numerous showers after midnight. Lows 59 to 68 in the valleys to around 56 above 4000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

New Years Day: Partly sunny with scattered showers. Highs 70 to 79 in the valleys to around 63 above 4000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 82. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 61 to 70. East winds 10 to 15 mph. Chance of rain 50 percent.

New Years Day: Partly sunny with scattered showers. Highs 72 to 82. East winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 71 to 83. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with numerous showers after midnight. Lows 62 to 73. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

New Years Day: Partly sunny with scattered showers. Highs 70 to 82. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Typical trade wind weather is expected for most of this week, with moderate to breezy wind speeds and scattered showers focused over windward and mountain areas. The exception is late Tuesday into early Wednesday, when a plume of moisture is forecast to move in from the east, boosting windward showers. Trades will weaken Friday through the weekend as a front approaches from the northwest.

Discussion

A band of widespread clouds and showers moved into windward areas of Maui County and the Big Island overnight, with rainfall totals up to a third of an inch. Mostly dry conditions persisted elsewhere. Meanwhile, surface high pressure centered far northeast of the state is driving locally breezy easterly trade winds across the islands, while a mid- to upper-level low remains located just southeast of the Big Island. Model Guidance suggests locally breezy trade winds will continue for the next few days. Overnight wind observations at the Big Island summits hovered just below advisory level, but are now coming back up. The Wind Advisory for the summits remains in effect through this afternoon, at which point models indicate winds aloft on the decrease.
A plume of moisture is still expected to move in from the east later today, which should give a boost to shower activity over windward and mauka areas of Maui County and the Big Island. The rest of the islands should see an increase in windward showers Tuesday night into early Wednesday morning as the plume continues westward and lingers around Kauai. A much drier air mass will follow during the day on Wednesday, with isolated to scattered windward showers moving in on the trades.
Thursday night into Friday, trades will begin to weaken and veer out of the southeast as a front approaches the state from the northwest. Friday will be a transition day, with light south- southeast flow over the western half of the state and moderate to locally breezy east-southeast winds over the eastern half. Expect light and variable winds over the eastern half of the state this weekend and into early next week, with increasing south to southwest winds over the western half as the front stalls just northwest of Kauai.
A hot spot over Halemaumau Crater on the Big Island continues to be seen on infrared satellite imagery. The University of Hawaii Vog Model shows that SO2 emissions should remain confined to portions of the Big Island and adjacent waters to the west and southwest through most of this week. However, vog will likely increase across the rest of the state Friday through the weekend as the trades weaken and veer out of the southeast.

Aviation

Expect continued moderate to locally breezy trade winds for at least the next two days. Periods of showers will pass through the windward and mountain areas today, favoring the overnight to early morning hours. Decreasing shower trends starting Wednesday.
AIRMET Sierra for Tempo Mountain Obscuration above 020 affecting north through east sections of Molokai, Maui and the Big Island.
AIRMET Tango for moderate turb remains in effect for the lower levels just down wind of the Kohala Mountains on the Big Island.

Marine

A ridge far northeast of the state will drive moderate to breezy trade winds, especially over the eastern end of the state. The Small Craft Advisory (SCA) for breezy winds across the typical windy zones around Maui County and the Big Island has been extended through Wednesday and may need to be extended further. Easterly winds will gradually ease and veer to the south later in the week in response to the ridge weakening ahead of a front approaching from the northwest.
Medium northwest swell will continue through Tuesday night. A large northwest swell is forecast to arrive late Wednesday and should produce advisory level surf Thursday and Thursday Night along north and west facing shores. An even larger northwest swell will arrive on Saturday and linger through Sunday. Surf along south and east facing shores is expected to remain small this week. Conditions will likely be choppy through Friday along east shores due to the breezy trade wind flow.

Fire weather

No critical fire weather conditions are expected for the next seven days. Trade winds will remain at moderate to locally breezy speeds with relative humidities staying above critical levels through the week. Trades should ease to become light to moderate this weekend.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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