Photo Credit: Tyler Rooke

West Side

Christmas Day: Sunny, with a high near 84. Light east wind becoming east northeast 5 to 9 mph in the afternoon.

Tonight: Partly cloudy, with a low around 67. East northeast wind around 9 mph.

Saturday: Scattered showers, mainly before noon. Mostly sunny, with a high near 83. East wind 7 to 10 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

South Side

Christmas Day: Isolated showers after noon. Mostly sunny, with a high near 84. East northeast wind around 5 mph becoming calm in the morning. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 65. East northeast wind 3 to 6 mph.

Saturday: Isolated showers after noon. Mostly sunny, with a high near 83. Light east wind increasing to 8 to 13 mph in the afternoon. Chance of precipitation is 20%.

North Shore

Christmas Day: Isolated showers before noon. Mostly sunny, with a high near 82. Breezy, with an east wind 11 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 66. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Saturday: Scattered showers. Partly sunny, with a high near 81. Breezy, with an east wind 14 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Central Maui

Christmas Day: Mostly sunny, with a high near 82. Northeast wind 8 to 13 mph.

Tonight: Isolated showers. Partly cloudy, with a low around 64. Northeast wind 10 to 13 mph. Chance of precipitation is 20%.

Saturday: Scattered showers. Partly sunny, with a high near 81. East northeast wind 10 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Upcountry

Christmas Day: Isolated showers after noon. Mostly sunny, with a high near 71. East northeast wind 3 to 6 mph. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 55. East wind 5 to 8 mph.

Saturday: Mostly sunny, with a high near 69. Breezy, with a northeast wind 5 to 10 mph increasing to 15 to 20 mph in the afternoon. Winds could gust as high as 26 mph.

East Maui

Christmas Day: Isolated showers. Partly sunny, with a high near 80. East wind 7 to 9 mph. Chance of precipitation is 20%.

Tonight: Scattered showers. Mostly cloudy, with a low around 62. East wind around 9 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Scattered showers. Mostly cloudy, with a high near 79. Breezy, with an east wind 9 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Lanai City

Christmas Day: Mostly sunny, with a high near 76. Breezy, with a northeast wind 9 to 16 mph, with gusts as high as 23 mph.

Tonight: Partly cloudy, with a low around 63. Breezy, with a northeast wind 11 to 16 mph, with gusts as high as 23 mph.

Saturday: Scattered showers, mainly after noon. Partly sunny, with a high near 75. East northeast wind 11 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kaunakakai

Christmas Day: Mostly sunny, with a high near 81. East northeast wind 9 to 13 mph.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 71. East northeast wind 10 to 13 mph. Chance of precipitation is 20%.

Saturday: Scattered showers. Partly sunny, with a high near 80. Breezy, with an east wind 10 to 15 mph increasing to 17 to 22 mph in the afternoon. Winds could gust as high as 31 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

Trade winds will strengthen over the next couple days as high pressure passes by far north of the area. Moisture associated with a nearly stationary dissipating front will bring periods of showery weather to windward sections of Kauai and Oahu, along with some leeward spillover through Saturday, while drier conditions persist over the eastern end of the state. The trades will begin to ease and shift east-southeasterly Sunday through the middle of next week. Drier conditions are expected statewide during this time, with a few showers possible in windward areas and locations near the coast during nights and early mornings, and over interior and leeward areas during the afternoon hours. The re-emergence of volcanic activity on the Big Island could send some VOG northward at times into the smaller islands next week as well.

Discussion

Currently at the surface, a weakening nearly stationary frontal boundary has shifted south of Kauai and lies across the northern most tip of Oahu. Meanwhile, a 1029 mb high is centered around 900 miles north-northwest of Honolulu. Moderate trade winds have returned to the island chain early this morning, with the strongest winds to the north of the frontal boundary. Infrared satellite imagery shows mostly cloudy skies over Kauai and windward portions of Oahu, with clear to partly cloudy conditions elsewhere. Radar imagery shows scattered to numerous showers moving into windward sections of Kauai and Oahu, with some of the decaying showers spreading into leeward areas as well. Elsewhere, a few isolated to widely scattered showers are moving into windward sections of Maui County and the Big Island. Main short term concerns revolve around trade wind trends and rain chances through the Holiday weekend.
High pressure will strengthen slightly as it slides eastward well to the north of the state during the next couple days, while the nearly stationary frontal boundary slowly dissipates in the vicinity of Kauai and Oahu. Trade winds are expected to increase through Saturday, and will likely become breezy across much of the state on Saturday. The trades will ease from west to east across the island chain Sunday through the first half of next week, as a cold front approaches from the northwest. The trades will diminish the most over the western islands during this time, where daytime sea breezes and overnight land breezes will be likely Monday through Wednesday. Over the eastern islands, the gradient will likely remain tight enough to allow some light to moderate east- southeasterly winds to hang on. Under this particular flow regime, the re-emergence of volcanic activity on the Big Island, may send some VOG northward into the smaller islands at times, mostly likely Tuesday and Wednesday. High pressure building to the north of the islands could bring a return of moderate trade winds and scour out any lingering VOG over the smaller islands on Thursday.
As for the remaining weather details, the moisture associated with the dissipating front is expected to hang up over Kauai and Oahu through Saturday, and this will likely result in periods of showery weather persisting over windward areas along with some leeward spillover. Elsewhere, drier conditions will likely persist over Maui County and the Big Island. The moisture associated with the frontal remnants is forecast to break apart Saturday night, so expect some decrease in shower coverage, although passing showers will likely persist in windward locales. Drier conditions are expected statewide Sunday through Wednesday. As the trades ease and shift east-southeasterly during this time, a few passing showers will remain possible during the nights and early mornings in areas favored under an east-southeasterly boundary layer flow, and over interior and leeward areas each afternoon. A return to a more typical windward/mauka shower pattern is possible on Thursday.

Aviation

A nearly stationary frontal band, over Kauai and Oahu today, will bring periods of MVFR conditions and showers to the northwestern islands through Saturday. Mostly VFR conditions will prevail over Maui and Hawaii Counties for the next 24 hours. However, brief periods of showers and MVFR conditions are possible over Molokai starting later this afternoon and evening. Trade winds will also strengthen today as the front weakens and high pressure builds in from the north.
AIRMET Sierra remains in effect for Tempo Mountain Obscuration for low MVFR cloud ceilings over Kauai and Oahu today. Expect this AIRMET to last through the morning hours, favoring the north and east sections of both islands. No additional AIRMETs are expected.

Marine

Increasing trade winds and a series of northwest and northeast swells will be affecting the coastal waters today into the weekend. The combination of stronger winds and higher seas necessitate the continuation of Small Craft Advisories (SCAs) in many coastal waters zones. The stronger trade winds also will require additional SCAs to be posted for Pailolo Channel, Maalaea Bay and Southeast Big Island waters today through at least Saturday.
The latest northwest swell has declined sufficiently for the high surf advisory to be cancelled. The next significant northwest swell may be arriving beginning Monday night or Tuesday morning, and a subsequent swell arriving Tuesday night into Wednesday is expected to be larger, which will likely push surf heights to advisory or warning levels.
Trade swell will be on the increase tonight and Saturday, leading to choppy surf on east facing shores approaching advisory levels by Saturday and Sunday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Saturday 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.
Small Craft Advisory from 10 AM this morning to 6 PM HST Saturday for Maalaea Bay, Pailolo Channel, Big Island Southeast Waters.

Data Courtesy of NOAA.gov