Photo Credit: Tyler Rooke

West Side

Today: Isolated showers before 1pm. Mostly sunny, with a high near 82. Northeast wind 6 to 13 mph. Chance of precipitation is 20%.

Tonight: Isolated showers after 7pm. Partly cloudy, with a low around 70. North northeast wind around 9 mph. Chance of precipitation is 20%.

New Year’s Day: Isolated showers before 1pm. Mostly sunny, with a high near 82. Windy, with an east northeast wind 9 to 14 mph increasing to 20 to 25 mph in the afternoon. Winds could gust as high as 36 mph. Chance of precipitation is 20%.

South Side

Today: Isolated showers after noon. Mostly sunny, with a high near 82. Calm wind becoming southwest 5 to 7 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 68. Southwest wind 5 to 7 mph becoming calm. Chance of precipitation is 20%.

New Year’s Day: Isolated showers after noon. Mostly sunny, with a high near 82. Breezy, with a light and variable wind becoming east northeast 10 to 15 mph in the afternoon. Winds could gust as high as 20 mph. Chance of precipitation is 20%.

North Shore

Today: Scattered showers, mainly before noon. Mostly sunny, with a high near 80. Breezy, with an east northeast wind 13 to 22 mph, with gusts as high as 26 mph. Chance of precipitation is 30%.

Tonight: Isolated showers. Partly cloudy, with a low around 69. Breezy, with an east northeast wind 15 to 20 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

New Year’s Day: Scattered showers, mainly before noon. Mostly sunny, with a high near 80. Windy, with an east wind 18 to 25 mph, with gusts as high as 31 mph. Chance of precipitation is 30%.

Central Maui

Today: Isolated showers. Mostly sunny, with a high near 80. Windy, with a northeast wind 9 to 14 mph increasing to 20 to 25 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 67. Breezy, with a northeast wind 17 to 22 mph decreasing to 10 to 15 mph in the evening. Chance of precipitation is 20%.

New Year’s Day: Isolated showers. Mostly sunny, with a high near 80. Windy, with a northeast wind 14 to 19 mph increasing to 24 to 29 mph in the morning. Chance of precipitation is 20%.

Upcountry

Today: Mostly sunny, with a high near 68. East southeast wind 5 to 9 mph becoming calm in the afternoon.

Tonight: Partly cloudy, with a low around 57. Breezy, with a light east wind increasing to 13 to 18 mph in the evening. Winds could gust as high as 25 mph.

New Year’s Day: Mostly sunny, with a high near 68. Breezy, with a light and variable wind becoming east 17 to 22 mph in the afternoon. Winds could gust as high as 31 mph.

East Maui

Today: Scattered showers. Partly sunny, with a high near 78. East northeast wind 9 to 11 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. East northeast wind 10 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

New Year’s Day: Scattered showers. Partly sunny, with a high near 78. Breezy, with an east northeast wind 11 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Isolated showers after noon. Mostly sunny, with a high near 75. Windy, with a northeast wind 20 to 28 mph, with gusts as high as 50 mph. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 65. Very windy, with a northeast wind 24 to 31 mph, with gusts as high as 50 mph.

New Year’s Day: Isolated showers after noon. Mostly sunny, with a high near 75. Very windy, with a northeast wind 21 to 31 mph, with gusts as high as 50 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Mostly sunny, with a high near 80. Breezy, with an east northeast wind 7 to 16 mph, with gusts as high as 22 mph.

Tonight: Partly cloudy, with a low around 71. East northeast wind 10 to 14 mph, with gusts as high as 20 mph.

New Year’s Day: Mostly sunny, with a high near 80. Windy, with an east northeast wind 14 to 19 mph increasing to 21 to 26 mph in the afternoon. Winds could gust as high as 38 mph.

Detailed Forecast

Synopsis

Breezy to locally windy trades will prevail today through Saturday as high pressure slides by well to the north of the island chain. Clouds and showers will favor windward and mauka areas, but the strong trades will blow some decaying showers over to leeward sides of the islands as well. Typical trade wind weather will continue next week, with winds easing a bit on Sunday, and holding at moderate to locally breezy levels through much of next week.

Discussion

Currently at the surface, a weakening cold front is located a few hundred miles north of Kauai, while a trailing 1027 mb high centered around 500 miles northwest of the Garden Isle and another 1030 mb high centered around 1650 miles northeast of Honolulu. The resulting gradient is producing moderate to locally breezy trade winds across the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy skies across the state, with some high clouds also beginning to overspread the western end of the island chain. Radar imagery shows scattered showers moving into windward areas, with some of these decaying showers spilling into leeward locales from time to time. Main short term concern revolves around the strength of the trades during the next few days.
The southern extent of a weakening cold front will stall out north of Kauai today, while a deep layer ridge builds to the north and northeast of the state. This will allow the trades to become breezy statewide today. The trades will strengthen to windy levels tonight and New Years Day, before dropping a notch back to breezy levels on Saturday as a high slides east-southeast well to the north of the island chain. The trades are expected to peak tonight and New Years Day, and Wind Advisories will likely be required for portions of Maui County and the Big Island during this time. The trades should ease a bit on Sunday and hold at moderate to locally breezy levels through much of next week.
As for the remaining weather details, fairly typical trade wind weather should persist through the forecast period. Showers will favor windward and mauka areas, with some decaying showers reaching leeward areas at times due to the strength of the trades. Showers are expected to be most prevalent during the night and early morning hours. No significant rainfall is expected during the next 7 days.

Aviation

A high pressure system passing north of the islands will keep breezy trade winds forecast today becoming windy by tonight. Passing showers over windward and mountain areas may bring brief periods of MVFR conditions. A few of these stronger showers will spill over into the leeward areas.
Breezy trade winds will produce tempo moderate low level turbulence over and south through west of all island mountain ranges. AIRMET Tango in effect for tempo moderate low level turbulence below 8000 feet over and south through west of all island mountains. This AIRMET will likely continue into New Years Day.

Marine

Surface high pressure building north of the state will tighten the pressure gradient back across the islands enough to strengthen trades the next several days. Fresh to strong trades will occur over both the near and offshore waters, locally near gale force over those windier channels surrounding Maui and the southern Big Island waters, through Saturday. These heightened wind speeds, in tandem with large incoming northwest swells, will lift significant sea heights to 12 to 15 feet. Very rough sea conditions will warrant the all water Small Craft Advisory (SCA) that is current in effect through Saturday night. Winds are expected to fall back to more moderate speeds early next week as the high shifts further east and relaxes the pressure gradient.
Current northwest swells continue to hold with only a minor decrease in overnight swells keeping early morning surf heights below warning levels. A large northwest swell (13 to 14 foot, 16 to 17 second energy) generated by a North Pacific storm is just beginning to pass across the northwest offshore buoys before sunrise. These swells will be reaching the western island north and west-facing shorelines around noon. These latest swells will boost surf back up to warning heights today and hold warning level surf through Friday. Thus, the ongoing High Surf Warning for exposed north and west-facing shores will be in effect through Friday afternoon. These swells are expected to peak tonight and will steadily decline from Friday into Saturday. Lower northwest swells will begin arriving over the weekend and peak Sunday and Monday. The combination of these swells and higher astronomical tides may result in minor coastal water inundation within low- lying areas during morning high tides the next couple of days.
Surf along east-facing shores will gradually increase through Friday in response to the strengthened trades. Eastern exposed shoreline surf may approach advisory levels of 8 feet on Friday. Wind-driven swell or some easterly wrap will maintain near seasonable surf along south-facing shores.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Friday for Niihau, Kauai Windward, Kauai Leeward, Waianae Coast, Oahu North Shore, Oahu Koolau, Molokai, Maui Windward West, Maui Central Valley, Windward Haleakala.
Small Craft Advisory until 6 PM HST Saturday for all Hawaiian waters,

Data Courtesy of NOAA.gov