Photo Credit: Tyler Rooke

West Side

Today: Sunny, with a high near 84. Breezy, with an east northeast wind 17 to 22 mph becoming light and variable in the afternoon. Winds could gust as high as 30 mph.

Tonight: Mostly clear, with a low around 65. Calm wind becoming northeast around 5 mph after midnight.

Monday: Sunny, with a high near 85. North wind around 5 mph becoming light and variable in the morning.

South Side

Today: Isolated showers after 1pm. Mostly sunny, with a high near 84. Northeast wind 5 to 7 mph becoming light and variable. Chance of precipitation is 20%.

Tonight: Isolated showers before 7pm. Mostly clear, with a low around 63. East northeast wind 3 to 7 mph. Chance of precipitation is 20%.

Monday: Isolated showers after 1pm. Mostly sunny, with a high near 85. East wind 8 to 10 mph. Chance of precipitation is 20%.

North Shore

Today: Isolated showers after noon. Mostly sunny, with a high near 82. Breezy, with an east wind 15 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 64. Breezy, with an east southeast wind 7 to 15 mph, with gusts as high as 21 mph.

Monday: Isolated showers before noon. Mostly sunny, with a high near 83. East wind around 11 mph. Chance of precipitation is 20%.

Central Maui

Today: Mostly sunny, with a high near 82. Northeast wind 11 to 14 mph.

Tonight: Partly cloudy, with a low around 62. East northeast wind 5 to 10 mph becoming light east after midnight.

Monday: Mostly sunny, with a high near 83. East wind around 7 mph.

Upcountry

Today: Mostly sunny, with a high near 69. East southeast wind 5 to 7 mph becoming light and variable in the afternoon.

Tonight: Partly cloudy, with a low around 52. Light east southeast wind becoming east 6 to 11 mph in the evening.

Monday: Mostly sunny, with a high near 70. East wind 8 to 11 mph.

East Maui

Today: Scattered showers. Partly sunny, with a high near 80. East southeast wind 11 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 60. Southeast wind 11 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Scattered showers, mainly before noon. Partly sunny, with a high near 81. East southeast wind 10 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Mostly sunny, with a high near 76. East northeast wind 5 to 9 mph becoming calm in the afternoon.

Tonight: Partly cloudy, with a low around 62. Calm wind becoming east northeast around 5 mph after midnight.

Monday: Scattered showers after noon. Mostly sunny, with a high near 76. East northeast wind 5 to 9 mph becoming north northwest in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Kaunakakai

Today: Sunny, with a high near 81. Breezy, with an east wind 14 to 20 mph, with gusts as high as 28 mph.

Tonight: Mostly clear, with a low around 67. East wind 9 to 14 mph becoming light and variable after midnight. Winds could gust as high as 18 mph.

Monday: Sunny, with a high near 82. Calm wind becoming northwest 5 to 7 mph.

Detailed Forecast

Synopsis

An upper level low moving through the Big Island will produce enhanced showers with isolated thunderstorms today. Drying trends are forecast for most islands through the day as the upper disturbance drifts south through the Big Island, and the low level cloud band lifts north of the state. Trade winds will decrease in strength and will become more east to southeasterly through Wednesday. These lighter winds from a more southerly direction will bring up a plume of VOG from Kilauea on the Big Island into the smaller islands during the first half of next week. Moderate to breezy northeasterly trade winds will return by New Years Eve just in time for the New Years celebrations.

Discussion

Satellite imagery this morning shows an upper level low drifting southward through the Big Island. A few thunderstorms are developing over Hawaii County under this upper low. Enough instability and forcing will keep isolated thunderstorms in the forecast over the eastern end of the state through the afternoon hours. The low level convergent cloud band associated with an old frontal boundary over the northwestern islands will slowly drift northward today. Expect decreasing shower trends across the state brief passing showers mainly affecting windward and mountain areas.
For today, Trade Winds will decrease in strength and veer towards the east southeast direction. The Wind Advisory was cancelled this morning as wind speeds are falling below advisory thresholds. Most islands will see a transition back into a more stable pattern with drier trends as the low level convergence band drifts north of the state and an upper level low slowly moves south of the Big Island. The one exception to these drying trends will occur over the eastern and southeastern slopes of the Big Island, as a low level trough moves into the island from the east and the upper low drops in from the north. The conjunction of both these systems along with easterly to southeasterly winds will enhance showers along southeastern and eastern slopes of the Big Island through the afternoon and evening hours.
Monday through Wednesday, a fairly stable weather pattern develops with an upper level ridge in place over the islands keeping a strong trade wind temperature inversion in place at 6000 to 8000 foot range. However, trade winds will become light and veer towards a more east to southeast direction. These large scale southeasterly winds tend to keep the smaller islands, northwest of the Big Island, in a wind and rain shadow area. This means local scale land and sea breezes will develop with brief passing showers are possible, trending towards island interior sections through Wednesday. East and southeast slopes of the Big Island will continue to see periods of shower activity in this pattern. These southeasterly winds may bring a light Volcanic smOG, also known as VOG, back to the smaller islands for the first half of next week.
Thursday and Friday, a migratory high moving from west to east across the Central Pacific will bring moderate to breezy trade winds back into the state from New Years Eve to New Years Day. These stronger trade winds will arrive just in time to blow out the VOG, and the firework smoke from our New Years celebrations.

Aviation

Thunderstorms that developed over Big Island early this morning in advance of the passing upper trough have begun to dissipate, giving way to more a more widespread coverage of stratiform showers. Some redevelopment of showers and localized MVFR will be possible over Big Island again today before the upper trough exits to the southeast. Breezy and drier trades supporting occasional windward showers and predominantly VFR conditions prevail elsewhere.
AIRMET Tango remains in effect for all islands for moderate turbulence between FL250-FL350 as well as mechanical lee turbulence.

Marine

An transiting high far northeast of the area will produce strong trade winds through the rest of the weekend. Because of a combination of winds and seas, a Small Craft Advisory is now in effect for most coastal waters east of Oahu through early evening. The Gale Warning that had been in effect has been cancelled. A High Surf Advisory is also in effect for exposed east facing shores through this afternoon because of strong trades and short- period choppy surf. The trade winds will weaken and veer east southeast by early this week.
The current northwest swell continues to trend downward, with a small reinforcement from the same direction expected late today. This will be followed by a more significant, advisory-level northwest swell Monday night. More larger, reinforcing northwest swells are forecast to arrive Tuesday and Thursday. Surf from these larger swells will likely produce warning level surf along most north and west facing shores, and will only gradually fade through next weekend. No other significant swells are expected.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for Kauai Windward, Oahu Koolau, Olomana, Molokai Windward, Maui Windward West, Windward Haleakala, Leeward Haleakala, South Big Island, Big Island North and East.
Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov