West Side

Today: Haze in the morning. Mostly sunny with isolated showers. Highs 79 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 67 to 73. East winds up to 20 mph increasing to 10 to 25 mph after midnight. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 76 to 81. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Highs around 86. Northwest winds up to 15 mph.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Lows 67 to 75. North winds up to 15 mph.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 84. Northeast winds 10 to 25 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs around 80 near the shore to around 66 near 5000 feet. Southeast winds 10 to 20 mph shifting to the east up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Occasional showers. Lows around 70 near the shore to around 52 near 5000 feet. Southeast winds up to 20 mph shifting to the east 10 to 20 mph after midnight. Chance of rain near 100 percent.

Tuesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs 81 to 87. East winds up to 20 mph.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 67 to 72. East winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs 78 to 84. Northeast winds 10 to 25 mph.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 62 at the visitor center to around 69 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 48 at the visitor center to around 45 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 59 at the visitor center to around 67 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs around 80 near the shore to around 66 near 5000 feet. Southeast winds 10 to 20 mph shifting to the east up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Breezy. Occasional showers. Lows around 70 near the shore to around 52 near 5000 feet. Southeast winds up to 20 mph shifting to the east 10 to 20 mph after midnight. Chance of rain near 100 percent.

Tuesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 63 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Haze through the day. Highs 72 to 80. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Lows around 66. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs 71 to 79. Northeast winds 10 to 25 mph.

Kaunakakai

Today: Mostly sunny in the morning then becoming partly sunny. Highs 70 to 86. East winds 10 to 15 mph.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 58 to 73. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 68 to 84. East winds 15 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Easterly trade winds will continue to strengthen to breezy levels by tonight and hold through Tuesday. A remnant front moving in from the north will increase showers tonight into Tuesday with mainly light to moderate showers focusing along windward and mauka areas with periods of showers spilling over to leeward sides. A drier more typical locally breezy trade wind pattern is expected from Wednesday to Thursday. A cold front will become nearly stationary northwest of the state Friday into the weekend, veering winds out of the east southeast. This lighter pattern will allow for a hybrid trade wind and sea breeze regime to set up over the weekend. A wetter pattern shift may be possible early next week.

Discussion

A storm force low far northwest of the state is sending some high clouds over the western half of the island chain this morning. A ridge of high pressure north of the state is generating locally breezy easterly winds across the state with limited low level clouds and showers along windward and mauka areas. Trade winds will strengthen to breezy levels speeds later this afternoon and early evening as the ridge continues to strengthen. A remnant band of clouds will push through the state tonight by these stronger easterly trade winds during this time. Expect increasing clouds and showers along windward and mauka areas with a few showers spilling over into leeward areas tonight into early Tuesday morning. Chances of showers will trend down through the day Tuesday after this band swiftly moves through the state.
The ridge of high pressure will weaken Christmas Eve through Christmas Day as the storm force low far northwest of the island lifts north. Trade wind speeds will gradually ease to locally breezy speeds during this time. Drier and more stable conditions will develop statewide as mid to upper level ridging develops over the state.
Friday the storm low will track east far north of the state with a trailing frontal boundary becoming nearly stationary northwest of Kauai by Friday. The proximity of this frontal boundary will place the weak surface ridge over the state veering winds out of the east southeast. Winds will become light to gentle over the western half of state while more locally breezy east southeast winds hang around the eastern half of the state. This setup will lead to a hybrid trade wind sea breeze pattern under a mostly dry and stable airmass as mid to upper level ridging holds over the state.
The extended range model guidance shows deep upper level troughing could lead to more instability developing over the western half of the state over the weekend into early next week. In addition, southerly flow at the surface will draw in more moisture, increasing chances of showers over the weekend into early next week. No significant weather is expected at this time but will continue to monitor for any changes.

Aviation

The trade winds will gradually strengthen to breezy levels today across the state. AIRMET Tango will likely be issued later today for low level turbulence downwind of terrain as winds continue to strengthen. Increasing showers embedded within the trade winds will bring brief MVFR conditions to windward and mauka areas, especially this evening through early morning Tuesday. Otherwise, VFR will prevail.
There are no AIRMETs currently in effect.

Marine

High pressure continues to build into the islands from the north, increasing easterly trade winds lasting into Wednesday morning. Trades then ease and wind directions will veer from a more southeasterly to southerly direction from Wednesday night onward as a low pressure system approaches from the northwest, driving the surface ridge axis over the islands. Briefly stronger winds are expected behind an old remnant frontal cloud band moving into Hawaiian waters from the north starting tonight through Tuesday. The Small Craft Advisory for the typical windier waters and channels near Maui and the Big Island remains in effect, this SCA will expand in coverage for most coastal waters starting tonight due to increasing trade wind speeds.
The current medium period north to north-northeast (360-020 degree) swell energy continues to slowly decline today and swell heights and periods are dropping at offshore and coastal buoys this morning. The forerunners associated with the next moderate north to north- northeast (360-020 degree) swell are forecast to arrive by late Wednesday, bringing moderate surf to favored northern exposures Wednesday night into Friday. Surf heights along west facing shores will be limited as the north-northeast swell direction and medium period swell energy is less favorable. A Marine Weather Statement may be needed for this next swell affecting north facing harbors possibly by Wednesday night, especially impacting the harbors of Kahului and Hilo.
Returning trades will build surf along E facing shores peaking with stronger trades on Tuesday. The north-northeast swell will likely boost choppy and rough surf heights a bit along east facing shores through Wednesday. Surf along south shores remains tiny with fleeting background south to southwest energy through the week.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 PM this evening to 6 PM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov