West Side

Today: Breezy. Partly sunny with scattered showers. Highs 75 to 84. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows 66 to 76. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Friday: Sunny and breezy. Isolated showers in the afternoon. Highs 75 to 84. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Breezy. Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 84. Northeast winds 10 to 25 mph. Chance of rain 30 percent.

Tonight: Mostly clear. Breezy. Lows 64 to 74. North winds 10 to 25 mph.

Friday: Sunny and breezy. Highs around 83. North winds 10 to 20 mph.

North Shore

Today: Breezy. Mostly cloudy with numerous showers. Locally heavy rainfall possible. Highs 76 to 81 near the shore to around 62 near 5000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 73 near the shore to around 51 near 5000 feet. East winds 15 to 20 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 63 near 5000 feet. East winds 15 to 20 mph. Chance of rain 30 percent.

Central Maui

Today: Breezy. Partly sunny with scattered showers. Highs 79 to 84. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows 66 to 73. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Sunny. Isolated showers in the afternoon. Highs 79 to 84. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Scattered showers. Highs around 58 at the visitor center to around 73 at the summit. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 44 at the visitor center to around 52 at the summit. East winds 10 to 25 mph. Chance of rain 40 percent.

Friday: Sunny and breezy. Isolated showers in the afternoon. Highs around 59 at the visitor center to around 73 at the summit. East winds 10 to 25 mph. Chance of rain 20 percent.

East Maui

Today: Breezy. Mostly cloudy with numerous showers. Locally heavy rainfall possible. Highs 76 to 81 near the shore to around 62 near 5000 feet. East winds 15 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 73 near the shore to around 51 near 5000 feet. East winds 15 to 20 mph. Chance of rain 50 percent.

Friday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to around 63 near 5000 feet. East winds 15 to 20 mph. Chance of rain 30 percent.

Lanai City

Today: Sunny and breezy. Isolated showers in the afternoon. Highs 70 to 79. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Clear and breezy. Lows 63 to 70. Northeast winds 10 to 25 mph.

Friday: Sunny and breezy. Highs 70 to 79. East winds 10 to 20 mph.

Kaunakakai

Today: Windy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 67 to 85. Northeast winds 15 to 30 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows 58 to 76. East winds 15 to 25 mph. Chance of rain 20 percent.

Friday: Sunny and breezy. Highs 68 to 85. East winds 15 to 20 mph.

Detailed Forecast

Synopsis

Strong trade winds are expected today as high pressure continues to build south toward the state. Windward and mauka showers increase today as decaying frontal boundary moves from north to south across the state. Moderate to locally breezy trades will return Friday.

Discussion

A weakening frontal boundary will bring some deeper moisture south through the islands today. Increased shower coverage is expected over mostly windward and mauka areas, but a few may make it into leeward areas too. The Wind Advisory has been cancelled but winds could still be strong and gusty today but look to remain below advisory thresholds.
The strong trade winds should ease some Friday down to breezy to locally strong speeds. Another high pressure ridge will slide east well to the north of the state this weekend. Some increase in the trades is possible again Saturday night and Sunday before the high stalls to our northeast early next week. A reduced pressure gradient should allow trades to relax some by that time. Brief pulses of better moisture in the trades will keep typical trade wind showers over windward and mauka areas mostly during the overnight and early morning hours through the period.

Aviation

Locally strong trade winds will continue today before gradually weakening through the second half of the week. A dying frontal boundary is making its way through the island chain this morning, providing an increase in shower activity. Windward and mountain areas will see most of the showers, but leeward areas could see some spillover showers as well. MVFR conditions are expected within showers while VFR prevails elsewhere. Showers will quickly decrease later this morning across Kauai and Oahu, and linger around Maui County and the Big Island a bit longer during the afternoon.
AIRMET Tango is in effect for low level moderate turbulence downwind of terrain, and for strong surface winds 30 kt or greater over Maui County and the Big Island. Expect the strong surface winds to weaken later this morning. AIRMET Tango will likely remain in effect for low level moderate turbulence through the next several days.
AIRMET Sierra is in effect for mountain obscurations across windward sections of the smaller islands as the frontal boundary moves down the island chain this morning.

Marine

Strong high pressure north of Hawaii will maintain fresh to near gale force winds across the marine areas through tonight. The Gale Warning has been discontinued in favor of a Small Craft Advisory (SCA) which covers all coastal waters. The SCA has been extended through tonight, with a gradual tapering of winds forecast and some uncertainty on how widespread strong trades will be by Friday. Seas are also in excess of 10 feet with a large north-northwest swell moving through the area. A weakening front will drop south across central waters today as it weakens to a trough. This disturbance will bring increased shower activity to the area until it dissipates tonight. Though trade winds diminish some for Friday and Saturday, high pressure restrengthening northeast of the islands may bring more widespread strong winds Sunday and Monday to all waters.
PacIOOS Buoy 51201 near Waimea Bay observed the peak of the large, north-northwest swell late last evening at nearly 11 feet with a 15 second period. A High Surf Advisory (HSA) remains in effect for north- facing shores of Kauai, Oahu, Molokai and Maui and west- facing shores of Kauai and Oahu through this afternoon. The large swell will generally maintain through the morning before declining this afternoon and falling below advisory criteria tonight. Surf will continue to decrease Friday, but will see a small bump on Saturday with a new north-northwest swell, followed by a more significant north swell which could push surf back to advisory levels on Sunday.
Surf along east-facing shores will remain rough and choppy due to the strong trade winds through Friday, then may diminish slightly this weekend. A small, long-period south swell may bring a small bump to south shore surf today. Surf becomes tiny again Friday into the weekend for south-facing shores.

Fire weather

With strong trades and low humidity levels critical fire thresholds may be reached today. However, fuel conditions remain below critical thresholds due to the above average rainfall over the past few months. Due to the fuels, Red Flag Warnings are not expected at this time. Winds should ease slightly with a modest increase of humidities on Friday. Temperature inversion heights will remain between 6,000 and 7,000 feet across the state.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov