Photo Credit: Travis Guthrie

West Side

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 83 to 90. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 70 to 77. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 81 to 88. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Highs 87 to 92. North winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows around 71. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Sunday: Mostly sunny. Breezy. Highs 85 to 90. Northeast winds 10 to 25 mph.

North Shore

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to 62 to 68 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 67 to 74 near the shore to around 54 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly sunny with scattered showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs around 90. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 69 to 75. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Windy. Highs around 88. Northeast winds 15 to 30 mph.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning. Highs around 60 at the visitor center to around 56 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows around 47 at the visitor center to around 43 at the summit. East winds up to 20 mph. Chance of rain 20 percent.

Sunday: Sunny and breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 63 at the visitor center to around 60 at the summit. Northeast winds 10 to 25 mph. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to 62 to 68 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 67 to 74 near the shore to around 54 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Sunday: Breezy. Mostly sunny with scattered showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 74 to 83. Northeast winds up to 10 mph increasing to up to 20 mph in the afternoon.

Tonight: Partly cloudy. Windy. Lows around 67. Northeast winds 10 to 20 mph increasing to 10 to 30 mph after midnight.

Sunday: Mostly sunny. Windy. Highs 73 to 82. Northeast winds 15 to 30 mph.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 79 to 89. East winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 64 to 75. East winds 10 to 20 mph.

Sunday: Mostly sunny. Breezy. Highs 78 to 88. Northeast winds 15 to 25 mph.

Detailed Forecast

Synopsis

Strengthening trade winds will usher in drier and more stable weather this weekend. Trades will gradually weaken and trade wind showers will increase during the first half of next week. The winds will become light Wednesday through Friday, allowing a sea and land breeze pattern to develop in most leeward areas, with showers favoring interior and leeward locales each afternoon.

Discussion

Currently at the surface, a trough of low pressure is located around 400 miles north of Kauai, while a 1029 mb high is centered around 1400 miles north-northeast of Honolulu. The resulting gradient across the islands is producing gentle to moderate trade winds early this morning, strongest over the eastern end of the state. Infrared satellite imagery shows some high clouds streaming over the far eastern and western portions of the state, with lower clouds streaming into windward areas with the trades. Radar imagery shows a few light showers moving into windward areas, with very little if any shower activity in leeward locales. Main short term focus revolves around trade wind trends and rain chances.
The trough of low pressure north of the islands will slide westward through the weekend, while the high to the distant north-northeast of the state strengthens. This will allow the trade winds to strengthen today, with moderate to breezy conditions expected this afternoon through the remainder of the weekend, strongest on Sunday. The trades should drop a notch into the moderate to locally breezy range early next week as old frontal remnants north of the islands keep the strongest gradient north of the state. The boundary layer flow then appears to tip east-southeasterly Wednesday through Friday as troughing develops north of the islands. This would ease the trades into the light to locally moderate range, with sea and land breezes common across many leeward areas.
As for the remaining weather details, fairly dry trade wind weather should prevail through the weekend, with showers confined primarily to windward and mauka areas during the overnight and early morning hours. Some more moisture is forecast to get caught up in the trade wind flow Sunday night through early next week as a mid/upper level low approaches the islands from the east. This should lead to an increase in trade wind showers and allow a few more showers to reach leeward areas as well. A convective shower regime could then develop Wednesday through Friday in the lighter wind regime, with showers favoring interior and leeward areas during the afternoon and evening hours.

Aviation

Moderate trade winds will keep clouds and showers focused over windward and mauka areas today and tonight. Webcams over windward Big Island continue to show some low clouds over the area, but coverage continues to wane. Will keep AIRMET Sierra for mountain obscuration going for now, but may drop it with the next issuance. Otherwise, expect mainly VFR conditions across the state the next 24 hours with occasional MVFR cigs possible through the morning hours.

Marine

Easterly trade winds have surged back into the fresh to strong category overnight in response to high pressure building to the north and a weak trough moving away from the region. A Small Craft Advisory is now in effect for the windier waters around Maui County and the Big Island, and may need to be expanded to include other marine areas tonight through Sunday. This pattern will persist through Monday (trades becoming northeast Sunday night), before trending down Tuesday through midweek as the gradient relaxes.
The long-period south swell that filled in Friday will hold today, then ease Sunday into early next week. The next pulse out of the south is expected late Sunday, which will keep the surf up along southern exposures through Tuesday before lowering. After this source fades, not much is shown out in the extended due to a progressive pattern setting up down south within Hawaii's swell window.
Surf along east facing shores will ramp up and become rough over the weekend into early next week due to strong trades locally and upstream. Distant tropical activity in the eastern Pacific may send a small, long-period east swell through the islands around midweek.

Fire weather

Building trade winds this weekend will usher in a dry airmass over the area. The resulting dry and breezy weather will result in elevated fire danger, with red flag conditions possible Sunday afternoon. A Fire Weather Watch remains in effect for all leeward portions of the state on Sunday. Trade winds are expected to gradually decrease Monday through the first half of next week.

HFO Watches/Warnings/Advisories

Fire Weather Watch from Sunday morning through Sunday afternoon for Niihau, Kauai Leeward, Oahu South Shore, Waianae Coast, Olomana, Molokai Leeward, Lanai Makai, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, South Big Island, Kohala, Big Island Interior.
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Maui Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Maui Helicopter Tours today!

Data Courtesy of NOAA.gov