Photo Credit: Jeni Ji Cousins

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 78 to 84. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 72. East winds 10 to 20 mph. Chance of rain 40 percent.

Wednesday: Breezy. Partly sunny with isolated showers. Highs 80 to 86. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

South Side

Today: Sunny. Isolated showers in the afternoon. Highs around 84. North winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 67. North winds up to 15 mph.

Wednesday: Mostly sunny. Breezy. Highs around 86. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

North Shore

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 near the shore to around 62 near 5000 feet. East winds 10 to 20 mph. Chance of rain 60 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 64 to 70 near the shore to around 51 near 5000 feet. Southeast winds 10 to 20 mph shifting to the east up to 20 mph after midnight. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 84 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 60 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs around 82. East winds up to 20 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 70. East winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 84. East winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 54 at the visitor center to around 51 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 43 at the visitor center to around 39 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Partly sunny in the morning then becoming cloudy. Scattered showers. Highs around 56 at the visitor center to around 53 at the summit. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 near the shore to around 62 near 5000 feet. East winds 10 to 20 mph. Chance of rain 60 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 64 to 70 near the shore to around 51 near 5000 feet. Southeast winds 10 to 20 mph shifting to the east up to 20 mph after midnight. Chance of rain 70 percent.

Wednesday: Mostly cloudy. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 84 near the shore to around 65 near 5000 feet. East winds 10 to 20 mph. Chance of rain 60 percent.

Lanai City

Today: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 80. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 66. Northeast winds up to 15 mph.

Wednesday: Breezy. Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 74 to 81. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 77 to 85. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows 62 to 71. East winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 76 to 84. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A weakening upper low near Kauai will keep wet easterly trade winds in the forecast into Wednesday morning with locally heavy showers possible and isolated afternoon thunderstorms over the Big Island. Expect shower coverage to slowly decrease through the day with typical trade wind weather expected from Wednesday into Friday. Increasing shower trends return by this weekend as another weak upper low forms just north of the state. Easterly trade winds will continue to blow across the region through much of next week.

Discussion

Shower activity has trended upward across the Hawaii region this morning as shown on the latest local radar and satellite imagery. These trends follow the typical diurnal cycle of peak rainfall amounts during the early morning hours under the unstable influence of an upper level low near Kauai.
In the short term, this upper low will continue to enhance trade wind shower activity with decreasing chances for heavy showers and thunderstorms through tonight. Isolated thunderstorms will linger mainly over Kauai through tonight, and over the Big Island slopes in the afternoon hours.
A weak high pressure ridge will build over the island chain from Wednesday into Friday. This ridge aloft will produce stronger subsidence (downward moving air), and strengthen (lower) the trade wind temperature inversion heights into the 5,000 to 7,000 foot range across the region. Brief trade wind showers will favor windward and mountain areas mainly during the overnight to early morning hours.
The longer range forecast continues to show subtle changes towards increasing shower trends from Friday night through this weekend as a weak upper low/trough forms just north of the state. How much shower activity will highly depend upon the strength of this upper level feature. Confidence is only moderate that increasing shower trends will be noticeable in our island trade wind weather pattern. Additional opportunities remain for periods of enhanced showers in next week's weather forecast picture. Stay tuned.

Aviation

High pressure northeast of the state will keep moderate to breezy trade winds in place during the next 24 hours. The airmass will remain unstable due to troughing aloft, resulting in a more showery trade wind pattern, particularly for windward areas. A thunderstorm or two could pop on the Big Island slopes this afternoon as well. A more stable and drier airmass should begin to build into the islands tonight.
AIRMET Sierra remains in effect for Kauai, Oahu, Molokai, Maui and the Big Island. This AIRMET will likely remain in place through much of the morning. AIRMET Tango remains in effect for moderate upper level turbulence over the eastern half of the state. This AIRMET will likely remain in effect today. AIRMET Tango may also be needed for moderate low level turbulence over and downwind of the terrain beginning late today or tonight.

Marine

Trade winds have returned due to high pressure building far northeast of the state, and should hold through the week. Small Craft Advisory level winds (25 kt) will persist over the windier waters around Maui County and the Big Island. The advisory may need to be expanded to Kaiwi Channel waters tonight into Wednesday. Winds may lower slightly by this weekend as the ridge settles southward and weakens.
Surf along east facing shores will steadily rise today due to the trades that have returned locally and upstream across the eastern Pacific. Guidance shows this holding into the second half of the week before easing next weekend as the trades upstream trend down.
The quiet conditions across the northern Pacific continues through the first week of April, with minimal swell anticipated. This will translate to the nearly flat conditions continuing for north and west facing shores. The exception will be for north facing shores exposed to trade wind energy wrapping in, which could generate some small surf for the typical standout locations this week. For the extended, there is a potential for a short/medium period northerly swell associated with a decent sized area of north-northwest winds setting up and expanding southward from the Aleutians around the Date Line Friday through Saturday. If this materializes, this swell would arrive locally early next week and linger through midweek.
For south facing shores, guidance supports the small conditions continuing well into April with mainly background energy moving through.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov