Photo Credit: Jeni Ji Cousins

West Side

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 81 to 88. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows around 69. Northeast winds 10 to 20 mph shifting to the east after midnight. Chance of rain 20 percent.

Wednesday: Sunny. Highs 81 to 88. East winds up to 15 mph.

South Side

Today: Mostly sunny. Breezy. Highs 85 to 90. North winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows around 68. North winds up to 20 mph.

Wednesday: Sunny. Highs 85 to 90. North winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

North Shore

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to 63 to 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 64 to 71 near the shore to around 52 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 30 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to 63 to 68 near 5000 feet. East winds up to 15 mph. Chance of rain 30 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs around 88. East winds up to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 66 to 72. East winds up to 20 mph.

Wednesday: Sunny. Highs around 88. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Upcountry

Today: Mostly sunny. Breezy. Highs around 62 at the visitor center to around 59 at the summit. Southeast winds up to 25 mph.

Tonight: Mostly clear. Breezy. Lows around 47 at the visitor center to around 43 at the summit. Southeast winds up to 25 mph becoming 10 to 20 mph after midnight.

Wednesday: Sunny and breezy. Highs around 62 at the visitor center to around 59 at the summit. Southeast winds up to 20 mph.

East Maui

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to 63 to 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows 64 to 71 near the shore to around 52 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 30 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to 63 to 68 near 5000 feet. East winds up to 15 mph. Chance of rain 30 percent.

Lanai City

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 72 to 81. Northeast winds up to 15 mph increasing to up to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows around 67. Northeast winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Wednesday: Mostly sunny. Highs 73 to 82. Northeast winds up to 15 mph.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 77 to 87. East winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows 60 to 71. East winds 10 to 20 mph.

Wednesday: Mostly sunny. Highs 78 to 88. East winds 10 to 15 mph.

Detailed Forecast

Synopsis

Breezy trades will continue today, before easing Wednesday and giving way to sea and land breezes Thursday and Friday. A fairly typical trade wind pattern will continue this morning, with trade wind showers then steadily decreasing through the middle of the week as a more stable airmass gradually settles overhead. Some lingering instability may allow for a thunderstorm to pop over interior Big Island this afternoon however. Very dry conditions will overspread the entire island chain Thursday through the weekend, greatly limiting shower activity. Returning and gradually strengthening trade winds could bring a slight increase in showers early next week.

Discussion

Currently at the surface, a 1025 mb high centered 950 miles northeast of Honolulu, is driving breezy trade winds across the island chain. Infrared satellite imagery shows partly to mostly cloudy conditions with cloud cover most prevalent over windward and mauka areas. Radar imagery shows isolated to scattered showers affecting windward slopes and coasts, with the occasional shower spilling leeward. Main short term focus revolves around trade wind trends and rain chances.
The high to the northeast of the islands will remain nearly stationary today, slowly weaken as it shifts eastward on Wednesday, with the ridge axis then moving over or very near the western islands Thursday and Friday. Breezy trade winds will continue today, then ease into the moderate range Wednesday. The winds will ease further and become light and variable over the smaller islands Thursday and Friday, allowing for daytime sea breezes and overnight land breezes to be dominant. Meanwhile, light trades will likely hold in the unprotected areas of the Big Island. The surface ridge axis is forecast to shift northward over the weekend into early next week, which should bring a return and gradual strengthening of the trade winds.
As for the remaining weather details, isolated to scattered windward showers should prevail this morning, with the trade wind inversion then expected to lower to around 5 kft greatly limiting trade wind showers this afternoon. There remains a slight chance that instability aloft could allow a thunderstorm to pop over the Big Island interior this afternoon as well.
Rather dry trade wind weather will continue tonight through Wednesday night as the trade wind inversion holds around 5 kft, with most leeward areas not seeing any rain. Little change in the trade wind inversion height is expected Thursday through the weekend, greatly limiting shower activity across the entire state. A slight increase in windward showers is possible late in the weekend into early next week as the trades gradually return and inversion heights begin to slowly rise.

Aviation

Breezy to locally strong trades will produce low cigs and SHRA on windward and mauka zones through the period. MVFR conds possible in any SHRA. The arrival of elevated instability favors a chance for isolated TS over interior and upslope sections of the Big Island this afternoon.
AIRMET Sierra is in effect for mtn obsc for windward Big Island and N thru SE sections of the smaller islands.
AIRMET Tango for lee turb remains in effect.

Marine

Broad high pressure north of the state will maintain fresh to strong trade winds today as a Small Craft Advisory (SCA) remains in effect for all waters around the Big Island and Maui County and select areas around Oahu and Kauai through this afternoon. The ridge will continue to weaken as the SCA will be trimmed back to the waters around Maui County and the Big Island through tonight. The ridge further erodes and displaces the ridge southward over the islands Thursday into Friday, causing the trades to diminish significantly and possibly become disrupted. The SCA will be dropped completely by this time. Increasing moderate trades are expected during the weekend as the ridge lifts northward.
An active south Pacific will continue the extended run of southerly swell almost certainly through mid June. The current south-southwest swell gotten another pulse overnight but just below High Surf Advisory Criteria. This swell will gradually decline through Thursday, followed by a reinforcing south- southwest swell late Thursday and Friday that will produce south shore surf around seasonal average. Coming into the weekend, a larger swell will move through the islands likely near or at the High Surf Advisory (HSA) criteria of 10 feet. Followed by a potentially larger swell in development looking increasingly likely to push surf well above the advisory level late next week.
A small northwest swell has continued to fill in overnight and looks to hold today. Another pulse from the northwest will follow Wednesday into Thursday. The fresh to strong trade wind flow is producing rough choppy elevated seas but the wind waves will diminish significantly after Wednesday coinciding with the light winds through the weekend.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov