West Side

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 81 to 87. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 70 to 79. Northeast winds 10 to 20 mph.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 80 to 86. Northeast winds up to 15 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Highs around 89. North winds 10 to 20 mph.

Tonight: Partly cloudy. Lows 70 to 77. North winds 10 to 15 mph.

Wednesday: Sunny and breezy. Highs around 88. Northeast winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs around 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows around 75 near the shore to around 56 near 5000 feet. East winds up to 15 mph. Chance of rain 90 percent.

Wednesday: Occasional showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 82 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 71 to 76. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 81 to 89. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 64 at the visitor center to around 70 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 52 at the visitor center to around 46 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 62 at the visitor center to around 68 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs around 84 near the shore to around 68 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then occasional showers after midnight. Lows around 75 near the shore to around 56 near 5000 feet. East winds up to 15 mph. Chance of rain 90 percent.

Wednesday: Occasional showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. East winds 10 to 15 mph. Chance of rain near 100 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 73 to 82. Northeast winds 10 to 25 mph.

Tonight: Partly cloudy. Lows 66 to 72. Northeast winds 10 to 15 mph decreasing to up to 15 mph after midnight.

Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs 73 to 82. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 71 to 89. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 62 to 77. East winds 10 to 20 mph.

Wednesday: Sunny and breezy. Highs 71 to 89. East winds 10 to 20 mph.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will continue through the weekend. Bands of low clouds and showers will be carried in on the trades, focused primarily over windward and mauka areas during the overnight and early morning hours. An enhanced area of moisture is expected to reach the islands Tuesday night through Wednesday, bringing more widespread showers. Humidity levels will rise, bringing muggier conditions across the island chain through the middle of this week. Additional areas of increased low level moisture are possible this weekend.

Discussion

Radar and satellite show partly to mostly cloudy skies but only isolated light showers as of 3 AM HST. The few showers detected by radar were over windward areas, mainly on Big Island. Clouds were a mixture of low level trade wind cumulus moving in from the east and high-level cirrus associated with the subtropical jet moving in from the west-southwest. Winds were averaging 5 to 15 mph sustained, with gusts generally 15 to 20 mph.
An upper level ridge will remain generally north of the state (centered around 40N) for the coming week as it slowly drifts west. At the same time, an area of surface high pressure will also remain north of the state around the same latitude, and it will also drift west with time. Trades will continue through the period, with showers mainly windward and mauka, and more numerous at night.
One significant area of increased low level moisture will move in from the east tonight and Wednesday, spreading more numerous showers to windward and mauka areas, and increasing the chance for noticeable spillover to leeward areas. Brief heavy rain is possible, but the risk for flooding is low. Surface dewpoints will increase into the lower 70s as this moist area moves through, then drop back into the mid to upper 60s from Wednesday night into the weekend.
All of this was already in the forecast, and changes have been minimal in this latest package.

Aviation

A brief break between passing low level troughs will produce mostly VFR conditions across the Hawaiian Islands through this afternoon. The next trough, slightly weaker than the last system, moves westward through the islands tonight through Wednesday. Expect increasing shower trends with brief periods of MVFR conditions and mountain obscurations, mainly along windward mountain areas.
AIRMET Sierra remains in effect for mountain obscuration along north and east slopes of Maui and the Big Island. This AIRMET will diminish in coverage later this morning, a few hours after sunrise.

Marine

A surface high pressure will remain centered well north of the Hawaiian Islands this week and help drive moderate to fresh trades trades across the region. A Small Craft Advisory (SCA) is in effect for the typical windy waters around Maui County and the Big Island. The SCA advisory will likely need to be extended for these areas through much of this week with the persistent trades.
The long-period south swell we had is slowly fading and will continue to decline leading to decreasing south and west shore surf through Wednesday. A small bump in surf along south- facing shores is possible Thursday into Friday with the arrival of a small, long-period south swell, but another larger long-period south swell energy pulse should arrive by late Saturday.
Surf along east-facing shores will remain rough and choppy through the week with moderate to fresh trades in place. Nearly flat surf heights will persist along north facing shores.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov