Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny with isolated showers. Highs 75 to 82. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 57 to 65. East winds 10 to 15 mph. Chance of rain 40 percent.

Tuesday: Mostly sunny with isolated showers. Highs 74 to 82. East winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Today: Sunny. Highs around 85. Northeast winds 10 to 15 mph.

Tonight: Mostly clear. Lows around 61. Northeast winds 10 to 15 mph.

Tuesday: Sunny. Highs around 84. Northeast winds 10 to 15 mph.

North Shore

Today: Breezy. Mostly sunny with scattered showers. Highs around 81 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 64 near the shore to around 47 near 5000 feet. East winds 10 to 15 mph. Chance of rain 60 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 82 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Central Maui

Today: Mostly sunny with isolated showers. Highs 81 to 86. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 59 to 64. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs around 83. East winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Breezy. Sunny with isolated showers. Highs around 56 at the visitor center to around 61 at the summit. East winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear with scattered showers. Lows around 42 at the visitor center to around 39 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers. Highs around 58 at the visitor center to around 64 at the summit. East winds 10 to 15 mph. Chance of rain 20 percent.

East Maui

Today: Breezy. Mostly sunny with scattered showers. Highs around 81 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows around 64 near the shore to around 47 near 5000 feet. East winds 10 to 15 mph. Chance of rain 60 percent.

Tuesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 82 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph. Chance of rain 40 percent.

Lanai City

Today: Mostly sunny with isolated showers. Highs 73 to 78. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows 54 to 62. East winds around 10 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 71 to 77. East winds around 10 mph. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 69 to 82. East winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 54 to 69. East winds 15 to 20 mph. Chance of rain 20 percent.

Tuesday: Breezy. Sunny with isolated showers. Highs 69 to 82. East winds 15 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will continue through Tuesday as a high pressure ridge lingers just north of Kauai. Passing trade wind showers will continue over the next two days favoring the typical windward and mountain areas. A cold front approaching the islands from the northwest on Wednesday will drive this ridge over the Hawaiian Islands, producing stable dry conditions with light and variable sea breeze winds each day through Friday. Clouds will develop over island mountain and interior sections each afternoon with clearing at night. Another high drifts eastward just north of the state on Saturday, producing another round of moderate to locally breezy trade winds with increasing shower trends for the weekend.

Discussion

Satellite imagery this morning continues to show an upper level low east of the Big Island producing a few unstable cloud bands drifting through the trade winds with radar data supporting scattered showers over windward areas of most islands. A high pressure ridge remains just north to northwest of Kauai, and a cold front currently near the dateline will slowly approach the islands over the next few days.
This high pressure ridge will keep the islands in a moderate to locally breezy trade wind weather pattern through Tuesday. An upper low just east of the Big Island will weaken the subsidence inversion just enough for typical passing trade wind showers mainly over windward and mountain areas, favoring the overnight to early morning hours. Isolated thunderstorms remains in the forecast for this afternoon along the leeward slopes of Mauna Loa on the Big Island.
A cold front approaching the islands from the northwest on Wednesday will push this ridge over the island chain, producing a dry and stable pattern, reducing clouds and showers, and weakening the large scale winds. This cold front will stall and dissipate just north of the islands. Local scale sea breezes will fill the void each day with clouds developing over island mountain and interior sections due to converging sea breeze winds and island surface heating. These clouds will diminish after sunset as radiational cooling of the land produces down slope land breezes that will clear out the cloud cover over each island. This land and sea breeze weather pattern will last through Friday with minimal shower activity.
The weather pattern switches back to trade winds again on Saturday as a few cloud bands associated with the remnants of the cold front drift into each island on the returning trade winds. Meanwhile an upper level low is brewing just northeast of the state that may extend shower activity over the region into the Sunday time period.
Island by island rainfall impacts will have to wait until this time period gets closer. However, both the American (GFS) and European (ECMWF) long range model solutions remain in fair agreement on the larger scale pattern change for the upcoming weekend. The position of this upper low will be key in how much or little rainfall we add to the forecast. Stay tuned as these long range wet weather trends will likely evolve over time.

Aviation

Locally breezy trades will focus showers over windward and mauka areas through the forecast period. Brief MVFR will be possible within any heavier showers, particularly over Windward Big Island where AIRMET Sierra for mountain obscuration may be needed during the early morning hours. An isolated thunderstorm or two will again be possible over upslope sections of Leeward Big Island during peak heating.

Marine

A surface ridge N of the islands will support moderate to locally strong ENE trade winds through tonight, and a Small Craft Advisory (SCA) for Maui and Big Island waters has been extended. Winds will gradually diminish and veer to the SE Tuesday through Thursday as an approaching front pushes the ridge S toward the islands. The ridge is expected to be near Kauai by Thursday as the front stalls and dissipates just N of Kauai. A new high passing N of the area will bring strengthening trade winds Friday and Saturday, with remnant frontal moisture potentially fueling an increase in showers.
NW swell at near shore PacIOOS buoys has gradually diminished over the last 12 hours, with a slow downtrend expected through the day. Another moderate pulse of WNW swell is expected to arrive tonight and Tuesday, potentially boosting surf to High Surf Advisory levels. This swell will slowly lower into Thursday, then persist at small to moderate heights into next weekend. Longer range guidance hints at a larger NW swell in just over a week. Slightly elevated, short-period E swell will continue the next couple of days, as well as a small S swell.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov