West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 78 to 89. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 68 to 77. East winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the morning. Highs 78 to 89. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Highs 79 to 91. North winds up to 15 mph.

Tonight: Mostly clear. Lows 70 to 75. North winds up to 15 mph.

Saturday: Sunny and breezy. Highs 78 to 90. Northeast winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs 81 to 87 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73 near the shore to around 56 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 87 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 83 to 90. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 72. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the morning. Highs 82 to 90. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny and breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 64 at the visitor center to around 66 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly clear with scattered showers. Lows around 51 at the visitor center to around 49 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Saturday: Sunny and breezy. Scattered showers in the morning. Highs around 65 at the visitor center to around 67 at the summit. East winds 10 to 20 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs 81 to 87 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73 near the shore to around 56 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly cloudy with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 81 to 87 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Sunny. Isolated showers in the afternoon. Highs 73 to 83. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Clear. Lows 62 to 70. Northeast winds up to 15 mph.

Saturday: Sunny. Highs 73 to 83. East winds 10 to 15 mph.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 74 to 91. East winds 10 to 20 mph.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 60 to 76. East winds up to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 73 to 90. East winds 15 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A broad subtropical ridge will linger across the Central Pacific basin into the middle of next week, producing moderate to locally breezy trade winds each day. Two wrinkles in the forecast will increase shower trends through this morning as an easterly wave passes through Oahu and Kauai. Brief passing showers over windward and mountain areas will return later this afternoon and last through Monday evening. Another low level wave in the easterlies will drift through the islands from Tuesday to Wednesday; increasing shower trends.

Discussion

The infrared satellite imagery shows a weak easterly wave drifting westward through the island of Kauai this morning. Expect continued enhanced cloud and shower coverage across the western islands of Oahu, Kauai and Niihau through the early morning hours. Drier trends are already returning to the eastern islands with more stable stratocumulus clouds developing east of the island chain as the high pressure ridge builds stable subsidence (downward vertical motions) back into the region. Bands of high level cirrus clouds, made of ice crystals, will drift over the islands through Sunday. These high level cirrus clouds will likely enhance sunrise and sunset colors for all islands.
A typical summer forecast with little changes to our day to day moderate to locally breezy easterly trade wind weather regime remains in the forecast through Monday evening. Only brief passing showers are possible with temperature inversion heights in the 5,000 to 7,000 foot range, favoring windward and mountain areas in the overnight to early morning hours. Dry trends will continue for leeward areas that are west of island mountains.
The latest medium range models continue to show another wrinkle in the force developing by early Tuesday morning, as a wave in the easterlies drifts from east to west across the island chain. Low level forcing from this passing low level trough will push subsidence inversion heights into the 8,000 to 9,000 foot range, deepening moisture levels, and increasing cloud and shower trends from early Tuesday morning near the Big Island and Maui, then spreading westward to the islands of Oahu and Kauai by Tuesday night into Wednesday morning. One challenge with this forecast will be in how far north the trough tracks through the islands. If the trough passes farther south of the state, then these shower trends will be more limited for the western half of the state. We have higher confidence that the eastern Hawaiian Islands will see enhanced shower activity, especially in the early Tuesday morning hours.
Long range model solutions are hinting at yet more chances for enhanced shower trends by the end of next week. Stay tuned.

Aviation

A weak trough moving through Kauai this morning will enhance clouds and showers over Oahu and Kauai through around 18Z today. Otherwise moderate to locally breezy trade winds will linger through the week. Brief passing showers will favor windward and mountain areas in the overnight to early morning hours. VFR conditions will prevail outside of showers.
No AIRMETs are in effect. AIRMET Sierra for mountain obscuration over select windward areas is possible through Saturday.

Marine

High pressure will remain far northeast of the state through this weekend and allow moderate to locally strong trades to prevail across the local coastal waters. Thus, a Small Craft Advisory will remain in place for the typically windy channels and waters of Maui County and the Big Island through at least Sunday morning. Winds may weaken slightly late Sunday into early next week, then strengthen once again by midweek.
A small, medium to long period, south swell will continue to fill in today and help bump up south shore surf to near or slightly above September averages. This swell will then slowly decline by late Saturday into Sunday. Small south swell/surf expected through the remainder of the forecast period.
Surf along north facing shores will be slightly elevated over the next several days as a small, moderate period, north northwest swell holds. Beyond Sunday, however, north shore surf will drop back into the tiny to small range. East facing shores will see typical trade wind generated energy throughout the forecast period.

Fire weather

Humidity levels will remain dry into next week with increasing humidity and shower trends from Tuesday into Wednesday as a weak low level trough drifts from east to west across the island chain. Wind speeds will likely remain below critical fire weather thresholds for the next seven days. Temperature inversion heights near the Big Island and Maui today will range from 5,500 to 6,500 feet.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov