Photo Credit: Jeni Ji Cousins

West Side

Today: Sunny. Highs 81 to 89. East winds up to 15 mph.

Tonight: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows 63 to 69. East winds up to 15 mph. Chance of rain 30 percent.

Sunday: Sunny and breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 88. East winds 10 to 20 mph. Chance of rain 30 percent.

South Side

Today: Sunny. Highs around 90. North winds up to 15 mph.

Tonight: Mostly clear. Lows around 65. Northwest winds up to 15 mph.

Sunday: Sunny and breezy. Highs around 89. East winds 10 to 20 mph.

North Shore

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 86 near the shore to around 68 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 68 near the shore to around 50 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Central Maui

Today: Sunny and breezy. Highs 86 to 91. Northeast winds up to 20 mph shifting to the east 10 to 20 mph in the afternoon.

Tonight: Breezy. Mostly clear with isolated showers. Lows around 65. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 85 to 90. East winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny. Highs around 62 at the visitor center to around 57 at the summit. East winds up to 15 mph.

Tonight: Mostly clear with scattered showers. Lows around 47 at the visitor center to around 43 at the summit. Northeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 62 at the visitor center to around 57 at the summit. East winds 10 to 15 mph. Chance of rain 40 percent.

East Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 86 near the shore to around 68 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 68 near the shore to around 50 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Lanai City

Today: Sunny. Isolated showers in the afternoon. Highs 71 to 80. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 65. East winds up to 15 mph in the evening becoming light.

Sunday: Sunny. Isolated showers in the afternoon. Highs 72 to 81. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Sunny. Highs 74 to 84. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Mostly clear with isolated showers. Lows 60 to 70. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Sunny and breezy. Isolated showers in the morning. Highs 74 to 84. East winds 10 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure ridge builds in north of the islands this weekend resulting in strengthening trade winds through Sunday. The returning easterly trades will push clouds associated with the remnants of a frontal band slowly northwest and away from the islands. More stable conditions are expected with the weather pattern shifting back to brief passing windward and mountain showers through Friday.

Discussion

Satellite imagery this morning shows a band of clouds associated with the remnants of a frontal band is currently located in the Kauai Channel between Kauai and Oahu. Local radar imagery indicates scattered showers developing within this cloud band. Expect the cloud band to drift back over Kauai later this morning through evening with some enhanced shower activity over the Garden Isle.
The pattern once again shifts back to our typical trade wind weather as the high pressure ridge builds back in north of the Hawaiian Islands. Easterly trade winds, flowing out of this high pressure system, will spread from east to west across the state and strengthen through Sunday. These trade winds will push the remnant cloud band northwestward back through Kauai today and then clear out of the state by Sunday.
The easterly trade wind weather will produce more stable weather conditions with a high pressure ridge aloft strengthening the subsidence inversion over the region. Expect temperature inversion heights between 6000 and 8000 feet elevation through the week. This inversion serves as a thermal stable cap on vertical cloud development and at these heights will limit shower activity. For most islands expect brief windward and mountain showers developing mainly in the overnight to early morning hours from Sunday onward. Leeward areas will see mostly sunny skies each day. The one exception to this forecast will be afternoon cloud cover on the western slopes of the Big Island, as typical afternoon sea breezes will build mostly cloudy skies each day with down slope mountain breeze clearing at night.
Decreased shower activity in this mornings forecast from numerous showers into a more isolated to scattered range to account for the increasing atmospheric stability over the next few days. This matches well with model cross sections over the island chain. Windward and mountain sections will typically see the higher shower coverage in the range as the trade winds return. Let the dry season begin.

Aviation

A remnant boundary remains over the western part of the state this morning. Most of the showers have ended over land, but pockets of low ceilings remain in Kauai and Oahu. However, high pressure is strengthening far northeast of the area. Thus, trade winds have been gradually spreading across the island chain from east to west, and will become moderate to locally breezy later today through Sunday. Most of the moisture associated with the old boundary will be shunted to the west of the state as the trades fill in.
AIRMETs for mountain obscuration remain in effect for Kauai and Oahu, but will likely be dropped later this morning or early in the afternoon.

Marine

A dissipating cloud band in the Kauai channel will continue to weaken and drift northward. High pressure will build into the region rest of today, with easterly trade winds strengthening from east to west through tomorrow. A Small Craft Advisory goes into effect at noon today for the typical windier waters and channels around Maui County and the Big Island through Monday afternoon. Typical trade wind weather with more stable conditions will continue into the middle of next week.
Surf heights along south facing shores will fluctuate between near to slightly below average, as a couple of long- period south swells move through the region today through mid-week. The next long-period swell will fill in Thursday through the rest of next week, bringing above average surf. In the long range, models continue to show quite a bit of activity in the southern hemisphere, which could translate to additional south shore surf events lasting into early June.
Surf along north and west facing shores will slowly decline today and become nearly flat tomorrow through the first half of next week. The next small bump is expected to arrive middle of next week.
East facing shores surf will get a slight boost tomorrow and Monday as the trades strength near the coast and upstream.

HFO Watches/Warnings/Advisories

Small Craft Advisory from noon today to 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov