Photo Credit: Tyler Rooke

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 88. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows around 69. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 81 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Highs 85 to 90. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows around 68. Northeast winds 10 to 20 mph.

Sunday: Mostly sunny. Breezy. Highs 85 to 90. Northeast winds 10 to 25 mph.

North Shore

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to around 51 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 88. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 66 to 72. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Breezy. Partly sunny with isolated showers in the morning, then mostly sunny in the afternoon. Highs around 88. East winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 66 at the visitor center to around 63 at the summit. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Windy. Partly cloudy with isolated showers. Lows 42 to 53. East winds 15 to 35 mph increasing to 25 to 35 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs around 63 at the visitor center to around 60 at the summit. East winds 20 to 25 mph. Chance of rain 20 percent.

East Maui

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 64 to 71 near the shore to around 51 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86 near the shore to around 64 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs 72 to 81. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 66. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs 72 to 81. Northeast winds 10 to 15 mph increasing to 15 to 25 mph in the afternoon. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 79 to 89. East winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Isolated showers. Lows 61 to 72. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday: Partly sunny. Breezy. Isolated showers in the morning. Highs 79 to 89. East winds 15 to 25 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A high pressure ridge remains locked in place north of the Hawaiian Islands through next Friday. Expect moderate to locally breezy trade winds with brief periods of passing showers, mainly over windward and mountain areas in the overnight to early morning hours. Another enhancement in shower coverage may develop over the islands on Wednesday and Thursday.

Discussion

The morning satellite imagery continues to show a weak upper level low drifting through the islands within a narrow upper level trough (TUTT) pattern. Radar imagery and surface observations confirm this upper low is lifting the trade wind temperature inversion height enough to allow a return to brief periods of windward and mountain area showers over most islands. Satellite microwave imagery from this afternoon already show signs of increasing wind speeds across the region.
The weather pattern has not changed much over the past 24 hours with the high pressure ridge building north of the islands through Saturday. Trade wind speeds will increase into the moderate to breezy range lasting through the end of next week. Meanwhile, three weak upper level lows will pass over the state from east to west within a narrow upper trough pattern (Tropical Upper Tropospheric Trough also known as the TUTT). These passing lows and stronger trade wind speeds will combine forces and produce small amounts of atmospheric lift. This additional lift will lift trade wind inversion heights enough to allow for brief periods of passing showers over all islands through much of next week. This slight increase in shower coverage will mainly affect windward and mountain areas and favor the overnight to early morning hours.
Long range global weather model solutions continue to show a band of unsettled clouds moving through the islands on Wednesday and Thursday. This cloud band is associated with the remnants of an old cold front that dissipated north of the region. If this band moves into the islands as the current American GFS and European models predict, then we could see another increase in shower coverage mainly over windward and mountain sections of the islands. There is a decent chance that some of the stronger showers in these bands will spill over light rainfall amounts into the drier leeward areas on Wednesday and Thursday nights. Stay tuned.

Aviation

Moderate to breezy easterly trade winds are expected through the weekend, with clouds and showers favoring windward and mauka locations overnight through the morning periods. MVFR conditions are possible in and around passing showers, but the limited coverage should preclude the need for an AIRMET for mountain obscuration.
AIRMET Tango may be needed for low-level mechanical turbulence over and just downwind of mountain ranges Saturday afternoon.

Marine

Winds will increase into the moderate to locally strong range through this weekend. The Small Craft Advisory (SCA) remains in effect for the typically windier waters around the Big Island and Maui County. The Pailolo channel has been added to this SCA as of this morning's package. Additional expansions of the SCA may be needed later in the forecast period.
No significant swells are expected through the next week. A small northwest swell is due Sunday and Monday. Expect background summertime surf for south facing shores, though a small pulse from the southwest is possible during the middle of next week. Small, short-period surf along east facing shores will build to seasonal average over the weekend as trade winds strengthen, then hold into next week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM 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