Photo Credit: Tyler Rooke

West Side

Today: Sunny and breezy. Scattered showers in the morning. Highs 78 to 88. Northeast winds 20 to 25 mph. Chance of rain 40 percent.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 67 to 74. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 89. Northeast winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 40 percent.

South Side

Today: Sunny and breezy. Highs around 89. Northeast winds 10 to 25 mph.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows 67 to 74. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Sunny and breezy. Highs around 90. North winds 10 to 20 mph.

North Shore

Today: Breezy. Mostly cloudy with showers in the morning, then sunny with isolated showers in the afternoon. Highs 76 to 85 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 80 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with showers after midnight. Lows around 70 near the shore to 49 to 55 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 90 percent.

Wednesday: Breezy. Mostly cloudy with showers likely. Highs 76 to 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Central Maui

Today: Sunny and breezy. Highs 82 to 89. Northeast winds 15 to 25 mph.

Tonight: Breezy. Partly cloudy in the evening, then mostly cloudy with isolated showers after midnight. Lows 66 to 71. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 82 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny and breezy. Highs around 64 at the visitor center to around 60 at the summit. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon.

Tonight: Windy. Partly cloudy with scattered showers. Lows around 48 at the visitor center to around 46 at the summit. East winds up to 30 mph increasing to 10 to 30 mph after midnight. Chance of rain 50 percent.

Wednesday: Breezy. Mostly sunny with scattered showers. Highs around 63 at the visitor center to around 59 at the summit. East winds up to 25 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 50 percent.

East Maui

Today: Breezy. Mostly cloudy with showers in the morning, then sunny with isolated showers in the afternoon. Highs 76 to 85 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 80 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with showers after midnight. Lows around 70 near the shore to 49 to 55 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 90 percent.

Wednesday: Breezy. Mostly cloudy with showers likely. Highs 76 to 85 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Lanai City

Today: Sunny and breezy. Highs 74 to 83. Northeast winds 10 to 20 mph increasing to 20 to 25 mph in the afternoon.

Tonight: Mostly clear. Breezy. Lows around 64. Northeast winds 15 to 25 mph decreasing to 10 to 15 mph after midnight.

Wednesday: Mostly sunny. Breezy. Scattered showers in the afternoon. Highs 75 to 83. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

Kaunakakai

Today: Sunny and breezy. Highs 69 to 89. Northeast winds 15 to 20 mph.

Tonight: Breezy. Partly cloudy in the evening, then mostly cloudy with isolated showers after midnight. Lows 57 to 73. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Wednesday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 69 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Showers over Maui County and the Big Island will shift west of the area early this morning giving way to mostly dry conditions areawide. Locally breezy trades will then focus increased showers over windward and mauka slopes through the end of the week. Occasional leeward showers will also be possible, mainly overnight.

Discussion

Locally breezy trades are pushing extensive low clouds and showers over the windward slopes of the Big Island early this morning. Pops have been adjusted upward for the next several hours there, along with windward sections of Maui County to account for another batch of showers that approaching from the east which will arrive shortly. Otherwise, the latest VIIRS imagery indicates very little cloud cover upstream of the smaller islands while local radar shows virtually no showers over the western end of the state. This trend will continue through today as the upper low becomes established overhead. Steady erosion of the inversion prior to the arrival of deeper upstream moisture will only facilitate further mixing-out of existing boundary layer moisture. As such, lowered pops considerably today, limiting mention of isolated showers only to the higher windward terrain.
The well-advertised pool of remnant frontal moisture will reach the islands during the latter half of tonight, gradually working through the forecast area tonight into Thursday. During this time, trades will slightly weaken as they deliver increased showers, some of moderate intensity, to windward zones. Likewise, more frequent leeward showers can be expected, especially overnight and in the morning.
Forecast soundings indicate that stability will be slow to return in the wake of the departing upper low late this week. Thus, another round of increased trade wind showers will be possible late Friday into Saturday as another batch of low-level moisture works through the area. Overall messaging is that Wednesday through the first half of the weekend will be characterized by slightly wetter-than-normal trades.

Aviation

Breezy to locally strong trade winds will continue through forecast period. Clouds and showers will favor windward coasts and slopes through the morning and overnight hours. The large area of low clouds that moved into windward Big Island last night is expected to linger through the early morning hours before scattering out later this morning as the sun rises.
AIRMET SIERRA for mountain obscuration will remain posted through at least 17Z, with conditions expected to slowly improve through 20Z.
AIRMET TANGO remains posted for TEMPO low-level turbulence below 8000 ft over and immediately south through west of mountains on all islands.

Marine

The overnight ASCAT passes showed Small Craft Advisory (SCA) level winds over additional waters, which paired up with some of the high resolution models. Have added additional coastal waters to the SCA through tonight based on those models, using the National Blend of Models to nudge the forecast higher. Confidence drops off after tonight, which was the reasoning for only adding those waters today and tonight. Have extended the SCA for the typical windier areas through Wednesday night. Otherwise, no significant changes to the forecast with the morning package.
High pressure to the north of the islands will maintain the moderate to locally strong trade winds through the end of the week. As the high moves to the east this weekend, the winds over the region may veer to the southeast, but time will tell how much of an impact that will have on wind speeds.
Rough, choppy surf is expected along east facing shores through the week from the locally generated wind waves. The current small, west-northwest swell will continue to decline over the next couple of days. A slightly larger, and longer period northwest swell will build Thursday night and continue through the weekend, boosting swell along exposed swell. Overlapping background south swells will continue to keep small surf heights along south facing shores through Wednesday. A slightly larger, long period southwest swell generated from the Tasman Sea basin will arrive on Thursday, elevating south shore surf through next weekend.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 AM HST Wednesday for Kauai Northwest Waters, Kauai Leeward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov