Photo Credit: Brittney Cruz

West Side

Today: Mostly sunny. Windy. Isolated showers in the morning. Highs 83 to 90. Northeast winds 20 to 30 mph. Chance of rain 20 percent.

Tonight: Windy. Partly cloudy with scattered showers. Lows 68 to 74. Northeast winds 15 to 30 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs 80 to 87. Northeast winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Windy. Highs 87 to 92. Northeast winds 10 to 30 mph.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows around 69. Northeast winds 10 to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Highs 84 to 89. Northeast winds up to 25 mph increasing to 10 to 25 mph in the afternoon.

North Shore

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 65 to 72 near the shore to around 55 near 5000 feet. Southeast winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 90 percent.

Monday: Partly sunny. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 80 percent.

Central Maui

Today: Mostly sunny. Windy. Highs around 90. Northeast winds 15 to 30 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 67 to 73. Northeast winds 10 to 25 mph shifting to the east 10 to 15 mph after midnight. Chance of rain 20 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs around 87. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Highs around 63 at the visitor center to around 60 at the summit. Northeast winds up to 15 mph.

Tonight: Windy. Mostly clear with scattered showers. Lows around 50 at the visitor center to around 47 at the summit. East winds up to 30 mph. Chance of rain 50 percent.

Monday: Breezy. Mostly sunny with scattered showers. Highs around 64 at the visitor center to around 61 at the summit. Northeast winds up to 25 mph. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 82 to 88 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Numerous showers in the evening, then frequent showers after midnight. Lows 65 to 72 near the shore to around 55 near 5000 feet. Southeast winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 90 percent.

Monday: Partly sunny. Breezy. Frequent showers in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 80 percent.

Lanai City

Today: Mostly sunny. Windy. Highs 76 to 85. Northeast winds 25 to 30 mph.

Tonight: Partly cloudy. Windy. Isolated showers after midnight. Lows around 66. Northeast winds 15 to 30 mph decreasing to 10 to 20 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 72 to 81. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny. Breezy. Highs 81 to 91. Northeast winds 15 to 25 mph.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 62 to 73. Northeast winds 15 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Monday: Breezy. Mostly sunny with isolated showers. Highs 77 to 87. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Strong trade winds have returned and will continue into Monday, with windward clouds and showers remaining limited due to drier air moving in. A transition period is expected late Monday through midweek as an upper disturbance approaches and moves in from the east. Diminishing trade winds along with increasing moisture may be enough to trigger a few showers over our dry leeward areas through the afternoon hours where sea breezes form Wednesday through the second half of the week.

Discussion

Guidance depicts rising upper heights over the islands today through Monday as a broad upper low lifts northwestward and away from the area. This combined with strong surface high building north of the state will translate to a dry and windy period. Satellite-derived precipitable water imagery reflects this and shows a large area of very dry air moving in from the east (less than 1″ PWs). Winds will be particularly strong near mountain tops and ridges, through gaps in the terrain, and in areas normally exposed in the trade wind directions. As a result, a Wind Advisory has been issued covering portions of each island. A band of moisture leftover from an old boundary far northeast of the state is forecast to move through the islands tonight into Monday, which will support better shower coverage for windward and mauka locations.
Trade winds will begin to ease late Monday through midweek as an upper low moves in from the east and the gradient begins to relax. A slight increase in moisture combined with a higher inversion height should correlate to better windward shower coverage. Extended guidance suggests the low-level flow will shift out of the east-southeast Wednesday into the second half of the week, allowing a land and sea breeze regime to become established. If this evolves, afternoon cloud build-ups along with a few showers will become a possibility over our leeward areas where drought conditions continue.

Aviation

Breezy to locally strong trade winds continue through the forecast period so AIRMET Tango for lee turbulence remains in effect.
Increasing stability and a drier airmass should help to limit cloud and shower coverage today. Expect mainly VFR conditions, with occasional MVFR cigs possible trough the morning hours.

Marine

High pressure building far north of the state will keep strong trades in place today. The trades will then gradually ease tonight through Tuesday, with only light winds expected Wednesday and Thursday. A Small Craft Advisory (SCA) remains in effect for all Hawaiian waters today, and for the typically windy waters around Maui and the Big Island through 6 PM Monday.
A pair of overlapping south swells will keep south shore surf near the summertime average through Tuesday. Only small background south swells are then expected Wednesday through next weekend, keeping surf well below normal along south facing shores.
Surf along east facing shores will hold steady through Tuesday due to strong trades over and upstream of the islands. The trade wind swell will lower Wednesday and remain well below normal through next weekend. Distant tropical activity in the eastern Pacific may send a small, long-period east swell through the islands Wednesday through Friday, giving a slight boost to east shore surf.

Fire weather

Dry and gusty trade wind conditions are expected today, which has led to the issuance of a Red Flag Warning for all leeward areas. Diminishing trade winds along with increasing moisture are anticipated through the first half of the week.

HFO Watches/Warnings/Advisories

Red Flag Warning until 6 PM HST this evening for Niihau, Kauai Leeward, Oahu South Shore, Waianae Coast, Olomana, Molokai Leeward, Lanai Makai, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, South Big Island, Kohala, Big Island Interior.
Wind Advisory until 6 PM HST this evening for Waianae Coast, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Leeward West, Kohala, Kauai South, East Honolulu, Honolulu Metro, Koolau Leeward, Molokai Leeward South, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Big Island South, Big Island Southeast, Big Island North.
Small Craft Advisory until 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov