Photo Credit: James Grenz

Hilo

Today: Mostly cloudy with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 84 near the shore to around 73 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then frequent showers after midnight. Lows around 69 near the shore to around 53 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 90 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 69 to 74 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 82 to 89 near the shore to around 71 near 5000 feet. South winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 71 to 76 near the shore to around 54 near 5000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.

Monday: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Waimea

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 83 near the shore to 71 to 81 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 68 near the shore to 56 to 61 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Kohala

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 83 near the shore to 71 to 81 near 3000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then numerous showers after midnight. Lows around 68 near the shore to 56 to 61 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Monday: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

South Big Island

Today: Mostly sunny. Windy. Highs around 87 near the shore to around 75 near 5000 feet. East winds up to 30 mph increasing to 10 to 30 mph in the afternoon.

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 67 to 75 near the shore to around 52 near 5000 feet. Northeast winds up to 25 mph becoming 10 to 15 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 86 near the shore to around 73 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 84 near the shore to around 73 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then frequent showers after midnight. Lows around 69 near the shore to around 53 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 90 percent.

Monday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 69 to 74 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Windy. Highs around 87 near the shore to 72 to 78 above 4000 feet. Northeast winds up to 30 mph.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 71 to 76 near the shore to 50 to 57 above 4000 feet. East winds up to 25 mph. Gusts up to 45 mph in the evening. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 86 near the shore to 70 to 76 above 4000 feet. Northeast winds up to 15 mph increasing to up to 25 mph in the afternoon. 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