Hilo

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 62 to 71 near the shore to 52 to 58 at 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 78 to 83 near the shore to around 66 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 61 to 69 near the shore to 51 to 58 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy after midnight. Lows 70 to 75 near the shore to 49 to 54 near 5000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Sunday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 83 to 88 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Sunday Night: Partly cloudy. Isolated showers in the evening. Lows 69 to 74 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny with isolated showers. Highs around 79 near the shore to 68 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 61 to 71 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly sunny with isolated showers. Highs around 79 near the shore to 68 to 78 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Sunday Night: Partly cloudy with isolated showers. Lows 61 to 71 near the shore to 55 to 62 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 74 near the shore to around 55 near 5000 feet. Northeast 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 afternoon. Highs around 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Sunday Night: Mostly clear. Lows around 74 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 62 to 71 near the shore to 52 to 58 at 4000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers. Highs 78 to 83 near the shore to around 66 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows 61 to 69 near the shore to 51 to 58 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 73 near the shore to around 53 above 4000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Scattered showers in the afternoon. Highs around 85 near the shore to 65 to 72 above 4000 feet. Northeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.

Sunday Night: Mostly clear. Lows around 73 near the shore to around 53 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Moderate trade winds will persist through the rest of the weekend and into the first half of the week. Showers will remain focused primarily over windward and mauka areas. An upper-level trough will move nearby on Sunday, which could briefly enhance shower coverage. Shower chances will then decrease through the first half of the week, before potentially increasing again near the Thanksgiving holiday.

Discussion

Locally breezy easterly trade winds that have prevailed over the past couple of days will decrease in intensity to moderate speeds this evening, then persist at moderate speeds through the first half of the week as a broad area of high pressure far northeast of the state slightly weakens and drifts eastward. Meanwhile, latest satellite and radar imagery shows that most low clouds and showers are favoring windward areas, in addition to the typical afternoon cloud buildups and showers along the Kona slopes of the Big Island. Notably, however, the slightly east-southeast flow today has resulted in some showers spilling into traditionally leeward locations at times, such as portions of Honolulu.
Latest model guidance shows a quick moving upper-level trough passing over the islands late tonight through Sunday. This will serve to briefly introduce instability into the region, though is not expected to have a significant impact on weather across the islands. With that said, it could trigger a few afternoon showers on Sunday across some leeward and interior areas, as well as increase cloud coverage throughout the day.
Following this upper-level trough, weak ridging will build back into the area, maintaining moderate trades through much of the week. Showers will generally favor windward and mauka sections of the islands throughout this time, though pockets of drier air will move into the region throughout the week creating small day-to- day variations in windward and mauka shower coverage.
Later in the week, model guidance shows another upper-level trough making its way across the region, though there remain significant timing differences (for example, the ECMWF offers an earlier, quicker solution than the latest GFS). Initial indications are that impacts will be limited with this upper trough as well, though confidence remains low at this time.

Aviation

Moderate trades have given rise to expanding sea breezes this afternoon and winds veering to ESE over coastal sections of Leeward Oahu. With little to no change in the background gradient, a similar outcome can be expected for Sunday. Trades deliver clouds and limited showers windward and mauka through the period. Isolated MVFR will be possible, but VFR prevails.

Marine

High pressure far northeast of Hawaii will weaken and drift to the east through tonight, leading to a decrease in trade winds. Gentle to locally fresh trades will prevail Sunday through Thursday as a surface ridge sits several hundred miles north of the islands. The Small Craft Advisory (SCA) has been cancelled for the typically windy waters around the Big Island and Maui, though winds in these areas will be at borderline SCA strength into Monday. Easterly winds across all waters will be slightly weaker on Tuesday as the ridge to the north is disrupted by a passing North Pacific front.
A series of large northwest swells will produce periods of elevated surf this week. Forerunners of the latest swell from 310 to 320 degrees arrived at NOAA buoy 51001 around midnight and peaked a couple of feet above guidance at around 9 feet 16 seconds this morning. Surf will continue to rise and will peak well above the High Surf Advisory (HSA) level along north and exposed west facing shores from Kauai to Maui late this afternoon and evening. Surf will begin a slow decline late tonight and should drop below HSA levels by Sunday afternoon. North shore surf will be well below seasonal average by Monday, and the swell will fade as it shifts out of the north-northwest on Tuesday. A potentially larger northwest swell is expected to arrive Wednesday and peak into Thanksgiving day. This swell will decline Friday and Saturday, though there are high odds for a larger west- northwest swell later next weekend.
As trade winds drop a notch over the next couple of days, surf along east facing shores will decline and will be well below seasonal average through much the coming week. A small south- southeast swell will fade on Sunday, and south shore surf will be tiny through much of the week.

Fire weather

Critical fire weather conditions are not expected throughout the next few days as trade winds trend slightly downward. Relative humidity levels could briefly decrease early in the week as pockets of drier air move through, but wind speeds are expected to stay below critical thresholds.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Sunday for north and west facing shores of Niihau, Kauai, Oahu, and Molokai, and for north facing shores of Maui.

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Data Courtesy of NOAA.gov